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Thermal Energy Networks (TENs) Examples

Thermal energy networks are designed opportunistically to use the resources of the location. Below are examples of sites that use different sources of thermal energy.

 

Geothermal Networks / Networked Geothermal Systems

Use shallow boreholes (100 to 750 ft) to harness the relatively constant temperature of the earth (∼55°F) to heat and cool buildings that are connected to the network. These boreholes can store excess heat to deliver cooling to the network even in times of extreme heat, flattening electric peak demand.

  • CO: Colorado Mesa University (CMU) geo-exchange system has been operational since 2008 and connects 16 campus buildings to provide heating and cooling for 1.2 million square feet of academic and auxiliary space with an ambient temperature loop.
  • IA: West Union completed a 5-year downtown transformation project in 2013 that includes a geothermal network connected to 60 downtown buildings and 330,000 sq ft of space. The project also included energy audits for downtown buildings, EV charging stations, LED street lighting, and 36,000 sq ft of rain gardens.
  • MA: Eversource Gas is building the first utility-installed networked geothermal system in the nation in Framingham, MA. The system will provide heating and cooling to 37 buildings and 140 customers, which include both homes and businesses. It is expected to be operational in 2024.
  • MA: National Grid broke ground on its first networked geothermal system in Lowell, MA in April of 2023. National Grid has been approved to build three additional demonstration projects in Massachusetts.
  • UT: Weber State University improved campus energy efficiency in 2016 by drilling over 200 wells, each 275 feet deep, to create an underground heating and cooling system, as well as transitioning to variable refrigerant flow (VRF) HVAC systems, leading to energy savings and a university pledge to become carbon neutral by 2050.
  • TX: Whisper Valley is a master-planned community that features a zero-capable system, utilizing an ambient temperature loop, geothermal heating and cooling, solar panels, and other sustainable technologies to minimize energy consumption and environmental impact. Currently, 450 homes are connected to the geothermal network but the development can expand to include up to 7000 homes.
  • Canada: Springwater Mattamy Homes in Toronto is Canada’s first residential neighborhood with heating and cooling provided by an efficient geothermal system, significantly reducing monthly utility bills for homeowners and showcasing the benefits of community-scale geothermal systems in cold weather climates.

 

Direct Use Geothermal Systems

Use underground hot water to heat buildings and for other applications such as snow melt under streets and sidewalks or warming water for fish farming.

  • ID: Boise has the largest municipally operated geothermal system in the country dating back to the 1890’s, when settlers started to use the heat from an underground hot water river (177°F ) to heat the local homes. More than 20 miles of geothermal pipeline heat some of Boise’s most iconic buildings – including JUMP, City Hall, the Treasure Valley YMCA, Boise State University, the Veterans Administration, and the State Capitol Building.
  • NV: Elko Heat Company began in 1982 with DOE funding, this geothermal heating system serves 17 customers, and distributes approximately 80 million gallons (364 million liters) of 178°F (81°C) geothermal water annually. Customers primarily use geothermal water for space heating and domestic hot water heating. Two customers are using their return water for wintertime snow and ice melting on walkways.
  • OR: City of Klamath Falls has a geothermal heating system constructed in 1981 that now serves 23 commercial, nonprofit, and government facilities in the downtown area. In addition, the system heats 9 blocks of the downtown’s sidewalks and crosswalks.

Sewer Heat Recovery Systems 

Use heat transfer to turn the water from sewer pipes into a renewable energy resource that can be used for space and water heating in buildings.

  • CO: National Western Center in Denver meets 90%of the heating and cooling needs of 7 buildings, more than 1 million square feet on this 250-acre campus. The sewer heat recovery systems prevent an estimated 2,600 metric tons of carbon (CO2) emissions per year.
  • WA: King County Seattle Wastewater Energy Transfer System is a wastewater utility that offers sewer heat recovery (SHR). Private commercial property owners and developers can recover heat energy from sewer pipes for heating or cooling space and hot water in buildings.
  • Canada: False Creek Energy Centre in Vancouver supplies energy from sewage heat recovery, where the latent heat from sewage is captured using a heat pump process to the Neighbourhood Energy Utility (NEU). That energy is the primary source of heating and hot water to 6.4 million square feet of mixed-use buildings. 

 

Waterbodies Thermal Energy Systems 

Harness the thermal energy of oceans, seas, lakes, or rivers to extract heating and or cooling. 

  • NY: Cornell University’s Lake Source Cooling (LSC) facility draws water from Cayuga Lake to cool campus buildings before discharging back into the Lake. LSC saves the university over 20 million kWh per year versus previous cooling methods and represents about an 85% reduction in energy use for campus cooling.
  • Canada: Toronto’s Downtown Deep Lake Water Cooling System uses the water from Lake Ontario to cool over 100 downtown buildings, ranging from City Hall and Toronto General Hospital to hotels and a brewery. The system saves  90,000 megawatt hours of electricity use annually, roughly enough to power a town of 25,000.
  • Canada: Vancouver: Convention Center has a state-of-the-art geothermal heating and cooling system powered by renewable energy uses seawater from the Burrard Inlet to heat and cool the buildings with almost zero carbon emitted to the atmosphere.
  • FL: Avian Pointe opened to residents in 2024 and is Florida’s first thermal energy network system. The Floridian Aquifer is a sustainable source of thermal energy for the 276-unit multifamily housing development. With additional efficiency measures including solar PV and LED lighting, it is projected to reduce CO2 emissions by 809 tons annually and reduce residential energy costs by more than 30%.

 

Waste Heat Networks (without boreholes) 

Use heat exchange to share heating and cooling between multiple buildings.

  • CA: Stanford University uses a Central Energy Facility (CEF) that relies on hot and cold water tanks for heating and cooling buildings and utilizes a heat recovery process where water travels 20 miles around the campus to meet the campus’ thermal needs.
  • WA: Amazon Headquarters in Seattle uses waste heat from a data center in the Westin Building Exchange that houses more than 250 telecom and internet companies. The waste heat from the Westin is transferred via water-filled pipes across the street to a 400,000-gallon tank that provides low-grade heat storage and an emergency water supply for Westin if needed.

 

Thermal Energy Network Feasibility Studies funded by the Department of Energy

  • AK: Kawerak, Inc. – direct-use geothermal district-scale system that will provide heating and hot water to buildings and cooling to food storage areas in Nome.
  • AK: City of Seward – community-scale heating and cooling system that will refine the existing design of a CO2 heat-pump system to meet nearly all heating demand for half of the municipal buildings.
  • CO: Clean Energy Economy for the Region (Carbondale) – geothermal heat pumps to support a net-zero energy district and heat and cool school district offices, a library, 20 affordable housing units, a high school, a center for nonprofits, and townhomes.
  • CT: Department of Energy and Environmental Protection – district geothermal heating and cooling system that will serve at least 50% of the heating and cooling load of a 132-unit, affordable housing complex
  • IL: Blacks in Green – shared community geothermal network across four city blocks containing more than 100 multi-family and single-family residential buildings in a disadvantaged section of the city’s South Side
  • MA: HEET and Eversource proposed a geothermal heat-pump heating and cooling system adjacent to the first geothermal demonstration project and integrated with other renewable energy systems in a socioeconomically and ethnically diverse city.
  • MI: The city of Ann Arbor – looped geothermal system paired with efficiency improvements, rooftop solar, and battery storage to heat and cool 262 households, an elementary school, a community center, a mental health facility, and a public works site.
  • MN: City of Duluth – a geothermal system using waste heat from the Western Lake Superior Sanitary District to cover 100% of heating loads in a disadvantaged neighborhood
  • NY: Electric Power Research Institute: geothermal heating and cooling system to serve a minimum of 25% of apartments in a portfolio of 5,000 apartments identified for geothermal upgrades.
  • OK: University of Oklahoma – Combined solar and geothermal heat pump heating and cooling system, to be demonstrated in a community owned and operated by a Tribal Nation.
  • VT: GTI Energy and Vermont Gas – geothermal system to meet at least 50% of the heating and cooling needs for a new affordable housing development of townhomes, duplex, and multiplex units, with more than 30% of units intended for low- and medium-income households