This seems like an interesting idea, the feasibility may drop with scale though.
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.
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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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.
From: Steve Stip on August 4, 2010 at 9:48 am
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.
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.
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
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.
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.
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).
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.
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.
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?
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
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
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.
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
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
A correction to the earlier post. The seawater air conditioning plant being built will have a 25,000 ton capacity.
James
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.
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.
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 … ;-(
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
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.
I wonder how much easier it is to just use the island’s plentiful hot spots to boil water an run steam turbines?
“”” 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.
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.
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 … 😉