Large-scale projects for the production of geothermal energy begin, essentially, with a detailed study of rocks. As AltaRock Energy's President/Chief Technology Officer Susan Petty told GEA by email, technology improvements "are no substitute for a thorough understanding of geology." The process of gathering and analyzing data on geologic layers of Earth is a complicated dance buoyed in recent years by a focus on innovative research and development from industry experts and aided in part by federal incentives and loans.
A distinguishing characteristic of exploring a geothermal system is that it requires drilling. “Drilling is the only definitive method available to identify and delineate heat, permeability, and fluid supply,” according to the prepared presentation by AltaRock Energy for the National Geothermal Summit, a Geothermal Energy Association (GEA) event in Sacramento this past August. Joe Lovenitti, VP of resource, contributed to a panel of drilling innovation experts.
Representatives from AltaRock were also at the event in another capacity; the geothermal industry presented their company a GEA Honors Special Recognition award for the renewable energy company’s efforts in commercialization of Enhanced Geothermal Systems (EGS) technology for power generation. The project, located outside Oregon’s Newberry National Volcanic Monument, targets improvements in stimulation methods that could benefit the entire geothermal industry.
While the award recognized the successful work of dozens of individuals or more, the panel discussion reflected the industry’s urgent need to overcome significant drilling risks to effectively bring down costs. Iovenitti’s statement on drilling came with a caveat; “Any improvement in drill site selection through enhanced geoscience data understanding and integration, as well as breakthrough methodologies, will reduce risk,” he said. Exploratory and drilling techniques essential for the success of the industry are costly and are largely ignored by incentive programs. Many industry experts hope that together the industry and investors, including government, can form solutions before time and/or money runs out.
Echoing this was James Faulds, director of the Nevada Bureau of Mines, University of Nevada, Reno - a panelist with Iovenitti at the Summit. A combination of government- and industry-sponsored efforts, Faulds noted in his presentation, is needed to reduce drilling risks in the geothermal industry.
"Geothermal exploration and wellfield development are expensive and risky propositions," says Karl Gawell, executive director of the GEA. "Government incentive policies and research efforts need to help address this problem for geothermal power production to really see dramatic expansion."
The message is clear: While some geothermal power plant technologies may be maturing as the industry grows, there is much to be done. The reduction of risks and costs, particularly of subsurface work, is key for future technology development. The options are being examined right now by scientific and industry professionals as well as by representatives in the federal government and Congress.
Developers hope the message will spread to other representatives and investors soon enough to defy one of the looming threats they face: the end to production tax credits. Tax credits for geothermal are an important driver to the industry, but are set to expire at the end of 2013 if not acted upon by Congress.
EGS Scientists Are Solving Practical Problems
The EGS technology concept differs from conventional geothermal development, as EGS allows energy extraction from geothermal resources where the naturally occurring combination of heat, water, and rock permeability is not sufficient for commercial development on its own but could be enhanced or created through methods of stimulation.
“Companies like AltaRock are focusing on some very practical problems, like how to stimulate multiple zones in a well,” Ann Robertson-Tait said in a conversation with GEA on innovative technologies and enhanced geothermal systems (EGS). Robertson-Tait, senior geologist and business development manager for GeothermEx, a long-established geothermal consultancy, chaired the August panel that seated Faulds, Iovenitti, and others: Hildigunnur Thorsteinsson, team lead at the U.S. Department of Energy (DOE); Bruce Kohrn, a manager at Lockheed Martin interested in the geothermal space; and Patrick Walsh, chief geologist with Ormat Technologies.
AltaRock along with Davenport Newberry were awarded a $21.4 million matching DOE grant to create and test the EGS reservoir. The partnership is using AltaRock’s hydroshearing technology at a well drilled by Davenport in 2008. According to the project’s Web site, their goal is “to bring the price of EGS in line with existing utility rates to demonstrate that EGS at Newberry can be an economically viable source of baseload renewable energy.” The project has garnered much attention from press as scientists explain the nature of using drilling and stimulation technology to learn more about the geology outside the Newberry National Volcanic Monument.
A main component of the project is to add diverters – granular materials – into the water injection line to temporarily plug-up existing fractures, thus diverting the water to form other fractures, as described on AltaRock’s website. The materials dissolve away with time and heat.
The ability to isolate multiple zones in a reservoir “is a critically important element of stimulating EGS wells,” Robertson-Tait explains. “Stimulating multiple zones is important because in low-permeability rock, we need to exploit as many small fractures as possible to maximize the productivity or injectivity of each well. AltaRock and other companies are seeking other robust solutions to accomplish this goal,” she says.
Subsurface Analysis without Drilling: Geothermal’s “Holy Grail”
The geothermal industry has grown at an increased pace over the last few years. Since 2006, when the Energy Policy Act's new geothermal tax incentive and leasing provisions took effect, 14 different companies have built 28 geothermal power plants or additions in nine states with a combined power capacity of 502.7 MW. The 2006-2012 growth represents an 18% increase in total U.S. megawatts (MW) online, and during this period 33% of U.S. geothermal power plants were either built or expanded.