It’s energy that has been around forever, used for years as a heating source across the world, particularly in areas with volcanic activity. Today, geothermal has surfaced as another renewable resource, with advancements in drilling technology bringing down costs and opening new areas to development.

Renewable energy continues to increase its share of the world’s power generation. Solar and wind power receive most of the headlines, but another option is increasingly being recognized as an important carbon-free resource.

Geothermal, accessing heat from the earth, is considered a sustainable and environmentally friendly source of renewable energy. In some parts of the world, the heat that can be used for geothermal is easily accessible, while in other areas, access is more challenging. Areas with volcanic activity, such as Hawaii—where the recently restarted Puna Geothermal Venture supplies about 30% of the electricity demand on the island of Hawaii—are well-suited to geothermal systems.

“What we need to do as a renewable energy industry is appreciate that we need all sources of renewable power to be successful and that intermittent sources of power need the baseload sources to get to a 100% renewable portfolio,” Will Pettitt, executive director of the Geothermal Resources Council (GRC), told POWER. “Geothermal therefore needs to be collaborating with the solar, wind, and biofuel industries to make this happen.”

1. The Nesjavellir Geothermal Power Station is located near the Hengill volcano in Iceland. The 120-MW plant contributes to the country’s 750 MW of installed geothermal generation capacity. Courtesy: Gretar Ívarsson

The U.S. Department of Energy (DOE) says the U.S. leads the world in geothermal generation capacity, with about 3.8 GW. Indonesia is next at about 2 GW, with the Philippines at about 1.9 GW. Turkey and New Zealand round out the top five, followed by Mexico, Italy, Iceland (Figure 1), Kenya, and Japan.

Research and Development

Cost savings from geothermal when compared to other technologies is part of its allure. The DOE is funding research into clean energy options, including up to $84 million in its 2019 budget to advance geothermal energy development.

2. This graphic produced by AltaRock Energy, a geothermal development and management company, shows the energy-per-well equivalent for shale gas, conventional geothermal, an enhanced geothermal system (EGS) well, and a “super hot” EGS well. Courtesy: AltaRock Energy / National Renewable Energy Laboratory

Introspective Systems, a Portland, Maine-based company that develops distributed grid management software, in February received a Small Business Innovation Research award from the DOE in support of the agency’s Enhanced Geothermal Systems’ (EGS) project. At EGS (Figure 2) sites, a fracture network is developed, and water is pumped into hot rock formations thousands of feet below the earth’s surface. The heated water is then recovered to drive conventional steam turbines. Introspective Systems is developing monitoring software that enables EGS systems to be cost-competitive.

Kay Aikin, Introspective Systems’ CEO, was among business leaders selected by the Clean Energy Business Network (CEBN)—a group of more than 3,000 business leaders from all 50 states working in the clean energy economy—to participate in meetings with members of Congress in March to discuss the need to protect and grow federal funding for the DOE and clean energy innovation overall.

Aikin told POWER that EGS technology is designed to overcome the problem of solids coming “out of the liquids and filling up all the pores,” or cracks in rock through which heated water could flow. The Introspective Systems’ software uses “algorithms to find the sites [suitable for a geothermal system]. We can track those cracks and pores, and that is what we are proposing to do.”

Looking for more insight into geothermal energy? Read our “Q&A with Geothermal Experts,” featuring Dr. Will Pettitt, executive director of the Davis, California-based Geothermal Resources Council, and Dr. Torsten Rosenboom, a partner in the Frankfurt, Germany office of global law firm Watson Farley & Williams LLP.

“In my view there are three technology pieces that need to come together for EGS to be successful,” said the GRC’s Pettitt. “Creating and maintaining the reservoir so as to ensure sufficient permeability without short-circuiting; bringing costs down on well drilling and construction; [and] high-temperature downhole equipment for zonal isolation and measurements. These technologies all have a lot of crossover opportunities to helping conventional geothermal be more efficient.”

Aikin noted a Massachusetts Institute of Technology report on geothermal [The Future of Geothermal Energy: Impact of Enhanced Geothermal Systems (EGS) on the United States in the 21st Century] “that was the basis for this funding from DOE,” she said. Aikin said current goals for geothermal would “offset about 6.1% of CO 2 emissions, about a quarter of the Paris climate pledge. Because it’s base[load] power, it will offset coal and natural gas. We’re talking about roughly 1,500 new geothermal plants by 2050, and they can be sited almost anywhere.”

NREL Takes Prominent Role

Kate Young, manager of the geothermal program at the National Renewable Energy Laboratory (NREL) in Golden, Colorado, talked to POWER about the biggest things that the industry is focusing on. “DOE has been working with the national labs the past several years to develop the GeoVision study, that is now in the final stages of approval,” she said.

The GeoVision study explores potential geothermal growth scenarios across multiple market sectors for 2020, 2030, and 2050. NREL’s research focuses on things such as:

■ Geothermal resource potential – hydrothermal, coproduction, and near-field and greenfield enhanced geothermal systems.

■ Techno-economic characteristics – the costs and technical issues of advanced technologies and potential future impacts and calculating geothermal capacity.

■ Market penetration – modeling of dozens of scenarios, including multiple reference scenarios.

■ Non-technical barriers – factors that create delays, increase risk, or increase the cost of project development.

The study started with analyses spearheaded by several DOE labs in areas such as exploration; reservoir development and management; non-technical barriers; hybrid systems; and thermal applications (see sidebar). NREL then synthesized the analyses from the labs in market deployment models for the electricity and heating/cooling sectors.

Geothermal Is Big Business in Boise The first U.S. geothermal district heating system began operating in 1892 in Boise, Idaho. The city still relies on geothermal, with the largest system of its kind in the U.S., and the sixth-largest worldwide, according to city officials. The current system, which began operating in 1983, heats 6 million square feet of real estate—about a third of the city’s downtown (Figure 3)—in the winter. The city last year got the go-ahead from the state Department of Water Resources to increase the amount of water it uses, and Public Works Director Steve Burgos told POWER the city wants to connect more downtown buildings to the system. 3. This plaque, designed by artist Ward Hooper, adorns buildings across downtown Boise, Idaho, denoting properties that use geothermal energy. Courtesy: City of Boise Burgos said it costs the city about $1,000 to pump the water out of the ground and into the system on a monthly basis, and about another $1,000 for the electricity used to inject the water back into the aquifer. Burgos said the water “comes out at 177 degrees,” and the city is able to re-use the water in lower-temperature (110 degrees) scenarios, such as at laundry facilities. The city’s annual revenue from the system is $650,000 to $750,000. “We have approximately 95 buildings using the geothermal system,” said Burgos. “About 2% of the city’s energy use is supplied by geothermal. We’re very proud of it. It’s a source of civic pride. Most of the buildings that are hooked up use geothermal for heating. Some of the buildings use geothermal for snow melt. There’s no outward sign of the system, there’s no steam coming out of the ground.” Colin Hickman, the city’s communication manager for public works, told POWER that Boise “has a downtown YMCA, that has a huge swimming pool, that is heated by geothermal.” He and Burgos both said the system is an integral part of the city’s development. “We’re currently looking at a strategic master plan for the geothermal,” Burgos said. “We definitely want to expand the system. Going into suburban areas is challenging, so we’re focusing on the downtown core.” Burgos said the city about a decade ago put in an injection well to help stabilize the aquifer. Hickman noted the city last year received a 25% increase in its water rights. Boise State University (BSU) has used the system since 2013 to heat several of its buildings, and the school’s curriculum includes the study of geothermal physics. The system at BSU was expanded about a year and a half ago—it’s currently used in 11 buildings—and another campus building currently under construction also will use geothermal. Boise officials tout the city’s Central Addition project, part of its LIV District initiative (Lasting Environments, Innovative Enterprises and Vibrant Communities). Among the LIV District’s goals is to “integrate renewable and clean geothermal energy” as part of the area’s sustainable infrastructure. “This is part of a broader energy program for the city,” Burgos said, “as the city is looking at a 100% renewable goal, which would call for an expansion of the geothermal energy program.” Burgos noted that Idaho Power, the state’s prominent utility, has a goal of 100% clean energy by 2045. As Boise grows, Burgos and Hickman said the geothermal system will continue to play a prominent role. “We actively go out and talk about it when we know a new business is coming in,” Burgos said. “And as building ownership starts to change hands, we want to have a relationship with those folks.” Said Hickman: “It’s one of the things we like as a selling point” for the city.

Young told POWER: “The GeoVision study looked at different pathways to reduce the cost of geothermal and at ways we can expand access to geothermal resources so that it can be a 50-state technology, not limited to the West. When the study is released, it will be a helpful tool in showing the potential for geothermal in the U.S.”

Young said of the DOE: “Their next big initiative is to enable EGS, using the FORGE site,” referring to the Frontier Observatory for Research in Geothermal Energy, a location “where scientists and engineers will be able to develop, test, and accelerate breakthroughs in EGS technologies and techniques,” according to DOE. The agency last year said the University of Utah “will receive up to $140 million in continued funding over the next five years for cutting-edge geothermal research and development” at a site near Milford, Utah, which will serve as a field laboratory.

“The amount of R&D money that’s been invested in geothermal relative to other technologies has been small,” Young said. “and consequently, the R&D improvement has been proportionally less than other technologies. The potential, however, for geothermal technology and cost improvement is significant; investment in geothermal could bring down costs and help to make it a 50-state technology – which could have a positive impact on the U.S. energy industry.”

For those who question whether geothermal would work in some areas, Young counters: “The temperatures are lower in the Eastern U.S., but the reality is, there’s heat underground everywhere. The core of the earth is as hot as the surface of the sun, but a lot closer. DOE is working to be able to access that heat from anywhere – at low cost.”

Investors Stepping Up

Geothermal installations are often found at tectonic plate boundaries, or at places where the Earth’s crust is thin enough to let heat through. The Pacific Rim, known as the Ring of Fire for its many volcanoes, has several of these places, including in California, Oregon, and Alaska, as well as northern Nevada.

Geothermal’s potential has not gone unnoticed. Some of the world’s wealthiest people, including Microsoft founder Bill Gates, Amazon founder and CEO Jeff Bezos, and Alibaba co-founder Jack Ma, are backing Breakthrough Energy Ventures, a firm that invests in companies developing decarbonization technologies. Breakthrough recently invested $12.5 million in Baseload Capital, a geothermal project development company that provides funding for geothermal power plants using technology developed by Climeon, its Swedish parent company.

Climeon was founded in 2011; it formed Baseload Capital in 2018. The two focus on geothermal, shipping, and heavy industry, in the latter two sectors turning waste heat into electricity. Climeon’s geothermal modules are scalable, and available for both new and existing geothermal systems. Climeon in March said it had an order backlog of about $88 million for its modules.

“We believe that a baseload resource such as low-temperature geothermal heat power has the potential to transform the energy landscape. Baseload Capital, together with Climeon’s innovative technology, has the potential to deliver [greenhouse gas-free] electricity at large scale, economically and efficiently,” Carmichael Roberts of Breakthrough Energy Ventures said in a statement.

Climeon says its modules reduce the need for drilling new wells and enable the reuse of older wells, along with speeding the development time of projects. The company says the compact and modular design is scalable from 150-kW modules up to 50-MW systems. Climeon says it can be connected to any heat source, and has just three moving parts in each module: two pumps, and a turbine.

4. The Sonoma Plant operated by Calpine is one of more than 20 geothermal power plants sited at The Geysers, the world’s largest geothermal field, located in Northern California. Courtesy: Creative Commons / Stepheng3

Breakthrough Energy’s investment in Baseload Capital is its second into geothermal energy. Breakthrough last year backed Fervo Energy, a San Francisco, California-based company that says its technology can produce geothermal energy at a cost of 5¢/kWh to 7¢/kWh. Fervo CEO and co-founder Tim Latimer said the money from Breakthrough would be used for field testing of EGS installations. Fervo’s other co-founder, Jack Norbeck, was a reservoir engineer at The Geysers in California (Figure 4), the world’s largest geothermal field, located north of Santa Rosa and just south of the Mendocino National Forest.

Most of the nearly two dozen geothermal plants at The Geysers are owned and operated by Calpine, though not all are operating. The California Energy Commission says there are more than 40 operating geothermal plants in the state, with installed capacity of about 2,700 MW.

Geothermal “is something we have to do,” said Aikin of Introspective Systems. “We have to find new baseload power. Our distribution technology can get part of the way there, toward 80% renewables, but we need base power. [Geothermal] is a really good ‘all of the above’ direction to go in.” ■

—Darrell Proctor is a POWER associate editor.