Can Closed-Loop Geothermal Bridge the Transition?

The world’s population reached 8 billion in November and, for some, that milestone highlights the sad fact that an estimated 1 billion still have no access to electricity.

As countries seek to transition to cleaner-burning fuel to address environmental concerns, it can also be argued that the need to eliminate energy poverty remains just as crucial. And, for many geoscientists, that means the future energy mix must be wide-ranging and diverse to meet the needs both of the environment and the people living on the planet.

“At the end of the day, we need more energy,” said Keith Stelter, corporate marketing and strategic developer at ARC Energy. “Oil and gas has such great innovations, which at the end of the day are going to get passed on to geothermal and other industries.”

Stelter recently hosted an online seminar entitled, “Troubleshooting Geothermal Energy.”

He explained that, while wind and solar have taken off in many places, the need remains for baseload and load-following energy to address intermittency issues.

Having watched firsthand how oil and gas technology is transforming the ability to bring geothermal energy to practically any place on the map, some geoscientists believe this natural energy source is on the verge of proliferating around the world.

New companies have begun developing, testing and selling their technology to bring geothermal energy to areas that aren’t adjacent to volcanoes or that don’t have access to tectonic settings, which allow for an easy harvesting of the Earth’s heat.

Some are embracing the niche operation of repurposing traditional geothermal wells and non-producing oil and gas wells. Others are promoting widespread geothermal energy through deep vertical and multilateral wells that can bring heat and electricity to the masses.

The benefits of geothermal energy are that it is baseload and load-following, it has no hydrocarbon footprint, it has a small surface footprint (less than the size of a drilling pad), it’s available 24/7, 365 – and it is scalable.

“I can see a time when there will be geothermal everywhere,” said Andy Wood, subsurface manager at CeraPhi Energy in the United Kingdom, who was the main speaker at the seminar. “With the new closed-loop technologies, you can put a geothermal well in every village and town. You can put massive geothermal complexes next to cities. We need an energy mix that gets rid of energy poverty.”

Exchanging Liabilities for Assets

In an effort to keep energy transition costs low while still supplying an ample amount of energy, CeraPhi uses technology that enables old, traditional geothermal wells and non-producing or abandoned oil and gas wells to be converted into closed-loop geothermal systems.

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The world’s population reached 8 billion in November and, for some, that milestone highlights the sad fact that an estimated 1 billion still have no access to electricity.

As countries seek to transition to cleaner-burning fuel to address environmental concerns, it can also be argued that the need to eliminate energy poverty remains just as crucial. And, for many geoscientists, that means the future energy mix must be wide-ranging and diverse to meet the needs both of the environment and the people living on the planet.

“At the end of the day, we need more energy,” said Keith Stelter, corporate marketing and strategic developer at ARC Energy. “Oil and gas has such great innovations, which at the end of the day are going to get passed on to geothermal and other industries.”

Stelter recently hosted an online seminar entitled, “Troubleshooting Geothermal Energy.”

He explained that, while wind and solar have taken off in many places, the need remains for baseload and load-following energy to address intermittency issues.

Having watched firsthand how oil and gas technology is transforming the ability to bring geothermal energy to practically any place on the map, some geoscientists believe this natural energy source is on the verge of proliferating around the world.

New companies have begun developing, testing and selling their technology to bring geothermal energy to areas that aren’t adjacent to volcanoes or that don’t have access to tectonic settings, which allow for an easy harvesting of the Earth’s heat.

Some are embracing the niche operation of repurposing traditional geothermal wells and non-producing oil and gas wells. Others are promoting widespread geothermal energy through deep vertical and multilateral wells that can bring heat and electricity to the masses.

The benefits of geothermal energy are that it is baseload and load-following, it has no hydrocarbon footprint, it has a small surface footprint (less than the size of a drilling pad), it’s available 24/7, 365 – and it is scalable.

“I can see a time when there will be geothermal everywhere,” said Andy Wood, subsurface manager at CeraPhi Energy in the United Kingdom, who was the main speaker at the seminar. “With the new closed-loop technologies, you can put a geothermal well in every village and town. You can put massive geothermal complexes next to cities. We need an energy mix that gets rid of energy poverty.”

Exchanging Liabilities for Assets

In an effort to keep energy transition costs low while still supplying an ample amount of energy, CeraPhi uses technology that enables old, traditional geothermal wells and non-producing or abandoned oil and gas wells to be converted into closed-loop geothermal systems.

While traditional, or open-loop, geothermal wells rely on rare geological conditions by which wells can be drilled into porous hot rocks and produce brines from a subsurface reservoir, closed-loop systems can be placed nearly anywhere. Essentially, two vertical wells are drilled in a single location and serve as pipes for the circulation of a working fluid – such as glycol – that helps to harvest heat from naturally hot rocks. A heat exchanger allows the thermal heat to be used for commercial applications, such as district heating, electricity generation, greenhouse projects and direct industrial use, such as hydrogen generation, desalination, sanitizing, distilling and brewing.

“Exploration risks are one of the reasons the open-loop system has not thrived,” Wood said, citing a failure rate of 10 to 25 percent due to lack of communication between wells. “Anyone who has worked in oil and gas will know that you can map the subsurface, but unfortunately the subsurface doesn’t always play ball.”

Yet with a closed-loop system, “you are not going to fail if you just have to tap heat,” he said, adding that the average temperature needed to produce geothermal energy is greater than 70 degrees Celsius (158 degrees Fahrenheit). “The most challenging thing about closed-loop solutions is always going to be the drilling of a well in the first place, and if you think about it, that’s where the oil and gas knowledge comes in. We know how to drill wells.”

CeraPhi has developed technology to retrofit oil and gas wells by removing the pumpjack infrastructure, casing materials, and installing new closed-loop geothermal wells that help companies gain a commercial return on an otherwise costly well abandonment.

The bottom of an oil and gas well is where it is most hot, so it is an ideal location for a downhole heat exchanger for the harvesting of the Earth’s heat at the surface.

“Effectively, what you are doing is taking a liability, which is an abandonment issue, and turning it into an asset. You get to produce green energy from an oil and gas well,” Wood said. “The heat is there, and it’s going to be competitively priced compared to modern-day fossil fuel prices. The closed-loop technology is the vital difference, and it’s going to lead to a massive industry that marries with oil and gas.”

Economic Factors

Wood said that the cost to convert an oil and gas well to geothermal ranges between $300,000 and $1 million. “

It really depends on where you are because there are so many economic and geological factors to take into consideration, as well as political and legislative issues,” he added.

The most efficient way to use geothermal energy is the direct use of heat, and companies that own tens of thousands of oil and gas wells are exploring geothermal closed-loop technology to extend the life of those wells for multiple decades, Wood said.

“A lot of big geothermal regions in the United States are in California and on the west side of the country – that’s where the hot zones are,” Stelter added. “There are a lot of older wells in that area, so they could make use of a new source of electricity tomorrow.”

On average, the ideal temperature needed to generate electricity is 150 degrees Celsius (about 300 degrees Fahrenheit). However, “if you have an oil and gas well that is 50 degrees Celsius (122 degrees Fahrenheit) at total depth and it brings 35 or 40 degrees Celsius (95 or 104 degrees Fahrenheit) to the surface, there is a use for that. It can support greenhouse projects and boost the heat generated by heat pumps and compressors. It’s ultimately malleable. Heat is a great thing to be able to work with,” Wood said.

“Repurposing wells is something that we are getting a great deal of attention about because the most expensive part of geothermal energy is drilling the well,” he added. “While it varies from project to project, location to location, and country to country, I’d say the average breakeven period (for heat generation) is two to three years.”

For a geothermal well to generate electricity, the breakeven period could be as long as 10 years, he added.

The lifespan of a geothermal well is much longer than an oil and gas well – typically between 50 and 100 years – because the closed-loop systems are cased off – not allowing fluids or toxins from the subsurface to compromise the integrity of the geothermal well system, Wood added. A geothermal well is simply steel casing that is sealed off.

It also is possible to co-produce oil and gas and geothermal energy, drilling a vertical geothermal well to tap into higher temperatures and converting the heat to electricity that would run to a sidetracked well, which would be drilled into a production zone, Wood explained. One well head would produce geothermal, and the other oil or gas. The geothermal energy would be used to power the oil and gas facility and decarbonize its operation, and the oil and gas could be pumped to a production facility, also powered by geothermal energy.

CeraPhi also is working to convert existing fossil fuel plants at scale. Because geothermal energy provides the same hot steam vapor that drives coal-fired plants, it can be used in the transition of these plants, replacing the coal feedstock with steam from geothermal wells. This is what Wood described as a “quick transition” from fossil fuels to cleaner power.

Evangelism for Geothermal

Known in the industry for spearheading large-scale geothermal projects using “next generation geothermal technology,” Calgary-based Eavor Technologies Inc., is working to bring heat to the masses by pairing deep, vertical wells with many multilateral wells that are several kilometers long, to increase contact with the hot rocks to generate enough heat or electricity to power large or remote populations.

Eavor’s ability to deploy in a relatively new market is in part because the Canadian government is helping to de-risk the capital investment needed for new energy infrastructure through its Sustainable Development Technology Canada grant funding, Natural Resources Canada Clean Growth fund, Business Development Bank of Canada equity investments, and the newly announced Investment Tax Credit for Clean Technologies.

In Canada, the heating and cooling sector comprises approximately 60 percent of its carbon footprint, said Jeanine Vany, geoscientist, executive vice president and a founder of Eavor.

“We need to incentivize and educate at scale, so people can understand that you can use geothermal energy to heat and cool, and there is more to the value proposition of geothermal energy than producing electricity,” she added.

Seeing how many countries in Europe – Denmark and Germany in particular, are investing in geothermal projects for hundreds of heating districts, Vany is working to open the eyes of consumers and policymakers to the benefits of geothermal in Canada and the United States.

For places that rely heavily on wind and solar, geothermal closed-loop systems are a perfect pairing, she said.

Wind and solar have intermittency issues, and battery technology may or may not be able to solve these issues. But a flexible power output system that has “dispatchability” solves that problem.

Wind and solar can share the same distribution lines with geothermal, and Eavor’s closed-loop technology can slow the flow of its working liquid, store heat and then ramp up and dispatch that heat on demand when the sun goes down and the wind stops blowing – making geothermal a load-following energy as well as baseload.

“Wind and solar were so effective in lobbying that geothermal has always been the stepchild,” Vany said. “Wind and solar are cheap to install and procure, so that’s a short-term mindset. But the true cost is borne by the people buying the electricity. That does not include backup for solar and wind. If you look wholistically at the grid, it’s easier to show the true value of geothermal energy.”

Vany said that geothermal energy solves two issues: climate change and energy security. When addressed, it allows for scalability and energy autonomy.

Eavor is currently working with the city of Hanover in Germany – with a population of approximately 500,000 – to provide geothermal heat through existing heating infrastructure currently fed in part by coal. It also is working with the Sonoma Clean Power, a California-based community choice aggregator, to investigate the installation of closed-loop systems for geothermal power, as they do not require a tremendous amount of water to function, as do many traditional geothermal wells. “Water is an issue in California now,” Vany reminded.

As Eavor begins to prove out technology that will allow drilling to depths of 6 and 7 kilometers and as many as 12 laterals, it will be able to produce 2-10 megawatts of electricity to power 1,000-10,000 homes with each closed-loop system.

“We want scalable solutions on a gigawatt scale,” Vany said. “The topic of energy security has never been more prevalent. We have been struggling with a disrupted electricity market over the last 10 years. We haven’t invested in the last five years in oil and gas, and when you throw in wars and pandemics, you have an energy security crisis that can be hard to deconstruct and understand.”

She added, “But the fact is that First World, developed countries like the United States and Germany are having energy problems. You know the energy is out there, but it goes back to policy.”

Wood reminded that the Earth is a big ball of fire, reaching 6,000 degrees Celsius (nearly 11,000 degrees Fahrenheit) at its core. The energy from that heat is waiting for use.

When asked why more governments are not aware of newly emerging, potentially life-transforming geothermal technology, Wood responded, “Ask the question again in 10 years and people will be saying, ‘Why didn’t this happen sooner?’ Because we have provided a very simple solution to a complex problem, it will be everywhere.”

Comments (2)

Converting oil and gas wells to geothermal may not be easy, but it could have a role to play
Lee Krystinik is a keen observer of the energy world, but I am not as pessimistic as he, having seen data from some wells that produce enough water that is hot enough to run binary cycle power units developed for waste heat generation. A Rocky Mountain Oil Field Testing Center project generated power for the Teapot Dome field for several years. I too am skeptical that heat can be extracted from more than a few meters away from a borehole, unless there are large volumes of mobile fluid connected to the borehole. But in that case, binary cycle systems that bring the fluid to the surface and return it directly underground have already been shown to be technically feasible in the Teapot Dome test. Lower temperature heat applications may be useful if wells can produce enough water, and repurposed wells may be applicable for storage of heat underground with a longer cycle time than batteries (what has been called a Synthetic Geothermal Reservoir). How big a niche such systems can fill remains to be seen. A variety of options are available, and I have seen reasonable economics and signs of interest in a variety of areas. Geothermal may not provide the rapid breakeven of a good oil and gas well, but it could provide extended life to certain wells. Even deferred abandonment has its value.
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12/15/2022 5:06:49 PM
Geothermal is great, but converting old wells for geothermal... not so much.
This article conflates two ideas. Converting old oil wells to geothermal applications and the broader new-drill geothermal options. As this article notes, temperature is a critical factor, as is flow volume. To make a closed circuit system work there must be a substantial volume of fluid moving through hot rock via co-axial tubing in the wellbore. Most oil wells are limited for both critical factors... temperatures are usually a bit too low and the diameter of the casing, usually 5.5" or 4.5" severely limits the volume of fluid/heat that can be cycled. Thermal depletion around small wellbores compounds the issue. Thus, as conceptually attractive as it might be to repurpose thousands of old oil wells this application will be of limited utility. Successful geothermal implementation at scale will generally require large-diameter, deep holes drilled into hot rock, potentially with multiple laterals involved as noted. I support geothermal energy as being worthy of expansion for baseload support of intermittent energy, but policymakers must understand that implementation at scale will be complex and expensive. Our drilling expertise and our understanding of subsurface flow will be invaluable to implementation, but our old wells won't be. Assuming the proper geological settings, and docile water/rock interactions, the cost of large, deep, complex wells will be the primary limiting factor. Power per unit of cost ultimately drives all energy equations and geothermal will have to find its place within that context.
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12/13/2022 8:39:49 PM

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