The next energy efficient generation scheme could be low-temp geothermal

Jul 28, 2009 2:13 PM

Capturing heat from low-temperature geothermal resources holds promise for generating virtually pollution-free electrical energy.

Scientists at the Department of Energy’s Pacific Northwest National Laboratory have figured out an innovative approach to economically extracting and converting heat from vast untapped geothermal resources. They aim to enable power generation from low-temperature geothermal resources economically.

“By the end of the calendar year, we plan to have a functioning bench-top prototype generating electricity,” says PNNL Laboratory Fellow Pete McGrail. “If successful, enhanced geothermal systems like this could become an important energy source.”

Researchers at the Massachusetts Institute of Technology looked at geothermal energy in general, not just PNNL's approach, and found geothermal systems could provide 10% of the nation’s overall electrical generating capacity by 2050. The MIT report is here:

http://geothermal.inel.gov/publications/future_of_geothermal_energy.pdf

PNNL’s conversion system depends on a new liquid researchers call biphasic fluid. When exposed to heat brought to the surface from water circulating in moderately hot, underground rock, the thermal-cycling of the biphasic fluid will power a turbine to generate electricity. Nanostructured metal-organic heat carriers, or MOHCs, boost the power generation capacity to near that of a conventional steam cycle.

“Some novel research on nanomaterials used to capture carbon dioxide from burning fossil fuels actually led us to this discovery,” said McGrail. “Scientific breakthroughs can come from some very unintuitive connections.”

You can watch a short YouTube video of McGrail talking about the process here:

http://www.youtube.com/watch?v=ierTocw1BG8