Low-temperature Geothermal Resources Research Articles

Decarbonising primary industries with geothermal heat – a pathway to greater direct use

ABSTRACT This paper discusses the opportunities and policy levers to increase the use of low-temperature geothermal resources in New Zealand for decarbonising primary industries, in particular, covered crops. Geothermal heat (geoheat) is a local, reliable, resilient and sustainable energy source. Low-temperature geothermal energy (220°C) is available in the Taupō Volcanic Zone with low awareness of the nationwide availability of lower temperature resources. Covered crop growers in New Zealand, needing to decarbonise their operations, are investigating the potential of utilising geoheat, following the example of the Netherlands. The Netherlands has strategically invested in low-temperature geothermal energy, utilising 80 °C water resources, from ∼ 2 to 3 km below the surface to heat greenhouses. Internationally, risk mitigation schemes and insurance programmes have proven pivotal policy instruments for fostering geothermal adoption. This paper discusses the opportunities that the adoption of using low-temperature geothermal provides to New Zealand drawing upon successful models from other countries.

Region specific economic model for solid sorbent direct air capture using geothermal energy resources (S-DAC-GT)

Low temperature geothermal resources, ranging from 80° to 120 °C, may substantially lower both the cost and the CO2 emissions footprint of CO2 direct air capture (DAC) systems. This paper provides a model for determining a region-specific economic analysis for DAC with solid sorbent (S-DAC) using geothermal resources (S-DAC-GT).This paper provides a methodology and program for calculating estimated cost and carbon emissions for potential S-DAC facilities on a region-specific basis. The paper outlines the necessary region-specific characteristics required as parameters for the techno-economic model. The region-specific characteristics are then applied to an S-DAC energy and cost model based on existing literature to calculate the levelized cost per tonne of CO2 captured and stored. Further, the model provides a reasonable approximation of the carbon intensity of the S-DAC-GT system. These calculations allow selecting and prioritizing regions appropriate for potential S-DAC-GT facilities operating at a scale of ∼1 Mt CO2 captured and stored per year.This paper presents a novel approach that addresses several gaps in current DAC techno-economic analyses found in literature. First, the model is highly customizable, allowing the user to apply their own proprietary sorbent properties and region specific parameters to determine precise costs and carbon emissions for their hypothetical S-DAC-GT facility. Second, the overwhelming majority of DAC techno-economic analyses in literature assume away variability of ambient conditions, presuming stable temperature and humidity during operations. This paper directly integrates these large local ambient effects on sorbent performance and evaluates S-DAC-GT costs and carbon emissions based on specific and variable conditions dictated by the user. Third, the flexibility of the model allows the user to rapidly compare S-DAC-GT costs and carbon emissions in different user selected regions, with custom sorbent characteristics. The model provides visualizations of the sensitivity of S-DAC-GT costs and carbon emissions to different parameters and provides visualizations of the cost and carbon emissions due to variability in ambient conditions.Existing techno-economic analyses are either region agnostic or constrain their results to a specific region. The novelty of this paper and its model is the deeper technical and economic analysis of using geothermal energy as the thermal resource, coupled with customizability and visualizations that enable accelerated differentiation of S-DAC-GT costs and carbon intensity by region.

Harnessing Geothermal Energy Potential from High-Level Nuclear Waste Repositories

The disposal of high-level nuclear waste (HLW) has been one of the most challenging issues for nuclear energy utilization. In this study, we have explored the potential of extracting decay heat from HLW, taking advantage of recent advances in the technologies to utilize low-temperature geothermal resources for the co-generation of electricity and heat. Given that geothermal energy entails extracting heat from natural radioactivity within the Earth, we may consider that our approach is to augment it with an anthropogenic geothermal source. Our study—for the first time—introduces a conceptual model of a binary-cycle geothermal system powered by the heat produced by HLW. TOUGHREACT V3.32 software was used to model the heat transfer resulting from radioactive decay to the surrounding geological media. Our results demonstrate the feasibility of employing the organic Rankine cycle (ORC) to generate approximately 108 kWe per HLW canister 30 years after emplacement and a heat pump system to produce 81 kWth of high-potential heat per canister for HVAC purposes within the same timeframe. The proposed facility has the potential to produce carbon-free power while ensuring the safe disposal of radioactive waste and removing the bottleneck in the sustainable use of nuclear energy.

Study Outlines Challenges of Repurposing Oil and Gas Wells for Geothermal Applications

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 215751, “Challenges for Repurposing Oil and Gas Wells for Geothermal Applications,” by Livio Santos, SPE, and Arash Dahi Taleghani, SPE, The Pennsylvania State University. The paper has not been peer reviewed. _ This work provides insights into the technical and economic viability of repurposing oil and gas wells for geothermal energy production for direct heating. The potential benefits—especially for areas that are highly dependent on fossil fuels for heating—and challenges of this approach are assessed, while technical, market, and policy barriers for future development are identified. Repurposing oil and gas wells for geothermal energy requires a multidisciplinary approach that involves expertise in geology, engineering, and regulatory affairs. Introduction Repurposing abandoned wells for power generation in geothermal energy projects can present challenges because of the low temperatures associated with these wells. The low temperature gradients and thermal energy available in such wells have been found to limit overall power-generation potential. The same low-temperature geothermal resources can still be used effectively, however, for community heating applications. Community heating systems have lower temperature requirements compared with those necessary for power generation and are compatible with available heat from low-temperature geothermal sources. In particular, closed-loop geothermal systems, specifically designed for community heating, offer several advantageous features. The closed-loop design ensures that the fluid remains contained within the system. These systems are environmentally compatible because they do not extract or discharge water from natural sources. Additionally, with better control over the working fluid and heat-exchange process, closed-loop systems deliver optimized system performance, energy efficiency, and cost savings. They also require less maintenance and feature lower operational risks because of the closed circuit. Closed-loop systems offer fluid-selection flexibility and streamlined regulatory compliance. Not all abandoned wells are suitable for repurposing, however. Thorough feasibility assessments and well-integrity evaluations are necessary to ensure that the abandoned well is structurally sound, has the appropriate depth and geological characteristics, and can extract geothermal heat effectively. The condition of the well casing, cementing, and any potential wellbore damage also must be evaluated. An economic analysis is performed to assess the financial viability and cost-effectiveness of the geothermal community heating system. Finally, an environmental impact assessment evaluates the environmental consequences of the geothermal community heating system.

An assessment of renewable energy generation in a conventional steam power plant with geothermal feedwater preheating

Hybrid steam power plant with geothermal feedwater preheating enables conversion of low temperature geothermal resources into electricity. The paper presents results of calculation of some performance parameters for 200 MWe fossil power unit associated with geothermal well. The paper gives separation rule of renewable energy from conventional one at hybrid power plant output. An influence of geothermal fluid temperature on hybrid power plant performance is discussed in a study and illustrated in several charts.

Analysis and Research on the Development of Geothermal Energy and Future Development Trend

Scientists and engineers from all over the world have acknowledged the significance of employing environmentally friendly energy to replace fossil fuels in manufacturing as global warming has gotten worse over the past century. Geothermal energy, which is a form of subsurface energy that is stored as heat and gas, is one of many sustainable energy sources. There are currently three popular exploitation techniques. The Xero-thermal power system is appropriate for regions with shallow heat sources and mild temperature gradients since it generates energy from low-temperature geothermal resources. Flash geothermal power systems are appropriate for locations with hot fluids. Binary cycle generation system employs a secondary working fluid with a boiling point that is lower than water, allowing for power generation from lower temperature geothermal resources, thereby expanding the potential for geothermal energy production. The study then largely focuses on the key elements, such as resource availability, technological hurdles, and market conditions, that can influence the utilization of geothermal energy. Researchers and engineers can more clearly comprehend the benefits and constraints in various resource environments by closely evaluating these elements. While the government should urge the people to pay greater attention to the exploitation and deployment of renewable energy, engineers could improve drilling techniques. The current situation of harnessing and exploiting geothermal energy highlights the necessity for ongoing research and development to fully realize geothermal energy's potential. This essay contributes to the larger conversation on renewable energy and offers insightful information about the significance of geothermal energy.

Research of Geothermal Resources on Hot Dry Rock in North Songliao Basin of China

With abundant oil and gas as well as geothermal resources, Songliao Basin is a famous large continental sedimentary basin in China. So far, the research of geothermal resources in North Songliao Basin has mainly concentrated in the shallow layers where low-temperature geothermal resource is mainly developed. However, the research of deep geothermal resource in high-temperature hot dry rock is still in a blank state. Based on the Songliao Basin exploration and research achievements as well as oil exploration well data, this paper further improves geothermal resource exploration and development theories of North Songliao Basin by researching geothermal resources in high-temperature hot dry rock. Hot dry rock distribution is relatively concentrated in the North Songliao Basin, mainly in the central, southern and southeastern part of the study area, where the depth of 150 ℃ isothermal surfaces substantially less than 5km is conducive to the development of hot dry rocks. Studies have shown that two high value areas of terrestrial heat flow in the North Songliao Basin are respectively located in the southern part of the central depression area as well as the junction of three first-order tectonic belts including central depression, southeast and northeast uplift areas, where geothermal resource potential of hot dry rock is great. By using enhanced geothermal system, mining hot dry rock is feasible. This study has some guidance and reference for the development and utilization of deep geothermal resources in hot dry rock of the North Songliao Basin.

Solid sorbent direct air capture using geothermal energy resources (S-DAC-GT) – Region specific analysis

This paper reviews the potential use of low temperature geothermal resources for thermal energy necessary for CO2 direct air capture (DAC) processes (geothermal DAC or S-DAC-GT). The paper includes a literature review of DAC processes and exiting techno-economic analyses on the subject. It also provides a list of global geothermal resources, maps, and databases that would be useful in finding areas of high favorability for S-DAC-GT deployment across the world. Finally, it concludes with a techno-economic analysis of four specific regions within the United States and one European region that may potentially be attractive S-DAC-GT sites: Texas Gulf Coast, Los Angeles Basin, Alaska's Cook Inlet, and Netherlands Groningen Gas Field.The objective of this paper is to provide region specific techno-economic analyses of DAC using geothermal resources. Existing DAC techno-economic analyses of DAC are region agnostic and include a breadth of energy sources. This paper provides a deeper technical and economic analysis using geothermal energy as the thermal resource for the DAC process, and the results of this paper differentiate S-DAC-GT costs and carbon intensity by region.There remains a substantial amount of uncertainty in forecasting DAC costs when deployed at scale. The goal of this paper is not to determine a precise S-DAC-GT cost. Rather, our goal is to provide indicative savings from using geothermal resources coupled with DAC, and to provide relative S-DAC-GT costs by region.Reflecting the uncertainty around the cost of DAC, our analysis suggests a S-DAC-GT cost range of $200 to $1040 per tonne CO2 captured, depending on the underlying cost model and the region of the S-DAC-GT facility. However, the savings calculated from using geothermal resources to provide the thermal energy are more consistent (Figure 1).We also analyze the relative carbon intensity of S-DAC-GT within each region. In our model, we rely on geothermal resources to provide only thermal energy for the DAC regenerative process. The carbon intensity of S-DAC-GT by region is captured in Figure 2.

Assessment of possibility of finding geothermal energy resources around Mount Meru in northern Tanzania using classical solute geothermometry

This study uses classical solute geothermometry analysis to estimate the temperature and circulation depth of the geothermal reservoir around Mount Meru. Five springs affected by magmatic gases from a deep magmatic heat source are investigated; these include two hydrothermal springs. Results from silica geothermometers show that estimated reservoir temperatures range from 70 to 110 °C; this corresponds to a low-temperature hydrothermal system. Since Mount Meru is an active volcano, one would expect a high-temperature hydrothermal system; the low temperatures are ascribed to the mixing of hydrothermal and cold recharge waters. The geothermal reservoir is estimated to be about 1.3–1.4 km deep. Thus, the study shows that a low-temperature geothermal energy resource can be found on the eastern flank of Mount Meru.

Experimental study on medium and low temperature geothermal ammonia power generation system based on vertical tube falling film

China’s geothermal energy resources are mainly low and medium temperature, the process of ammonia solution generation and absorption is introduced to simplify the condensation heat transfer of Karina cycle, and the vertical tube falling film structure is adopted for the generator and absorber in the system, which makes the system more suitable for medium and low temperature geothermal resources. A 5 kW ammonia water power cycle power generation experimental platform based on vertical tube falling film was built. The experimental results show that under typical working conditions, the maximum heat transfer coefficient of generator and absorber can reach 1034 w/(m2 K) and 563 w/(m2 K), respectively, and the maximum output power of the system is 3 kW.

Research on medium–low temperature geothermal power generation system

In order to make full use of the medium and low temperature geothermal resources and industrial waste heat resources, a power cycle system using ammonia–water mixed solution as the working fluid is proposed. The system can use medium and low temperature geothermal resources with a temperature of 350–450 K, and the basic circulating working fluid is ammonia aqueous solutions. Simulation calculations show that the Carnot cycle efficiency of the circulation system is 14.01%, and the theoretical cycle thermal efficiency of the circulation system is 10.28%. The article further analyzes the influence of steam turbine outlet pressure and heat source temperature on the thermal efficiency of the circulation system. This research provides a reference for the effective utilization of medium and low temperature waste heat resources.

Modelling and control strategy of a distributed small‐scale low‐temperature geothermal power generation system

At present, commercial geothermal power stations are mainly high-temperature and medium-temperature geothermal energy, while the large number of low-temperature geothermal energy resources are rarely used for power generation applications. This paper proposes a new model for energy conversion in low-temperature geothermal power systems. The basic structure and working principle of this new model are analysed, in detail, a low-temperature geothermal model and a Stirling engine model for geothermal energy conversion are established, and the control strategies on the rotor and stator sides of the Stirling-driven doubly-fed generator are discussed. Finally, the simulation analysis is carried out, and its results show that the thermal conversion efficiency of Stirling’s engine can reach 38%, the output AC voltage of the power generation system reaches the set value 50Hz, 190V, and the DC bus voltage is constant at 300V, which verified the validity of the proposed power generation model and related control strategies. This system expands the range of available heat sources in geothermal power generation, makes geothermal power generation more flexible in terms of site selection, power generation capacity and control, and provides a new idea for geothermal power generation structure.

Distributive Characteristics of Hot Dry Rocks in Sedimentary Basins of China: A Study Based on Vitrinite Reflectance of Hydrocarbon Source Rocks

Abstract Geothermal resources as a type of renewable clean energy are highly contributive to sustainable development. In this study, the geothermal resources in some sedimentary basins of China were characterized, and sedimentary basins from different eras and of different types were discussed. On this basis, the major influence factors on the geothermal resources of different regions were elaborated. The geothermal resource potentials in major sedimentary basins of China were evaluated. The geothermal resources in the sedimentary basins of China are extensively distributed and diverse, which are geologically different from East to West China. The target strata of faulted basins in East China, superimposed basins in Central China, and cratonic basins in West China are mainly Cenozoic strata, Mesozoic strata, and Paleozoic strata, respectively. These target strata experienced different types of thermal events in geological historical periods. The Cenozoic faulted basins in East China are mostly heat basins. The Cenozoic sediments are superthick and largely differ in thickness among regions. The effects of Cenozoic geothermal events and the major controlling factors both differed among regions, and the causes of differences included thermal subsidence activities and magmatic activities. These basins are major potential zones for exploitation of hot dry rocks in China. The Mesozoic superimposed basins in Central China are mostly temperate basins, and the ground temperatures nowadays are mainly controlled by thermal subsidence. The potential target zones of hot dry rocks in these basins are the Paleozoic strata in the southwest of basins, which can develop into medium-temperature geothermal resources. In the Paleozoic cratonic basins in West China, the Paleozoic marine sedimentary strata are the major target strata of hot dry rocks. The Paleozoic volcanic events little affected the formation of hot dry rocks, and the formation of major hot dry rocks relied on superthick sedimentary strata, where middle- to low-temperature geothermal resources developed.

Investigation Method and Utilization Mode of Geothermal Resources in Abandoned Mines in Huainan and Huaibei

With the depletion of coal resources due to excessive exploitation and the increasing adjustment of the national energy structure, in response to the call of national policy, some mines are forced to close, and the reuse of abandoned mine resources plays an important role in the sustainable development of mining industry. This paper analyzes the general situation of abandoned mines in Huainan and Huaibei, elaborates the research methods of geothermal temperature and calculation methods of geothermal reserves in abandoned mines, analyzes and studies the utilization prospect of geothermal resources in abandoned mines in Huainan and Huaibei, and draws the following conclusions: the temperature of geothermal resources in abandoned mines in Huainan and Huaibei is 25℃ - 60℃, which belongs to the moderate-hot water and warm water resources in low-temperature geothermal resources, and can be used for geothermal heating, industrial geothermal and entertainment industries. Based on the previous experience in geothermal resource utilization mode, this paper provides theoretical and technical support for the demonstration project of resource utilization and development of abandoned mines in the Huainan and Huaibei mining areas.

Advanced exergy investigation of a combined cooling and power system with low-temperature geothermal heat as a prime mover for district cooling applications

Present work deals with the conventional and advanced exergy analyses for an ammonia-water combined power and cooling cycle integrated with a low-temperature geothermal heat resource for district cooling applications. The energy and exergy calculation of the mentioned cycle was carried out by the Engineering Equation Solver (EES) software. The thermodynamic cycle method is used for advanced exergy analysis. The advanced exergy analysis by dividing the exergy destruction into the endogenous/exogenous and avoidable/unavoidable portions reveals the reducible exergy destruction part in each cycle element. Consequently, it determines the real improvement potential in the system. Results represented that the overall exergy efficiency with real and unavoidable conditions is 41.03% and 47.29%, respectively. It was found that from the 3681.2 kW of total exergy destruction for this cycle, about 941.5 kW (26% of total exergy destruction) can be mitigated by technology modification of components, where 75% is the endogenous avoidable, and 25% is related to the exogenous avoidable part. It also showed that the prioritizing of the components improving in terms of conventional and advanced exergy is different. The conventional exergy destruction presents the priority as the boiler, the absorber, the rectifier, the HER, the turbine, the RHE, and the pump. In contrast, the advanced exergy analysis’s suggested order is the turbine, the boiler, the rectifier, the HER, the absorber, the RHE, and the pump. They suggested that improving the Turbine and the boiler, and the rectifier is more efficient in increasing the system efficiency due to high endogenous avoidable exergy destruction.

Different design aspects of an Organic Rankine Cycle turbine for electricity production using a geothermal binary power plant

In recent years, pressure has been growing to increase the share of renewable energy sources in electricity generation, which may offer opportunities for the development of geothermal energy in regions that have been so far considered unprofitable in this respect. One such country currently undergoing an energy transition is Poland in which low-temperature geothermal resources are currently used for district heating and recreation purposes. Nevertheless, research on the possibilities of using geothermal energy for electricity production is ongoing. The objective of this paper was to perform a comprehensive analysis of a binary power plant construction in relation to low-temperature petro-geothermal resources. The potential binary power plant is located in the area characterized by temperature of 120 °C at depths of 5000 m. About half of Poland’s area, especially the regions of western and central Poland, has these characteristics. It was assumed that brine at volume flow rate of 400 m3/h is a heat source for the Organic Rankine Cycle with isobutane as a working medium. The thermal efficiency based on the First Law of Thermodynamics and the power output were estimated at 10.5% and 1.79 MWe, respectively. In addition, the thermal efficiency based on the Second Law of Thermodynamics was calculated at 29.0%. For the calculated cycle parameters, a preliminary design of a two-stage axial turbine was constructed. All results were compared to the other binary power plants and they confirm that establishing the binary power plant in Poland would be thermodynamically justified. The main novelty of the present work is the combination of three issues, namely the selection of the low- temperature heat source, the design and analysis of the cycle together with a turbine adapted to these conditions.

Experimental Study on Reservoir Physical Properties and Formation Blockage Risk in Geothermal Water Reinjection in Xining Basin: Taking Well DR2018 as an Example

The Xining Basin in Qinghai Province, China, is rich in mid–low temperature geothermal resources, but the reinjection of geothermal water has not yet started. In this paper, the physical properties of rocks sampled from the newly drilled geothermal well DR2018 were analyzed, and a series of core flooding experiments was conducted to assess the formation blockage risk during water reinjection. The experimental results show that the geothermal reservoir has a low porosity of 1.64–18.68% and a low permeability of 0.04–7.23 md. The rocks are weakly consolidated, and the movable clay and sand particles account for 0.18–23.42 wt %, which results in a significant rate and salinity sensitivity. Even at low water flow velocity of 0.31–1.64 cm/min, the core permeability will drop by 35–53% after 25-144PV injection. An obvious fluctuation and decline in core permeability can also be observed as the injected water salinity decreases. The blockage risk induced by the invasion of low-content scaling and suspended particles in injected water can be covered up by the migration of movable particles in cores. The particle migration and blockage in the near-wellbore formation will be the main reason to cause the decline in the well’s geothermal reinjection capacity.

Influence of Superheated Vapour in Organic Rankine Cycles with Working Fluid R123 Utilizing Low-Temperature Geothermal Resources

An organic Rankine cycle (ORC) system with R123 working fluid has been utilised for generating electricity from low-temperature geothermal resources. The degree of superheated vapour warrants attention to be studied further. This is because the degree of superheated vapour is the last point to absorb heat energy from geothermal heat sources and influence the amount of expansion power produced by the expander. Therefore, achieving high ORC system efficiency requires a parameter of superheated vapour degree. This paper presents an experimental study on a binary cycle, applying R123 as the working fluid, to investigate the effect of variation in superheated vapour degree on the ORC efficiency. Geothermal heat sources were simulated with conduction oil as an external heat source to provide input heat to the ORC system. The temperature high inlet (TH in) evaporator was designed to remain at 120 °C during the experiment, while mass flow rate was adjusted to make superheated vapour variations, namely set at 278, 280, 282, 284, and 286 K. Furthermore, the effect was observed on heat transfer inlet, pinch, heat transfer coefficient, expander work output, isentropic efficiency, expander shaft power, power generation, thermal efficiency, and ORC efficiency. The experimental results showed that the mass flow rate nearly remained unchanged at different degrees of superheated vapour. The ranges of heat transfer inlet, pinch temperature, and heat transfer coefficient were 25.34–27.89 kJ/kg, 9.35–4.08 °C, 200.62–232.54 W/m2·K, respectively. In conclusion, ORC system efficiency can be triggered by various parameters, including the temperature on the exit side of the evaporator. The superheated vapour of R123 working fluid to higher temperatures has caused a decrease in ORC system efficiency due to the decrease in heat transfer inlets, although theoretically, the work total increased. Further investigation has found that the magnitude of the mass flow rate affects the behaviour of the components of the ORC system.

Geothermal driven micro-CCHP for domestic application – Exergy, economic and sustainability analysis

Abstract Geothermal energy is going to play a key role in future smart energy systems. Geothermal-driven domestic energy systems, specifically, will largely contribute to the baseload supply of heating and cooling demand of societies. A low-temperature geothermal resource is considered to drive a domestic-scaled multi-generation system supplying power, heating, and cooling. The proposed cogeneration system includes a small-scale organic Rankine cycle (ORC), a single effect LiBr–H2O absorption chiller, and heat exchangers to supply domestic space heating and hot water. The waste heat of the ORC is harvested, also, to be used in space heating. Energy, exergy, economic, and sustainability principles are applied to the system to evaluate the system thermodynamic and thermos-economic performance. Results associated with the exergy destruction are obtained and effects on the system performance of chiller supply are investigated. Besides, the thermodynamic performance of the system is evaluated under the summertime and wintertime conditions. Under the base condition, the generator employed in the absorption chiller is found to be the most exergy destructive unit followed by the evaporator utilized in the ORC. Furthermore, results revealed that by increasing the chiller supply rate, the system sustainability index enhances from 1.6 to 2.5 while the system’s first law efficiency reduces.

High-Temperature Geothermal Utilization in the Context of European Energy Policy—Implications and Limitations

The European Union (EU) has made climate change mitigation a high priority though a policy framework called “Clean Energy for all Europeans “. The concept of primary energy for energy resources plays a critical role in how different energy technologies appear in the context of this policy. This study shows how the calculation methodologies of primary energy content and primary energy factors pose a possible negative implication on the future development of geothermal energy when comparing against EU’s key energy policy targets for 2030. Following the current definitions of primary energy, geothermal utilization becomes the most inefficient resource in terms of primary energy use, thus contradicting key targets of increased energy efficiency in buildings and in the overall energy use of member states. We use a case study of Hellisheidi, an existing geothermal power plant in Iceland, to demonstrate how the standard primary energy factor for geothermal in EU energy policy is highly overestimated for efficient geothermal power plants. Moreover, we combine life cycle assessment and the commonly utilized combined heat and power production allocation methods to extract the non-renewable primary energy factor for geothermal and show how it is only a minimal fraction of the total primary energy factor for geothermal. The findings of the study apply to other geothermal plants within the coverage of the European Union’s energy policy, whether from high- or low-temperature geothermal resources. Geothermal has substantial potential to aid in achieving the key energy and climate targets. Still, with the current definition of the primary energy of geothermal resources, it may not reach the potential.