Abstract
The burning of fossil fuels in modern energy production is a leading cause of climate change. Clean and renewable energy will be vitally important to prevent climate change from causing further harm. Traditional clean energy sources, like solar, wind, and hydro power have great potential, but will not be able to supply all the world’s energy needs alone. Geothermal energy, another clean energy source, has low emissions but is limited in where it can be produced. Current geothermal power plants only exist in areas with naturally occurring heat and water near the surface. New drilling and rock fracturing technologies, adopted from the oil industry, may enable geothermal energy to be produced in places without heat near the surface—a concept known as enhanced geothermal systems (EGS). ESG has the possibility of providing great amounts of energy with a low environmental impact, but the concept is still in its infancy. The depths at which geothermal resources are found is often beyond the grasp of current technology. Drilling is difficult and costly, making enhanced geothermal energy more expensive to produce than other forms of energy. New technologies and innovations will be needed to allow enhanced geothermal energy to compete. If that does happen, it has the potential to be an important source of energy in the future.
Introduction
One of the contributors to climate change, the biggest environmental issue society faces, is the production of energy. The need for energy rose dramatically in the early to mid 20th century to power things like appliances, television, and heating and cooling systems. In recent years that demand has grown, because of the reliance on computers and the increasing electrification of transportation. In the United States, total energy production was 13 times greater in 2021 than in 1950. But energy production and use itself is not what has been contributing to climate change—it is how energy has been produced. About 88% percent of energy production in the US in 2021 came from non-renewable sources, with the three biggest sources being petroleum, natural gas, and coal (U.S. Energy Information Administration, 2022). All are made up of ancient organic matter, and give off greenhouse gases when burned for energy.
Given the importance of energy to our modern society and how our current production is impacting the climate, it is critical that we shift towards renewable and, perhaps more importantly, clean sources of energy. Our current major sources of renewable energy—hydro, solar, and wind—are effective, but all have limitations. In 2021, 12% of energy came from renewable sources (U.S. Energy Information Administration, 2022). The finite quantity of fossil fuels on the earth, and the damage that they do when burned for energy, means that nearly all of our of energy will need to come clean and renewable sources in the future.
A new way of producing energy, from what are known as enhanced geothermal systems (EGS), is becoming a possibility due to technology borrowed from the oil and natural gas industry. You may be familiar with traditional geothermal energy production, which comes from naturally generated heat from within the earth. The biggest issue geothermal energy has faced to this point is that it has only been able to be produced where heat naturally occurs near the surface. EGS pushes geothermal energy forwards by allowing for production of geothermal energy in much greater quantities and in more areas of the world. In this paper I will provide a brief history of energy production and the problems current energy production faces. The next section lays the groundwork for understanding EGS by describing the fundamentals of geothermal heat. Then I will discuss how EGS works and the technology behind it. That will be followed by a discussion of EGS test projects. The final two sections deal with the issues preventing widespread use of EGS, and what the future of EGS may look like.
Past and Present Energy Production
It is important to provide a clear understanding of energy, as it is the main focus of this paper. It is broadly defined as the ability to do work. Life itself relies on this process. The food we eat contains energy that we store until we need it to do work. Humans have known how to harness other sources of energy to do work for a long time. Ancient civilizations in Greece, Rome, China, and Egypt constructed buildings to take advantage of heating from the sun (Neumeither, 2022). Biomass, mostly in the form of burning wood, was a primary source of energy for a long time due to its availability and effectiveness. Wind was used to power boats, and animals like horses and oxen used for transportation and farming. In the late 18th century, new sources of energy came into use. What we now know as fossil fuels, the compressed remains of organisms that died eons ago, came into use. Commercial coal mines began operating in the early 19th century, and by the end of the century it was the dominant form of energy. The early 20th century saw advancements in drilling that made oil and natural gas cheap enough to be competitive with coal. These powerful new energy sources powered things like steam engines and trains, and ushered in a new era of humanity—the industrial revolution. What was not understood at the time was the tremendous damage that burning fossil fuels does to the atmosphere. Despite knowing what we know now, coal, natural gas and oil remain the top sources of energy in the U.S. (King, n.d.) (Crosby, 2006).
In 2021, petroleum, or crude oil, was the largest source of energy in the U.S. (U.S. Energy Information Administration, 2022). There are a host of issues that arise from oil production and use, primary of which is the release of carbon dioxide when burned . The U.S. produces and buys so much oil that simply using up all oil reserves would well surpass the carbon budget needed to keep the planet under 2°C of warming by 2050 (Scott & Pickard, n.d.). Oil spills are a regular occurrence during harvesting and transporting that can have devastating environmental impacts. There are thousands of spills each year. Most are small, but even those can damage local ecosystems. Big spills, like the Deepwater Horizon spill in 2010 can be disastrous. The explosion that caused the spill resulted in 11 deaths and 134 million gallons of oil being dumped into the Gulf of Mexico. Oil has great potential to kill plants and animals and devastate ecosystems. It can prevent birds from being able to fly, poison fish and harm the ability of some animals to thermoregulate (National Oceanic and Atmospheric Administration, 2020). Fracking, a common method for extracting oil by fracturing rock, can have negative consequences for people living in the area. It can pollute the air with the release of gases trapped in the ground. and contaminate groundwater that is near the fracturing. People living near fracking operations often experience headaches, skin and eye irritations, and respiratory issues (McDermott-Levy et al., 2013).
Natural gas comprised 32% of energy production in 2021 (U.S. Energy Information Administration, 2022). Natural gas, at least by fossil fuel standards, is comparatively clean. It is made up mostly of methane, and when burned produces less carbon dioxide (117 pounds per million British thermal units) than oil (160 pounds) and coal (200 pounds). But there are some hidden emissions not included in that calculation. It is estimated that 29% of methane emissions in the U.S in 2019 came from abandoned oil and natural gas wells (U.S. Energy Information Administration, 2022). Methane can also be released during fracking operations. These are problems because methane is a powerful greenhouse gas. It is relatively short lived in the atmosphere, lasting about a decade, in comparison to carbon dioxide, which can stick around for centuries. Its brevity is made up for by its potency—natural gas is 100 times better at trapping heat than carbon dioxide (Moseman & Trancik, 2021).
The dirtiest of all fossil fuels, and third in 2021 U.S. energy production at 11%, is coal (U.S. Energy Information Administration, 2022). Coal is rich in carbon and produces a lot of energy, and also a lot of toxins, when burned. Heavy metals like mercury, lead and sulfur dioxide are released, in addition to carbon dioxide. Huge amounts of ash are leftover in plants that burn coal for energy. It is estimated that 100 millions tons are ash are produced this way, much of which ends up in the environment. Mining for coal can cause major health side effects, like the famous black lung disease. In recent years mountaintop removal has also been used to harvest coal. This practice destroys the local ecosystem and permanently harms the landscape (Union of Concerned Scientists, 2019).
The last major source of non-renewable energy in the U.S. is nuclear power, accounting for 8% of energy production in 2021 (U.S. Energy Information Administration, 2022). Nuclear power does not come from fossil fuels, but from the fission and decay of radioactive elements, primarily uranium. It produces virtually no emissions and is one of the cleanest energy sources in use. Unfortunately the process of producing nuclear power produces radioactive waste that will be dangerous for many thousands of years. Dispose and storage are very complicated, and something that may pose risks to people far into the future that had nothing to do with creating the problem (Jacoby, 2020). Nuclear plants have also seen some failures. Chernobyl in 1986 and Fukushima Daiichi in 2011 are the most famous examples, and have released nuclear fallout into the environment (Cohen, 2022).
Oil, natural gas, coal and nuclear power produce the overwhelming majority of power in the U.S. While natural gas and nuclear power may have a role in a clean energy future, it is clear that oil and coal do not. They alone combine for nearly half of all energy production, and trying to replace that will be difficult. Renewable energy currently accounts for only 12%, and getting that number higher will not be easy. For it to happen, existing energy sources will need to be more heavily relied upon and new sources will need to emerge. EGS, which uses the heat hidden deep below the surface, could be one of those new sources.
Geothermal Heat
To understand EGS, it is important to understand the concept of geothermal heat. Geothermal heat comes from deep within the earth. The earth is composed of four different layers, the innermost of which is the inner core. This is an extremely large—about the size of the moon—and dense ball made up mostly of iron and nickel. It is not the material that concerns us though—it is the heat. The inner core is around 10.000 degrees Fahrenheit, roughly the same temperature as the surface of the sun. The heat comes partially from the friction created when the earth was born, but mostly from the decay of radioactive isotopes. The next layer, the outer core, is similarly made up of iron and nickel. But in this case, they are in a liquid state due to the lower pressure. The layer beyond the outer core is the mantle, the thickest layer of the earth. Despite being thousands of miles away from the 10,000-degree inner core, the mantle is still very hot, as is revealed when its magma erupts onto the surface in the form of lava. The surface layer that we call home is called the crust, the fourth and final layer. The crust is not just one continuous piece of rock covering the entire surface of the earth. It is broken up into large pieces, tectonic plates, that slowly move, sometimes away from each other and sometimes into each other. The cracks in between these pieces allows the heat from the core of the earth, along with the heat produced by decaying elements in the mantle, to reach the surface (Geiger, 2019).
Much of this heat can be seen in natural occurrences, such as hot springs common around the world. Many people are familiar with the images of the Japanese Macaque, the red faced monkeys, using the heat of the earth, in the form of hot springs, to survive in cold mountain environments that no other primate could live in. Even more famous are the geysers of Yellowstone. The water is heated underground and when the pressure is high enough, the water comes bursting through the surface in a wonderous display. For millennia humans have recognized the usefulness of the earth’s heat, and have used to it great effect. There is evidence of people in North America using hot springs for heating and bathing as long as 10,000 years ago. Ancient Romans famously used hot springs for their public baths and for heating their homes. Many people believe these hot springs also provide health benefits (Alberta Culture and Tourism, n.d.).
It has only been in the past century that humans have started to realize the potential of geothermal sources for producing energy. The first geothermal power plant was created by Prince Pero Ginori Conti of Trevignano, Italy. In 1904 Conti was able to power 5 light bulbs using geothermal energy. He improved upon and expanded his operation, and opened the first geothermal power plant in 1913. Today the operation includes 34 plants that provides 2% of Italy’s energy (Unwin, 2019). The mechanisms of producing energy from geothermal systems are not terribly complex. This first of three systems-developed by Conti-is known as a dry steam power plant. In this systems the wells are hot enough to turn water into steam. The steam spins a turbine, which powers a generator that produces electricity. The leftover water can be pumped back into the well, where it will reheat and can be used for energy again. The second type, known as a flash steam power plant, works very much the same way as the dry steam plant. The difference is that the water is in liquid form when it reaches the surface due to lower underground temperatures. The water is kept at high pressure as it is being pumped, and enters a lower pressure tank when it reaches the surface. The pressure differential vaporizes the water which can then spin the turbine. The third, and currently last, way of producing energy is known as the binary cycle power plant. In this system, the hot water from the geothermal well does not spin the turbine itself. It instead comes into contact with another fluid flowing through a separate pipe. The liquid in this pipe is not water, but a liquid with a lower boiling point. The lower boiling point liquid vaporizes, and is used to spin the turbine. The water is then immediately pumped back into the ground to be reheated. This allows the use of lower temperature water for energy production, and prevents water loss (Office of Energy Efficiency and Renewable Energy, n.d.).
Today geothermal energy is produced in many countries around the world. The U.S. is the leader, producing 16.7 billion kilowatt hours a year. The majority, 70.5%, is produced in California. Other counties producing geothermal energy include Indonesia and the Philippines. There are advantages that geothermal energy has, primary of which is the lack of emissions. The only emissions geothermal plants produce are water vapor and a small number of isotopes the water picks up while underground. Binary cycle plants can even get around this issue because the water never leaves the pipe. Unfortunately, a major issue with geothermal energy is that we are just not able to produce that much of it. Geothermal energy currently provides only a quarter of one percent of the U.S. energy supply. (NS Energy Staff Writer, 2020).
Underground temperatures are the most important aspect of geothermal power. The reason so much geothermal energy is produced in the western U.S., Indonesia, and the Philippines is that they lie near major fault lines in the earth’s crust. In these regions heat is much closer to the surface, resulting in a lot of volcanic activity. It also allows for the easy creation of geothermal power plants. Historically places like these have been the only viable sources of geothermal energy, as drilling technology only allowed for wells that are a few hundred feet deep. Recent advancements made in drilling, for the purpose of finding more sources of oil and natural gas, can also be used to find hot rocks in new places. And with that, we have arrived at enhanced geothermal systems. (Tester et al, 2006).
Enhanced Geothermal Energy
Enhanced, or engineered, geothermal systems (EGS) have the potential to greatly expand our capabilities of producing this nearly emission free energy source. Traditional geothermal energy uses sites where rocks hot enough for producing energy are relatively close to the surface. EGS separates itself from traditional geothermal energy by utilizing areas that are not naturally suitable for energy production. The heat might be found far below the surface, or the rocks might not be efficient at transferring heat. As mentioned before, most current geothermal plants have wells that are only a few hundred feet dep. Current technologies allow the drilling of wells to depths of 30,000 feet, or in some cases even deeper. The current deepest oil well, known as Z-44 Chayvo in Russia, is now over 40,000 feet deep (Desjardins, 2017). At depths such as these, many more rocks of suitable temperatures for heating water are available, and thus the possibility exists for geothermal energy to be harnessed in new places.
As you can probably imagine, a significantly larger percentage of land is suitable for geothermal energy at depths of 30,000 feet than a few hundred feet, due to the higher likelihood of finding rocks that are hot enough. Typically, rock temperatures of 150 to 200 degrees Celsius are required to produce energy. Only a select few sites in the US, almost entirely in the west, are suitable for energy production at less than 1000 feet. If that depth is increased to 30,000 feet, huge portions of the country become suitable sites for energy production. These wells can be used for other purposes as well. If a well is drilled but the rocks are not hot enough for commercial use, it can still be used to provide heating. This achieves the same effect of lowering our dependance on non-renewable energy (Tester et al, 2006).
Choosing a site in which to create an EGS plant is more complicated than finding hot rocks underground. Another important factor is the porosity of the rocks, which creates permeability. All rocks have tiny pores in them, often invisible to the naked eye. Some rocks are more porous than others. The pores are important for the movement of oil, natural gas and water through the rocks. Traditional geothermal energy production requires high permeability so that water can circulate through the rocks and absorb heat. A benefit of low porosity rocks is that they are generally much hotter, but are not able to naturally circulate water. Shallow drilling can allow samples of rock to be taken that may indicate the permeability of the rock at deeper points. If choosing a low permeability rock, as will commonly be the case, further work will need to be done to make it suitable to produce energy (Tester et al, 2006).
Once a proper site is chosen, the next step in constructing an EGS plant is drilling a well. The process of drilling a well is, theoretically, nearly identical to what has been used in oil and natural gas drilling. The advancements in drilling for those traditional energy sources is largely what has allowed EGS to become possible. There are additional challenges that EGS well constructions face, like the high heat and the hardness of the rocks, which will be addressed later. At least two wells must be drilled. One is called the injection well, in which cool water is injected to be heated. The second, called the production well, brings the hot water or steam back to the surface. Of course more wells can be drilled to increase production, but any more than two is optional (Sircar et al. 2021).
Several other technologies borrowed from oil production assist in creating and widening the well. Deeper wells, like those used in EGS projects, require casing for stabilization. Expanded tubular casing has been developed in the oil industry, and offers a cheaper option than traditional casings. Under-reamers are another bit of technology used to increase the width of the well for the casings. Once the wells have been created and are fully stabilized, the next step is stimulating the rocks far below the surface (Sircar et al. 2021).
Stimulating rocks increases their permeability, allowing for more surface area to heat water. Because sites chosen for EGS often have low permeability, stimulation is necessary. One method used to stimulate the rocks is hydraulic fracturing, commonly known as fracking. This involves flushing water into the well at high pressure, fracturing some of the rock. An adjacent method, thermally induced fracturing, pumps cold water into the well containing hot rocks, and the difference in temperature creates fracturing. Fracking in the fossil fuel industry can result in oil getting into groundwater and methane being released into the atmosphere. That is not the case in EGS wells because there is no oil—only rocks. Another way to stimulate the rocks is called hydro shearing. In this method preexisting fractures are stimulated with water. (Sircar et al. 2021).
Advantages of EGS Over Other Energy Sources
So why is EGS important when we already have multiple other sources of clean energy, such as wind, solar and hydro power? These sources all have limitations that may prevent them from being the dominant source of energy everywhere in the world, and EGS can help fill in some of the gaps. I believe that solar power will likely lead the way and be the dominant source of energy in the future, simply due to the abundance of sunlight and the low cost of harvesting the energy from it. Additionally solar power, like EGS, will be viable as long as the earth exists. But there are some issues that it will face that EGS does not. Of course, solar power will be most effective when it is sunny, which is problematic in some areas of the world. Perhaps the bigger issue is the growing waste from old solar panels. Most solar panels have a 30-year theoretical life span, but that is often not realized. Solar panels are getting cheaper and more efficient as technology improves. Some individuals may see the dipping output from their solar panels as they age and decide it is more cost effective to get new ones. If many people do that, there will be a lot of waste from old solar panels, and the panels are not easy to deal with. Some places categorize them as hazardous waste, as they frequently contain heavy metals like cadmium and lead. Even when not hazardous, they are not easy to recycle and often end up in landfills. Solar panels are mostly made of glass, a cheap product that is often not worth the cost of recycling. It is estimated that the cost of recycling a solar panel is $20-30, while it costs $1-2 to send it to a landfill. It is possible, perhaps likely, that the cost of recycling will decrease over time. But at current levels of waste it is estimated that 78 million tons of solar panel waste will be produced by 2050. For this clean energy source to live up to its potential, this issue will need to be solved (Atasu et al., 2021).
Hydropower has played an important role in the history of the U.S. Many mills were constructed on rivers and streams to help farmers grind down grain. Thousands of dams were built in the 19th and early 20th century, and their power helped the US grow into the country it is today. Despite its enormous historical importance, there are a couple of major issues that hydropower faces. First, there is a huge ecological cost to constructing dams. Organisms that make their homes in rivers have evolved to live in environments with free-flowing water. Dams stop natural flow and create deep reservoirs, essentially lakes, in the middle of rivers. These lake-like habits often cannot support the same biodiversity that a free-flowing river can. Sediment that naturally travels with the flow of water and is essential for plants and bottom feeders is disrupted by dams. The dams also act as barriers that most river inhabitants cannot cross. Many species of fish, most famously salmon, travel long distances through rivers to reach their spawning grounds. Freshwater muscles live part of their lifecycle as parasites on fish gills, which enables them to travel long distances otherwise impossible due to their own lack of mobility, so anything that stops fish from moving will also stop mussels. Dams can seriously impact the abundance of these species, and the welfare of the people and other organisms that rely on them.
The second issue facing hydropower is the failing infrastructure of many currently operational dams. Many dams are decades old, and have failing pipes and levers, and crumbling concrete. The U.S. Army Corp of Engineers (n.d.) maintains a national inventory that lists 91,784 dams in the U.S. The average age of these dams is 60 years old. Little is known about the exact number of dams that are in need of repair, but it is reported at least 1700 are in poor or unsatisfactory condition. And dam failures can cause major damage. One such failure occurred in 2020 in central Michigan, when the Edenville Dam collapsed, causing massive flooding of homes and businesses-and drained an entire lake. Failures like this are likely to become more common as dams continue to age. It is estimated that the cost of repairing and upgrading all dams to a satisfactory level would cost around $70 billion (Wei-Haas, 2020). Without that level of investment, dams will likely continue to fall into disrepair, and current levels of hydropower production will fall.
Wind power is another clean energy source with huge potential, but of course has problems of its own. One such problem is that it requires a huge amount of land. The amount of energy produced over a 13 square mile area filled with wind turbines produces as much energy as a natural gas power plant contained with a city block (Merrill, 2021). If wind power is to be scaled up, a lot of land will be needed. That means less land for things like housing, businesses, and natural aeras. This could be mitigated by combining agricultural and wind farms, producing food and energy on the same land. Wind turbines can also impact wildlife, particularly birds. It is estimated that 140,000 to 500,000 birds are killed each year in collisions with wind turbines. But again, this damage can be mitigated by properly placing wind farms that are not in the paths of migratory birds (Merriman, 2021).
An issue that will not be as easy for wind energy to solve, much like solar power, is waste. The blades on wind turbines are massive, needing special equipment to transport. They are built of strong fiberglass meant to withstand the strong winds and heavy rains that they face in the huge open fields where they reside. Despite their strength, they do eventually become ineffective and need to be replaced. In the coming years it is expected that the US will have to dispose of about 8,000 blades a year, most of which are about 10 years old. This problem is only going to grow, as the wind energy business is about 5 times bigger than it was 10 years ago. Many of these blades end up in landfills specialized to accommodate them, buried 30 feet underground. They may very well be there as long as the earth exists, as fiberglass does not naturally break down. In Europe the blades are sometimes burned in kilns, but that emits a lot of pollutants. One company, Global Fiberglass Solutions, is grinding the blades down and making them into pellets to be used in construction. Much like used solar panels, these waste products must be dealt with in a sustainable manner if we are going to achieve a true clean energy world (Martin, 2020).
These faults are not meant to show that EGS is vastly superior to any other clean energy source, but to show that there is a need for more sources, as any one of these would face massive challenges in providing the bulk of the world’s power needs. But I do believe EGS has several advantages over traditional clean energy sources. The primary point is the EGS has a very small environmental impact on the surface. It does not need huge amounts of land like wind power because it goes straight underground. There is also not nearly the same quantity of waste products as some other sources of energy. Once a well is constructed all that is needed is an infusion of water, and to keep the electricity generating equipment in working order.
EGS Test Projects
There have been several efforts to test EGS and show its potential. The first was conceived at the Los Alamos National Laboratory in the 1970s. At the time it was known as hot dry rock energy, a concept which would eventually evolve into enhanced geothermal energy. The site chosen for well construction was Fenton Hill, New Mexico, located 40 miles west of Los Alamos. A pair of wells were constructed at depths of 2800 meters, which reached 195°C, and 3500 meters, which reached 235°C. Over the life of the project six more wells were drilled. This turned out to be perhaps the most successful EGS program to date, producing energy over a 15 year period, with some interruptions, from 1980 to 1995 (Brown, 2009).
Several important lessons were learned from this experiment. The first, and most important, was simply a proof of concept. This idea was conceived with no previous evidence that energy could be produced from artificial geothermal reservoirs, and it worked. The project also disproved the potential for significant water loss within the rocks. It is easy to imagine that sending water down a well filled with cracks would mean that a lot of it would be lost. This would be especially problematic going forward as water is likely to be increasingly scarce as the climate warms. But the Fenton Hill project lost water at a rate of 0.15 liters per second, about the rate of water coming out of a garden hose (Brown, 2009). This project also showed that a temporary shutdown in production will not reduce the permeability of the rock. Production at Fenton Hill was shut down in 1993 and resumed almost two years later in 1995. There was no impact on how productive the wells were after the layoff. The final lesson concerns the construction of the wells. It is important when constructing the injection and production wells that they be connected with fractures so that water can move from the injection to the production well while being heated by the rocks. Initially the Fenton Hill project attempted to drill both wells, and then fracture the rock between them. This turned out to be very difficult. It is much easier to create one well, fracture the rock, and then build a second well. There have been several attempts at recreating the success of Fenton Hill and expanding upon it in the years since. One in Switzerland ended up producing more energy than the Fenton Hill project. A few smaller plants are currently operating, one in Germany and a couple in France (Kelkar et al., 2016).
EGS Complications
Unfortunately progress on EGS has been slow, and there are several reasons for that. The U.S. Department of Energy notes that “EGS is in the same technological place today that shale gas was twenty years ago—theoretically robust, practically feasible, but so-far-unproven.” One of the difficulties it currently faces is finding an appropriate site. Geothermal resources are hidden far below the surface, and it is difficult to know where to build wells. Currently the depths at which the best geothermal resources are located is often too deep for computer modeling. Drilling to great depths just to find out if the rock underneath is viable for EGS is simply not practical. If technologies advance enough to be able to “see” several miles down into the earth’s crust, then EGS will have a much better chance (U.S. Department of Energy, 2022).
The greatest issue EGS faces is that drilling into the earth and greatly increasing the pressure inside the wells has a potential to cause earthquakes. Most of these are very small shifts that go nearly unnoticed. But there is the potential for greater damage, as was the case in Pohang, South Korea. On November 15, 2017 a 5.5 magnitude earthquake hit a densely populated area, resulting in 90 injuries and $52 million in damages. This was the largest earthquake to ever hit the area in modern times, because Pohang is not close to any major fault lines. Investigation revealed that the source of the earthquake was likely at the bottom of a well in a nearby EGS project. One of the wells was built in an area containing a previous unknown minor fault line, and stimulated the release of energy in it that way have not otherwise been released anytime soon. The operation was shut down in 2018 because of this issue. Clearly this is a huge problem, and something that will rightfully scare a lot of people away from EGS. It is especially problematic because this project was using techniques meant to minimize the risk of earthquakes by more gently injecting water into the well (Voosen, 2018). The oil and natural gas have been dealing with this issue as well, and methods to avoid seismic activity in that industry may be able to be applied to EGS. A better understanding of the earth’s crust will surely help to avoid any fault lines that are currently unknown. Another solution may be to place EGS plants in areas where even if any earthquake were to occur, it would not cause much damage. This would unfortunately mean having to transport energy over long distances to homes and businesses.
Another big problem is the difficulty in drilling. The drills used for oil and natural gas wells may not be suited for the job. Rocks best suited for EGS are extremely hard, 10 to 20 times harder than a sidewalk. Drilling into that can damage drill bits. The extreme heat can damage drilling equipment. There is also the possibility of corrosive compounds within the rocks. These factors likely make building a well for EGS more costly than one for oil and gas. This is another challenge that will only be overcome with better technology (U.S. Department of Energy, 2022).
All of these factors combine to make EGS more costly than other energy sources, at least for now. Consumers will likely choose the cheapest energy option, rather than the cleanest ones, so this cost will need to be lowered. In 2021, the average price of energy per kilowatt hour in the U.S. was 11.10 cents. (U.S. Energy Information Administration, 2022). It is estimated that current technologies would put EGS at 5.43 cents per kilowatt hour (Sanyal et al., 2007). It may be possible for consumers to pay a slightly higher price for energy, but 5 times as much is simply not going to happen. There are several ways to lower this cost. Choosing sites with high rock temperatures closer to the surface will reduce drilling costs. Better drilling techniques would do the same. More efficient methods of turning hot water and steam into energy would also lower costs. In any case, technology will need to improve for EGS to live up to its potential.
The Future of EGS
What would the future look like if people are able to solve these problems and EGS becomes a major source of energy? One big plus is jobs. There is always a lot of handwringing when new technologies come on the scene and people think they will lose their jobs, and their skills will be useless in other fields. A great benefit of EGS is that well construction is similar to the oil and gas industry, and workers skills will easily transition. Additionally the benefits to the climate could be enormous. The only emission, other than trace amounts of compounds picked up in the ground, is water vapor. By 2050, geothermal energy has the potential to offset 500 million metric tons of greenhouse gases, the equivalent of 26 million driving cars a year. Additionally by 2050, there could be a reduction of 279,000 metric tons of sulfur, 417,000 metric tons of nitrogen oxides, and 54,000 metric tons of soot. This would dramatically increase air quality across the world, especially in areas with a lot of oil drilling like Texas (U.S. Department of Energy, 2022).
Steps are being taken to ensure a bright future for EGS. The Infrastructure and Jobs Act, signed into law by President Biden last year, provided $84 million for research and development of EGS technologies. The goal is to reduce the cost of producing energy by 90%. A large chunk of this money, 40%, is going to be funneled into communities that have been harmed the most by our current energy production. This idea, known as environmental justice, is extremely important as we reshape how our energy is produced. Marginalized groups have often been unfairly harmed, with coal plants and other polluting facilities being built in the areas where people lack the power and resources to be able to keep them out. In addition to working towards a clean climate, it is critical that our energy sources also serve the needs of the people. Everyone should have access to clean air, unpolluted water, and fruitful economic opportunities. I am hopeful that the government’s awareness of this issue will help, and that EGS can provide a path for environmental justice. (U.S. Department of Energy, 2022).
The private sector is also working on making EGS more commercially viable. One company, Stada Global, is trying to improve geothermal drilling. Their technology, called the Fluid Hammer Operating System (FHOS), uses two fluid paths, rather than the traditional one, in an attempt to keep the drill stable. Drills want to take the path of least resistance, which is a problem in geothermal drilling that often contains a mix of permeable and impermeable rocks. A deep well, as is often needed for EGS, needs a consistent perimeter for stability. The FHOS also includes sensors to let the drill operator know when the drill bit needs to be changed, which also assists in maintaining a uniform perimeter (Cilliers, 2020).
The New York based company Quaise Energy is attempting to retrofit an abandoned coal power plant to produce carbon free geothermal energy. It is planning to do this not by drilling a traditional well, but by using microwave beams emitted by a device known as a gyroton. The lead researcher, Paul Woskov, has demonstrated gyrotons ability to blast holes in rocks. He believes that he will be able to increase the depth of these holes, and eventually be able to reach rocks hot enough for energy production. If he is successful, the ability to turn an abandoned power production plant into an operational one that uses clean energy, and in a cost effective manner, may make EGS much more viable (Winn, 2022).
Conclusion
The promise of a clean energy source with few externalities is almost too good to be true, but I believe EGS has the potential to do so if the challenges it faces can be overcome. This does not mean EGS is going to solve all our problems, but it can be an important source of energy in the future. We are currently living at a critical time in history, where we are on a razor’s edge of catastrophe. The impacts of climate change are already visible. Glaciers are receding, and if lost will dry up rivers and lakes. Wildfires have caused tremendous damage in many parts of the world. Intense droughts have led to desertification, making vast tracts of land virtually uninhabitable. Modern practices for producing energy, because of the reliance on fossil fuels, bear much of the responsibility for climate change. Going on any longer with such a dependance on fossil fuels is not an option.
A transition to clean and sustainable energy is perhaps the easiest way to mitigate climate change. Solar, wind and hydro power are currently the leading sources of clean energy, but more energy sources will be needed if clean sources alone are to meet modern demands. Society has become dependent on reliable energy for everything from work to entertainment. Many businesses, especially in the automobile industry, are moving towards electricity to reduce emissions, which only works if the electricity comes from sources that are cleaner than the original source of energy. ESG has the potential to provide a large portion of the clean energy needed to meet the demand, provided the remaining challenges are overcome. There has been a push from the government and the private sector in recent years to solve the issues preventing the commercial viability of EGS. If the issues do get solved, EGS can change the world for the better.
References
Alberta Culture and Tourism. (n.d.). Geothermal Energy throughout the Ages. Retrieved from http://www.history.alberta.ca/energyheritage/energy/alternative-energy/geothermal-energy/geothermal-energy-throughout-the-ages.aspx#:~:text=Geothermal%20energy%20is%20one%20of,both%20spiritual%20and%20practical%20reasons.
Atasu, A., Duran, S., & Van Wassenhove, L. N. (2021, June 18). The Dark Side of Solar Power. Harvard Business Review. Retrieved from https://hbr.org/2021/06/the-dark-side-of-solar-power
Brown, DW (2009) Hot dry rock geothermal energy: important lessons from Fenton Hill. Stanford University, Stanford, Thirty-fourth workshop on geothermal reservoir engineering, pp 9–11
Cilliers, S. (2020, July 16). Strada Global: How Our Geothermal Drilling Technology Works. Medium. Retrieved from https://medium.com/strada-global/strada-global-how-our-geothermal-drilling-technology-works-9fc5f9e42e20
Cohen, J. (2022, August 24). History's 5 Worst Nuclear Disasters. History. Retrieved from https://www.history.com/news/historys-worst-nuclear-disasters
Crosby, A. W. (2006). Children of the Sun: A History of Humanity's Unappeasable Appetite for Energy (pp. 59–62). W.W. Norton and Company.
Desjardins, J. (2017, March 21). The world's deepest oil well is over 40,000 feet deep. Insider. Retrieved from https://www.businessinsider.com/worlds-deepest-oil-well-2017-3
Geiger, B. (2019, November 11). Explainer: Earth - layer by layer. Science News Explores. Retrieved from https://www.snexplores.org/article/explainer-earth-layer-layer
Jacoby, M. (2020, March 30). As nuclear waste piles up, scientists seek the best long-term storage solutions. Chemical & Engineering News. Retrieved from https://cen.acs.org/environment/pollution/nuclear-waste-pilesscientists-seek-best/98/i12
Kelkar, S., WoldeGabriel, G., & Rehfeldt, K. (2016). Lessons learned from the pioneering hot dry rock project at Fenton Hill, USA. Geothermics, 63, 5-14.
King, H. M. (n.d.). History of Energy Use in the United States. Geology.com. Retrieved from https://geology.com/articles/history-of-energy-use/
Martin, C. (2020, February 5). The latest landfill problem comes from the renewable energy indusry. Fortune. Retrieved from https://fortune.com/2020/02/05/wind-turbine-fiberglass-landfill-disposal-renewable-energy/
McDermott-Levy, R., Kaktins, N., & Sattler, B. (2013). Fracking, the Environment, and Health. AJN, American Journal of Nursing, 113(6), 45–51. https://doi.org/10.1097/01.naj.0000431272.83277.f4
Merrill, D. (2021, June 3). The U.S. Will Need a Lot of Land for a Zero-Carbon Economy. Bloomberg. Retrieved from https://www.bloomberg.com/graphics/2021-energy-land-use-economy/?leadSource=uverify+wall
Merriman, J. (2021, January 26). How Many Birds Are Killed by Wind Turbines? American Bird Conservancy. Retrieved from https://abcbirds.org/blog21/wind-turbine-mortality/
Moseman, A., & Trancik, J. (2021, June 28). Why do we compare methane to carbon dioxide over a 100-year timeframe? Are we underrating the importance of methane emissions? MIT Climate Portal. Retrieved from https://climate.mit.edu/ask-mit/why-do-we-compare-methane-carbon-dioxide-over-100-year-timeframe-are-we-underrating
National Oceanic and Atmospheric Administration. (2020, August 1). Oil spills. Retrieved from https://www.noaa.gov/education/resource-collections/ocean-coasts/oil-spills
Neumeister, K. (2022, April 20). A brief history of solar energy. EcoWatch. Retrieved from https://www.ecowatch.com/solar-history.html
NS Energy Staff Writer. (2020, January 8). Profiling the top geothermal power producing countries in the world. NS Energy. Retrieved from https://www.nsenergybusiness.com/features/top-geothermal-power-producing-countries/
Office of Energy Efficiency & Renewable Energy. (n.d.). Electricity Generation. Retrieved from https://www.energy.gov/eere/geothermal/electricity-generation
Sanyal, S. K., Morrow, J. W., Butler, S. J., & Robertson-Tait, A. (2007, January). Cost of electricity from enhanced geothermal systems. In Thirty-Second Workshop on Geothermal Reservoir Engineering (Vol. 32, pp. 1-11).
Scott, A., & Pickard, S. (n.d.). FAQ 3: oil and gas, poverty, the environment and human rights. ODI. Retrieved from https://odi.org/en/about/our-work/climate-and-sustainability/faq-3-oil-and-gas-poverty-the-environment-and-human-rights/
Sircar, A., Solanki, K., Bist, N., & Yadav, K. (2021). Enhanced Geothermal Systems – Promises and Challenges. International Journal of Renewable Energy Development, 11(2), 333–346. https://doi.org/10.14710/ijred.2022.42545
Tester, J. W., Anderson, B. J., Batchelor, A. S., Blackwell, D. D., DiPippo, R., Drake, E. M., Garnish, J., Livesay, B., Moore, M.C., Nichols, K., Petty, S., Toksöz, M. N., & Veatch, Jr., R.W. (2006). The Future of Geothermal Energy. Massachusetts Institute of Technology.
U.S. Army Corp of Engineers. (n.d.). National Inventory of Dams. Retrieved from https://nid.sec.usace.army.mil/#/
U.S. Department of Energy. (2022, September 8). Enhanced Geothermal Shot Frequently Asked Questions. Retrieved from https://www.energy.gov/sites/default/files/2022-09/EGSFAQ_Sept22.pdf
U.S. Energy Information Administration. (2022, June 10). U.S. energy facts explained. Retrieved from https://www.eia.gov/energyexplained/us-energy-facts/
U.S. Energy Information Administration. (2022, November 10). US Electricity Profile 2021. Retrieved from https://www.eia.gov/electricity/state/
U.S. Energy Information Administration. (2022, November 7). Natural gas explained. Retrieved from https://www.eia.gov/energyexplained/natural-gas/natural-gas-and-the-environment.php
Union of Concerned Scientists. (2019, July 9). Coal Power Impacts. Retrieved from https://www.ucsusa.org/resources/coal-power-impacts
Unwin, J. (2019, October 8). The oldest geothermal plant in the world. Power Technology. Retrieved from https://www.power-technology.com/features/oldest-geothermal-plant-larderello/
Voosen, P. (2018, April 26). Second-largest earthquake in modern South Korean history tied to geothermal plant. Science. Retrieved from https://www.science.org/content/article/second-largest-earthquake-modern-south-korean-history-tied-geothermal-plant Wei-Haas, M. (2020, May 27). The problem America has neglected for too long: deteriorating dams. National Geographic. Retrieved
