Geothermal energy is the heat from the Earth. It’s clean and sustainable. It’s a renewable energy source, meaning it’s inexhaustible to humans. It can be used at a large scale (utility-level) to generate electricity, but also at a smaller scale in homes and businesses in order to provide heating and cooling, It’s also a green source of energy, meaning it does not emit greenhouse gasses that are hazardous to human and environmental health.
Geothermal is the only readily dispatched source of renewable energy. While wind and solar energy production is variable, geothermal energy is essentially always available. And, without loss, production levels can be adjusted as a function of demand from zero to the capacity of the respective developed resources. As electric power grids become more distributed and as the other fluctuating renewable energy sources provide larger percentages of the total supply capacity, this inherent quality of geothermal energy will become increasingly more valuable.
Geothermal energy has the highest capacity factor (92 percent) and one of the lowest total system levelized costs/MWh ($89.6) of all power plant sources according to the U.S. Energy Information Administration, but significant costs associated with geothermal development occur during exploration when the return on investment is undefined.
Supply of geothermal energy is limited and confined to certain areas only. The entire resource of geothermal energy is fairly bigger than that of coal, oil and gas. According to the Geothermal Energy Association’s 2013 Annual US Geothermal Power Production and Development Report, the United States has approximately 3,386-MW of installed geothermal capacity— more than any country in the world.
Although geothermal has great potential and there are many successful applications in the western United States, it is not a panacea, nor is it necessarily available everywhere it is needed. Specifically with regard to military installations, while there are many large bases in the Known Geothermal Resource Areas identified by the U.S. Geological Survey, only one full-scale power production facility has been developed to date on land controlled by the Department of Defense (DOD).
Looking beyond the use of thermal sources for generating energy, low-enthalpy geothermal energy is at present the most widely available source of energy, especially for use in generating heat, and it can be integrated into other local facilities that rely on renewable energy sources, says European report. Low enthalpy energy resources are currently being used in many communities across Europe to assist in domestic heating. This source of energy still requires more research to become more effective as part of larger scale models but clearly the technology is becoming more widely available
After many years of failure to launch, new companies and technologies have brought geothermal out of its doldrums, to the point that it may finally be ready to scale up and become a major player in clean energy. In fact, if its more enthusiastic backers are correct, geothermal may hold the key to making 100 percent clean electricity available to everyone in the world. And as a bonus, it’s an opportunity for the struggling oil and gas industry to put its capital and skills to work on something that won’t degrade the planet. Vik Rao, former chief technology officer at Halliburton, the oil field service giant, recently told the geothermal blog Heat Beat, “geothermal is no longer a niche play. It’s scalable, potentially in a highly material way. Scalability gets the attention of the [oil services] industry.”
In 2019, the world’s geothermal power capacity stood at 13,931 MW—up 40% from 9,992 MW in 2010, according to the International Renewable Energy Agency (IRENA). In 2019, 682 MW of new capacity came online, with Turkey leading the expansion (232 MW); followed by Indonesia (185 MW); Kenya (160 MW); Italy (33 MW); and the U.S. (14 MW).
Geothermal Energy for Military bases
The mission of military installations is to support the troops protecting America’s people and national interests at home and abroad. These military installations and the buildings within them must operate securely and effectively – whether their function is to house military personnel and their families, train soldiers and pilots, or re-supply troops in combat zones.
Military bases must operate without interruption. To do so, they need continuous power availability that is independent of the grid if required. Every activity at a military installation supports troops. The more effectively those activities are carried out, the better the support they provide. For example, the capability to reduce energy consumption and generate electricity from renewable resources on-site at a forward base eliminates the need to truck in fossil fuels and puts fewer personnel in harm’s way.
Geothermal energy can be useful for military installations, the ideal scenario would be to find a geothermal resource within its fence line of sufficient quality and quantity to satisfy all the electricity and heating needs. Such a scenario could reduce general dependency on fossil fuels; achieve a Net Zero energy state; provide an incredibly robust level of energy assurance (independence from the commercial power grid); and optimally reduce power costs. It will also aid in the implmentation of the Energy Policy Act of 2007, and ensuing Presidential Executive Orders, military installations must reach specific energy and greenhouse gas reduction targets
The earth’s core is composed of three layers; the outer silicate and solid crust, a highly viscous mantle, and a liquid outer core. The outer core consists of extremely hot magma or melted rock wrapping around a solid iron center known as the inner core. The molten core of the Earth, about 4,000 miles down, is roughly as hot as the surface of the sun, over 6,000°C, or 10,800°F. The heat is continuously replenished by the decay of naturally occurring radioactive elements, at a flow rate of roughly 30 terawatts, almost double all human energy consumption. That process is expected to continue for billions of years.
The ARPA-E project AltaRock Energy estimates that “just 0.1% of the heat content of Earth could supply humanity’s total energy needs for 2 million years.” There’s enough energy in the Earth’s crust, just a few miles down, to power all of human civilization for generations to come. All we have to do is tap into it.
Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth’s surface, and down even deeper to the extremely high temperatures of molten rock called magma. The direct use of the heat where it breaks the surface, in the form of hot springs, geysers, and fumaroles (steam vents near volcanic activity) have been exploited since the earliest humans. The warm water can be used for bathing or washing, and the heat for cooking.
Slightly more sophisticated is tapping into naturally occurring reservoirs of geothermal heat close to the surface to heat buildings. Almost everywhere, the shallow ground or upper 10 feet of the Earth’s surface maintains a nearly constant temperature between 50° and 60°F (10° and 16°C). Geothermal heat pumps can tap into this resource to heat and cool buildings. A geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near the building. In the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system. In the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger. The heat removed from the indoor air during the summer can also be used to provide a free source of hot water.
Wells can be drilled into underground reservoirs for the generation of electricity. Some geothermal power plants use the steam from a reservoir to power a turbine/generator, while others use the hot water to boil a working fluid that vaporizes and then turns a turbine. Hot water near the surface of Earth can be used directly for heat. Direct-use applications include heating buildings, growing plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes such as pasteurizing milk.
Hot dry rock resources occur at depths of 3 to 5 miles everywhere beneath the Earth’s surface and at lesser depths in certain areas. Access to these resources involves injecting cold water down one well, circulating it through hot fractured rock, and drawing off the heated water from another well. Currently, there are no commercial applications of this technology. Existing technology also does not yet allow recovery of heat directly from magma, the very deep and most powerful resource of geothermal energy.
The pros and cons of geothermal energy
|Generally environmentally friendly; does not cause significant pollution||Some minor environmental issues|
|Renewable and sustainable||Sustainability relies on reservoirs being properly managed|
|Reliable||High initial costs|
|Great for heating and cooling||Can cause earthquakes in extreme cases|
Geothermal Technology Breakthrough to Disrupt Geothermal Industry
Geothermal energy is still not explored fully. Geothermal energy can be made more widely available if the methods and technologies used to extract it are improved. Directional drilling in high temperatures, above 150°C or so, remains difficult, with equipment prone to melting (again, oil and gas engineers did not design their technologies with high heat in mind). As rock becomes harder, equipment must also be hardened to additional vibrations. And electronics need to be better insulated.
In October 2017, the EU Commission has released a Call for Applications: Developing solutions to Reduce the Cost and Increase Performance of Renewable Technologies. The call specificially addresses geothermal and the need for the development of novel drilling technologies to reach cost-effectively depths in the order of 5 km and/or temperatures higher than 250°C. Many technologies are being developed to take advantage of geothermal energy – the heat from the earth.
A key initiative of federal EGS research involves improving costs associated with drilling and well construction. As the National Renewable Energy Laboratory’s (NREL’s) Kate Young explained to the Senate Committee on Energy and Natural Resources last year, the cost of geothermal development is split 50% on the surface (such as for power plants and piping) and 50% below ground. “Many of the below-ground costs are borne at the front end of the project development, which can make project financing challenging,” she said. “And though drilling and well construction activities are present in many industries, time and costs are significantly higher for geothermal.”
Because it typically involves boring into harder, hotter rocks, with more lost circulation, geothermal drilling “averages about 150–200 feet per day, compared to oil and gas wells that average more than 750 feet per day, and sometimes are as fast as a mile a day (a.k.a. ‘MAD’ wells),” she noted. But breakthroughs are possible with the right research focus and funding, such as have been achieved by the oil and gas industry, Young said.
So far, to boost geothermal drilling efficiency in the near-term, NREL has embarked on a number of measures, including holding its first collaborative workshop with oil and gas efficiency experts. Research is also underway to develop sensing electronics for data collection, and machine learning to improve geothermal reservoir management. As critically, NREL is focusing on materials development for well construction, which poses another significantly high cost of geothermal development.
In Oct 2020, U.S. Department of Energy (DOE) announced the winners of the Ready! contest of the American-Made Geothermal Manufacturing Prize. Launched in April 2020, the prize is designed to spur innovation using additive manufacturing to address challenges fundamental to operating in harsh geothermal environments.
The winners of the Ready! contest – the first in a series of four progressive competitions – were announced at the Geothermal Resources Council’s Virtual 2020 Annual Meeting and Expo by Daniel R Simmons, Assistant Secretary for the Office of Energy Efficiency and Renewable Energy. “Geothermal has the potential to play an important role in our energy future,” said Simmons. “These projects will help unlock that potential through innovative approaches to additive manufacturing.”
The Geothermal Manufacturing Prize offers participants a total of up to $3.25 million in cash prizes for technologies that harness the rapid advances that additive manufacturing can provide in tool design, fabrication, and functionality. This rapid, scalable approach to prototype development not only provides cash prizes, but also engages America’s unique innovation ecosystem to help participants achieve their goals.
Advanced geothermal systems (AGS)
AGS refers to a new generation of “closed loop” systems, in which no fluids are introduced to or extracted from the Earth; there’s no fracking. Instead, fluids circulate underground in sealed pipes and boreholes, picking up heat by conduction and carrying it to the surface, where it can be used for a tunable mix of heat and electricity.
At least one project is showing good potential for AGS. In February 2020, Calgary, Alberta–based Eavor Technologies’ completed and third-party validated a demonstration of its Eavor-Loop technology at the full-scale Eavor-Lite facility near Rocky Mountain House in Alberta. Drilling, which began in August 2019, involved using two Precision Drilling rigs to connect two vertical wells through multi-lateral horizontal wellbores at a depth of 2.4 kilometers—essentially to create a closed buried-pipe system. The system uses a proprietary working fluid that is added at the surface and then circulated to harvest heat from deep in the earth.
After drilling was completed on time (within 46 days) and construction of surface facilities were constructed, it was commissioned and switched to “thermosiphon mode” in December. As well as developing the project, Eavor said it has “assembled a multi-year, multi-billion-dollar prospect pipeline,” and it is now working with strategic partners and investors to begin first commercial projects.
Because the loop is closed, cool water on one side sinks while hot water on the other side rises, creating a “thermosiphon” effect that circulates the water naturally, with no need for a pump. Without the parasitic load of a pump, Eavor can make profitable use of relatively low heat, around 150°C, available almost anywhere about a mile and a half down.
MGX Minerals Inc. together with its technology partner PurLucid Treatment Solutions Inc. have developed a novel filtration technology for the purification of geothermal brines and the associated extraction of minerals and metals, including lithium, magnesium and gold. Most importantly, MGX and Purlucid have developed an environmentally friendly, proprietary, low energy, low cost process for ultra-high temperature geothermal brines. This technological breakthrough will open doors globally to the geothermal sector, or as MGX President & CEO Jared Lazerson commented in today´s landmark press-release:
Similar to oilfield brines, it is well known that geothermal brines contain concentrated amounts of metals and dissolved salts. The presence of these impurities, combined with the necessity to reduce brine temperature in order for traditional filtration to occur, is a large industry barrier known as scaling that severely reduces flow and heat transfer of geothermal heat exchangers. This in turn negatively impacts the long-term operating performance and in many cases eliminates the economic viability of these systems. Geothermal brines are known to contain lithium, magnesium and other minerals and metals including gold.
After an initial period of research and development, MGX and engineering partner PurLucid have developed a proprietary, low energy design process that removes these scale-forming ions and dissolved salts while not requiring a reduction in brine temperatures for filtration to occur. This process utilizes PurLucid’s existing patented and exclusively licensed replaceable membrane skin layers (RSL) filtration system, originally developed by David Bromley Engineering, which creates highly charged pore spaces to force dissolved ions into colloidal particles, simultaneously filtered down to 0.01 microns. The RSL is designed specifically to foul and is removed and replaced in situ, resulting in 100% flux rate recovery. The ultrafiltration can then be followed by a patent-pending membrane distillation system in projects where heat is available. The matrix is composed of materials capable of operating at up to 700 degrees Celsius. Geothermal temperatures rarely exceed 250 degrees Celsius.
This new technology also represents an environmentally friendly alternative for geothermal brine disposition, which is largely limited to non-treated reinjection. Similar to MGX’s existing wastewater treatment and rapid petrolithium recovery units, MGX and PurLucid are conducting engineering studies to fabricate treatment systems capable of being integrated into existing geothermal infrastructure or incorporated as standalone systems for mineral and metals extraction.
Geothermal is buzzing with startups that specifically need innovation and expertise in drilling technology, the very skills many oil and gas workers already have. The “Frack King” — Mukul Sharma, an O&G engineer at UT Austin who has been key in the development of hydraulic fracturing — launched a new EGS venture called Geothermix. “When we started in the unconventional [oil and gas] space, there were a lot of issues that needed to be resolved, but over time we have increased well productivity by a factor of 4 to 10 in many shale basins,” he told Heat Beat. “We are very early on the learning curve in the EGS context, but I have no doubt that we will be able to translate oil and gas learnings from the past decade and successfully deploy these methods in EGS.” Latimer was an O&G engineer before he shifted to geothermal. Sage Geosystems was founded by Lev Ring and Lance Cook, two longtime O&G veterans. Eavor employs several O&G veterans.
For now, however, “The immediate future for geothermal power is ‘conventional’ geothermal, where you seek hot water in place,” said Pettit. Though burdened by protracted regulatory timelines, the industry at least has the backing of state environmental goals. “I think any form of policies that can help alleviate the risk on the projects are really welcomed by the industry,” he said. So far, at least 25 states and the District of Columbia include geothermal as an approved resource to meet renewable portfolio standards (RPSs).
Meanwhile, more immediate—and heartening—signals that interest in geothermal is surging has been an uptick of signed power purchase agreements (PPAs). “Last year, there were one or two, and so far in 2020, there are six PPAs in place,” said Pettitt. These include one for supply to Utah (from a Cyrq Energy plant in Nevada); one to Hawaii from an Ormat plant; and the other three to California.