Generating energy from ocean waters off Hawaii

This seems like an interesting idea, the feasibility may drop with scale though.

Average ocean temperature differences (at water depths of between 20 meters and 1000 meters depths) around the main Hawaiian Islands for the period July 1, 2007, through June 30, 2009, (the color palette is from 18°C to 24°C); the relatively more favorable area in the lee of the islands is clearly visible. Credit: Data from HYCOM (an academia-industry consortium, see: http://www.hycom.org/ and NCODA, public data from the U.S. Navy, see: https://www.fnmoc.navy.mil/public/. Image provided by Gerard Nihous.

College Park, MD (August 3, 2010) — Researchers at the University of Hawaii at Manoa say that the Leeward side of Hawaiian Islands may be ideal for future ocean-based renewable energy plants that would use seawater from the oceans’ depths to drive massive heat engines and produce steady amounts of renewable energy.

The technology, referred to as Ocean Thermal Energy Conversion (OTEC), is described in the Journal of Renewable and Sustainable Energy, which is published by the American Institute of Physics (AIP).

It involves placing a heat engine between warm water collected at the ocean’s surface and cold water pumped from the deep ocean. Like a ball rolling downhill, heat flows from the warm reservoir to the cool one. The greater the temperature difference, the stronger the flow of heat that can be used to do useful work such as spinning a turbine and generating electricity.

The history of OTEC dates back more than a half century. However, the technology has never taken off — largely because of the relatively low cost of oil and other fossil fuels. But if there are any places on Earth where large OTEC facilities would be most cost competitive, it is where the ocean temperature differentials are the greatest.

An example of early OTEC field work in Hawaii: aerial view of the land-based experimental open-cycle OTEC plant that operated between 1993 and 1998 on the Big Island. The facility still holds the world record for OTEC power production, with turbo-generator output exceeding 250 kW and more than 100 kW of net power exported to the grid. Credit: Luis Vega

Analyzing data from the National Oceanic and Atmospheric Administration’s National Oceanographic Data Center, the University of Hawaii’s Gérard Nihous says that the warm-cold temperature differential is about one degree Celsius greater on the leeward (western) side of the Hawaiian Islands than that on the windward (eastern) side.

This small difference translates to 15 percent more power for an OTEC plant, says Nihous, whose theoretical work focuses on driving down cost and increasing efficiency of future facilities, the biggest hurdles to bringing the technology to the mainstream.

“Testing that was done in the 1980s clearly demonstrates the feasibility of this technology,” he says. “Now it’s just a matter of paying for it.”

###

More information in the project, see: http://hinmrec.hnei.hawaii.edu/ongoing-projects/otec-thermal-resource/

The article, “Mapping available Ocean Thermal Energy Conversion resources around the main Hawaiian Islands with state-of-the-art tools” by Gérard C. Nihous will appear in the Journal of Renewable and Sustainable Energy. See: http://jrse.aip.org/jrsebh/v2/i4/p043104_s1

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120 thoughts on “Generating energy from ocean waters off Hawaii

  1. It’ll work but it’s going to suck energy from the oceans and put it into the machinery and the atmosphere. Then what?

  2. those with an interest in Ocean Thermal Energy might find this story from Amerian Heritage Invention and Technology interesting.
    http://www.americanheritage.com/articles/magazine/it/2009/4/2009_4_24.shtml
    “Sixty miles east of Havana, along Cuba’s north coast, swimmers and skin divers like to gather at a squarish pit filled with lovely aquamarine water, hewn into the rugged basalt just off Matanzas Bay. From a distance it has the look of a Stone Age swimming pool, until one sees electrical wires protruding from aged concrete.
    This is the sole remnant of a power plant built by a French inventor so far ahead of his time that his time still has not arrived: the proud and prolific Georges Claude, known as “the Edison of France” for his breakthrough developments of neon lights, industrial gases, and synthetic ammonia. But it was on this gouged reef that his fortune began to founder. Cubans still regard him as the father of ocean thermal power—a process of harnessing energy from the sea—and mark this spot as its birthplace. If so, the child has been a long time aborning. No ocean thermal plants of commercial scale have been built, and the power output from the scattering of pilot plants to date could be exceeded by firing up the generators at a single big-box home improvement store. Still, today’s volatile mix of energy politics and economics is stirring long-dormant hopes among the faithful.”

  3. The greater the temperature difference, the stronger the flow of heat that can be used to do useful work such as spinning a turbine and generating electricity… or pumping cold water up from the ocean floor?

  4. Wouldn’t it make much more sense to tap the geothermal energy of the hotspot, than minor variances in the sea temperature. How hard would it be to drill to a depth where the temperature would superheat steam, explode a device to create a chamber, run some piping to a turbine and bada bing, clean green energy.

  5. this is beyond old news … studied this in the ’70’s at the Naval Academy … it just doesn’t scale up to real power … the better technology combines waves and wind turbines with ships … think of it like this … ship with large holes/columns open to the sea … as waves pass by the ship at anchor the water in these columns rises and falls … wind turbines at the top of the columns generate power on both the upstroke and the downstroke … simple, workable and buildable … though not sure if it will ever compete with gas and coal on price …

  6. Another “grant” black hole. This is not a project that is going to deliver ‘cheap’ energy to the peoples of Outer Mongolia.
    If the efforts and finical resources, were deployed in research to obtain ‘economical energy’ like a ‘ no cost additive’ to water to produce electricity then 99.9% of the worlds lights could stay switched on 24 hours a day, now who is going to be the first to write a patient on this ? Any Static?

  7. They need to do an environmental impact study on the little critters that live down in the deep part of the ocean. Heck, one of them might be a snail darter or something. But more seriously, this has always been tomorrow’s next big thing in renewable energy. I suspect the status will not change.

  8. Thanks for the great picture. It appears the windward side of the island has much cooler waters. Since they claim all warming is from man made CO2, that set of islands must really be cranking out CO2 to warm the water so much.

  9. Sounds like a very good idea. Also, transferring heat to the bottom of the ocean should stir up nutrients via convection and help feed marine life.

  10. However, the technology has never taken off — largely because of the relatively low cost of oil and other fossil fuels
    “Now it’s just a matter of paying for it.”
    ============================================================
    So it’s going to cost more……
    At least pumping nutrient rich water up to the surface will fuel more phytoplankton, which will consume more CO2.
    Wonder if any of these things really work, and what would happen if we really did them and lowered CO2 levels too low.

  11. A Carnot engine is the best that you can do in terms of classical heat engine efficiency. The maximum possible efficiency = (T1 – T0)/T1, where T1 is inlet temperature and T0 is outlet temperature, in degrees Kelvin.
    Here, we have
    T1 = 24 C = 297 K
    T0 = 18 C = 291 K
    Carnot efficiency = (297 – 291)/297 = 2.02%. The best you can do is extract 2% of the total energy represented by the temperature difference between two volumes of water.
    If we increase the temperature difference by 1 C (=1 K), then the efficiency increases to 2.34%. That is an increase in efficiency of about 15%, like the article says. The reason 1 C helps so much is that you are starting with soooo little.
    You can try to make up for the crappy efficiency by increasing the flow. But that, of course, requires much more energy to move all that water.

  12. Since they claim all warming is from man made CO2, that set of islands must really be cranking out CO2 to warm the water so much.

    I think you’ll find that some of that warming is caused by a lovely lady called Pele.

  13. Back in the ’60s, Analog SF had a story about such a generator. It seems it was torn up by a large squid. A very large squid.
    It’s not a reasonable way to generate large quantities of power. Some form of fission is the only real way to provide long term, cost effective power. Oil will become too valuable in the future to burn. At that point, we’ll see lots of fission plants, but not until then.

  14. This is a simple Carnot cycle engine. The theoretical (maximum) efficiency is given by:
    eff = 1- (Tc/Th)
    where Tc is the cold temperature (Kelvin) and Th is the hot temperature (also Kelvin).
    So the best thermal efficiency (extracted energy compared to energy moved from the hot to the cold reservoir) is about 1 – (277/301) = ~8%. Take into account the energy needed to pump all that water around, and the inevitable less-than-theoretical efficiency of any real Carnot engine, plus the losses in conversion of mechanical energy to electricity, and it becomes clear that this whole enterprise is unlikely to be economically useful. Enormous capital investment is required, and very little energy is produced. Heck , the concept has been studied to death already; it was and is an economic loser.
    Does provide nice funding grants for professors and their staffs though…

  15. So testing in the 80s shows the feasibility; “now it’s just a matter of paying for it.” If it doesn’t soon pay for itself, in what way is it feasible? It sounds more expensive than conventional (fossil-fuel) generation; hence, not feasible.

  16. I fear ShrNfr is close to the truth on the EIS problem. Seems all the alternative energy ideas end up either uneconomical or un-approvable due to enviro issues.
    While not energy related, the enviros in the NW lobbied against rainwater harvesting when the legislature tried to reconcile this with the Washington Water Code. Their issue? It would allow folks to build a home in areas where groundwater or surface water could not supply domestic needs.
    Similarly, the enviros in forever green state oppose aquifer storage and heat pump technologies. Storage because they believe that drinking quality water “might” negatively alter the chemistry of groundwater. Heat pumps because the change in groundwater temperature “might” harm groundwater bacteria.
    What the enviros fail to comprehend (or perhaps understand all too well) is that any human activity affects the environment. The only way to eliminate human impacts on the environment is to eliminate humans (again, this may be their goal).

  17. “Testing that was done in the 1980s clearly demonstrates the feasibility of this technology,” he says. “Now it’s just a matter of paying for it.”
    ________________________
    Here we go again! Money! Money! Money! It’s always about Money!
    Someone needs to hold a Press Conference and tell the President and Congress that there ain’t no more money!
    We’re broke! Busted! Up to our keesters in debt! We’re where the Brits were in 1945.
    Maybe we can “Lend-Lease” Hawaii and Alaska to the Chinese for 99 years with an option to renew.
    Think we can do the same with the Mexican and Cloumbian Drug Pushers? Texas and California to Mexico and Florida and New York to the Columbian Mob? Hay! I think it just might work!

  18. The trouble with the world is that scientists and engineers are not economists. We love to tackle an engineering challenge but are reluctant to face the annoying truth that many things are not cost effective.

  19. Well, I guess this should work, although how much it will cost doesn’t really bear thinking about.
    Here in the UK the BBC is droning on about the latest gee whizz “renewable energy scheme”, harnessing wave power.
    http://www.bbc.co.uk/news/uk-england-cornwall-10808260
    technical details at:-
    http://www.southwestrda.org.uk/working_for_the_region/areas/cornwall__the_isles_of_scilly/wave_hub/documents1.aspx
    So that looks like £43.5 Million of taxpayers’ money. And counting.
    And, without wishing to be a grouch, isn’t wave power going to suffer the same problems as wind power? Have they not heard of calm seas?
    Meanwhile, we have some of the biggest tidal ranges in the world. There has been talk of building a tidal barrage across the Severn estuary for at least 60 years. And anyone can predict when high and low tide is, even 90 years from now. Which is more than anyone can say about climate predictions (or even weather forecasts for more than a few days ahead). But, of course, the Greenies and amateur bunny huggers won’t hear of the idea.
    But it’s nice to know that “An independent economic impact assessment has estimated the £42m project could create about 1,800 jobs and inject £560m into the UK economy over the next 25 years.”
    Yeah. Right. And I could get to be Pope next month.
    But this Wave Hub is rated to produce a stonking 20MW. Presumably if the sea is rough enough. £43.5 million to produce 20MW. Hmmmmmmm.

  20. There being No Free Lunch, pumping and moving the massive quantities of cold water to the surface, and altering temperatures in general, that would be required to produce the energies needed, neglecting the whole problem of transporting the energy to WHERE it is needed, would probably invoke The Law of Unintended Consequences, altering aspects of the oceans that would affect other features.
    Just like large scale wind and solar energy, the best sources of these intermittent (and, thus, inferior) energy sources are not where they are needed, yielding them even more inferior for industry.
    Wind and solar are going to be most useful at the smaller scales, where homes can use current technology to lower their draw from the grid, freeing up more power for industrial purposes and lowering the need for more.

  21. You can try to make up for the crappy efficiency by increasing the flow. But that, of course, requires much more energy to move all that water. chris y
    Here’s a way to generate fresh water and power at the same time:
    Take a large vertical tube and mount it vertically in the ocean. It should be long enough to reach substantially cooler water and wide enough to allow for a large water vapor flow. Mount a turbine generator in it. Evacuate all the air from the tube. Allow warm water from the surface to evaporate at low pressure in the tube (allow for the resulting brine to fall out) thereby driving the turbine and condensing at the bottom of the tube as fresh water. Pump out the fresh water with power from the turbine. Sell remaining power and fresh water.

  22. Another ill advised attempt to tap diffuse sources of energy. As has been pointed out above, the 2nd Law will eat your lunch. How? Large capital investments would be needed to get the power. It is always capital investment dollars per watt that count.

  23. chris y says:
    August 4, 2010 at 8:21 am

    A Carnot engine is the best that you can do in terms of classical heat engine efficiency. The maximum possible efficiency = (T1 – T0)/T1, where T1 is inlet temperature and T0 is outlet temperature, in degrees Kelvin.
    Here, we have
    T1 = 24 C = 297 K
    T0 = 18 C = 291 K
    Carnot efficiency = (297 – 291)/297 = 2.02%. The best you can do is extract 2% of the total energy represented by the temperature difference between two volumes of water.

    You misread the caption. The temperatures are not sea surface, they are the difference between near-surface and 1000m. If the surface temp is 300 kelvins, and the 20 kelvins less at 1000m, then your equation is (300-280)/300, or some 6.6%.
    Note also you’re moving water 1000m, not hundreds of Km!
    I’ve long thought one could do well with air conditioning by running a coolant loop up the side of someplace like Mt. Washington. Cool it at the top to ambient air temp (20-30F cooler than at the base), use as cooling at the bottom, perhaps augmented with a heat pump, circulate warm coolant uphill. I don’t know the fluid drag formulae, but if you could circulate the coolant just by thermal expansion and gravity, so much the better!

  24. if the warm water was available on the seabed there MIGHT be something to all of this. but i’d like to call attention to the law of conservation of energy. unless someone changed the rules recently the amount of energy required to move the water MUST be greater than the energy produced

  25. Wouldn’t it be better to get all the energy saved in that dreamland CO2 heat piggy bank in the tropical atmosphere of the recent fallen angel Al Baby?

  26. Jeff says:
    this is beyond old news … studied this in the ’70′s at the Naval Academy … it just doesn’t scale up to real power …
    I worked on this in 1975 a few miles from the US Naval Academy, and yes, Hawaii was the best location. In addition to Jeff’s comments about scalability, a fatal problem was the marine fouling of the enormous heat exchangers. It used low pressure anhydrous ammonia as the working fluid. Of course the capital investment only makes sense if Obama can carry out his campaign promise of making electricity prices “skyrocket”.

  27. Why not making a big, big, transparent crystal box, fill it with heat absorbing CO2 and utilize that “gigantic” source of energy?
    It could power a big, big, diapers’ factory to cover the increasing market of bedwetters.

  28. Great idea, but limited scope to change the global energy profile, even if a large scale system worked. There are simply not enough places on land with deep water close by.
    Fusion is the only practical approach to achieving cheap, clean energy. It is a travesty that governments around the world are not putting more money and effort into this.

  29. re Rick Werme- “You misread the caption. The temperatures are not sea surface, they are the difference between near-surface and 1000m. ”
    Yep, thanks for pointing out my error. It looks like delta T = 24 C max, and assume T0=4 C = 277K, so as Steve Kirkpatrick points out, the efficiency is maximum 6.7%. But then, increasing the delta T by 1 C only improves the efficiency to maximum 7%, a 5% improvement and a smaller increase than 15% that the article claims.
    “Note also you’re moving water 1000m, not hundreds of Km!”
    It needs to be lifted vertically by 1000 m, through a pipe having frictional losses. The energy needed for this cannot be dismissed compared to the energy produced by the heat engine.
    “I’ve long thought one could do well with air conditioning by running a coolant loop up the side of someplace like Mt. Washington.”
    Same problem- energy needed to move cooling fluid, compared to energy use avoided by relying on low ambient temperature at the top of the mountain.

  30. Take into account the energy needed to pump all that water around,
    Bingo! Unless the heat differential is HUGE, I doubt this will be cost effective.
    And here’s a thought…. If it’s heat you want? Hell, we’re talking about Hawaii…. Volcanoes anyone????
    Note: There is a reason why Geothermal has never taken off. My understanding from my days as a geology student is that the steam produced by geothermal vents tends to be very corrosive, which both eats away at critical components, and mineral rich, which also deposits on those components, sulfur being the obvious example.

  31. Steve Fitzpatrick says: “…So the best thermal efficiency (extracted energy compared to energy moved from the hot to the cold reservoir) is about 1 – (277/301) = ~8%. Take into account the energy needed to pump all that water around, and the inevitable less-than-theoretical efficiency of any real Carnot engine, plus the losses in conversion of mechanical energy to electricity, and it becomes clear that this whole enterprise is unlikely to be economically useful….”
    Spoilsport.

  32. This seems to be a rather complex way to do things. Especially on a volcanic island with active volcanos (one of which is the most active on the planet.)
    If extracting power from Kilauea is too difficult Mauna Kea is dormant and snow capped.
    So the temperature difference available is at least 100C, far more than you could get from water out of the Pacific.
    Also suitable geothermal power will enable electricity generation using conventional steam turbines. To keep the AGW lot happy it can even be declared “carbon neutral” 🙂

  33. I’m sure there’s some tipping point or other involved with sucking heat out of the oceans.

  34. It’s a boondoggle. At one point, Natural Energy Laboratory of Hawaii was using the cool deep water to cool soil to grow strawberries on the hot coast, although the world’s finest land for growing strawberries already existed a few miles inland (and upland) at Waimea.
    If it weren’t for Sen. Dan Inouye, this joke would never have come into being, and when he leaves the Senate, it will go back to being what it used to be, a shelf of hot, bare lava rock.

  35. I visited the http://www.nelha.org/ site on the big island on vacation about 3 years ago (that IS why you go on vacation, right?). The site just provides and disposes of the ocean water. They have a couple of large pipes going down deep, and several at intermediate depths. They lease space to tenants that wish to make use of the water. They had an algea grower, a bottled water company (yes, they take the very pure deep ocean water, filter out the salt and sell it for big bucks), and someone experimenting with concentrated solar power when I was there. They talked about having a bid from someone to put in a power plant.
    They have a very nice (million dollar) visitors building that is covered with solar cells and cooled by the deep ocean water. They have regular talks there for visitors (call first).
    The docent giving the talk said some interesting things:
    1. This is salt water, so it really eats up whatever machinery you put in place. The test plant of years ago rotted out pretty fast.
    2. You have to build BIG to get any real power out of it. ($$$)
    3. The geothermal power being generated down in Puna has a lot of potential (I think far more). http://www.punageothermalventure.com/
    4. They don’t release the deep, mineral-rich water to the surface. That would change the costal echosystem, so the re-release the water at various depths, depending on it’s final temperature.

  36. I’m as big a curmudgeon about “sustainable” energy as anyone, but I’ve always been fascinated by OTEC. As one commenter noted, it can produce saleable byproducts such as fresh water along with electricity. One ingenious scheme floated a few decades ago was to produce ammonia on OTEC barges, with the low-pressure, heat differential turbine providing the electrical power. But the ultimate price competitor for electricity production is always going to be coal, and it’s hard to see how any sustainable source will ever be able to beat it.

  37. “”” chris y says:
    August 4, 2010 at 8:21 am
    A Carnot engine is the best that you can do in terms of classical heat engine efficiency. “””
    HOORAY !!!
    Finally somebody sane does some real scientific thinking.
    Chris why don’t you ask those dummies for a piece of their research grant ?
    Unless somebody imagines that sea water can actually “focus” solar energy; as in compact it into a smaller space than it arrived in; we can presume that the input to this heat engine is less than 1 kWatt/m^2; then throw in your Carnot efficiency on top of that and you have a real fizzer as far as fireworks go.
    SPACE COSTS MONEY !! EFFICIENCY IS EVERYTHING !!
    Chris the same pestilence (Carnot Efficiency) plagues the wind energy idea. A wind generator is a gas tubine engine; with air being the working fluid, and the sun being the source of “heat” energy to raise the kinetic energy of the working fluid, and its Temperature to feed to the output turbine wheel (propellor) to convert it to shaft horsepower and thence to electricity by way of a conventional alternator or other generator. The working fluid comes in over a vast space from some solar heated hot place; often over the ocean, and the cooler exhaust gas must be discarded to some vast cooler exhaust space.
    Any sturctures in the way of the working fluid intake; or the exhaust fluid outflow, will create turbulence and spoil the flow pattern and turbine blade efficiency.
    So if you think that a simple wind turbine just takes up a quarter acre or so; you are in need of a serious attitude adjustment.
    And this Hawaii boon doggle is the same darn thing.
    Yes there’s a vast amount of energy in the system. Don’t people ever consider how much of that energy is available to recovery.
    I was reading down to see if anyone at all had caught the Carnot Trap; because I was going to post it; if you hadn’t already Chris.

  38. “…one degree Celsius greater on the leeward (western) side of the Hawaiian Islands than that on the windward (eastern) side.
    This small difference translates to 15 percent more power for an OTEC plant…”
    ___
    Would someone please explain to me how this could be physically possible.
    Was Carnot truly wrong for all these years?

  39. Interesting. Drawbacks include corrosive effects of seawater, similar to why geothermal is so hard and expensive. Assuming more efficient engineering and materials in the 21st century another reason OTEC might actually be a good idea in this particular instance and actually economical is the very high price of oil, etc. in Hawaii. These schemes are best tried out where the cost of energy is highest.

  40. from OP:

    This small difference translates to 15 percent more power for an OTEC plant, says Nihous, whose theoretical work focuses on driving down cost and increasing efficiency of future facilities, the biggest hurdles to bringing the technology to the mainstream.

    This is one of those instances where 15% of almost zero is still almost zero. It needs a lot more heat differential than the ocean can provide except perhaps from thermal vents. Heat engines have been of interest to many inventors for nearly 200 years and counting since Carnot came up with the Carnot Heat Cycle. Every conceivable way of extracting power from small temperature differentials less than about 250F has been tried and found greatly wanting.
    The source of cooling water is nice if they use solar to heat the water up to 500 degrees or more to run steam turbines but that’s about it. A small scale (large but not commercially large) experimental site is still struggling to attain modest efficiency in a Stirling engine in a SW US desert where they have relatively little problem getting nice fat temperature differentials from solar heated hot water.

  41. “”” chris y says:
    August 4, 2010 at 10:26 am
    re Rick Werme- “You misread the caption. The temperatures are not sea surface, they are the difference between near-surface and 1000m. ”
    Yep, thanks for pointing out my error. It looks like delta T = 24 C max, and assume T0=4 C = 277K, so as Steve Kirkpatrick points out, the efficiency is maximum 6.7%. But then, increasing the delta T by 1 C only improves the efficiency to maximum 7%, a 5% improvement and a smaller increase than 15% that the article claims. “””
    The numbers were wrong (I never even bothered to read them) but your conclusion Chris was correct.
    Carnot inneficiency kills this idea.
    Anybody who thinks a 6-7 % efficiency is viable just hasn’t ever bought any real estate.
    A serious large scale PV solar project proposed for the Desert SouthWest “wastelands” of the USA in Jan 2008 issue of Scientific American took up just 30,000 square miles for soalr cells; that’s 19.2 million acres; which just coincidently is the exact size of the entire arctic National Wild life Refuge.
    So the Evil Fossil Fuel Barons wanted to drill on 2400 acres of ANWR for their filthy petroleum; about the size of The Great Mall of America Shopping Center in San Jose CA ; and the solar cell gurus want to put their 20% conversion efficiency solar cells over the whole 19.2 million acres near the four corners region; plus another 10l.24 million acres for a solar steam farm of mirrors.
    Now comes the Polynesian Luau with its 6-7% Carnot efficiency.
    Now who was it that claimed that this machine even achieves anything near Carnot efficiency, with whatever heat engine cycle they are planning to run; so I would discount that 6-7%
    Now how about the heat losses fromt that column of water that they are planning on raising 1000 metres. How do they propose to thermally insulate all that 1 km of pipe to stop losing what little energy they have .
    And probably my tax dollars went into this silliness.
    Yes by all means give some private investors permission to build the darn thing and reap their just rewards; but don’t ask me to invest in their company.

  42. Wouldn’t the work needed to bring the warm and cold water together negate the energy derived from allowing them to exchange heat?

  43. Wait till they find out the realities of engineering: the ocean is a corrosive, fickle biatch that likes to tear anything Man makes apart. Trying to keep something together long enough to make it pay off is NOT EASY.
    …..but hey for the greenies it’s easy to just make up stuff that never works in the real world….

  44. What about all of those lovely Hydrogen and Deuterium atoms, swimming around, not doing any work.

  45. Marshal T Savage’s “The Millennial Project:colonizing the galaxy in eight easy steps” outlines using OTECs on a massive scale. He mentions that water having neutral buoyancy only needs to overcome the difference in density so pumping massive quantities up a vertical pipe is not as difficult as may seem (unless you find a 12m diameter pipe going down 1000m difficult!) He naturally picked equatorial locations to maximize delta T. His best delta T location was Sri Lanka if I recall.
    “The Millennial Project” would certainly appeal to many WUWT readers though, a fun blend of engineering and speculation. A good read on a cold winter’s evening!

  46. Steve W. says:
    August 4, 2010 at 11:02 am
    1. This is salt water, so it really eats up whatever machinery you put in place. The test plant of years ago rotted out pretty fast.

    Spot on. I fail to understand the fascination of placing machinery in the most corrosive environment the planet has to offer. Ask any boat owner about maintenance – that’s why they’re called boats – Break Out Another Thousand.
    Tidal, wave and offshore wind may be attractive from the planning point of view but as a potential shareholder (electricity customer), I am horrified when I think of the maintenance costs. After a number of years these begin to look like the usual portrayal of the CO2 graph.

  47. “and the solar cell gurus want to put their 20% conversion efficiency solar cells”
    Last I checked an affordable 20% efficient solar cell is still a wet dream. Seems I recall 14% in modestly expensive thin film is about as good as it gets and have an expected service life of 20 years or so. Advances in manufacturing and economy of scale are hoped to halve the price in tens years or so and then make some economic sense in large installations.
    Keep in mind distribution costs are sky high for power coming from a remote desert and you have significant transmission losses. For a home installation with net metering where distribution is already taken care of it’s looking practical or can easily be made practical with some modest advances in economy of scale in the hardware. Displacing a significant amount of transportation fuel with electricity is still a pipe dream due to, among other things, no grid anywhere near able to carry the additional load. We get big brownouts now all over the country during periods of peak demand. No way it can move more juice without serious expansion. Just imagine how much everyone is going to love more high tension transmission lines going over their homes and schools and way more substations filled with big buzzing transformers.

  48. Besides corrosion, one of the early problems NELHA had was that the pipes are so big they provided space for their own ecosystems.
    The environmentalists had to figure out how to kill many innocent sea critters just to keep the water flowing.

  49. Dave A says:
    August 4, 2010 at 12:37 pm
    He mentions that water having neutral buoyancy only needs to overcome the difference in density so pumping massive quantities up a vertical pipe is not as difficult as may seem (unless you find a 12m diameter pipe going down 1000m difficult!)

    Two pipes with venturi foot valve. Called a jet pump. Water goes down one pipe and suction generated by a venturi brings a greater volume up the other pipe. No electrical lines or underwater motors involved. Rather common method in water wells and surface water pumping.
    The pipes, per se, aren’t the problem. They have to be well insulated pipes to preserve as much temperature differential as possible. Nobody usually cares about temperature change in normal well pump operations.

  50. Let’s not confuse thermal efficiency with economic efficiency. If I can build a process that ends up producing power at a levelized cost of $0.05/kWh over a 20 year period, I build the thing regardless of its Carnot efficiency, which in and of itself is a contextless number.
    Let’s compare two fairly well known scenarios. A coal fired power plant and a natural gas in combined cycle plant. The capital to build a 100MW plant is less for the natural gas plant and the efficiency of the natural gas plant is considerably higher, yet the cheaper power will always be from coal. Why? Fuel costs. If you looked straight at efficiency here, you would wrongly come to the conclusion that natural gas power is cheaper.
    Using the 20% efficiency of solar cells is also a bit of red herring. It’s not the efficiency that does in the economic feasibility of a solar cell. It’s not even the land costs. It’s the capital tied up in solar cells collecting a low energy density source (sunlight). If you don’t believe me, think about this. A 1 KW system requires roughly 1 m^2 of space and costs $6K. That means to fill an acre with solar cells where only 50% of the land is occupied by the cells, it would cost $2.4 million dollars. That dwarfs the tens of thousand you are paying for the land. Even if you got 55% efficiency (in the natural gas combined cycle realm), it barely makes economic sense without subsidies.
    So what’s the biggest difference between the low energy density source (the ocean) and the other low energy density source (the sun)? You can control how much water flows through your energy production system. With the sun, it is what it is. So long as you can economically generate energy beyond the parasitic load of pumping the water, thermal efficiency matters not. In this case the metric that matters will be $/KW capacity installed (net of parasitic load.), not the thermal efficiency. Efficiency, while interesting, can never tell the whole story on its own.

  51. BTW… I did not mean to suggest with my previous post that $0.05/kWh was what this power would cost. I only used that number to demonstrate that I cared more about the levelized cost of producing the power than the actual efficiency in producing it. I have no actual knowledge as to what it would cost to build a large scale OTEC plant.

  52. Fusion is the only practical approach to achieving cheap, clean energy. It is a travesty that governments around the world are not putting more money and effort into this.

    Why ITER is a boondoggle. Billions of dollars, and ITER won’t achieve break-even even if successful.
    Polywell and Dense Plasma Focus Fusion have a chance, and they aren’t massive money sinks to find out. Polywell is adequately funded, and Focus Fusion has raised enough money privately to see if it’s workable.
    Note that only the aneutronic proton-Boron fuel cycle can really be called “clean”, unless you’re willing to disregard the neutron irradiated reactor parts.

  53. Friends:
    Several here have commented that this is not new. But the article and the comments miss some important points. The Hawaiian OTEC process does have economic potential but only in a very few geographical locations.
    The Pacific Institute in Hawaii perfected the technology for economic power from OTEC in the 1990s, but most of the product from their system is cold water (from deep ocean) with some (very small amount of ) electricity as a by-product. Using this cold water as a coolant for air conditionig would be cheeper than electricity for air conditioning (air conditioning is a major user of electricity in warm climates) .
    The system is only useable in locations with direct access to deep ocean (e.g. Hawaii and parts of the coast of India).
    So, the Hawaiian OTEC system could be very economic as a source of air conditioning and as a soil coolant for horticulture but only in the few places with direct access to deep ocean.
    Hence, in common with most other renewables, it has a potential niche market but lacks potential for use to displace the bulk of fossil fuel usage.
    Richard

  54. Just as a sciencey aside for home experimenters small air and water venturis for generating vacuums are less than $20. The water venturi is fast at drawing a vacuum and any old household tapwater source 30psi or more has enough pressure to drive them. The water venturi’s best vacuum is limited by the vaporization temperature of the water source. One you have a hard enough vacuum to hit vaporization point you’re sucking steam not water and have reached the limit. The colder the water source the better the vacuum. Air venturi’s have no such limit and will draw a substantially harder vacuum but they need a lot of air at 90psi or better. A small shop compressor with 2-3hp motor and 10 gallon air tank can’t keep up for long but will evacuate vessels up to a gallon or so in one or two minutes. The water venturi’s can be had from scientific supply houses. The air venturi’s are most economical purchased from hardware stores and are designed to evacuate water from air conditioner freon pumps & lines.
    One nifty little thing I made out of a couple rubber corks, copper tube, a water venturi, a hot air blow dryer (small handheld for drying hair), two wine bottles (one full of wine), and an ice bath. Basically connect the two bottles through the tube & corks and put the vacuum source on the empty bottle. Hot air gently heats the bottle filled with wine, alcohol vaporizes and passes into second bottle which is in the ice bath. First bottle is turned into non-alcoholic wine and second bottle ends up 100+ proof grape brandy that will burn nicely for flaming drinks, deserts, and so forth. Very low heat is the key to good flavor. The wine never gets above room temperature. The hot air dryer just replaces the latent heat of vaporization being carried away as the alcohol evaporates. By keeping the temperature low none of the heat sensitive taste & aroma components in the wine or the brandy are disturbed. Start to finish is about 10 minutes for a liter of wine. Whole setup costs about $25 in parts and a couple hours to make. Beer & wine homebrew stores have the right rubber corks (one with a single hole and one with two holes). Home Depot has everything else.

  55. “”” Dave Springer says:
    August 4, 2010 at 12:51 pm
    “and the solar cell gurus want to put their 20% conversion efficiency solar cells”
    Last I checked an affordable 20% efficient solar cell is still a wet dream. Seems I recall 14% in modestly expensive thin film is about as good as it gets and have an expected service life of 20 years or so. Advances in manufacturing and economy of scale are hoped to halve the price in tens years or so and then make some economic sense in large installations. “””
    Well Dave, I hear you Mate; I have some actual product literature ( commercially available panels) from Sun Power Syatems and they claim 22% efficiency.
    Now they don’t say whether that is an actual final assembled panel as installed operating solar to AC grid efficiency or whether it is Air Mass zero or one measured or what. They are so far as I know purely silicon cells; and likely not so-called Blue cells, since that would not seem to be useful for Air Mass one applications.
    I could almost buy that efficiency for a bare cell under lab ideal air mass zero conditions; but like you I am skeptical of such operational efficiency claims. There’s no reason teo expect a 20 year life limit. Like all semi-conductor devices they will have infant mortality failures; but with proper QA, they could easily exceed 20 years life.
    Fred Singer’s comment on the 30,000 squ mile thing was: “Who is going to clean 30,000 square miles of solar cells every now and then ?”
    Such a farm would have to fenced and patrolled by armed guards after removal of ALL human inhabitants; since it would be too much of a vandal/terrorist target.
    TJ Rodgers is nobody’s fool, and if anyone is going to have success in the solar cell business; Sunpower is a most likely candidate. Other schemes, which I won’t mention to save them and their “investors” including us poor sap taxpayers from embarrassment, have never made a dime, and aren’t going to make a dime, even after they run through their taxpayer funded loans.
    Stanford University announced just this week, a possible breakthrough that could make some solar cell farms viable.
    The big problem with PV cells is that they only convert a certain fraction of the solar spectrum because of their band-gap; and Silicon is the only economically viable choice. The rest of the solar spectrum and photon energy over the bandgap just becomes waste heat which raises the cell temperature; which drops the cell Voltage and lowers the efficiency.
    The Stanford scheme appears to deposit a spectrally selective reflective layer on top of the silicon to reflect almost all of the spectrum outside what the silicon can directly convert to electricity; so that greatly reduces cell heating adn keeps the efficiency up.
    But the panels now become efficient reflectors of the remainder of the soalr spectrum; so they can be oriented to reflect the sunlight on to a central tower and run a thermal collector steam turbine system. They claim they can reach 1100 deg (probably F).
    So this would work for the major plant concept; but even there they have a new problem.
    Those steam turbine plants require that almost ALL of the panels be tilted off the normal to the sun direction; since they must focus on an off-axis central collector. They all need to be steered through the day, which is a complication and control expense; given that the thing needs to withstand a 100 year storm; not to mention sand storms; but the off-axis Optics means that an even larger surface area of solar cells must be constructed, since only the are projected on the sun dirtection is collecting.
    They claim they can get about 60% total solar to electric power conversion efficiency from this combined PV/Thermal collector.
    But it is not your home rooftop solution.

  56. Oh, even cooler thing about the wine vaporizer described above is that once you have an initial vacuum in the empty wine bottle you no longer need the vacuum source running so it only uses a few gallons of tap water in the process. The volume of liquid alcohol coming out of the first bottle is exactly the volume the condenses in the ice bath bottle so, no net change in volume spells no net loss of initial vacuum. The connections are super easy to get vacuum tight. The vacuum pressure sucks the corks down into the bottles and compresses the rubber against the copper tubes – loosely set corks self-seal on their own recognizance.
    I love tinkering!

  57. Thanks for keeping this blog accessible for scientifically unsophisticated layman like me. I found this blog in July 2008 when I realized the the Sun was weaker working outside on my market gardens.
    I love this beautiful graphic. I grew up in Hawaii and always wondered why the North Shore beaches where colder than the Leeward beaches of Honolulu. I am very interested in understanding how the inner earth transmits heat to oceans and the impact this has for understanding and predicting climate. The recent gravitational variation map was sensational but unsure if it is useful in the measure of heat transfer from the mantle to the oceans. Is it possible this mesure will be useful in predicting future La Nina and El Nino months before they happen? Is it known to what degree the inner Earth heats it’s oceans. Do we know if there is a relationship between the Sun’s magnetic dynamic and the dynamics happening with in the inner earth that would explain changes ocean heating, regional variations in gravity, volcanism and earthquakes?

  58. “”” L. Bowser says:
    August 4, 2010 at 1:28 pm
    BTW… I did not mean to suggest with my previous post that $0.05/kWh was what this power would cost. I only used that number to demonstrate that I cared more about the levelized cost of producing the power than the actual efficiency in producing it. I have no actual knowledge as to what it would cost to build a large scale OTEC plant. “””
    Well then you care about something that is entirely of no consequence.
    The problerm of alternative energy schemes is NOT ECONOMIC ! If it WAS economic, then it could be solved with the stroke of a pen; as I have described elsewhere; simply place a tax of $1,000,000 per barrel equivalent on fossil fuels; and Voilla ! instantly your renewables are economically viable; whether they are 50 cents per Watt or $50 per Watt (peak power level); or $500 per Watt for that matter.
    But the problem is NOT economic; it is TECHNOLOGICAL. There are no alternative renewable energy schemes that are competitive technologically with fossil fuels; if they existed, they would already be in widespread use; and no amount of Governmental duck shoving could render them uneconomical.
    The fundamental real cost of any enterprise is the sum total of all of the energies it takes to arrive at the finished product.
    When our ancestors already had free clean green renewable energy; it proved to be so energy intensive to get at; that it had a hard time maintaining even their puny numbers at the time. They spent nearly every waking hour clambering around in fig trees picking figs to get their free clean green renewable energy.
    It wasn’t till they discovered stored chemical energy, and the means of accessing it through fire, that they were able to sustain themsleves, and grow their numbers and enrich their societies.
    Renewables didn’t work back then; and they won’t work today either.
    Yes they are renewable; but the are simply too diffusely dispersed; and they renew far too slowly for our needs.
    Yes I plan to stick around till the oil runs; out just to watch the green weenies squirm when they run into the cold reality of their folly.

  59. L. Bowser- Interesting comments in comparing gas with coal.
    “In this case the metric that matters will be $/KW capacity installed (net of parasitic load.), not the thermal efficiency. Efficiency, while interesting, can never tell the whole story on its own.”
    Agreed. What I find useful with the Carnot efficiency calculation is that it gives a starting point to calculate whether the energy needed to run the parasitic losses (moving water up 1000 m through a lossy pipe, thermal losses along the way, losses in the engine) will exceed the energy generated by the temperature differential that finally arrives at the heat engine. If you start with a low efficiency, the losses need to be really small to even break even. I have serious doubts it will generate enough energy to move the column of water.

  60. And I just read your full story above; L. Bowser so let me ask you. WHAT ON EARTH DO YOU IMAGINE CAUSES THOSE UNECONOMICAL COSTS YOU ARE TALKING ABOUT ??
    If I can double the efficiency of a solar cell, I can halve the area needed to produce acertain amount of electricity. Many people believe that if you halve the land area you need for a project that you will about halve the cost of the installation. Fancy that; isn’t that radical that you can impact the cost of an enterprise by increasing the efficiency of that enterprise.
    The very mention of your “subsidy” indicates you don’t have the foggiest idea what is driving the system.
    A $1 taxpayer subsidy for your renewable energy plant requires roughly a $2.86 taxable profit (35% Corporate Income Tax Rate) from private enterprise businesses. The long term average profitability of all corporations and small businesses is something like 4%; so on average they have to do $25 worth of taxable enterprise to make a $1 profit; or about $71 to make the $2.86 profit to subsidize your scam with a $1 subsidy.
    If you think that efficiency doesn’t matter and cost is paramount; then L. I have the perfect solution for you.
    How about ZERO cost for your renewable energy; for as large a power plant as you want to build.
    You tell me what your favorite renewable energy scheme is; and how big a plant you would like (how many GigaWatt’s peak generating capacity).
    Now I will build you that plant and give it to you for free; ZERO capital cost. Now you can run your free factory accessing the free clean green renewable energy so your costs are, and always will be ZERO !
    Oh there is one small thing I would like you to do for me; before you start selling your free clean green renewable energy at a totally sinful profit margin.
    Using the free energy output from your plant that I gave you for free; along with all of the natural resources in the universe in their natural state; wherever they are; Please construct for me, a duplicate of the plant I gave you.
    After you have built me a duplicate copy of my gift to you; using only the energy it provides you with; then you may hang up your shingle and open up for business; and make yourself filthy rich.
    I believe you can get filthy rich; if you choose for me to gift you, a modern Fission Nuclear Power Plant.
    Sans Fossil Fuels, I am not ware of any other way to get rich.

  61. Martin Brumby says:
    August 4, 2010 at 9:33 am
    “[…] …Greenies and amateur bunny huggers won’t hear of the idea. […]”
    ROTFLOL! As opposed to professional bunny huggers!?!?
    I think the professionals are paid by NGOs. (And just think of the questions during the job interview for that position…)
    Thanks, Mr. Brumby! First time I’ve seen that phrase on here and it’s ripping good.

  62. chris y says:
    August 4, 2010 at 10:26 am
    It needs to be lifted vertically by 1000 m, through a pipe having frictional losses. The energy needed for this cannot be dismissed compared to the energy produced by the heat engine.
    ____________________________________________________________
    No, you are completely wrong, as the hydraulic pressure term is cancels out, you are left with the head loss term and the v^2/2g term via the Bernoulli Equation, both of which can be made negligently small by making the intake riser pipe sufficiently large.
    You are not lifting water 1000 meters, as there is ambient ocean water outside the pump/OTEC plant at the same elevation of the ocean water inside the pump.
    BTW, I did graduate research work on the OTEC concept in the late 70’s, and even published a paper in the peer reviewed Hydraulics journal of the ASCE.
    It is my opinion that OTEC is not as promising a technology as wind, or solar, or geothermal. It may not even be as promising a technology as wave energy extraction, which I also don’t consider as promising a technology as solar, or wind, or geothermal.

  63. @Dave Springer,
    Your wine vaporizer sounds very much like the sea water vaporizer I describe above. Yours produces distilled alcohol, the one I describe above would produce distilled water plus power.

  64. engineers are not economists.

    What? Engineeing programs always have a component of engineering economics. Engineers have to propose realistic projects after all, and cost effectiveness is a large component of that.
    The cost estimates I have seen for OTEC lie between $10,000-$20,000 per kW installed capacity which makes it “only” about 5-10 times more expensive than wind power, which is itself about 6 times more expensive than a coal-fired plant. Installed capital cost is not the only factor involved in determining the cost of delivered energy, but it is a dominating factor, especially as someone has pointed out here, the replacement time for equipment could be very short.
    As Chris and others have pointed out, maximum possible efficiency is around 6%, and the feasible efficiency might be as much as 80% of maximum considering that pumps and turbines are pretty efficient (wind turbines achieve about 86% of the betz limit when operated at optimum wind speed). The resulting 4-5% efficiency of OTEC simply runs the cost per kW outta’ sight.

  65. chris y:
    At August 4, 2010 at 2:19 pm you say:
    “What I find useful with the Carnot efficiency calculation is that it gives a starting point to calculate whether the energy needed to run the parasitic losses (moving water up 1000 m through a lossy pipe, thermal losses along the way, losses in the engine) will exceed the energy generated by the temperature differential that finally arrives at the heat engine. If you start with a low efficiency, the losses need to be really small to even break even. I have serious doubts it will generate enough energy to move the column of water.”
    Please see my comment at August 4, 2010 at 1:37 pm .
    The Hawaiian OTEC system lifts water up one tube, uses it as a coolant (for air conditioning or soil cooling in horticulture), then returns the water via another tube. Once started, the energy required for the lifting is not great because the mass of rising water equals the mass of falling water and only the ‘friction’ of the water in the pipes has to be overcome.
    More problematic is the energy required to pump the water around the small-bore pipes used for the cooling. And the only energy used by the system is provided by the temperature difference between the cold water from depth and the warm near-surface water. Furthermore, the energy extraction transfers heat from the warm water to the cold water, and if the cold water is warmed too much then it loses its usefulness. These factors provide a limit to the area that can be supplied with the cold water for cooling.
    But the Pacific Institute in Hawaii built and demonstrated a full-scale working system in the 1990s (I saw it working and I wrote an article about it).
    However, the fact that the system works and is cost-effective does not mean much because, as I said,
    “The system is only useable in locations with direct access to deep ocean (e.g. Hawaii and parts of the coast of India).
    So, the Hawaiian OTEC system could be very economic as a source of air conditioning and as a soil coolant for horticulture but only in the few places with direct access to deep ocean.
    Hence, in common with most other renewables, it has a potential niche market but lacks potential for use to displace the bulk of fossil fuel usage.”
    Richard

  66. For carnot – at low temp differences you will be very lucky to get even 30% of the carnot eff. A 2% overall efficiency would be impressive. Think on that – 50GW of heat transfer for 1GW of power.
    Hawaii has a 4000m tall strato volcano that is a better resource, with temps that are (depending on lapse rate) 30-40°C cooler at the top than at sea level, and on land where it is easy to work. A 2-3km tall radio-mast type tower on top of the mountain with some nice big heat exchangers at top and a hydrogen loop running down to sea level through a gas turbine would get perhaps 10% overall efficiency with a 60°C temperature differential. It would also make one hell of a tourist attraction.

  67. I was the Lead Operating Engineer on board the Ocean Energy Converter, an old WWII T2 tanker that was the platform for OTEC-1 off of Keahole point in Hawaii in 1980. It was operated for the Department of Energy by Rockwell International, my employer at the time. I started and ran the plant for most of its operating life, less than a year. The operating fluid was Ammonia. The system did not generate electrical power, instead it just flashed the Ammonia across a drag valve on the way to the condenser. Electrical output was estimated (modeled) at about 1 Megawatt. The system did operate well within its design parameters. We had a 2000 foot long cold water pipe that was three, five foot diameter polypropylene pipes bound together to supply the condenser. A ten foot diameter warm surface water pipe for the evaporator supply and 150 foot long, fifteen foot diameter fabric tube to handle the combined water discharge. The subsurface discharge was an environmental necessity because the discharge water might disrupt the lives of the surface fish (God forbid!). Total water pump horsepower was around 15000 hp, about 10 Mwt! for a modeled net output of minus nine MWt, not bad for an alternate energy project. /sarc
    The next step in the project was to be the 400 MWt. near commercial plant. Construction highlights would be slip forming a 100 foot diameter concrete cold water pipe, two thousand feet down into the ocean from the platform. Plus the invention of a 100 mile long submersible extension cord so we could plug the thing into the grid. We would also need enough pump power to handle about one fourth of the average annual Mississippi River flow. We inquired discreetly to the manufactures of the largest water pumps on earth if they could provide something like this and their response was to ask what we were smoking and could they have some?
    After a year, sanity (and I guess Ronald Reagan) prevailed, we pulled the plug on the experiment, gave most of the equipment to the State of Hawaii, declared victory and went home.
    The efficiency of this type of engine is so low that it require equipment of unbelievable size. Even though it was a high point of my career, it saddens me to think this very poorly thought out idea could possibly be making a comeback.

  68. Dave Springer says:
    August 4, 2010 at 1:52 pm
    Just as a sciencey aside for home experimenters…
    A retired air conditioning engineer in Greenfield NH (Sanford Farms) used something similar to make the most incredible tasting blueberry jam. The jam was “cooked” at low temperatures and ended up tasting just like fresh blueberries…. drool

  69. Dave Springer,
    Thanks for the air venturi idea. My electrically driven lab vacuum pump runs out of grunt at 38000 feet when calibrating soaring flight recorders. I do have a shop compressor so I’ll try an air venturi for the few occasions I need more than 38000 feet. Some heroes seem to want to try to go higher than that with their primitive oxygen systems.

  70. From: Steve Stip on August 4, 2010 at 9:48 am

    Here’s a way to generate fresh water and power at the same time:
    Take a large vertical tube and mount it vertically in the ocean. It should be long enough to reach substantially cooler water and wide enough to allow for a large water vapor flow. Mount a turbine generator in it. Evacuate all the air from the tube. (…)

    At which point you have a very large float trying very hard to force itself to the surface. This will require severe anchoring to the sea floor, deep into solid bedrock, and/or some very heavy anchors which will have to somehow not be allowed to drift. A thick tube, possibly with internal bracing, will be needed so the pressure at the bottom doesn’t just crush the tube outright, and it will have to be very well sealed. And if anything disrupts the tie-down cables, be it corrosion, storm surge (tsunami?), accident (cables snagged by a wayward anchor), and there is not sufficient multiply-redundant cables that are very well balanced to allow for cable failure predominantly on one side… Let’s just say I really wouldn’t want to be around there when it lets go.

  71. George E. Smith:
    Calm down before you blow a gasket. I never said that this technology was economical, nor did I imply it. What I said is that making the argument solely on efficiency is a bad argument. Capital costs in conjunction with parasitic load compared against market price will determine when and if this technology makes sense. I quote myself directly “In this case the metric that matters will be $/KW capacity installed (net of parasitic load.), not the thermal efficiency.” This is a 100% true statement. If you want to argue the point, have at it. But please back yourself up with something more than a holier-than-thou rant assuming that I know nothing.
    My point with solar power, which was completely lost on you, is that the cost of the solar cells drive the cost of a solar power installation, not the land. And irrespective of how efficient your solar cells may be, you can never capture more than 1000 W/m^2 at any given time (and for no more than the equivalent of 6-7 hours of peak time per day.) We do not get to play God and control solar intensity or when the sun shines.
    To your point about the sum of energies wasted to get at the renewable power, based on what was posted above, the plant in Hawaii was producing 100KW of net power from a 250KW generator. So there was a parasitic load of 60%, which means that you can generate more power from the above configuration that what is used to operate all the equipment used in generation. As far as the energy to produce the equipment, install it, maintain it, etc… I don’t know if it takes more to create it than you will ever get out, but then again neither do you.
    But from this information, we do know that there is a price of power at which this becomes economically feasibile. What is it? I don’t know an exact number. Mr. Kilty threw out a $10-20K/KW number above (which is better than today’s cost of solar power when you adjust for daily hours of usable sun.) Making a few gross assumptions, I would say the economic price is something like $0.30 per KWH at the low end, with 35% of that number indexed to inflation to cover any escalation in coporate overheads, operating labor and maintenance. This is assuming a 20 year analysis with no terminal value, 12 quarter WIP curve, 140 days working capital at on-stream, 20 year MACRs depreciation schedule, 90% on-stream availability, 37% effective tax rate (state & federal), 35% target leverage with a 9% return requirement. Of course there are a lot of other variables I would personaly wish to consider before making such an investment, but I find that the ones above generally get you within 10% of the end point.
    If you decide to find fault with my logic, fine. Do I have all of the details around this specific technology? No. But in my experience, the quickest way to go broke or miss a potential opportunity is to focus on a metric like Carnot efficiency and ignore all the other facts, or lack of facts, at hand. Efficiency is a piece of the puzzle, but without the context of other variables, it is 90% meaningless. In the end, if you get more power out than you put in during operation, you have to look at the whole picture before passing judgement. What little information was presented above indicates the power available is enterprise sustaining, so we need to dig a little deeper before we can make a gross assertion that this will not work.
    One last point, and then I’ll shut up for the night. You mention stored chemical energy and our pre-historic ancestors in your argument. So you tell me, what’s the difference between that and the stored thermal energy found in the ocean? The answer is the level of sophistication needed to harvest it. Primitive peoples don’t get to jump from know-nothings to advanced overnight. Stored chemical energy worked for them because there were low barriers they had to overcome in order to harness it. Rub two pieces of wood together to create an ember, place it in a bird’s nest, blow on it and feed it fuel to sustain it. But let’s also not pretend that what they did was anywhere near efficient. They wasted most of that energy heating the great outdoors. Does it take a lot more effort and sophistication to harness stored thermal energy? Yes. Does that mean that it can’t be done by an advanced people with a reasonable amount of labor and raw materials? No.

  72. A one degree difference? Why not dig down and get a one or two hundred degree difference?
    New Zealand has 129 identified geothermal areas and generates power from a number of them. Fourteen are in the 70-140ºC range, seven in the 140-220ºC range and fifteen in the >220ºC range.
    Here’s everything that you want to know about geothermal power, and more. It will take you weeks to read the whole site!
    Wairakei Power Station:
    http://www.nzgeothermal.org.nz/education/turb-and-gen.html

  73. At which point you have a very large float trying very hard to force itself to the surface. kadaka (KD Knoebel)
    Well, one could weight the tube to reduce the need for anchoring. But assuming it could be anchored, the only pumping necessary would be to pump out the fresh water condensate.

  74. I think that I found some more information on the Hawaii facility, the Natural Energy Laboratory of Hawaii Authority (NELHA).
    http://www.nelha.org/about/about.html
    There are three pipes bringing up cold water with ID = 1m, 0.45m and 1.4m. Lets use the 1 m pipe. The spec claims a pumping capacity of 0.84 m^3/second, or 13,400 gpm, at a temperature of 277K. The warm water pipe we will assume can support the same flow rate at 24 C = 297K. The maximum thermal power available from this flow is P = CdTdm/dt = (1000 J/kgC)(0.84 m^3/sec)(1000kg/m^3)(20) =16.8 MW. The caption above claims they were able to generate a world-record 100 kW of net exportable electrical power. That gives an overall efficiency of 0.10/16.8 = 0.6%. So it does work, barely. When operating, this plant was a factor of ten below the Carnot limit.
    This is known as treading water. I think we’d better look elsewhere for renewable energy.

  75. There are three pipes bringing up cold water with ID = 1m, 0.45m and 1.4m. chris y
    Why pump up the cold water when all one wants to do to dump heat into it? A giant vertical heat pipe could do the trick (assuming it could be anchored).

  76. Richard Courtney sez: ‘most of the product from their system is cold water (from deep ocean) with some (very small amount of ) electricity as a by-product’
    This is true but neglects that the designed purpose was to generate electricity (with the thought that it could be used on small islands, remote military bases and the like), and the original concept treated the warmed water as a waste product that would cost something to dispose of.
    I had a standing offer from 1987 on that I would pay a dollar for every kilowatt-hour OTEC produced over what it had consumed if NELHA would pay me 10 cents for every kwh it consumed over what it produced.
    The collection of cold water at the surface was an afterthought and became profitable only because hundreds of thousands of Japanese are willing to pay $18/l for ‘pure water’ from the deep ocean.
    Besides strawberries, NELHA tried raising salmon and abalone in the cold water. The salmon was a bust but last I heard the abalone was modestly successful — if you don’t count the $10 million or $20 million wasted on salmon, strawberries etc.
    I assume that the scientists there know as much about the Second Law as anybody else and understand that they are wasting their time in a pleasant climate. It wouldn’t be the first time an alternative energy boondoggle was sold to ignorant politicians in the name of nonsense. The Pic du Midi solar collector was sold to DeGaulle as a necessary part of the ‘force de frappe’ (atomic bomb program).
    In 1973, the French government leased it to Georgia Tech for a dollar. The French were smarter than us. At least they got a dollar back.

  77. re Alan Drennan-
    Thanks for your first-hand account of this technology. That must have been a ton of fun to work on.
    “Total water pump horsepower was around 15000 hp, about 10 Mwt! for a modeled net output of minus nine MWt, not bad for an alternate energy project.”
    LOL!!!!
    “The efficiency of this type of engine is so low that it require equipment of unbelievable size.”
    Exactly.

  78. Great article – always good to read about non-mainstream ways to create clean energy.
    Hopefully Hawaii can use it for all its energy needs sometime in the future?

  79. I would remind you that despite Savory and the rest the first practical engine was the Newcomen engine also called the Atmospheric engine which was about one half of one percent efficient. Nevertheless not only was it the wonder of it’s age but of enormous practical use chiefly in pumping water out of mines.
    One Mr. Watt with his condenser turned it into a steam engine at at about two percent efficiency which was a great saving in coal. He sold quite a lot of them some of which were working up till a hundred years ago.
    Others notably Hornblower in England and Evans in the USA understood that high pressure steam with compound cylinders could do better than this and needed no condenser. Even so to the end of their days, a steam locomotive manages little better than six percent: and compounding hardly changes this, the classic two cylinder simple with basic valve gear is difficult to improve upon.
    With the very best Scotch boilers and either quadruple expansion or turbine engines or a mixture al la Titanic eighteen percent is about the best you might do.
    A coal fired variable load following electricity generating station using turbines can usually manage around twenty five percent whereas its base load counterpart, where essentially the boilers and turbines either run at full power or not at all can manage about thirty two percent depending on ambient temperature. On a nice cold winters day with air temperature about freezing thirty four percent is easily achieved: on a hot, humid, 20C roughly 70F, day it would struggle to reach thirty one percent.
    By contrast the US, mostly in California, solar stations, built in the seventies and eighties with huge government subsidies in case you had forgotten, and still working today, cannot manage better than around ten percent in cool weather and only a third of this in the summer.
    You see back in the nineteen seventies we really did investigate this thoroughly and build the real working test plants: including thermal extraction from sea water. Despite much hype the technology has barely changed in my lifetime, I am still awaiting the cheap efficient solar cell along with the fusion reactor and have been all my life, and it is just as far away, about thirty years or so, as it was then and still is.
    I don’t know where people have got this idea of cheap green renewable energy comes from, we tried and tested it all back then and the technology has hardly improved. What did not work then won’t work now. The difference is we tried it out to see what it could do. And found it did not work then and won’t now: as those Californian solar stations built with enormous government subsidies, will tell you.
    And nobody then was bothered by CO2, it was all about the price of fossil fuel. But there is no shortage of coal or oil or indeed natural gas: there is enough for a thousand years or two and if you start to run out there is enough fissionable stuff for ten thousand years.
    So fear not, King Coal will continue to drive prosperity around the world as he has done for the past two hundred years and will do until all the human race has access to cheap energy and wealth. Despite the efforts of those who would deprive people of the growing benefits of technology that we see around us.
    Kindest Regards

  80. a. jones;
    How ’bout a small (3x2x2m) 5MW fusion reactor with enough energy profit (Q) to generate power at about ¼¢/kwh marginal, priced at ~5¢/W prefab FOB factory door? The fundamental science should be proven in 6-12 mo., and a licensed design available to manufacturers world-wide within 3-5 years.
    LLPX.com, focusfusion.org

  81. Everyone is missing the most promising technology. Genetically engineered microorganisms. Once somebody like Craig Venter builds a bacteria that converts sunlight, air, and water into alcohol and/or fuel oil in one step the energy problem is solved. Solar power collectors won’t be manufactured they’ll be grown on site from a thimbleful of innoculants. A huge thin mat that can cover any irregular surface with self-made network of capillaries and channels to deliver the product to a central point.
    There’s little biological invention required. It’s more a matter of cut & paste from a number of extant natural organisms (photosynthetic & yeasts) and then fashioning a control program so the little beasts build the capillary networks to deliver the juice.
    This actually is just a few decades away at most. Genetic engineering, unlike heat engines and photovoltaics and fusion power, is progressing at a rapid rate that reminds me of Moore’s Law for semi-conductors.
    Craig Venter seems to be leading the pack. He’s already been able to reduce one of the smallest known bacterial genomes down to something like half its original size while keeping the essential bits for metabolism and reproduction. He can assemble that genome from mail-order DNA snippets according to written sequence, remove the DNA from a different species of bacteria, implant his artificial DNA in the shell, and grow a colony from it. The first fully functioning entirely artificial minimal genome in the world is already a done deal. All that’s needed now is further refinements on the lab gear (engineering not science) to make the process of creating and testing artificial genomes faster and cheaper (that’s the technology that’s advancing at a rate reminiscent of Moore’s Law for semi-conductors) then start adding the bells and whistles to make the new bug do practical things (like make fuel directly from sun, water, and air).
    Interestingly, once we get fuel-making bug done our energy supply will be carbon limited. The bugs need a supply of carbon from somewhere and they’ll be getting it from the same place that photosynthetic plants get it now – atmospheric carbon dioxide.
    Ironic, eh? The very thing a bunch of boneheaded academic chuckle monkeys with PhDs and political tax & control freaks in national governments and greedy corporate chieftans conspire to reduce (atmospheric CO2) is something we’re going to be wanting more of, not less of, to supply us with plentiful clean energy. We need our carbon cycle and we need it bigger & faster not smaller & slower.

  82. Harry Eagar:
    Discussion of Carnot efficiency is mistaken in the context of the discussed OTEC technology because the purpose of the technology is NOT power generation.
    Carnot efficiency for the Hawaiian OTEC technology would be pertinent if the purpose of the technology were to generate electricity, but it is not.
    At August 4, 2010 at 6:01 pm you quote me then make an irrelevant assertion, as follows:
    “Richard Courtney sez: ‘most of the product from their system is cold water (from deep ocean) with some (very small amount of ) electricity as a by-product’
    This is true but neglects that the designed purpose was to generate electricity (with the thought that it could be used on small islands, remote military bases and the like), and the original concept treated the warmed water as a waste product that would cost something to dispose of.”
    But the original “designed purpose” is of no relevance; none, not any, zilch.
    As Alan Drennan clearly explained in his excellent post at August 4, 2010 at 4:37 pm , that original purpose was electricity generation but that was a really silly idea so, as he says;
    “After a year, sanity (and I guess Ronald Reagan) prevailed, we pulled the plug on the experiment, gave most of the equipment to the State of Hawaii, declared victory and went home.”
    After that, as I first explained at at August 4, 2010 at 1:37 pm, the Pacific Institute in Hawaii saw a different use for the technology; i.e. use the little energy from OTEC to provide a self-sustaining provision of cold water from deep ocean.
    The obtained cold water would be a coolant for use in air conditioning. The result would be cheaper air conditioning than that provided by electrically-powered air conditioners. And, in turn, this could displace electricity generation needed for air conditioning. This would reduce costs of air conditioning and would be a major reduction to electricity demand in warm climates.
    Very importantly, as I said at August 4, 2010 at 3:28 pm;
    ” the Pacific Institute in Hawaii built and demonstrated a full-scale working system in the 1990s (I saw it working and I wrote an article about it).
    However, the fact that the system works and is cost-effective does not mean much because, as I said,
    “The system is only useable in locations with direct access to deep ocean (e.g. Hawaii and parts of the coast of India).
    So, the Hawaiian OTEC system could be very economic as a source of air conditioning and as a soil coolant for horticulture but only in the few places with direct access to deep ocean.
    Hence, in common with most other renewables, it has a potential niche market but lacks potential for use to displace the bulk of fossil fuel usage.””
    Richard

  83. 1979 ~50 Kilowatts
    Keahole Point (Off the Kona coast)
    40 kW were used to pump cold water leaving a net of 10-17 kW.
    Funding: State of Hawaii and private industrial partners.
    1980 Kawaihae (Off the Kona coast)
    Tested heat exchangers and other components, and investigated the environmental effects of an ocean –stationed OTEC plant.
    Funding: USDOE
    1984 Design plans completed for a 40-megawatt pilot plant to be located on an artificial island at Kahe Point (Oahu)
    Funding: USDOE
    1992 – 1998 210 kW Experimental device was operated at the Keahole Point facility.
    2008 Lockheed-Martin is awarded contract develop technologies: cold water pipe fabrication using modern fiberglass technology and recent low-cost composit material manufacturing methods.
    Funding: USDOE
    2008 Hawaii governor Lingle announce a partnership to develop a 10 megawatt pilot plant between Lockheed-Martin and Taiwan Industrial Technology Research Institute.
    2009 Comments from NOAA
    NOAA believes the serious efforts underway by industry to bring OTEC to commercialization deserve a serious response by NOAA. Noting that the U.S. Navy is moving ahead aggressively with OTEC, he said “the last thing NOAA wants is to be behind everybody else.”
    He said a regulatory gap exists for OTEC and that a “demonstration plant” isn’t even defined in existing regulations. NOAA would have a predicament if an OTEC demonstration plant applied for licensing. Kehoe said as many as 10 federal agencies have a role in authorizing the first OTEC demonstration plant.
    “When people in these agencies hear about this technology, they tend to be shell-shocked,” Kehoe said, explaining that OTEC issues are arriving on desks that already are piled high with other work. “OTEC is on a scale so much larger than anything we’ve dealt with before,” he said. Others noted that a large OTEC plant will require the vertical movement of huge rivers of water – a realization that contributes to the shock.
    Conclusion of NOAA conference
    NOAA is so gummed up with bureaucratic inertia due to the “shell shock” it feels over the enormity of ocean thermal energy conversion that it will demand five years of operating data from even a pilot plant before giving OTEC its regulatory blessing.
    Five years to build a plant, then five years of data gathering could effectively scare off investors unwilling to sit in a waiting game before OTEC could be meaningfully rolled out in Hawaii or anywhere else to counter our oil dependence
    2010 NOAA and DOE hold a pre-rule open house on development requirements
    Environmental baseline study
    Environmental Impact Statement for 10 mW pilot plant.
    Technical Issues:
    Fouling and corrosion of heat exchangers
    Expense of pipe construction – 100 mW plant would require a 30 foot diameter cold water pipe.
    Electrical line connection.
    2010 Makai Ocean Engineering is involved is designing and building sea water air conditioning for downtown Honolulu.
    2010 Honolulu Seawater Air Conditioning, LLC is currently developing a 20,000-ton seawater air conditioning district cooling system for downtown Honolulu. The project should come online in early 2012.
    Final Conclusion: While we may get air conditioning in the downtown office buildings, commercial level power generation is at least a decade away.
    James

  84. A correction to the earlier post. The seawater air conditioning plant being built will have a 25,000 ton capacity.
    James

  85. George E. Smith says:
    August 4, 2010 at 1:55 pm
    I could almost buy that efficiency for a bare cell under lab ideal air mass zero conditions; but like you I am skeptical of such operational efficiency claims. There’s no reason teo expect a 20 year life limit. Like all semi-conductor devices they will have infant mortality failures; but with proper QA, they could easily exceed 20 years life.

    Aloha, George.
    30 year service life is what they all shoot for but I figured in reality it’s probably more like 20.
    Problems are wind, dirt, and acid rain etching away at the surface along with ultraviolent light from the sun slowly destroying the ancillary polymers.
    For rooftop installations you run into an additional problem in that few roofs in the real world have a 30 year or even 20 year service life even if you lay new shingles right before installing the photovoltaics. In order to install new shingles you have to uninstall the PV collectors first then reinstall them over the new roof.
    Some thin film flexible PV’s I was reading about are trying to make the PVs double as shingles and are trying to get a 25-year service life out of them which is about the best you can expect from normal high quality shingles.
    I just recently finished an 800 square foot flat roof (1:14 actual slope) over a deep cut i made into a hillside. One side of the roof begins about 18″ above grade and the far side 24′ away is about 12′ above grade. Three walls and floor are 12″ steel-reinforced concrete with vapor barriers on both sides and french drain on the uphill side. Year round soil temp here is 72F so with some modest insulation in the wooden roof and front wall it’s pretty cheap to heat and cool. The one exposed wall faces north so in my hemisphere it never gets any direct sun.
    Anyhow, I was going for cheap cheap cheap in the construction and with a flat roof you can’t use regular shingles. I used roll roofing which is basically shingles that are 30’x3′ and come in a roll. After overlap I needed 10 rolls. I used a nifty little battery powered caulk gun from Ryobi to lay down beads of roofing cement in between the overlaps to seal them up.
    The expected service life of roll roofing is just 10 years. For a few hundred bucks I can get 5 gallons of high reflectivity (>95%) elastomeric paint I could put on with a roller over the roll roof (asphalt & mineral) and expect to get 20 years from that and maybe 40 if I put on fresh paint once or twice and it bonds well with the weathered surface.
    That roof is perfect for mounting solar panels. It has a clear view of the sun for about 120 degrees of arc, cloud filled skies are infrequent, and you can step onto the roof from grade level and walk about on it. There are only two kinds of flat roofs, by the way, those that do leak and those that will leak.
    The nightmare for solar panels would be in securing them as they’d create scores of potential leak points and when it comes time to resurface the roof a job that would take 20 man-hours would probably turn into 100 man-hours.
    I’m on the grid here and my electric co-op allows net metering. They only pay a few cents per kilowatt hour you put back on the grid so there’s no profit to be made but for every kilowatt you can generate and use it saves the delivered cost of a kwh which is roughly 12 cents each.
    The price of net metering equipment was discouraging. Thousands of dollars for the inverter and net metering device but it sure beats the sh!t out of putting in a huge bank of lead acid batteries that can power the place through the night and through cloudy days.
    If the cost of net metering gear and solar panels dropped in half I’d pull the trigger and start building it tomorrow morning. In the meantime I’m still very tempted because it looks pretty close to cost effective right now with maybe a 7-10 year recovery time for the initial capital outlay and a 20+ year service life. If I was reasonably confident that capital recovery time was under 7 years and service life over 20 it seems like a no-brainer decision to do it.
    I’ve actually got better places to put PV panels (on level ground) so wouldn’t put them on the roof in any case but a lot of folks don’t have the space anywhere but on their roof so just used mine to describe typical problem scenario.

  86. Dave Springer says:
    August 5, 2010 at 2:48 am
    “Ironic, eh?”
    The “Socialisticly Inclined Brain” (SIB) only wants 100% safety. In order to get this safety they need 100% control over all aspects in society.
    The SIB believe governments must reduce and control burning of fossile fuels now, because there will be a shortage some day in the future. That shortage threatens the safety of their children. They love trend lines showing doom, because that can give them power and control to remove this threat.
    People like Venter invents stuff. Finds solutions. But they need libelarism, capitalism, to thrive.
    The SIBs dont like the Venters in this world. In fact they think of such people as profit hungry wannabe criminals which must be controlled and taxed.
    It is very ironic, indeed.

  87. All SIBs should be required (by the Uber-SIBs, of course) to spend 10 hrs/day pedalling flat-out on chain drives attached to generators. It’s their moral dooty! And only potential value to the planet. Oh, wait — they’d have to be fed extra calories, which costs more energy to produce than we’d get back. OK, cancel that … ;-(

  88. James McFatridge:
    Thankyou for your very fine post at August 5, 2010 at 4:25 am. It is a superb summary of the history of the Hawaiian OTEC development up to the present.
    I have only one small quibble. You say;
    “2010 Honolulu Seawater Air Conditioning, LLC is currently developing a 20,000-ton seawater air conditioning district cooling system for downtown Honolulu. The project should come online in early 2012.
    Final Conclusion: While we may get air conditioning in the downtown office buildings, commercial level power generation is at least a decade away.”
    But I do not think the system will ever be able to provide “commercial level power generation” without immense subsidy. In my opinion, the system is likely to prove to be a good investment for the air conditioning, but there is sufficient data to determine that the system is never likely to be a useful contributor to electricity generation at significant scale.
    Again, thank you for your informative post.
    Richard

  89. Jack McFatridge- thanks for the excellent information.
    The 25,000 ton project being built by Honolulu Seawater Air Conditioning, LLC will have pipes running 5 miles out from the shore, followed by an 1800 foot plunge down into the ocean. It will provide supplemental cooling for up to 40 buildings.
    The total project (estimated) cost is $200 Million.
    Trane sells large chilled water systems. A set of units that provide 25,000 tons of cooling would cost about $20 Million – $25 Million. It requires about 0.5 kWhr/ton-hr to operate, or 100 Million kWh/year. If commercial electricity is 10 cents/kWhr in Honolulu, as I found at one source, then that comes to $10 Million in saved electric costs per year.
    Is a roughly 20 year payback time considered cost-effective?
    Hmmm.

  90. I wonder how much easier it is to just use the island’s plentiful hot spots to boil water an run steam turbines?

  91. “”” L. Bowser says:
    August 4, 2010 at 5:11 pm
    George E. Smith:
    Calm down before you blow a gasket. I never said that this technology was economical, nor did I imply it. What I said is that making the argument solely on efficiency is a bad argument. Capital costs in conjunction with parasitic load compared against market price will determine when and if this technology makes sense. I quote myself directly “In this case the metric that matters will be $/KW capacity installed (net of parasitic load.), not the thermal efficiency.” This is a 100% true statement. If you want to argue the point, have at it. But please back yourself up with something more than a holier-than-thou rant assuming that I know nothing.
    My point with solar power, which was completely lost on you, is that the cost of the solar cells drive the cost of a solar power installation, not the land. And irrespective of how efficient your solar cells may be, you can never capture more than 1000 W/m^2 at any given time (and for no more than the equivalent of 6-7 hours of peak time per day.) We do not get to play God and control solar intensity or when the sun shines. “””
    So If I have a solar cell array that gets 20% conversion efficiency from air mass one Solar energy to DC electric power out of the array that I can sell you for $100 per square metere (in volume); and I have a cheaper technology solar cell array that I can sell you for $20 per square metre but it only has 4% conversion efficiency from air mass one solar energy to DC electric power out; so the price per Watt is absolutely the same for the solar cell arrays; whcih one would you buy to put on your house (if you bought any). ?
    Economic problems can be fixed with a pen stroke; but we normally assign economists to solve them in a more rational way.
    Technological problems on the other hand can only be solved by scientists and engineers; and if you send economists to solve them; they will never be solved.
    All so-called renewable clean green alternative enrgy schemes are limited by Technological problems that have not been solved. If those problems were solved the economic problems would vanish with them.
    But have yourself a good time working on the economics; the very fact that subsidies are necessary; demonstrates they are neither technologically feasible nor economically feasible. And I have more than enough to back myself up; I’ve been working at it since at least the mid 1960s.

  92. There should be a DF (Desperation Factor) assigned to each of these alternate energy sources: some weighted number which encompasses R&D difficulty getting it to work, plus near-term (30-yr?) subsidy required to make it viable, plus availability/suitability for wide application, etc. This might allow rational prioritization of efforts, and make it clear which ones are dreams and delusions.

  93. By the way, to those who want to just pump heat out of geothermal sources, there’s complex equipment and some nasty chemicals involved. And the heat conductivity of rock etc. is so low that you can readily exhaust the available resources at any one point you drill, and then you have to relocate. The only exception is perhaps if you create your own tame volcano … 😉

  94. Now if you REEAALY want to change our climate – how about changing the temperature gradients or the current flows of the oceans. !!
    What a brilliant idea….. 🙁

  95. Thanks to Richard S Courtney for the kind words. I thought some general information on OTEC might be interesting.
    According to DOE: http://www.eia.doe.gov/electricity/epm/table5_6_a.html
    Hawaii average electricity rates for April 2010 are 27.15 cents/kW for residential, and 25.01 cents/kW for commercial. So payback on the seawater air conditioning is a little better than 20 years.
    I was amazed last year when NOAA confessed that they hadn’t even considered requirements for having an OTEC plant built. The experimental and development project had only been off the Kona coast for 30 years.
    James

  96. re James McFatridge-
    “…and 25.01 cents/kW for commercial. So payback on the seawater air conditioning is a little better than 20 years.”
    Agreed on the 25 cents/kWhr commercial rate in Honolulu. The payback will probably be less than 20 years, depending on maintenance costs.

  97. 25¢/kwh is grotesquely high! Get some nice modern coal plants fired up and cut that back to 6-7¢, and do everyone a favor. Of course, that extends the payback for ocean energy out to infinity … :-Ds

  98. From: Dave Springer on August 5, 2010 at 4:44 am

    Some thin film flexible PV’s I was reading about are trying to make the PVs double as shingles and are trying to get a 25-year service life out of them which is about the best you can expect from normal high quality shingles.

    They existed. I first heard of them on a Scientific American Frontiers piece, they had featured Stanford Ovshinsky, with his wife and scientific partner Iris, and their company ECD Ovonics [Wikipedia entry (shows corporate structure), ECD site, United Solar Ovonics (Uni-Solar)]. They are printing flexible solar cell sheets long enough to cover a football field. They were making solar shingles you could cut holes in, nail in place, that went on like normal shingles, save for two small lead wires each that a small hole through the roof would be drilled to feed the wires into the attic where they were all wired together. I had read they had somehow lost their UL (Underwriters Laboratory) rating thus they are no longer sold, possibly related to all those small holes being drilled.
    Uni-Solar’s main product is a roll roofing-type solar laminate, unroll and wire up. They’re adhesive backed. Click the “Real Stories” link, big companies love the product. They also work for residential, like on a metal roof installed between the standing seams. CertainTeed has now partnered with ECD to make EnerGen residential systems that (allegedly) blend the laminates with traditional asphalt shingles (see the pics, you be the judge).
    Note that while their laminates are less efficient than traditional crystalline silicon cells, they have a better energy yield as they can generate with less light than those other cells require. They can even generate on overcast days (see graph in roll laminate pdf’s).
    So for your case, putting up panels is optional. You could just unroll another layer on that roof. As far as cost, the company has more than enough demand and has been ramping up production. Eventually the price should come down, but for now they are selling those laminates as fast as they can make them. As it is, for example, the 68W 12V strip can be found online for $200 and up despite a mentioned MSRP of $340.
    ————–
    Interesting item I found during researching:
    This Old House magazine article about assorted solar shingles, apparently from 2008 (undated article, dated comments), featuring a new product by Atlantis Energy Systems, with more being developed.
    The current Atlantis Energy website going from the pg. 2 link. Click around, and find out it’s now a dispenser of “sponsored links” using some fixed solar-related canned searches.
    ECD Ovonics has been around for several decades and shows no signs of evaporating into space anytime soon let alone a mere two years hence, BTW.

  99. Brian H said on August 5, 2010 at 4:41 pm:

    By the way, to those who want to just pump heat out of geothermal sources, there’s complex equipment and some nasty chemicals involved. And the heat conductivity of rock etc. is so low that you can readily exhaust the available resources at any one point you drill, and then you have to relocate. The only exception is perhaps if you create your own tame volcano … 😉

    Nah. Not if you’re talking about basic ground-source heat pump systems, suitable for residential and certain commercial-type buildings. Those actually work and do save money.

  100. Depends where you are. And you still gradually drain the local heat supply. The speed of heat conduction through the ground is very low, unless you’re tapped into a steam vent or SLT.

  101. Brian H said on August 6, 2010 at 6:55 pm

    Depends where you are. And you still gradually drain the local heat supply. The speed of heat conduction through the ground is very low, unless you’re tapped into a steam vent or SLT.

    Here, enjoy the Wikipedia geothermal heat pump entry:

    Almost everywhere, the upper 10 feet (3.0 m) of Earth’s surface maintains a nearly constant temperature between 50 and 60°F (10 and 16°C), depending on latitude.
    (…)
    But unlike an air-source heat pump, which transfers heat to or from the outside air, a ground source heat pump exchanges heat with the ground. This is much more energy-efficient because underground temperatures are more stable than air temperatures through the year. Seasonal variations drop off with depth and disappear below seven meters due to thermal inertia.
    (…)
    A ground source heat pump extracts ground heat in the winter (for heating) and transfers heat back into the ground in the summer (for cooling).
    (…)
    The geothermal pump systems reach fairly high efficiencies (300%-600%) on the coldest of winter nights, compared to 175%-250% for air-source heat pumps on cool days.[4] Ground source heat pumps (GSHPs) are among the most energy efficient technologies for providing HVAC and water heating.[5][6]

    Here’s a system I really like:

    Standing column well
    A standing column well system is a specialized type of open loop system. Water is drawn from the bottom of a deep rock well, passed through a heat pump, and returned to the top of the well, where traveling downwards it exchanges heat with the surrounding bedrock.[15] The choice of a standing column well system is often dictated where there is near-surface bedrock and limited surface area is available. A standing column is typically not suitable in locations where the geology is mostly clay, silt, or sand. If bedrock is deeper than 200 feet (61 m) from the surface, the cost of casing to seal off the overburden may become prohibitive.
    A multiple standing column well system can support a large structure in an urban or rural application. The standing column well method is also popular in residential and small commercial applications. There are many successful applications of varying sizes and well quantities in the many boroughs of New York City, and is also the most common application in the New England states. This type of ground source system has some heat storage benefits, where heat is rejected from the building and the temperature of the well is raised, within reason, during the Summer cooling months which can then be harvested for heating in the Winter months, thereby increasing the efficiency of the heat pump system.

    Basically you end up drilling a second well on rural property, only water is used for the energy transfer to and from the depths of the well. With only mildly creative plumbing arrangements you could possibly use one well for heating/cooling and domestic water, likely on a temporary basis only if one well pump goes out.
    The low heat conductivity works in your favor. Note the last line. The heat gets put in during summer, then extracted in winter. For a more advanced version there is seasonal heat storage.
    So not only do you get the high efficiency, “draining the local heat supply” really isn’t an issue.

  102. Yes, that works as long as you stick to the range of seasonal fluctuations at that locale. As for Wikipedia’s “maintains constant temperature”, that’s if undisturbed. There is always a “carrying capacity” and replenishment rate. As an e.g., here’s an excerpt from study of the potential use of an abandoned mine near Yellowknife NWT:

    With re-injection, the amount of energy extraction from the mine would be controlled by the usable heat in the rocks (presently estimated in the order of 20 MW). Any production beyond the heat flux into the mine would lead to gradual heat exhaustion (i.e. cooling of
    the rocks, and degradation of the geothermal value of the mine). It should be noted that in case of monitoring heat exhaustion, the rate of heat extraction can be corrected to prevent damaging the resource sustainability.

    Just common sense, really.

  103. And re the above: you will note the output level anticipated: 20 MW. This is not a big deal or large amount of energy; the costs are probably tolerable there only because of the very high power rates and current costs of heating. A pilot proposal suggests that equipment would run at about $3/W, which is very high, and best-case power extraction at around 10-11¢/kwh equivalent.
    Bottom line: neither cheap nor easy.

  104. Re: Brian H on August 7, 2010 at 10:04 am and 10:13 am
    We’re arguing now about scale. The real bottom line, it can be cheap and easy. It matters what you are asking for. For residential heating and cooling it makes sense, especially that standing column well version. It’s not free money, you will be spending less with a relatively quick payback on investment but it takes a little extra money up front. It scales up so far and still works fine.
    However the example you cite (found a link) is a large industrial application, where the heat is to be removed as opposed to a heating/cooling ground source system, thus is different.
    BTW, what source did you use? You’re citing 20MW, mine says:

    The company projects the mine’s tunnels could heat up to 39 buildings in the downtown core and provide some 52,000 megawatt hours of heat per year.
    “Just to give you a sense of what 52,000 megawatt hours is, that’s approximately 7 million litres of diesel, of heating oil,” he said. “So it’s a fairly large customer base, and a lot of fuel.”

    That’s quite a difference. Now while I don’t like the projected cost more than doubling the original expected amount, and haven’t crunched the numbers after finding out the cost of heating oil in Canada, offhand it looks like it might be worth it. Note it probably would be if this was financed by private investors, as they wouldn’t have gone this far if they didn’t expect a profit, but since government and government funding is involved then “might be” is the best that can be said. 🙂

  105. You’re confusing delivered energy and power at the source. There are 8760 hours in a year; if the system were running non-stop, that’s 52,000/8760 = ~6MW.
    What do you consider cheap? How much per watt for the installation? How much maintenance and energy to the heat pumps, etc.? When all costs are included, geothermal is rarely ‘cheap’.

  106. BTW, as I said, the Yellowknife example is a very favorable one for geo, as it is a Northern city, pop. ~20,000, with very high existing energy costs and a significant need for heating: average annual temperature is -4.9°C, or about 24°F. 🙂 Note also that the exhausted mine is already there, no drilling/excavation needed, and it is slowly filling with water on its own.
    As for gubmint subsidies, they’re pure and simple — but very serious and potentially damaging — cost distortions. As Germany, Spain, etc. are discovering to their horror.

  107. Re: Brian H on August 7, 2010 at 6:11 pm
    That’s a difference right there, your source is citing 20MW and potential problems, mine is figuring only a 6MW draw.
    Sorry to say this, but your dislike of geothermal is bordering on pathological, especially with regard to residential systems. Heat pump heating/cooling systems are rather common and accepted, with costs and maintenance considered comparable to traditional central heating and cooling methods. Hey, if you’re planning on using central air conditioning then you have most of a full heat pump system already budgeted for, right? After that comes thermodynamic efficiencies, as it’s easier to extract heat from 50°F water than 20° air, and easier to dump heat into 50° water than 90° air. For the standing column well version, it’s about $5-8,000 for a new water well around here, which includes everything needed (pump, pressure tank, trenching and running the lines, etc) to hook right up inside and start using the water. Used for ground source heating/cooling, a return line will be needed, which will add a little additional cost, however water filtration and conditioning will likely not be needed.
    There will be one notable difference to a traditional heat pump system, the equipment can be inside and out of the weather.
    For residential use, geothermal, actually ground source heat pump systems, do work, they are relatively cheap, and they will save money with relatively fast payback on investment.
    When done on the scale of the Yellowknife example, which has great differences, other factors intrude. Namely increased installation and operating costs, as stronger regulations get invoked, permanent staff are used, and even *gasp* higher-priced union labor gets involved. Then it ceases to resemble cheap energy, with government grants making these projects look more worthwhile.

  108. Actually, no particular arguments with that. (Though the Yellowknife example is your number; there must be some serious inefficiencies if the 20MW total capacity is only able to generate 52,000 MWh in a year. Of course, it would not probably be run 24/7-365, so the total hours is maybe somewhat less, and the power output higher than 6MW.) As for home use, your $5-8,000+ is surely not generating 5-8 KW, so right away you’re into expensive territory. But once operating, it probably makes sense.
    If you try to use it on a large scale to generate electricity, you have to add heat concentrators and a steam turbine.
    My hobby-horse and hoped-for solution is currently under development at LPP, documented at focusfusion.org . They are in the late stages of proving out an “aneutronic” fusion process that would run pulsed in a very small reactor. A generator based around it would be about the size of a home garage and turn out ~5MW, with a cost per watt and cost-to-produce around 1/20 of current technology. It would make said technology, much less the pricier “renewable sources”, economic roadkill.

  109. From: Brian H on August 8, 2010 at 12:33 pm

    If you try to use it on a large scale to generate electricity, you have to add heat concentrators and a steam turbine.

    Maybe someday soon improved thermoelectric devices could help out with that.

    My hobby-horse and hoped-for solution is currently under development at LPP, documented at focusfusion.org . They are in the late stages of proving out an “aneutronic” fusion process that would run pulsed in a very small reactor. (…)

    From the Wikipedia Aneutronic fusion entry:

    Temperature
    Despite the suggested advantages of aneutronic fusion, the vast majority of fusion research effort has gone toward D–T fusion because the technical challenges of hydrogen-boron (p–11B) fusion are so formidable. Hydrogen-boron fusion requires ion energies or temperatures almost ten times higher than those for D–T fusion. For any given densities of the reacting nuclei, the reaction rate for hydrogen boron achieves its peak rate at around 600 keV (6.6 billion degrees Celsius or 6.6 gigakelvins)[5] while D–T has a peak at around 66 keV (730 million degrees Celsius).[6]
    Power balance
    In addition, the peak reaction rate of p–11B is only one third that for D–T, requiring better plasma confinement. Confinement is usually characterized by the time τ the energy must be retained so that the fusion power exceeds the power required to heat the plasma. Various requirements can be derived, most commonly the product with the density, nτ, and the product with the pressure nTτ, both of which are called the Lawson criterion. The nτ required for p–11B is 45 times higher than that for DT. The nTτ required is 500 times higher.

    They haven’t even got plain old regular fusion working yet, and this is your great hope?
    I think we’d do better with “solar roofing” everywhere possible, with grid-tie systems, local battery storage (neighborhood level), and gas turbine backup which can use waste methane from landfills and sewage treatment. That is energy independence we could achieve now, at a bearable initial cost.

  110. Rely on Wiki at your peril.
    Check out the site; there is a theory called HMFE which has been incorporated into the basics of the design (High Magnetic Field Effect) which stops “X-ray cooling” at certain energy levels almost entirely. Second, the FF design does not attempt to stabilize a plasma; it uses microscopic imploding “plasmoids” to generate the temps and pressures required for a few nano-seconds, and pulses the system. Each “pinch” event results in opposed alpha and beta beams, which are tapped directly for power.
    Bottom line, all those scary multiples you cite are rendered irrelevant.
    RESULTS so far are better than predicted. Current target for first-ever “scientific break-even” fusion is early 2011.

  111. From: Brian H on August 8, 2010 at 5:29 pm

    Rely on Wiki at your peril.

    True for many subjects, although the wiki method does generally work. It does so by the more strident viewpoints canceling each other out while the submitters stay polite to maintain the semblance of having the (in)famous Wikipedia “Neutral Point Of View (NPOV),” on all but the most innocuous and generally non-debatable items, which is not how the Wikipedia experiment was envisioned, but still…

    Check out the site…

    I have seen many such pretty sites where everything is explained. Sites like that are best considered as glossy sales brochures, since they exist to sell you a concept if not a specific item.

    Bottom line, all those scary multiples you cite are rendered irrelevant.

    Per the site.

    RESULTS so far are better than predicted. Current target for first-ever “scientific break-even” fusion is early 2011.

    As I would expect to be claimed, although I suppose this has more of an “investment brochure” feel to it. Too bad there’s no science version of the FTC to review such claims…
    They’ve been trying to get fusion to work for decades. This has yielded: Tokamaks, which can’t get hot enough. The National Ignition Facility (NIF) trying for Inertial Confinement Fusion (ICF), where they try to shatter a large rock with a hundred thousand perfectly timed tiny chisel strikes. Polywell, currently barely kept alive on a dribble of Stimulus money, which looks to have a better shot at being weaponized long before a working power-generating version could ever escape Department of Defense secrecy. Etc. Etc.
    The long trudge to basic D-D or D-T fusion is no longer that interesting, thus come the ads for the new-and-improved “No neutrons! No weapons!” version where we will miraculously do far more than we could ever imagine, when we have yet to accomplish the basic step we imagined many decades ago. We’ll be going straight to space exploration without ever making a practical airplane. And you accept that?

  112. This project has been gestating and being inched ahead for decades, only recently having adequate funds to do substantive “proof of concept” work. It pivots on a specific hypothesis, mentioned above, HMFE. This is being substantiated by the behavior of the many “pinches” (hundreds) run in the test equipment so far. They have been using D-D fuel, since it is easier to work with and track (lots of neutrons to count, e.g.) . But the step to pB11 fuel is imminent (this fall).
    The major distinction between the Tokamak/ITER projects and this one, is that those are in what I call the “meso-fusion” zone, inbetween the stellar and microscopic. As such, they must forgo gravitational and self-generated containment, respectively, and interpose super-conductive magnets and walls and the like — which invariably turn out to be leaky, and/or subject to destructive degradation by heavy neutron flux. Hence the notorious “floating” 30-50 years in the future projection for usable output.
    Polywell also operates in that “meso-fusion” zone, I think, though at a much less massive scale, and may or may not succeed in attaining good containment. But it’s behind a government secrecy wall for the most part, so it’s hard to track.
    As for the focusfusion.org site mentioned, it is run by the support “Society”, a non-profit, but contains links to the technical papers and actual research firm doing the work. Easily located links, if you care to bother.

  113. I should also mention that the principal output of the design is alpha and beta beams, easily directly converted into electricity; no need for massive Carnot steam turbines running at 30% efficiency (which impose a requirement for a Q (energy payoff ratio) of >3 or 4 right off the top).

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