Electratherm, inventor of the Green Machine that takes low grade waste heat and turns it into electricity, has announced its first geothermal installation, hooking up the little wonders to the 220°F groundwater at the Florida Canyon Mine in northern Nevada.
This is real geothermal power, not a rebranding of a ground source heat pump.
Surplus heat captured by the evaporator is used to "boil" the working fluid into a vapor. Under pressure, the vapor is forced through the screw expander, turning it to spin an electric generator. The vapor is cooled and condensed back into a liquid in the condenser. The working fluid liquid refrigerant is pumped to higher pressure and returned to the evaporator to repeat the process.
While Electratherm's main market is industry, which kicks out a lot of waste heat, the geothermal market is a no-brainer. According to the press release:
"We are fielding interest from geothermal sites around the world who want to take advantage of ElectraTherm's new technology to create power from untapped heat," said Rob Emrich, ElectraTherm Vice President of Sales. "Compared to other forms of renewable energy technology, ElectraTherm offers one of the fastest payback periods in the industry, with long-term costs of under a penny per kilowatt hour. Our five foot by five foot system can access small and remote geothermal resources, which opens up a large market for creating electricity from geothermal heat."
He notes that hot water can be exploited at mines, tens of thousands of capped oil wells where heat is captured in "geothermal brine", not to mention the natural sources.
There is a bit of a greenwashing disconnect here; this is a big honking open pit gold mine. While Earthworks Action complains that the mine is a major source of mercury pollution, reporting 440 pounds of emissions in 2006, the General Manager is comfortable saying:
"We are proud to have a solution that makes green power from our geothermal energy that has, until now, been lost as waste heat," said Joel Murphy, Vice President of Operations and General Manager at Florida Canyon Mines. "That green power is nearly free because we already pump the water for our mining operations. Florida Canyon Mining is committed to being part of the energy efficiency solution in America and we are developing multiple sources of clean power at the mine."
But I shouldn't be churlish; I hope they put these things everywhere.
As we noted last year, there is a lot of low grade heat around, and it is easy to get from solar. As the price and size of these units drops we may soon be putting them in our houses.
Electratherm see also: