Enhanced Geothermal Systems
Examining Social Impacts for Equitable Development
Geothermal Energy Systems
What is Geothermal Energy?
Geothermal energy is heat energy from the earth—Geo (earth) + thermal (heat). It is a renewable energy that (unlike solar and wind) can be steadily produced all day every day.
Watch this video from the Department of Energy to learn more about how geothermal energy systems work.
What are Enhanced Geothermal Systems (EGS)?
Naturally occurring geothermal systems exist in places where there is heat, water, and permeability (or spaces in the ground for that fluid to circulate), such as where the tectonic plates of the Earth are converging or diverging. In Montana, the most famous natural geothermal system is Yellowstone, which can be seen with its geysers, hot springs, and boiling mud pots. But, places where that permeability naturally exists are limited. Enhanced Geothermal Systems (EGS) involve creating a human-made reservoir, where there is hot rock underground, but insufficient or little natural permeability. In an EGS, fluid is injected into the subsurface under carefully controlled conditions, which cause pre-existing fractures to re-open, creating permeability. With EGS, we could exponentially expand our capacity to tap into the earth's energy all over the world, rather than rely on places with naturally occurring systems. The U.S. Geological Survey estimates that potentially 500,000 megawatts of EGS resource is available in the western U.S. or about half of the current installed electric power generating capacity in the United States.
Where is Geothermal energy?
Areas with greater geothermal activity are more likely to be developed for geothermal energy prodcution. In the United States this primarily occurs in the West. On this map areas that are red have the greatest geothermal activity while the blue areas have the least.
Current Geothermal Projects.
As of 2014 most of the operating geothermal sites are in California, Nevada, and Utah. These are viewable on the map as the larger green pins. The smaller pins mark sites that sites being developed. Zoom in to see geothermal production zones in more detail. Enhanced Geothermal Energy
Benefits & Risks
All types of energy production can produce both positive and negative impacts to individuals, households, and communities. These can include economic impacts, environmental impacts, health impacts, cultural impacts, and other impacts to our wellbeing. It is important to consider the impacts that geothermal energy might have and how it compares to alternatives to ensure that it is developed responsibly.
Importance of Domestic Renewable Energy
Experts and planners expect domestic energy demand to increase beyond our current production capacity, especially with the growth of manufacturing, industry, and data centers. In order to preserve domestic energy security, current standards of living, and economic growth the United States needs to increase energy production.
Simultaneously, electricity production continues to be the largest source of CO2 emissions for the United States through the use of fossil fuels. Renewable and cleaner energy sources are needed and several different kinds of sources are likely needed to meet demands. Geothermal energy offers an important resource for meeting domestic electricity needs while assisting in curtailing national impacts on anthropogenic climate change through its low production of CO2.
Emissions and Economics
Geothermal energy is renewable and produces comparably low CO2 emissions. Binary-cycle geothermal plants, which operate in a closed-loop cycle, release essentially zero emissions.
Geothermal, which can run at all times, offers a more constant supply of energy than wind or solar. It does not depend on the weather and can be used to meet spikes in energy demand or adjusted for intermittent energy production. Furthermore, because geothermal produces energy at a constant rate consumers get consistent energy prices.
Developing more geothermal energy would increase the available domestic energy supply, which would also decrease consumer energy prices.
Mineral Production
Geothermal power plants can also produce important minerals without the environmental impacts associated with hard rock mining (Pacific National Laboratory, PNNL 32-717) .
Geothermal plants produce large amounts of brine, which contains economically significant amounts of valuable elements such as lithium, magnese, silica and others. concentrations of such minerals have been found in plants in the U.S. mWest ( Neupane and Wendt, 2021 ).
Access to lithium in particular is essential for renewable energy development as an essential material for the development of batteries.
Economic Comparison
In the short-term, developing geothermal energy systems requires higher initial costs than renewable alternatives. Initial costs are high because geothermal requires pre-drilling geotechnical studies, exploratory drilling, and development drilling.
However, in comparison to other renewables geothermal energy has fewer costs to run and maintain. When their initial and operational costs are combined into their levelized cost of energy they are clearly a cost-competitive energy option. While some alternatives are cheaper, geothermal is the most efficient alternative since they can run at full capacity for longer period of time.
Geothermal and Water
Geothermal Energy production requires much less water than other energy sources and can utilize non-freshwater sources (Jia et al., 2021). By 2050, geothermal energy could respresent 8.5% of total U.S. electricity generation while being accountable for only 1.1% of power sector water withdrawals ( Department of Energy ) . This is a significant advantage of geothermal compared to hydropower and first-generation biofuels, though wind and solar usually require even less water because they do not require cooling systems.
Some worry that geothermal energy production could impact surface geothermal water features such as hot springs and geysers, either by draining the water features or impacting water quality. These concerns may depend on the kind of geothermal technology used. With enhanced geothermal technology that utilizes a binary closed-loop system, plants draw from water sources far deeper in the earth and re-inject that water so that surface water is not reduced. Chena Hot Springs Resort installed the state of Alaska's first geothermal plant in 2006, which powers the resort in addition to creating small-scale commercial geothermal energy.
Pollution
Risks of pollution also depend on the kind of conversion and cooling technology that geothermal energy plants use, but some types of geothermal energy plants can cause air and water pollution during operation. Any steam vented at the surface may contain hydrogen sulfide, ammonia, methane and carbon dioxide. Dissolved solids discharged from geothermal systems include sulfur, chlorides, silica compounds, vanadium, arsenic, mercury, nickel and other toxic heavy metals ( U.S. Fish and Wildlife Service ). While large concentrated releases of these substances, can be harmful to both humans and other organisms, usually the amounts from geothermal plants are small and less than the pollution emitted from coal and gas production. Risks can be reduced by using newer (though more expensive) binary closed-loop technology that circulate geothermal fluid underground, rather than releasing it and establishing regulations.
Harm to animal and plant species would be especially significant to communities that depend upon for cultural, economic, health, and environmental services. Additionally, some chemicals such as mercury even in small quantities can become dangerous through the processes of bioaccumulation and biomagnification, where chemicals saturate an ecosystem over time. Currently, however, one of the biggest drivers of bioacculumation and biomagnification of toxins in marine and aquatic ecosystems are oil spills and pollution from crude oil production. ( Almeda et. al, 2013 ) Regardless, safely containing and removing any toxic substances will be important to geothermal energy development.
Earthquake Risks
Enhanced geothermal systems cause seismic activity because drilling into the Earth and removing material releases pressure that causes the ground above the geothermal pocket to shift, subside, and create seismic activity. Usually, however, this is at such a low level that it is not felt by humans at all or any more than when a large truck drives down the street.
Moreover, geothermal resources are typically found in places where there are already high levels of seismic activity that are carefully monitored and infrastructure that is designed to withstand such activity. Zoom in on map to compare developing and operational geothermal production sites, fault lines.
Still, caution is required to protect against the possibility of triggering a larger seismic event. Luckily, we know a lot about how to minimize and manage such risks, as we do so now in extracting natural gas through fracking (which has similar risks of seismic activity). This can be done by carefully monitoring the injection of fluid through rock and having a safety system in place. Utah Forge, for example, has an adaptive "traffic light" system in place that does real-time monitoring of the probability of seismic events that allows them to adjust both the pumping of fluid and speed of injections (including stopping altogether if necessary).
Siting
Where geothermal energy plants are sited has impacts on local communities. Some communities have addressed the visual impact of geothermal plant wells and pipes by making them more visually appealing. For example as seen in this image, Enel Green Power has installed decorative lighting projected onto its geothermal power plant at Larerello, Italy.
Geothermal Energy plants also require infrastructure such as roads, transmission lines, and housing for workers. This infrastructure can provide greater transportation and electricity access, and stimulate local economic activity. However, these changes can increase the cost of living and strain current infrastructure services.
Energy Justice
In assessing how geothermal energy development might impact communities, it is important to consider not just overall benefits and risks, but also in how those benefits and risks are distributed across communities.
Justice in energy transition requires ensuring that the benefits and risks are fairly distributed, so that those who are shouldering any risks also receive significant benefits. It is also important to take into account certain populations who may already experience inequalities due to past injustices. We conducted GIS mapping of environmental and social data to evaluate how plant siting and geothermal energy production may impact rural communities, communities with lower household incomes, communities of color, Tribal Nations, and coal-impacted communities (or communities where jobs and economic opportunities are decreasing in the transition away from coal and other fossil fuels).
Who Can build Geothermal Energy?
Utility scale geothermal energy sites are initially incredibly expensive to build because of the speculative nature of trying to determine where geothermal energy is available and because of the high cost of drilling thousands of feet into earth.
These high costs require large amounts of capital, which makes its production prohibitive for many communities to build themselves. Additionally, knowledge of geothermal energy production is highly specialized and complex, which creates another barrier for communities hoping to construct this energy source. Partnerships with geothermal companies and investors, as well as access to Federal subsidies and grants offer communities the best opportunities to develop geothermal energy.
This graph shows that the initial costs of enhanced geothermal energy development is high, but diminishes overtime. CAPEX combines infrastructure, generation equipment, installation, operation, development, and siting costs.
Who will be impacted by Geothermal Energy Development?
Many of the planned and/or potential sites are in rural communities where the average household income is below the federal poverty line. These might be places that could benefit from economic development related to geothermal, but only if they can be part of the geothermal workforce or jobs are created to support the geothermal workforce. Geothermal Energy plants initially require a large workforce for construction of the plant and necessary infrastructure, but when in operation they only need a small workforce of highly trained specialists.
At the same time an influx of workers to construct and operate a geothermal energy plant while potentially providing local economic stimulus would also likely raise the cost of necessities such as housing.
The size of the "house with people" pin shows the relative household income with larger pins reflecting higher incomes. Note that many of the planned geothermal energy sites are in counties with lower household incomes with the exceptions being central Colorado, California Bay Area, and around Salt Lake City, Utah.
Environmental Justice and Race
Lower income communities and communities of color have been disproportionately impacted with the burdens of energy production, such as waste dumping and pollution. At the same time, those communities often have less access to the benefits of energy production, such as electricity.
For Example the 32% of homes within the largest Native American Tribe in the US, the Navajo Nation, lack electricity and another 86% lack natural gas heating. ( https://sourcenm.com/2023/08/09/navajo-nation-gives-updates-on-program-to-bring-electricity-to-communities/ ) Despite this lack of access the Navajo Nation has long been a major supplier of coal, oil, uranium, and more recently solar power. The energy produced has been shipped out of the Navajo Reservation while Navajo communities still wrestle with the negative health impacts of its production.
Health risks may be particularly significant for populations that already suffer from health disparities or other environmental health risks, including poor, rural, African American, Native American, and Latino or Hispanic communites.
With geothermal energy development, it will be important to ensure that any groups, particularly ones that have been disproportionately impacted by other environmental risks, benefit from geothermal energy development. This can be done by building equitable partnerships in places where plants are sited, ensuring access to energy produced, and minimizing risks of any pollution.
On this map by clicking on "the person" pins you can view the racial and ethnic demographics within a county to get an idea of which groups may be impacted by ongoing, planned, or potential geothermal energy projects.
Vulnerability
Vulnerability and access to healthcare is spread unevenly around the country, which makes some populations more vulnerable to potential negative health impacts from geothermal energy. The Social Vulnerability Index is a composition of factors (shown below) that act as indicators for a communities capacity to deal with threats to health and disasters. Access to healthcare improves a communities ability to manage health and disaster risks. In the West, Tribal and rural primary communities have the highest social vulnerability and lowest access to healthcare.
Geothermal Energy and Native American Tribes
Many geothermal energy development projects have been sited near or on Native American Tribal lands. Zoom in on Southern California, Northern/Central Nevada, Eastern Arizona, and Western Utah to see examples of proposed geothermal energy sites near or on Reservation lands. Alaska and Hawai'i while not shown on this land also have significant geothermal energy development opportunities on and near indigenous lands.
The Federal Government has a trust responsibility to support Tribal interests, but historically this has not been the case. However, recent legislation has made more federal money available for tribes especially for renewable energy development. Many, but certainly not all tribes, have lower indicators of well-being than the average US citizens as a lasting legacy of settler colonialism. Geothermal energy could be used by Tribes as a way to improve their quality of life, but only if they control or co-manage the process. Tribes have their own histories and cultures that makes geothermal energy development on their lands complicated. The following case studies will explore this complexity in more detail.
Rural Communities
Many planned geothermal energy sites are in rural parts of the West. As highlighted in the previous graphic, rural populations often have less access to healthcare and have to travel further to reach amenities. With smaller populations these communities also often have less infrastructure than other parts of the country. In the West, most rural populations participate in agricultural economies, which makes them particularly vulnerable to negative environmental impacts. Together these factors make rural communities particularly vulnerable to potential negative environmental, health, and economic impacts.
From this map the smaller "the person" pin is the smaller that counties population size, which is a good indicator that the county is rural. A lack of major roadways also represented on this map is another indicator of how a rural a community is. This map shows that the majority of planned geothermal sites are in rural communities.
Coal Impacted Communities
Coal Impacted Communities are communities that once were dependent upon local production of coal, but as a result of closures of mines and plants are now struggling economically. There are some places where coal impacted communities may have the opportunity to transition their economies to geothermal energy production, which may help with jobs and other economic benefits.
As this map shows, there is crossover between counties with coal impacted communties (pink) and potential geothermal sites, especially in Utah.
Compounding Factors
Sites selected for geothermal energy development are often impacted by one if not several of these factors. In fact, factors such as health care access, presence of transportation infrastructure, electricity, demographics, and income are often interrelated. These factors can compound and exacerbate the impacts that geothermal energy development can have for a community especially when multiple vulnerabilities are present.
By using the magnification feature (the "+" in the bottom right) and dragging the map with your cursor you can zoom in on the yellow circle region. In this part of Southeastern Utah the relationships between these factors becomes more pronounced. These coal impacted communities have both low populations and household income. A string of proposed and constructed geothermal energy sites runs from the Southwest to the Northeast. These geothermal energy sites are also placed along the few electricity transmission lines in the region. By magnifying in on the Cover Fort Geothermal site, we can see a geothermal site adjacent to the Reservation of the Kanosh Band of the Pauite Indian Tribes of Utah.
The following case studies will explore the complexity of how geothermal energy production impacts Native American Communities.
Impacts to Indigenous People
The development of EGS in the U.S. West, has and will likely continue to impact Native American, Native Alaskan, and Indigenous Hawaiian communities. Established by a series of Supreme Court rulings colloquially referred to as the "Marshall Trilogy" the Federal Government has a Trust responsibility to manage land for the benefit of Native American peoples. However, over the past two centuries the Federal Government has often utilized Tribal lands for the benefit of non-Native American peoples at the detriment of Native American peoples. This along with the longer history of Native American removal, violence, and lack of recognition has created a culture of distrust for the Federal Government. These processes have also produced a gap in health and economic wellbeing between indigenous peoples and non-indigenous peoples in the United States.
Geothermal energy could provide indigenous communities with a reliable source of energy and support economic development. These outcomes would also support Tribal Sovereignty, which is defined here as Tribal Nations capacity to govern their own resources, land, and people according to their own interests and values. However, barriers including costs of development, recognition of indigenous sacred lands, inadequate risk communication, and inclusion of indigenous peoples in the decisions making process have all collectively challenged the development of geothermal energy by indigenous peoples or on indigenous lands.
These issues can best be addressed by making more federal money and technical expertise available for indigenous peoples to develop their own geothermal energy sites. Additionally, effective communication about costs and benefits of geothermal energy to indigenous communities as well as consulting and co-managing with indigenous peoples offers a pathway towards greater acceptance for geothermal and access to the wealth of geothermal energy on indigenous lands.
Paiute-Shoshone Tribe and Dixie Meadows
The Fallon Paiute-Shoshone Tribe or the Toi-Ticutta ("Cattail Eaters") occupy a reservation in Central Western Churchill County.
The Toi-Ticutta live in two communities. The Stillwater Reservation 12 miles from the city of Fallon and the Fallon Colony which is 1 mile outside of Fallon. To the Northeast of these territories is the Dixie Valley (Paunma) that the Toi-Ticutta have lived in and around for 10,000 years.
Dixie Valley is a sacred land for the Paiute-Shoshone. It contains their burial sites of their ancestors and historic objects. The natural hot springs in the region continue to be used by the Toi-Ticutta for healing, ceremony, and medicine. These hot springs also support a wetland ecosystem in the otherwise dry Dixie Valley.
In 2021 the Bureau of Land Management gave Ormat Technologies approval to develop the Dixie Meadows Geothermal Project. This project includes 2 geothermal power plants and 18 wells in the Dixie Valley.
On this map, the Dixie Valley Region is colored blue and the green marker within it marks the proposed Dixie Meadows Geothermal Project.
The continous orange block and surrounding orange groups to the West of the Stillwater National Wildlife Refuge make up the land of the Toi-Tocutta.
Geothermal energy production has been found to have major impacts on the surrounding hydrology. Geothermal production has been shown to decrease or stop nearby hot spring activity.
This is evidenced by Ormat's nearby Jersey Valley Geothermal Project that dried up the local hot springs within several years of beginning its operation. Ormat is now responsible for pumping water back into the this emptied hot springs via pipeline.
The Dixie Valley wetlands supported by its hot springs is the only home for the endangered Dixie Valley Toad. Prompted by fear of the hot spring drying up from this geothermal energy development the Center of Biological Diversity sued BLM. The Fallon-Paiute Shoshone joined this suit against the BLM for not consulting with them about this geothermal development on their sacred lands.
Now Ormat has scaled down their plans to one geothermal plant and is currently undergoing a environmental impact assessment. This video provides a tour of another of Ormat's geothermal energy plants.
Without consultation of local communities developers are unaware of the significance of landscapes for those communities. In this example, the Dixie Meadows Geothermal Energy Project was approved before Tribal consultation. Which resulted in the projects disregard for the valleys environmental, cultural, and historical significance for local peoples, the Toi-Tocutta.
Puna Geothermal Venture and Native Hawaiians
Hawai'i currently has the goal of transitioning to 100% renewable energy by 2045. Pull the slide to see current renewable energy projects in the state of Hawai'i.
Graphic from Hawaii Electric 2023 Sustainability Map
Puna Geothermal Venture (PGV) is situated on Hawai'i Island. Built in .. The project ran from .. to ... Despite its significant contribution to Hawai'i's renewable energy portfolio it remains controversial.
PGV is built alongside Kīlauea .
The red pin marks Kīlauea and the yellow pin marks PGV.
The development of renewable energy is essential for combating climate change. Yet, it is important we consider who will bear the costs of a transition to renewable energy. PGV was build by Ormat Technologies, a company founded in Israel in 1965 and now headquatered in Reno, Nevada. Ormat Technologies technology and geothermal energy plants are found on every continent except Antarctica.
Red pins show geothermal sites built by Ormat Technologies in North America.
PGV has received criticism from Kānaka Maoli as a desecration of the Hawaiian Goddess of fire and volcanism, Pele. In indigenous Hawaiin religion Pele presence is found wherever volcanic activity on the big island takes place, but her home along with her sibling deities is on Kīlauea. Worship of Pele and other indigenous Hawaiian religious practices were outlawed through the colonization and christianization of the state in 19th century.
Reverence to her is an act of cultural preservation for indigneous Hawaiians. Some Kānaka Maoli have protested PGV as a desecration of the sacred Kīlauea.
PGV had some of its facilities destroyed and forced to shurt down between 2018-202 because of Kīlauea's volcano's eruption in 2018.
There are mixed opinions about the relationship between geothermal energy production and earthquakes. A correlation has been found, but whether this is because geothermal projects are often cited near fault zones for access to geothermal energy or because they actually cause seismic activity is currently unknown.
PGV has also faced opposition because of its release of pollutants. In 2016, the EPA fined PGV for not meeting the safety standard for the pollutant, hydrogen sulfide. Hydrogen Sulfide is a pollutant that at low levels is simply an irritant, but at high levels can cause unconscioussness or death. Geothermal energy has the potential to release pollutants into surrounding water, air, and ground surface. While Geothermal releases less pollutants than other energy production processes, it is not an entirely "clean" process.
Between pollutants and potential seismology there are real concerns for communities hosting geothermal projects. Communities need to have the opportunity to decide whether they are willing to bear the risks. This can be done through risk education and community engagement during the geothermal planning process.
Unanagan and Makushin Geothermal Project
In 2020, Ounalashka Corporation and Chena Power LLC (OCCP) partnered to build the Makushin Geothermal Project on Unalaska island's Makushin volcano. Makushin Geothermal aims to provide enough energy to support the busy shipping town of Unalaska.
Ounalashka Corp. was established by the 1971 Alaska Native Claims Settlement Act is a Native Village Corporation for the Aleuts (Unangan) of Unalaska and Amaknak islands.
Over the past 4 years the Makushin Geothermal Project has made little progress and is struggling to raise sufficient funds. The town of Unalaska is looking to dissolve their agreement with the OCCP and find a new arrangment of partners.
Unalaska Island, as one of the Aleutian Islands stretching into the Pacific is remote. Like many Alaskan communities the city of Unalaska currently relies upon the expensive importation of diesel to create electricity. The production of local renewable energy provides a way for Unalaska to cut carbon emissions and save money.
The yellow pin on the map is Makushin Volcano. Directly East is the city of Unalaska and the busy port of Dutch Harbor. By zooming out with the buttons on the bottom right you can see the remoteness of this isalnd.
This promotional video for Makushin Geothermal reveals how geothermal energy can meet Unalaska's energy needs and support its growth.
While geothermal energy development is always initially expensive, this specific project has been made more expensive because of the area's challenging topography and isolation.
As this map reveals the Makushin Geothermal Project will require extensive infrastructure. This plan calls for roads, helicopter pads, power cables, communication cables, 3 production wells, and 2 injection wells.
Not only is infrastructure needed, but also specialists, construction teams, and engineers to build it. Supporting this scale of infrastructure can put strain on local communities especially if they are small and isolated. Influxes of workers can also add stress to essential services such as policing and medical care, as well as basic necessities such as housing.
Over the past 4 years the Makushin Geothermal Project has made little progress and is struggling to raise sufficient funds. OCCP was only able to raise $7.5 million of the necessary $250 million. The town of Unalaska is dissolving their agreement with the OCCP and is hoping to win the $500 million Climate Pollution Reduction Grant from EPA.
Even when indigenous communities do approve of geothermal energy development they often need financial support to make it succeed. This can be accomplished through a combination of Federal Grants, Federal renewable energy subsidies, investment and private energy company collaboration.
Yet, collaboration, outside investment, and often grants require Indigenous communities to relinquish some control of the project.
Photo of field research at Makushin
Lessons for Equitable Energy
Local Consultation and Participation
Geothermal energy availability is highly localized determining where geothermal plants can be built. Most of those locations are in rural areas, near or on indigenous lands, and in counties with lower incomes and higher social vulnerability. Consideration must be given to how these local communities will be impacted both negatively and positively by geothermal energy implementation. Consultation with local communities is the first step towards building local acceptability. As projects continue ensuring community participation with the planning, decision, and management processes is essential for project success.
Risk Communication
Without full communication of all of the risks of geothermal systems stakeholders cannot make an educated decision about developing geothermal energy. Risk communication requires sharing knowledge of potential harms in terms that are understandable to stakeholders. The likelihood of risks as well as acknowledgement of differential vulnerability is also important. When risks are fully communicated communities can make educated decisions.
Risk Management
As has been the case with other forms of energy production, risk minimization and management will be necessary. With geothermal, this will mean involving communities at early stages, minimizing risks of pollution, and carefully monitoring seismic activity. Utilizing newer geothermal technologies will also be important. (Binary-Cycle Geothermal Systems have several advantages over flash and dry steam geothermal energy plants. They are closed systems, which means they have a low probability of releasing pollutants and have almost zero greenhouse gas emissions. Since binary-cycle systems release few pollutants into the atmosphere they are a safer alternative and therefore are more likely to receive community support.
Federal Financial Support
While geothermal energy has relatively low management costs the initial exploration of geothermal sources, well siting, and well construction is incredibly expensive. While private industry can play an important role here, industry may need some incentives. Moreover, relying on private industries to develop and produce industries can threaten Tribal sovereignty (for sites on or near Tribal Nations) or community autonomy (particularly in vulnerable areas). Yet neither Tribal Nations or socioeconomically disadvantaged communities are likely to have the capital that would be needed for doing their own geothermal energy development. Therefore, it is likely that continued federal support will be necessary for the early stages of geothermal system construction, particularly for ensuring equitable partnerships. In recent years, the Federal Government has made more grants, capital, and tax deductions available to renewable energy projects, but these have primarily been focused on solar energy.
Acknowledgements
This storymap was created by Angus Cummings, Kristen Intemann, and Margaret Althaus and based on work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under award #4212028 and the Center for Science, Technology, Ethics and Society at Montana State University. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the U.S. Department of Energy, the U.S. Government, or Montana State University.