Positives of fracking

"Geothermal is homegrown, reliable and clean," says Rohit Khanna, program manager at the World Bank for its Energy Sector Management Assistance Program. That is a big part of the reason it is being pursued in developing countries such as Chile, Indonesia, Kenya and the Philippines.

Australia's first enhanced geothermal system, spicily named Habanero, began producing power in May, and Europe has brought three such power plants online. A geothermal power plant in Larderello, Italy, has churned out electricity this way in Tuscany for more than a century, and big power plants can be built this way.

By some estimates, the U.S. could tap as much as 2,000 times the nation’s current annual energy use of roughly 100 exajoules (an exajoule equals a quintillion, or 10¹⁸ joules) via enhanced geothermal technologies. With respect to electricity, the DoE concludes at least 500 gigawatts of electric capacity could be harvested from such EGS systems. Even better, hot rocks underlie every part of the country and the rest of the world. The Geysers in California can produce 850 megawatts of electricity alone.

The idea is simple: pump water or other fluids down to the hot rocks beneath the surface. Heat from the rocks turns the water to steam. The steam rises and turns a turbine that spins a magnet to make electricity.

Some places have the natural bounty of hot rocks and cracks in them. But such sites are not plenty.  That's where fracking, the controversial practice of pumping fluid underground to shatter shale and release oil or gas, can help. Fracking “enhances” geothermal by making cracks in hot rocks where none existed, allowing heat to be harvested from Earth’s interior practically anywhere, although this reduces the total power produced because of the need to pump water through the system.

Yet, geothermal’s abundant, renewable, clean potential for making electricity largely languishes, producing "less than 1 percent of global energy," according to a recent perspective in Science. Indeed, only 6 percent of naturally occurring geothermal resources have been tapped to date, according to Bloomberg New Energy Finance (BNEF).

The reason is simple: money. In addition to the $6-million to $8-million risk of drilling a dry hole or a well that does not produce steam as it should there is the multimillion-dollar expense of building a power plant on top of those wells that do produce steam as they should. That adds up to a total cost for a geothermal power plant of roughly $90 per megawatt-hour,

Gradient holes have to be drilled to explore a particular area. Explosions need to be set off at the surface to send seismic waves through the rock that allow for surveying the underground landscape—a technique familiar from the oil and gas industry. It can take years and millions of dollars to do this exploration with the prospect of earning that money back slowly via electricity sales—or all those funds could be lost.

 BNEF puts the odds of successfully completing a geothermal well at 67 percent, which means one third of all geothermal projects fail. The analyst outfit has called for a "global geothermal exploration drilling fund" of some $500 million provided by investment agencies like the World Bank.

Another problem: some EGS projects have been associated with small earthquakes, much like oil and gas drilling and wastewater disposal. That has caused some projects to be abandoned.