Hopes of unlocking the vast amounts of renewable energy trapped deep underground in hot rocks have received a double boost, with Google.org and, separately, the Australian government putting significant funds into the technology.
The web search company's philanthropic arm announced that it will invest more than $10m (£5.4m) into ways to tap geothermal energy in locations where the technology has traditionally not been applied. The money is part the organisation's wider mission to find renewable energy sources that could replace coal in the future.
Geothermal energy is seen by many experts as a vast potential source of clean, carbon-free energy if it can be tapped efficiently. Google's money will be used specifically to develop enhanced geothermal systems (EGS).
Traditional geothermal technology harnesses naturally-occurring pockets of steam or hot water that rise from deep underground, bringing with them the energy stored by the rocks there. EGS allows those traditional techniques to be applied almost anywhere. By drilling deep into the Earth and pumping water into the hole, the underground hot rocks fracture, allowing the water to circulate and be heated. The hot water comes back the surface and is then used to drive turbines and produce electricity (watch EGS explainer video).
"EGS could be the killer app of the energy world," said Dan Reicher, director of climate and energy initiatives for Google.org. "One of the attractive aspects is that it's baseload, it's 24-hour power and that's a nice complement to solar and wind, which are intermittent sources.
"If you can put all three of these technologies together, we're going to have a much more attractive green electricity mix."
A recent report by the Massachusetts Institute of Technology estimated that tapping just 2% of the EGS resource between 3km and 10km below the surface of the continental USA could supply more than 2,500 times the country's total annual energy use. Around the world, geothermal projects in countries from Australia to Iceland and Germany already generate thousands of megawatts of electricity.
The Australian government announced on Wednesday that it would invest A$50m (£23.4m) in developing ways to convert geothermal energy into baseload electricity. Experts there believe that tapping just 1% of the potential geothermal energy in the country could provide 26,000 years of energy supplies.
Funding
Google.org's funding will provide cash for three projects in the US. The first is $6.25m for AltaRock Energy, a company based in Sausalito, California, that is researching ways to improve the efficiency of EGS projects. Potter Drilling of Redwood City, California, will receive $4m to develop ways to make drilling deep holes in hard rock less expensive. And the Southern Methodist university's geothermal laboratory, based in Dallas, Texas, will receive almost $500,000 to produce updated geothermal maps of North America.
Larry Brilliant, executive director of Google.org, said that innovation would be the "path to massive quantities of cleaner, cheaper energy. The people we're funding today have a real shot at lowering the cost of EGS, and bringing us closer to our goal."
The investment is part of Google.org's Renewable Energy Cheaper than Coal initiative, which is primarily focusing on solar thermal power, wind and EGS. The organisation has set itself a goal to produce one gigawatt of renewable energy capacity, enough to power a city the size of San Francisco, within a few years.
"EGS is critical to the clean electricity revolution we need to solve the climate crisis, but EGS hasn't received the attention it merits. That's why we're pressing for expanded support from government and increased investment from the private sector," said Reicher.
He criticised the US government for ignoring the EGS potential on its doorstep. "We have a new president and congress starting in November and we're optimistic that whoever is elected president is going to seize the opportunity here and we expect support."
Mike Crocker, a spokesperson for Greenpeace USA, said geothermal energy was one of several renewable sources that could help the US wean itself from fossil fuels. "Geothermal power plants produce electricity about 90% of the time, compared to 65%-75% for fossil-fuel power plants and causes virtually no greenhouse gas emissions. Today, it is technically feasible to access enough geothermal power to meet all the world's energy demands."
He added: "While Google is investing in 21st century energy solutions, Congress continues to be hung up on 19th century technologies like oil and coal."
Reicher noted that, though the cost of generating electricity from EGS today sits somewhere between solar photovoltaics at the high end and normal coal-fired power at the low end, the costs could be quickly brought down.
