Bp and Chevron, oil drilling for geothermal energy

Oil drillers are now digging geothermal wells and drilling is fuelling clean energy. As the Wall Street Journal reports, oil and gas companies including Chevron, BP and Devon Energy, are investing hundreds of millions of dollars in geothermal energy start-ups, using the same technology as drilling to search for underground heat, which can be used to generate a constant 24-hour supply of carbon-free electricity.

The new geothermal industry is the result of a surprising confluence of interests between the oil and gas, technology and green energy sectors. Finding pockets of underground heat is relatively easy in places with lots of geothermal activity, including parts of the United States, Indonesia and New Zealand. When the heat is deep, however, it is more difficult and more expensive to track it down, so much so that the sector's share of US electricity generation is less than 1%.

Now, however, technological advances in well drilling and sensor technology are expected to change this: the Department of Energy estimates that geothermal energy could power over 65 million US homes by 2050