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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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….. 🙁
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
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.
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
From: Dave Springer on August 5, 2010 at 4:44 am
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.
Brian H said on August 5, 2010 at 4:41 pm:
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.
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.
Brian H said on August 6, 2010 at 6:55 pm
Here, enjoy the Wikipedia geothermal heat pump entry:
Here’s a system I really like:
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.
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:
Just common sense, really.
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.
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:
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. 🙂
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’.
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.
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.
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.
From: Brian H on August 8, 2010 at 12:33 pm
Maybe someday soon improved thermoelectric devices could help out with that.
From the Wikipedia Aneutronic fusion entry:
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.
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.
From: Brian H on August 8, 2010 at 5:29 pm
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…
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.
Per the site.
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?
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.
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).