Denmark renewable energy case study

What is geothermal?

• Geothermal energy is a form of renewable energy. It consists of heat from the interior of the Earth as well as solar heat absorbed by the Earth. In practice, it also often includes the ability of the Earth to efficiently absorb and store unwanted heat from buildings.
• Geothermal energy is harvested in two primary forms.
  • Where the geology permits – as in California – heat from deep in the planet’s crust is extracted in the form of steam or very hot water and is used to generate electricity or heat buildings.
  • Elsewhere – as in New England – lower-temperatureheat is extracted from shallow rock and soil to heat buildings in cold months, and excess heat from buildings is deposited into the rock and soil in warm months. Heat is transferred through a geoexchange system – a series of pipes and pumps that carry a fluid into a horizontal loop field 6-10 feet below the surface or through a vertical loop in one or more boreholes that typically are several hundred feet deep. Geoexchange systems usually are closed loops: the heat-transfer fluid (typically water) is fully enclosed and does not come into direct contact with soil, rock, or groundwater.

  Why is geothermal important?

  • As U.S. DOE notes, geothermal systems have a reputation for reliability, longevity, low maintenance costs, and user comfort.
  • Because geothermal is a local resource, it can reduce New England’s dependence on imported fossil fuels.
  • Ground-source heat pumps provide extremely efficient access to abundant, renewable, naturally occurring heat – and, conversely, access to extremely efficient cooling.
  • Owing to this efficiency, geothermal heating and cooling provides an outstanding means to reduce greenhouse gas emissions. And this carbon reduction will become even more potent as additional zero-carbon energy resources come onto the regional electricity grid.
  • Geothermal also eliminates other air pollutants associated with combustion, protecting indoor and neighborhood air quality and providing important health benefits such as reduction of asthma symptoms.
  • Because a ground-source heat pump system requires considerably less electricity than an air-source heat pump or a conventional air conditioner, it minimizes impacts on the electricgrid as Connecticut homes and businesses shift heating and transportation loads from fossil fuels to electricity and as demand for summertime cooling increases.
  • Geothermal is scalable. It can serve an individual residential or commercial property, a cluster of buildings, or an entire neighborhood or community.

  Affordability

  • Geothermal systems have a reputation as pricey – but can be quite affordable.
  • The cost of installing a heat pump for a geothermal system is comparable to that of installing an air-source heat pump (which relies on heat from the atmosphere). However, the cost of installing a geoexchange system (drilling, trenching, piping) makes a geothermal system considerably more expensive. Comparatively high upfront cost – even though it is offset by incentives and savings over time – has been the largest obstacle to widespread deployment of geothermal.
  • Fortunately, state and federal incentives can substantially reduce upfront costs. Energize CT provides state incentives up to $15,000 for residential systems and up to $4,000 per ton for commercial, institutional, and municipal systems. At the same time, federal tax credits available under the Inflation Reduction Act (IRA) cover 30-50 percent of upfront cost; and rebates that will be available under IRA may provide additional incentives for some households.
  • Because a geothermal system is more efficient than air-source heat pumps and far more efficient than systems relying on combustion of fossil fuels, and because it has relatively modest maintenance requirements, its operating cost typically is quite low, enabling homeowners and businesses to reduce their monthly expenses.
  • U.S. DOE notes that low operating costs make it possible for geothermal systems to have payback periods of 5-10 years.
  • Other factors that enhance affordability:
    • Zero- or low-interest financing available through Energize CT and Connecticut Green Bank make it possible to spread installation costs across periods as long as 20 years.
    • Because a geothermal system provides both heating and cooling and can heat domestic hot water, it eliminates the need for multiple appliances.
    • Geothermal systems last a long time. According to IGSHPA, GSHPs typically last more than 24 years and geoexchange systems are expected to have operating lives of more than 50 years.
    • Electricity generated with an on-site solar array can further reduce operating costs.

    Other key economic considerations

    • Broader geothermal deployment (especially via networked systems) and improvements in the efficiency of geoexchange installations are expected to furtherreduce capital costs for geothermal.
    • Because it utilizes locally available energy, geothermal reduces export of energy dollars.
    • The U.S. Department of Energy estimated in 2019 that ground-source heat pumps and geothermal district heating could economically provide twice as much thermal energy as Connecticut’s residential and commercial buildings require for space and water heating.
    • Connecticut and other New England states have been jointly awarded a $450 million federal grant to advance deployment of GSHPs and other HPs in the region.

    Connecticut projects

    Click on the map below for an interactive version providing information on commercial, institutional, and municipal geothermal projects that are in operation, under construction, in design, or under consideration. The database is not comprehensive. Please contact deep.geothermal@ct.gov to provide updates, corrections, or additions. (Updated on August 2, 2024.)

    

    Important trends

    

    • Rapid growth – The rate of residential ground-source heat pump installations in Connecticut is low but increased 8-fold between 2020 and 2023 (about twice as fast as installation of residential air-source heat pumps).
    • Municipalities leading – At least 14 Connecticut municipalities have installed ground-source heat pump systems. This technology now heats and cools dozens of town halls, libraries, schools, and other public facilities.
    • Colleges and universities leading – At least 6 Connecticut institutions have installed (or are installing) ground-source heat pump systems for academic buildings and residence halls.
    • Diverse commercial systems – Geothermal systems are in use in a wide range of commercial settings across Connecticut: corporate headquarters, retirement communities, museums, day-care centers, condominium developments, private schools, and health facilities.
    • Networkedsystems emerging – In Massachusetts, New York, and several other states, investor-owned natural gas utilities are authorized to develop networked geothermal projects that provide heating and cooling services to entire neighborhoods. These projects not only accelerate deployment of geothermal but help the utilities and their skilled workers transition to a clean energy economy. DEEP and the Connecticut utilities are monitoring these pilots. Meanwhile, leaders in several Connecticut communities are considering how municipalities can lead neighborhood-scale geothermal projects.
    • Federal strategy – The U.S. DOE’s Geothermal Technologies Office has set a federal strategic goal of 17,500 geothermal network installations and 28 million individual ground-source heat pump households by 2050.
    • Geothermal Market Capacity Coalition – A broad coalition is promoting development of regional training centers and mobilization of larger numbers of geothermal drilling rigs.

    

    Credit: U.S. Department of Energy

    Case studies

    • CT Green Bank – Redding – Dan and Sarah
    • Energize CT – New Milford – Holton family
    • Energize CT – Bethel – Spence family

    Installer and manufacturer case studies:

    • Water Energy – Guilford – Kelly house
    • Geothermal Innovations – Meriden – 24 Colony Street
    • Water Furnace – South Glastonbury – Benker family
    • Energize CT – Manchester – Manchester schools
    • U.S. EPA – Willimantic – Eastern Connecticut State University
    • CMTA – Manchester – Buckley Elementary School
    • CMTA – Mansfield – Mansfield Elementary School
    • International Ground Source Heat Pump Association case studies

    Energize CT consumer guidance

    • Ground source heat pumps (web page)
    • Your Guide to Ground Source Heat Pumps (booklet)
    • Heat Pump Consultation (free service)
    • Find a Participating Installer (in Specialty menu, select Ground Source Heat Pumps)

    Other resources: Connecticut

    • Energize CT, Clean Heating & Cooling (web page)
    • Northeast Energy Efficiency Partnerships, Connecticut Geothermal Industry Workforce Needs Assessment(report, 2024)
    • CT DEEP, Ulbrich Heights Community Geothermal Project (web page)
    • Northeast Energy Efficiency Partnerships, “Geothermal Heating and Cooling for CT Affordable Multifamily Housing” (webinar recording, 2024)
    • CT DEEP, “Neighborhood-scale Decarbonization: Geothermal and Beyond” (webinar recording; slides; 2024)
    • Connecticut Farm Energy Program, “Geothermal Energy” (brochure, 2018)

    Other resources: Northeast

    • Eversource, Geothermal Pilot Project in Framingham, MA (web page)
    • New York State Energy Research & Development Authority, Community Heat Pump Pilot Program (web page)
    • New York State Energy Research & Development Authority, Community Heat Pump System Projects (web page)
    • Vermont Community Networks, “How to Develop a Thermal Energy Network: A practical guide to adding thermal energy networks to decarbonization plans for your community” (toolkit, 2024)

    Other resources: National

    • Oak Ridge National Laboratory and National Renewable Energy Laboratory, “New analysis highlights geothermal heat pumps as key opportunity in switch to clean energy” (2024)
    • U.S. Department of Energy, Office of Geothermal Resources, “GeoVision: Harnessing the Heat Beneath Our Feet,” presentation for CT Climate Solutions Webinar Series (webinar recording; slides; 2019)
    • U.S. Department of Energy, Geovision(report, 2019)
    • Geothermal Market Capacity Coalition, “A National Network of Geothermal Drilling Centers of Excellence: Supporting an Equitable Transition to Clean Energy” (white paper, 2024)

    Contact

    Content last updated on August 22, 2024

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