New Geothermal Data System Could Open Up Clean-Energy Reserves

 

Forgotten and filed away decades ago, millions of documents on geothermal research are now helping scientists make harvesting Earth’s energy affordable

Geologic data does not come cheap, especially when you are using it to build a multimillion-dollar geothermal power plant. Just ask Susan Petty, president and chief technology officer at AltaRock Energy. Her company is part of a $43.8-million pilot project to tap thermal energy from Oregon’s Newberry Volcano. Engineers are injecting water deep underground to fracture superheated rocks and create a geothermal reservoir. Their eventual goal is to recirculate pressurized steam back to the surface to test a new kind of technology called an enhanced geothermal system (EGS). Unlike conventional power plants that rely on near-surface hydrothermal systems like springs and geysers, EGS can draw energy up to depths of three to five kilometers. Over the next 50 years, the U.S. Geological Survey estimates, EGS power plants could produce 100 gigawatts of economically viable geothermal energy, an amount equivalent to about 10 percent of the country’s current electrical capacity.

Yet geothermal wells need to be drilled in the right place. Without data on the distribution and quantity of geothermal energy in the upper part of the earth’s crust or a volcano as a reference point, wells may not produce much energy at all. To date, two to five out of every 10 geothermal wells prospected end up dry. Petty says that, in terms of the available exploration data, the geothermal industry is in the same place oil and gas companies were during the early 1900s. Wells cost between $2 million and $5 million, meaning geothermal investors risk losing millions on poor odds, Petty says. “The risk involved in geothermal prospecting sets the industry apart from other renewables.”

The risky nature of the business could soon change, however.

A wealth of geologic data from all 50 states and the Gulf of Mexico has been sitting unused in state and federal filing cabinets for decades. The Arizona Geological Survey is leading a coalition of universities and federal agencies on a nationwide treasure hunt to find and digitize these legacy data in a National Geothermal Data System (NGDS) to eliminate some of the financial risk companies like AltaRock face while prospecting for geothermal resources. Since the project’s inception in 2008 under $35-million in grants from the U.S. Department of Energy Geothermal Technologies Office, collaborators have digitized information from over 1.25 million oil and gas, water, and geothermal wells and expect to have as many as three million wells in the system by the end of the year.

“It has been a rescue mission,” says Roland Horne, director of Stanford University’s geothermal program. Project collaborators have found a wellspring of geothermal exploratory data in basements and old file cabinets. The legacy data come from extensive surveys of geothermal resources that were funded by the states and federal government in the 1970s, 1980s and 1990s. A prime example is a 1975-to-1992 DOE survey of geopressured resources in the Gulf of Mexico. The survey documents data from 16 wells off the coasts of Louisiana and Texas that show geopressured and geothermal energy reserves in the Gulf exceed the energy contained in all the conventional natural gas reserves of the continental U.S. At the time, the geothermal energy could not be profitably commercialized, so the data were filed away and forgotten.

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