Policymakers' Guidebook for Geothermal Heating And

Total Page:16

File Type:pdf, Size:1020Kb

Policymakers' Guidebook for Geothermal Heating And National Renewable Energy Laboratory Boreholes being drilled for a ground coupled heat pump system to provide heating and cooling at the U.S. army Fort Knox Disney Barrack, completed in 2005. Fort Knox is home to one of the largest geothermal heating and cooling systems in the world. Policymakers’ Guidebook for Geothermal Heating and Cooling This document identifies and describes five steps for implementing geothermal policies that may reduce barriers and result in deployment and implementation of geothermal heating and cooling technologies, such as ground source heat pumps (GSHP) and direct-use applications. STEP 1 STEP 2 STEP 3 STEP 4 STEP 5 Assess the Local Identify Challenges Evaluate Current Consider Policy Implement Increased Industry and to Local Policy Options Policies Development Resource Potential Development Step 1: Assess the Local contact for more information. This contractors, as well as geothermal will provide you with insights into the trade organizations, can help you Industry and Resource scale of the geothermal opportunity understand local activity. Existing Potential in your area, and allow you to design and recent geothermal heating and Increasing the use of geothermal policy that is realistic and feasible cooling installations are a sign of energy requires a baseline level of while addressing your area’s existing resource potential. knowledge about the industry and strengths and weaknesses. market trends in your locality. As you Evaluate Deployment Potential assess your area, consider the historical Review Historical Activity If there is a substantial amount of activity of the local geothermal of Local Industry geothermal heating and cooling industry, take a look at the current Conducting interviews and surveys installations, there may be significant geothermal resource availability, and with local heating, ventilation, and air deployment potential. However, identify possible stakeholders you can conditioning (HVAC) engineers and deployment potential can be heavily NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. Step 2: Identify Challenges to Development Identifying specific challenges associated with geothermal heating and cooling development in your area will help you recognize the point in development where new policy should be targeted. Understanding development barriers, stakeholder concerns, and development capital needs will help boost your knowledge about the local geothermal market condition and further increase the likelihood of effective policy. Development Barriers Geothermal heating and cooling technologies must be able to compete with other clean energy technologies to ensure successful deployment. Direct-use applications of geothermal energy, such as this greenhouse near New However, numerous barriers must Castle, Utah, require a local geothermal resource. By evaluating the resource be overcome to make geothermal potential in your area, you’ll be able to assess if direct-use applications are feasible. heating and cooling technologies a viable option. A lack of specific impacted by system costs and players, and potential champions machinery, equipment, financing, other regional requirements; make or opponents of geothermal knowledge, and the personnel needed sure to take these into account as development in your area. To identify to develop geothermal heating and you evaluate. stakeholders, contact state and federal cooling technologies are some of the environmental agencies, your state most common barriers to successful System costs for GSHP are dramatically energy office, or university experts. development. Direct-use applications affected by the local geologic and soil conditions, which can impact the cost of the required underground or underwater loop system. Evaluate the range of expected costs for drilling or excavating the underground loop system within specific areas of your state or community to assess the economic viability of GSHP. Direct-use geothermal applications require a local geothermal resource. To head off any additional barriers, conduct an in-depth, comprehensive assessment of local direct-use resource potential to identify specific viable sites, reduce development risk, and inform the local population about opportunities for geothermal direct- use applications. Identify Stakeholders By identifying possible stakeholders you’ll find information on existing or potential workforce personnel, New and existing GSHP systems, like this one in Greensburg, Kansas, are a sign of equipment vendors, regulatory resource potential in your area. A lack of qualified workers to One way to address stakeholder and public concerns is to provide information on install and maintain geothermal geothermal technologies by giving a system demonstration. equipment is one barrier to development that should be addressed when designing policy. face additional barriers, such as leasing or development capital. Find out Some states already have policies backlogs, regulatory and permitting the level of financial and industry in place that apply to direct-use roadblocks, and insufficient resource support needed to make GSHP or applications and GSHP. Additionally, access. GSHP barriers also include high direct-use technologies competitive federal, state, and local policies can installation costs and varying system in your area by contacting existing interact to create or correct designs. or potential geothermal heating and market failures. cooling consumers. Involving the HVAC Learn more about current federal Stakeholder Concerns industry will allow you to make direct policies in the table on the next page Conducting surveys and interviews, comparisons between the economics and view current state policies already networking at conferences or of geothermal heating and cooling in place by visiting the Policymakers’ meetings, and holding formal technologies and current heating and Guidebook for Geothermal Heating public comment opportunities with cooling technologies, such as HVAC and Cooling website at www.nrel.gov/ stakeholders on specific local and loads, local climate variations, utility geothermal/guidebooks/heating_ industry needs can increase the value prices, and required funding. of your geothermal heating and cooling/current_policy.html. cooling policy by revealing barriers Step 3: Evaluate Additionally, visit the Database of to development. These types of Current Policy State Incentives for Renewables and activities will be most effective if a clear Efficiency,www.dsireusa.org/ , to find Review current state and federal policy distinction is drawn between GSHP information on state, local, utility, and major provisions that impact the and direct-use applications. and federal incentives and policies development of geothermal heating that support renewable energies like and cooling technologies to create a Development Capital geothermal. Geothermal heating and cooling coordinated plan that will enhance technologies require specific new policy effectiveness by addressing equipment, personnel, and financing current policy gaps and leveraging existing policy. Step 4: Consider applications depending on your • Outreach and training Policy Options area’s goals, resources, and needs. • Utility mandates and standards. Options include: Developing geothermal heating and Learn more about these policy options • Direct cash incentives cooling policy involves considering in the table to the left and get specific different types of policy options that • Lead-by-example policies details on each at www.nrel.gov/ can help expand the deployment • Tax incentives geothermal/guidebooks/heating_ of geothermal heating and cooling cooling/policy_options.html. • Financing technologies. Options may be directed to both GSHP and direct-use • Regulatory provisions Step 5: Implement Policies Implementing policies that will achieve Policy Options for Geothermal Heating and Cooling increased deployment of GSHP and direct-use technologies will require Policy Definition Example different sets of policies to facilitate Direct Cash Used to fund a portion of initial Grants deployment because each technology Incentives equipment and installation costs, is different. Weigh the options for which are often high, or to offset Rebates developing new policies or changing resource assessments, feasibility existing policies to include geothermal studies, or other pre-development heating and cooling technologies as costs. you move forward. Lead-By- Used to increase awareness and Attain Green-Building New Policies Example test or demonstrate geothermal Certification New policies may be most effective Policies technologies. Meet Energy-Reduction if targeted to market barriers that are Goals not already addressed by existing local, Procure Energy-Efficient state, or federal policy. For example, Equipment if the existing federal ITC can provide Tax Used to offset purchasing, Property Tax Incentives the necessary financial incentive to make direct-use projects economically Incentives installation, and ownership costs. Sales Tax Incentives Easy to administer and do not feasible, new policy is likely to be most require special funding or annual Tax Credits effective when designed to address appropriations. resource access, ownership, local expertise, and knowledge barriers that Financing Allows projects to become more Loan Guarantees can halt development. feasible by spreading costs over time. Loans Regulatory Used to address deployment
Recommended publications
  • Microgeneration Potential in New Zealand
    Prepared for Parliamentary Commissioner for the Environment Microgeneration Potential in New Zealand A Study of Small-scale Energy Generation Potential by East Harbour Management Services ISBN: 1-877274-33-X May 2006 Microgeneration Potential in New Zealand East Harbour Executive summary The study of the New Zealand’s potential for micro electricity generation technologies (defined as local generation for local use) in the period up to 2035 shows that a total of approximately 580GWh per annum is possible within current Government policies. If electricity demand modifiers (solar water heating, passive solar design, and energy efficiency) are included, there is approximately an additional 15,800GWh per annum available. In total, around 16,400GWh of electricity can be either generated on-site, or avoided by adopting microgeneration of energy services. The study has considered every technology that the authors are aware of. However, sifting the technologies reduced the list to those most likely to be adopted to a measurable scale during the period of the study. The definition of micro electricity generation technologies includes • those that generate electricity to meet local on-site energy services, and • those that convert energy resources directly into local energy services, such as the supply of hot water or space heating, without the intermediate need for electricity. The study has considered the potential uptake of each technology within each of the periods to 2010, 2020, and 2035. It also covers residential energy services and those services for small- to medium-sized enterprises (SMEs) that can be obtained by on-site generation of electricity or substitution of electricity.
    [Show full text]
  • Geothermal Energy
    Geothermal energy Adele Manzella CNR - Institute of Geosciences and Earth Resources Via Moruzzi 1 – 56124 PISA, Italy [email protected] Geothermal Energy Pros Cons Research What is How is used frontiers Status and perspectives What is the source of geothermal energy? What part is used? What is Geothermal Energy IGG – Institute of Geosciences and Earth Resources National Research Council of Italy WHAT is Geothermal energy Geothermal Energy The basis of geothermal energy is the From Greek gêo (earth) e immense heat content of the earth’s thermòs (heat) interior: the Earth is slowly cooling down. Since billions of years the heat in the Earth Crust is constantly supplied by Heat inside the Earth the decay of natural radioactive isotopes or the cooling of hot, shallow magmatic ~ 30 °C/km bodies. > 1000 °C > 3000 °C The resource is vast and ubiquitous and > 5000 °C has a corresponding large potential for utilization. WHAT is Geothermal energy Temperature in the ground has a daily (few cm) and seasonal (few meters) fluctuations, becoming essentially constant and equal to the average air temperature at about 18-20 m depth. Below this depth, it essentially increases with depth (geothermal gradient). Shallow geothermal: exploits the underground constant T= average air T The resource is vast and ubiquitous and has a corresponding large potential for Deep geothermal: exploits the utilization. underground heat at T>> air T WHAT is Geothermal energy The temperature increase with depth, as well as volcanoes, geysers, hot springs etc., are in a sense the visible or tangible expression of the heat in the interior of the Earth, but this heat also engenders other phenomena that are less discernable by man, but of such magnitude that the Earth has been compared to an immense "thermal engine”.
    [Show full text]
  • Geothermal Gradient Calculation Method: a Case Study of Hoffell Low- Temperature Field, Se-Iceland
    International Research Journal of Geology and Mining (IRJGM) (2276-6618) Vol. 4(6) pp. 163-175, September, 2014 DOI: http:/dx.doi.org/10.14303/irjgm.2014.026 Available online http://www.interesjournals.org/irjgm Copyright©2014 International Research Journals Full Length Research Paper Geothermal Gradient Calculation Method: A Case Study of Hoffell Low- Temperature Field, Se-Iceland Mohammed Masum Geological Survey of Bangladesh, 153, Pioneer Road, Segunbagicha, Dhaka-1000, BANGLADESH E-mail: [email protected] ABSTRACT The study area is a part of the Geitafell central volcano in southeast Iceland. This area has been studied extensively for the exploration of geothermal resources, in particular low-temperature, as well as for research purposes. During the geothermal exploration, geological maps should emphasize on young corresponding rocks that could be act as heat sources at depth. The distribution and nature of fractures, faults as well as the distribution and nature of hydrothermal alteration also have to known. This report describes the results of a gradient calculation method which applied to low-temperature geothermal field in SE Iceland. The aim of the study was to familiarize the author with geothermal gradient mapping, low-temperature geothermal manifestations, as well as studying the site selection for production/exploration well drilling. Another goal of this study was to make geothermal maps of a volcanic field and to analyse if some relationship could be established between the tectonic settings and the geothermal alteration of the study area. The geothermal model of the drilled area is consistent with the existence of a structurally controlled low-temperature geothermal reservoir at various depths ranging from 50 to 600 m.
    [Show full text]
  • Geothermal Energy Thermal Energy Is Constantly Gene- Rated in the Earth Interior by the De- Cay of Radioactive Nuclei
    Geothermal energy Thermal energy is constantly gene- rated in the Earth interior by the de- cay of radioactive nuclei. The heat content of the Earth is 1031 Joules. This heat naturally flows up to the surface by conduction at a rate of 45 TW, or three times the rate of human consump- tion from all prima- ry energy sources. However, the bulk of this natural flow is too geographically Current global usage of energy is about 5×1020 J/year. diffuse (0.1 W/m2 on So, a small fraction of the Earth’s total heat capacity average) to be would satisfy our needs for many millennia. recoverable. However, the problem is HOW to use this bonanza! So, not much heat diffuses “by itself” to the Earth surface per average. So, how to harness the geothermal energy to be our servant? Easy way: there are some areas where the geothermal activity is much higher than average – where there are hot sources, steam sources, geysers, or lava streams. In such places geothermal energy can be readily utilized. Less easy way: In other locations, geothermal energy has to be mined. Almost everywhere on Earth the geothermal gradient – i.e., the rate of temperature increase with the depth under the Earth surface – has a similar value of ~ 30 ºC /km. So, by drilling a 5 km well one can have very hot water! (150 ºC, or 300 ºF). Let’s begin with the “easy” geothermal energy – we have to tell the story of Earth’s continents, and tectonic plates. There are several major tectonic plates that are in constant motion relative to one another.
    [Show full text]
  • Geothermal Gradient - Wikipedia 1 of 5
    Geothermal gradient - Wikipedia 1 of 5 Geothermal gradient Geothermal gradient is the rate of increasing temperature with respect to increasing depth in the Earth's interior. Away from tectonic plate boundaries, it is about 25–30 °C/km (72-87 °F/mi) of depth near the surface in most of the world.[1] Strictly speaking, geo-thermal necessarily refers to the Earth but the concept may be applied to other planets. The Earth's internal heat comes from a combination of residual heat from planetary accretion, heat produced through radioactive decay, latent heat from core crystallization, and possibly heat from other sources. The major heat-producing isotopes in the Earth are potassium-40, uranium-238, uranium-235, and thorium-232.[2] At the center of the planet, the temperature may be up to 7,000 K and the pressure could reach 360 GPa (3.6 million atm).[3] Because much of the heat is provided by radioactive decay, scientists believe that early in Earth history, before isotopes with short half- lives had been depleted, Earth's heat production would have been much Temperature profile of the inner Earth, higher. Heat production was twice that of present-day at approximately schematic view (estimated). 3 billion years ago,[4] resulting in larger temperature gradients within the Earth, larger rates of mantle convection and plate tectonics, allowing the production of igneous rocks such as komatiites that are no longer formed.[5] Contents Heat sources Heat flow Direct application Variations See also References Heat sources Temperature within the Earth
    [Show full text]
  • Geothermal Heating Will Pave the Way for Sustainable and Locally Produced Biomass Consumption in District Heating
    Opiniated editorial published (in Danish) by ing.dk 1 September 2020 GEOTHERMAL HEATING WILL PAVE THE WAY FOR SUSTAINABLE AND LOCALLY PRODUCED BIOMASS CONSUMPTION IN DISTRICT HEATING By Susanne Poulsen, Technical Director at A.P. Moller Holding Geothermal We have to end the use of coal in our heat production system and significantly lower the use of biomass to more sustainable levels. The key question which then begs is which heat source(s) will be their adequate replacement? The answer lies in combining different green sources. Without geothermal, the green heat from the earth's core, we will not reach this goal. Large heat pumps, which extract heat out of seawater or air are excellent heat sources, however, they cannot supply enough heat to facilitate a phase- out of coal and lower biomass consumption. Put bluntly, if geothermal is not part of tomorrow’s energy mix, there will not be sufficient sustainable heat sources. Therefore, we encourage swift introduction of regulatory and economic framework conditions in support of large-scale geothermal heating. Before the summer recess, a broad majority of the political parties in the Danish parliament (Folketinget) agreed upon on a long list of climate related issues, which are expected to be negotiated in detail this autumn. Today, solid biomass accounts for roughly two-thirds of the renewable energy in the Danish energy system, underpinned by the statistical approach – in accordance with UN and EU rules – that count the carbon emissions from the burning of biomass as zero in the Danish climate accounts. However, the Danish think tank CONCITO has stated that actual Danish carbon emissions stemming from the direct burning of biomass is 14 million tons a year, with negative repercussions on the world's biodiversity.
    [Show full text]
  • Direct Utilization of Geothermal Energy 2020 Worldwide Review
    Proceedings World Geothermal Congress 2020 Reykjavik, Iceland, April 26 – May 2, 2020 Direct Utilization of Geothermal Energy 2020 Worldwide Review John W. Lund1 and Aniko N. Toth2 1Geo-Heat Center, Oregon Institute of Technology, Klamath Falls Oregon, USA 2Ana-Geo Ltd., Miskolc, Hungary [email protected], [email protected] Keywords: Geothermal, direct-use, spas, balneology, space heating, district heating, aquaculture, greenhouses, ground-source heat pumps, industrial application, snow melting, energy savings, wells, drilled, manpower, investment ABSTRACT This paper presents a review of the worldwide applications of geothermal energy for direct utilization and updates the previous survey carried out in 2015. We also compare data from WGC1995, WGC2000, WGC2005, WGC2010, and WGC2015 presented at World Geothermal Congresses in Italy, Japan, Turkey, Indonesia and Australia. As in previous reports, an effort is made to quantify geothermal (ground-source) heat pump data. The present report is based on country update papers received from 62 countries and regions reporting on their direct utilization of geothermal energy. Twenty-six additional countries were added to the list based on other sources of information. Thus, direct utilization of geothermal energy in a total of 88 countries is an increase from 82 in 2015, 78 reported in 2010, 72 reported in 2005, 58 reported in 2000, and 28 reported in 1995. An estimation of the installed thermal power for direct utilization at the end of 2019 is used in this paper and equals 107,727 MWt, a 52.0% increase over the 2015 data, growing at a compound rate of 8.73% annually. The thermal energy used is 1,020,887 TJ/yr (283,580 GWh/yr.), a 72.3% increase over 2015, growing at a compound rate of 11.5% annually.
    [Show full text]
  • Geothermal Heat and Power HIGHLIGHTS
    © IEA ETSAP - Technology Brief E07 – May 2010 - www.etsap.org Geothermal Heat and Power HIGHLIGHTS PROCESS AND TECHNOLOGY STATUS – The global capacity of geothermal power plants is approximately 9 GWe, with an annual electricity generation of about 60 TWhe, which is equivalent to less than 1% of the global electricity demand. Geothermal heating plants have a global capacity of approximately 18,000 MWth and produce about 63 TWhth per year. By and large, technologies for the exploitation of what is called ‘conventional and shallow’ geothermal energy resources are commercially available. These technologies include: Dry steam plants; Flash plants; Binary plants; Combined-cycle or hybrid plants; Combined Heat and Power based on geothermal energy; Heating based on geothermal energy. However, these resources are rather limited. The current challenge is the development of Enhanced Geothermal Systems (EGS) – also known as ‘Hot Dry Rocks’ - to exploit deep geothermal resources, which could expand the potential of geothermal energy considerably. An overview of temperature levels, applications and the variety of exploitation technologies of geothermal resources, is shown in Figure 1. COSTS – The investment cost of geothermal power plants depends considerably on the site, depth and characteristics of the geothermal resources. A value of $4000/kWe (US$ 2008) may represent an average indicative cost, with considerable variations. Assuming an average annual operation and maintenance (O&M) cost of 3.5% of the investment cost (approximately $140/kWe per year), the resulting generation cost is approximately $90/MWh. For geothermal-based combined heat and power plants, the investment cost is higher (typically, $10,000/kWe), the O&M costs are around $250/kWe per year, and the generation cost may reach approximately $200/MWh.
    [Show full text]
  • Geothermal Basics: Q&A September 2012 Are You a GEA Member?
    Geothermal Basics: Q&A September 2012 Are you a GEA member? What is GEA?: The Geothermal Energy Association (GEA) is a trade association composed of U.S. companies who support the expanded use of geothermal energy and are developing geothermal resources worldwide for electrical power generation and direct-heat uses. Our members have offices or operations in many states and in numerous countries throughout the world. GEA advocates for public policies that will promote the development and utilization of geothermal resources, provides a forum for the industry to discuss issues and problems, encourages research and development to improve geothermal technologies, presents industry views to governmental organizations, provides assistance for the export of geothermal goods and services, compiles statistical data about the geothermal industry, and conducts education and outreach projects. Why Join GEA?: The Geothermal Energy Association is the definitive voice of the geothermal industry and works adamantly on your behalf to (1) support long-term industry growth through education, information, outreach and advocacy and (2) increase public awareness of geothermal energy and understanding of its near- and long- term potential. Membership dues provide the bulk of financial support for GEA and directly facilitate our efforts to engage policy makers on critical industry issues, organize events, produce geothermal industry data, reports, and publications, engage the press in an aggressive public relations effort, publish the most widely-circulated geothermal newsletter, and more. We provide our members with the most up-to-date information on what is going on in the geothermal industry today and the factors that are shaping the industry for tomorrow.
    [Show full text]
  • Characterization of Aquifer Hydrochemistry from the Operation of a Shallow Geothermal System
    water Article Characterization of Aquifer Hydrochemistry from the Operation of a Shallow Geothermal System Hanna Choi 1, Jaeyeon Kim 2, Byoung Ohan Shim 1,* and Dong-hun Kim 1 1 Groundwater Research Center, Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, Korea; [email protected] (H.C.); [email protected] (D.-h.K.) 2 School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Korea; [email protected] * Correspondence: [email protected]; Tel.: +82-42-868-3055 Received: 30 March 2020; Accepted: 5 May 2020; Published: 13 May 2020 Abstract: The use of shallow geothermal energy systems utilizing groundwater temperature for the air-conditioning of buildings is increasing worldwide. The impact of these systems on groundwater quality has become crucial for environmental regulations and system design. For the long-term operation of geothermal systems, it is important to evaluate their influence on the geochemical properties of groundwater, including precipitation and dissolution of secondary minerals. This research was conducted in a real-scale geothermal system, consisting of a groundwater heat pump (GWHP). Hydrochemical data were obtained from samples collected from an aquifer before heating, during heating, and before cooling operations of the GWHP. The Langelier Saturation Index and Ryznar Stability Index were calculated, and the saturation index was simulated with the PHREEQC program. Evidence from water table variation, temperature change, and 87Sr/86Sr isotope distribution showed that groundwater flows from a well located on the northwest side of the geothermal well. The saturation index values showed that the pristine groundwater favors carbonate dissolution, however, manganese oxides are more sensitive to temperature than carbonate minerals.
    [Show full text]
  • Groundwater Circulation Wells for Geothermal
    PROCEEDINGS, 43rd Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, February 12-14, 2018 SGP-TR-213 Groundwater Circulation Wells for Geothermal Use: Preliminary Results of the Project Integralsonde Type II Eva Dinkel1*, Burga Braun2, Moritz Muhrbeck3, Winfried Reul3, Alexander Meeder3, Ulrich Szewzyk2, Traugott Scheytt1 1Hydrogeology Research Group, Berlin Institute of Technology, Sekr. EB 10, Straße des 17. Juni 145, 10623 Berlin, Germany 2Department of Environmental Microbiology, Berlin Institute of Technology, Ernst-Reuter-Platz 1, 10587 Berlin, Germany 3Geo-En Energy Technologies GmbH, Schwedter Str. 9a, 10119 Berlin, Germany * Corresponding author: [email protected] Keywords: Groundwater circulation well, geothermal use, open loop, low-enthalpy, GWHP, groundwater quality, microbial community ABSTRACT Groundwater heat pump (GWHP) systems are a widespread technique to provide buildings with heating and cooling. Most open loop shallow GWHPs are doublet systems which consist of two wells, one for extraction and one for reinjection of groundwater. Hence, there has to be enough space to set up such a system. Shallow groundwater circulation wells (GCW) are an alternative. These open loop low-enthalpy shallow geothermal energy systems extract and inject groundwater in the same well via two filter screens at different depths. GCWs also demand less space, but so far there are only few installations. Our aim is to investigate the efficiency of those systems, their influence on groundwater chemistry and microbiology and evaluate their long-term productivity. These are the main research goals of the research project “Integralsonde type II” (01LY1507B /BMBF, KMU-innovativ). GCWs for geothermal use and their impact on groundwater quality are investigated at several sites in the quaternary main aquifer (Saalian age) in the Berlin (Germany) area.
    [Show full text]
  • Deep Geothermal Energy K
    Draft: October 15, 2015 Deep Geothermal Energy K. Max Zhang, Mark Romanelli and Camelia Hssaine Executive Summary The main objective of this section is to examine the potential of enhanced geothermal systems (EGS) in serving the heating demand in Tompkins County, and the opportunities and challenges in implementing EGS. The U.S. Department of Energy has broadly defined EGS as engineered reservoirs that have been created to extract economical amounts of heat from low permeability and/or porosity geothermal resources at depths of 2 km (or 6,500 feet) or more. Compared to hydrothermal geothermal systems, EGS can be adopted in areas with low-grade geothermal resources and not enough natural fluid or permeability. It is important to distinguish EGS from Geothermal heat pumps (GHPs), sometimes referred to as ground-source heat pumps (GSHP), which also utilize low-grade thermal energy from the earth, but at much shallower depth, typically 2-200 m (or ~7 to 600 feet), than EGS. Soil temperature typically does not vary with seasons at depths beyond 2 m. GSHPs are treated as energy efficiency measures rather than as an energy supply in the Energy Roadmap, and discussion of their potential may be found in the Demand-side Management and Energy Efficiency chapter. While EGS are still in the demonstration stage, GSHPs are readily available commercially and for that reason, EGS potential is not factored into the scenario development, but GSHPs are included. Tompkins County has modest temperature gradient around 25 oC/km +/- 1 oC/km. In other words, ground temperatures within the County reach around ~140 oC at 5 km (or 3.7 miles).
    [Show full text]