Geothermal energy plant at The Geysers near Santa Rosa in Northern California, the world's largest electricity-generating geothermal development. | Photo courtesy of the National Renewable Energy Laboratory.
GreenFire Energy began work to demonstrate a process that would use CO2 to harness geothermal energy to make electricity. What is more, the technology has the potential to add carbon sequestration – not to mention reduced water consumption – to the benefits already associated with geothermal power.
Few start-ups are founded by retirement-aged scientists – and even fewer have Google.org backing. That's the unique position of Potter Drilling, a start-up founded in 2004 by a pioneering now-90-year-old and his son.
Since 1960, steam from the 45 square mile field spanning Lake and Sonoma counties has been extracted to drive turbines and generate baseload renewable electricity. Fifty years later, Houston-based Calpine Corporation operates 15 geothermal plants at The Geysers.