Session 2F: Regional Updates

Fort Providence, Kakisa, Hay River, and Enterprise are four South Slave communities located in the Northwest Territories (Canada). These communities rely on fossil fuels for space and water heating, and could benefit from geothermal systems. The South Slave Region is estimated to have the highest heat flow (>100 mW m-2) in the Western Canadian Sedimentary Basin (WCSB), therefore is a target for geothermal exploration. However, an analysis of the characteristics of a deep geothermal system has not been undertaken in this region. This research project objective is to fill this knowledge gap by providing a Precambrian basement temperature assessment below the sedimentary basin, around the four communities.

The Devonian sedimentary rock sequence on which the communities lie is relatively thin (500 to 750 m) and has relatively low permeability (on average < 10-14 m2). The lack of information on the Precambrian basement below Devonian sedimentary rocks limits the development of deep geothermal energy resources due to high uncertainty and risk. Deep borehole heat exchangers (DBHE) could be an appealing technology for direct use of heat applications in this geological context. However, a comprehensive assessment requires a detailed understanding of the thermal properties of the rocks. This information is mandatory to model such systems accordingly and provide accurate temperature estimates at depth that could be used for heating.

A rock sampling campaign focusing on the Precambrian basement rocks was made in summer 2023, during which 91 outcrops and drilling cores were sampled to analyze their thermal properties. A range of thermal conductivity expected in the Precambrian basement was determined for the location of each community. Then, the results were used to extrapolate the subsurface temperature in the Precambrian basement until 10 km depth. The newly available information confirmed the presence of a significant geothermal potential in these communities.

In the more likely scenario (the normal one), the basement temperature ranges from 30.5 to 36.5 °C, with a basement surface heat flow of 102.6 mW m-2 to 151.4 mW m-2. At 3 km depth, temperature ranges from 101.5 to 151.5 °C; at 10 km depth, temperature ranges from 306.5 °C to 495 °C for each community. Hay River has the highest values and most promising geothermal potential for deep closed-loop system.

Motivated by a Department of Defense directive to reduce coal consumption and guided by the 2022 United States Army Climate Strategy, the Army Office of Energy Initiatives began pursuing geothermal energy opportunities for various locations throughout the United States, carried out through the Defense Innovation Unit (DIU). One of these projects was awarded to Teverra, to explore, quantify, and design a geothermal prototype energy utilization system for Fort Wainwright (FWA) in Fairbanks, Alaska. Fairbanks is within the Tanana Valley in interior Alaska. The Tanana Valley has no significant hydrocarbon or geothermal exploration but may have geothermal potential because of the regional tectonic setting and limited far field heat flow data. As such, the FWA geothermal initiative is a greenfield exploration project located within a favorable regional tectonic setting. To date, existing datasets have been collated and used to build a simplistic 3D geologic model, and new data were collected during Summer 2024, which are being incorporated into the existing model. Here, we present a review of the project goals, existing data, and new data that were collected that will be used for defining next steps in the exploration and development process.

Geothermal power generation started at Lardarello, Italy in 1904, resulting in the first commercial plant of 250 kW being installed in 1913. New Zealand came on-line in 1958 with a 1.2 MWe plant at Wairakei followed by Mexico in 1959 with a 3 MWe plant at Pathe. The first plant in the USA was at The Geysers in northern California at 11 MWe in 1960. All these plants were of the flash steam type. The first binary power plant was at Paratunka, in Kamchatka, Siberia, Russia (1967), followed by binary plants in Japan and Iceland in 1966, and China in 1970. Today (2024), 29 countries produce electricity from geothermal resources for a total estimate of 18,000 MWe generating 108,000 GWh of electricity. The leading countries generating geothermal electricity are USA, Indonesia, Philippines, Turkey, Kenya, New Zealand, Mexico, Italy, Iceland, and Japan (>500 MWe). Geothermal direct use is one of the oldest, most versatile, and most common forms of utilizing geothermal energy. Direct use has been documented for over 2000 years throughout the world. Today (2023), the estimated installed capacity is 126,000 MWt and the annual energy use is 1,280,000 TJ (355,600 GWh) in over 88 countries. The average worldwide capacity factor over the past 25 years for direct use is 0.327, indicating 2,866 full-load equivalent capacity hours per year. Direct uses include bathing and swimming, space heating including district heating, greenhouse and aquaculture pond heating, industrial applications, and snow melting and cooling. Geothermal (ground-source) heat pumps using ground or ground-water temperatures between 5 and 30 degrees C for both heating and cooling are found throughout the world and are the largest direct use application (72% of installed capacity and 59% of utilization). The leading countries for geothermal direct use are China, United States, Sweden, Germany, Turkey, France, Japan, Iceland, Finland, and Switzerland (>2000 MWt). In summary, lower temperature resources ( < 90 degrees C) are becoming more economical for greenhouses, aquaculture and drying agricultural products such as fruit and vegetables. Lower temperatures are now possible down to 90 degrees C for power generation with units less than 1 MWe becoming economical. Geothermal heat pumps are becoming more popular and economic with over 6.5 million units presently installed worldwide.

Canadian companies and Canadian experts have made a mark in the global exploration and development of all types of mineral and hydrocarbon resources including geothermal energy. Most of the worlds exploration funds are raised on the Toronto Stock Exchange (TSX and TSX-V) that fuels the global search for mineral wealth. This is also true of the geothermal sector. But Canada’s global ambitions came after focus on Canadian geothermal resources starting in 1975. The early 1970’s worldwide oil crisis spurred increased interest in geothermal resources globally. The crises fostered an increased interest in both the USA and Canada, major oil producing nations, in geothermal resources. In 1973, a small group of energy professionals, scientists and academics came together in California to explore potential synergies and research projects that might help their countries combat the coming fuel shortages with another way to produce power. This was the nascent beginnings of the US-based Geothermal Resources Council (now Geothermal Rising). Several Canadians attended that meeting and upon returning to Canada, established the Canadian Geothermal Association as a not-for-profit technical association to bring together Canadians interested in geothermal energy both domestically and globally. The association is still active today, 50 years later, after rebranding as Geothermal Canada in 2018. During these 50 years Canadians have been active globally in all aspects of geothermal development from green-field exploration to brown-field development, to building and operating plants, to reservoir management. Canadian drilling expertise was also sought after based on the drilling of 1000’s of wells since the early 1940s. Canadian drillers and engineers found themselves involved in geothermal exploration projects in Japan, USA and elsewhere. Research also included exploration technologies such as the development of electromagnetic geophysical methods. These methods were developed and first used in Canada at Mount Meager, supported by funding from Canada’s Federal Government Natural Resources Canada (Geological Survey of Canada and the Earth Physics Branch).

Geothermal energy technologies have sometimes been excluded from large-scale renewable energy analysis efforts because of deficient geothermal representation in energy analysis models. Beginning in 2022, NREL launched a three-year effort supported by the Geothermal Technologies Office (GTO) in the Department of Energy to address this problem. The first phase consists of enabling geothermal representation in flagship NREL analysis tools and models with the same fidelity as solar and wind technologies. These tools and models are key in future-grid scenario studies that identify pathways to meeting U.S. goals for widescale electrification and decarbonization.

This paper summarizes Phase 1 progress, addressing expanded functionality of eight existing NREL modeling tools and data collection. This includes: (1) Updating the Regional Energy Deployment System (ReEDS) capacity expansion model and examining future scenarios to understand how the value and competitiveness of geothermal power is represented (e.g., grid decarbonization; emergent technologies; resource availability). (2) Updating the Geothermal Electricity Technology Evaluation Model (GETEM) with geothermal energy system costs and learning curves. (3) Enabling the Renewable Energy Potential (reV) geospatial platform to interface with GETEM for the entire continental U.S., providing geothermal supply curves that account for conventional and emerging technologies. (4) Coupling of dGeo (demand-side geothermal model) & GEOPHIRES (GEOthermal energy for Production of Heat and electricity (“IR”) Economically Simulated) and integrating ambient temperature loops in dGeo. (5) Developing a template for binary geothermal power plants via GEOPHIRES technoeconomic model to derive cost-capacity relationships for Engage, a flexible web-based energy planning model for district energy to national scales. (6) Updating the ground source heat pump model in ResStock and ComStock, which are a probabilistic representation of the U.S. national building stock. (7) Expanding the GHP module of the Renewable Energy Optimization (REopt) platform for energy system integration and optimization by including more technology diversity and techno-economic optimization of GHP systems. (8) Updating and integrating the URBANopt model (campus- to building-scale energy model) with robust, validated, and extensible open-source software that enables the computational analysis for designing community-scale district geothermal heat pump systems.

In addition to these model updates, large data collection efforts include analysis of heating and cooling demand in the United States for residential, commercial, industrial and data center sectors; and inventorying, classifying, and analyzing low-temperature datasets in Alaska, Hawai’i and the conterminous U.S.

Long-term resource planning is a primary mechanism for driving geothermal procurement in the western United States, while transmission development is increasingly required to further unlock the region’s abundant hydrothermal resources. In a prior paper, Thomsen (2021) described some of the regulatory processes and analyzed geothermal selection across a wide range of resource plans and other resource procurement decisions issued in 2019 to mid-2021. A key finding was that geothermal selection was highly variable from year to year, and the paper recommended several modeling improvements and proposed improved regional coordination. Since publication, geothermal has received significant boosts from procurement decisions by the California Public Utilities Commission (CPUC) and new projects are in evidence across the western region. This paper updates prior findings, evaluates whether the prior recommendations have been addressed, and provides suggestions for further resource planning improvements. In addition, the paper will examine whether access to geothermal resources is being sufficiently considered in transmission planning and evaluate whether the new transmission projects (which are currently most advanced) will assist in geothermal development.