Google's philanthropic arm, Google.org, yesterday announced plans to invest $10.25m (£5.5m) in research into a new form of geothermal energy technology that advocates claim could provide more than 2,500 times the US annual energy use.

Conventional geothermal power plants work by finding naturally occurring pockets of steam or hot water, limiting their usefulness to areas such as Iceland and New Zealand where such locations are more common. However, so-called Enhanced Geothermal Systems (EGS) seek to replicate that approach more widely by artificially fracturing hot rocks and circulating water through the cracks to create steam, which in turn drives turbines.

Read more on Google's eco-investment here.