Jan
31
A Great Geothermal Design Is Running at Low Source Temperatures
January 31, 2008 | 3 Comments
Gwen Holdmann has answered her community’s call for a solution for the rise in oil prices with her own ingenuity and common sense. When the local electrical generators daily diesel costs at $1,000 and the local grid 32 miles away across the Alaska wilderness, the investment for a geothermal answer looked especially good.
The problem was the local source rock only puts out 165 degree F water. But Holdmann realized the prior thinking that needed over 230 F to drive a binary system where the source heat to drive a low boiling fluid was a product of thinking in the geography, not technical feasibility. Holdmann’s innovation is the bringing the knowledge of heat pumps and the conditions for highly efficient use to geothermal – a 100 degree differential from the heat source to the heat sink in Alaska is a cinch.
Meanwhile United Technologies was looking for a partner to collaborate on a pilot project: an air conditioning unit that had been reverse engineered to run off geothermal water. So, instead of putting in electrical power to drive an air conditioner Holdmann proposed to reverse another way and use the heat pump to produce electricity.
Holdmann and United Technologies solved the two problems of low temperature power generation. First, by integrating refrigerants that operate more efficiently than isopentane the common choice in power generation. Second, the components are already mass produced which greatly reduces installed investments. The Chena Resort and the local village have $2.2 million invested including the exploration and drilling. That makes payback in the local situation of between 4 to 5 years. Slick!
The $2.2 million invested yields 2 – 200 kilowatt generation modules at a running cost of 5 cents a kilowatt – in Alaska no less! There is power left over to electrolyze hydrogen.
To check if your location is over a potential geothermal source look here. There is a 3mb version link in the lowest left hand corner that will serve for first order review.
This fall the Chena Resort and United Technologies received a DOE grant to install a demonstration plant at an oil or gas well in the U.S. With 40 billion gallons of wastewater a year the entropy that could be recovered by this system may reach up to 6,000 to 11,000 megawatts of electricity as figured by Southern Methodist University in Dallas, Texas. Holdmann says, “We feel we just need to show that it works and companies will pick up on it.” Gee, do you think?
That makes two sources for private power plants or plants built for sales to grids.
Admittedly, I find this whole thing very interesting and exciting. This size of geothermal installation looks to be priced within reach of mid sized companies and communities worldwide and with the need for the 100-degree differential, a lot of the world is included.
Its important to hat tip to Al Fin who spotted the story in the Popular Mechanics website Tuesday. Please use this link to reach the first page of the PM article. The article also offers a bunch of photographs and other information. MIT has this page discussing a study they did to examine the geothermal prospects. This new innovation from United Technologies and Gwen Holdmann at the Chena Resort takes the map potential much further out than the contour lines would suggest.
And if you’re interested and still harboring doubts, well, just book a vacation and go see for yourself!
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You mean “enthalpy,” not “entropy” here –
“With 40 billion gallons of wastewater a year the entropy that could be recovered by this system may reach up to 6,000 to 11,000 megawatts of electricity as figured by Southern Methodist University in Dallas, Texas.”
Also, that should be 40 billion **barrels** of wastewater, not **gallons**. One barrel is 42 gallons, so that’s a whole lot more water. Well, 42 times more, to be precise.
Further, the power cost is 5 cents per kilowatt-hour, not per kilowatt.
The $2.2 million that was invested in the project wasn’t all from the resort or the villagers — it included a $246,288 grant from the Alaska Energy Authority and a $650,000 loan from an Alaskan agency, the Alaska Industrial Development and Export Authority.
Finally, ya gotta give credit where credit is due–If the Chena Hot Springs Resort owner Bernie Karl hadn’t had the bright idea that his low-temperature geothermal resource could generate power, Holdmann would never have entered the picture.
Whichever way you look at it, that is a whole lot of “enthalpy” that will not become “entropy.” So it is actually entropy saved, looked at that way–converted to useful energy.
The next step beyond low-mid temperature water schemes such as this is the “hot rocks” deep drilling/rock fracture technique that borrows a great deal from oil drilling technology. Hot rocks geothermal potential goes far beyond natural geothermal steam/hot water resources.
3,000 times annual US energy use in North American hot rocks geothermal alone.
[…] pump from United Technologies set up to drive a generator instead of a motor driving the compressor as done successfully by Gwen Holdmann up in Alaska. At that time UT was looking for a collaborator to sell more units. Perhaps Raser and UT have a […]