Two-thirds of the fuel used in conventional power plants is exhausted as waste heat to oceans, rivers and the atmosphere. In total, U.S. power plants waste more energy than most countries – including major economies like Japan – consume for their entire economies. This waste heat can be recovered and put to productive use through combined heat and power (CHP) systems. In addition, the United States has abundant renewable sources of thermal energy, including biomass, geothermal, solar, and natural sources of air conditioning.

The Thermal Renewable Energy and Efficiency Act of 2010 (TREEA, S. 3626 / H.R. 5805) was introduced by Sens. Al Franken (D-MN) and Kit Bond (R-MO) in the Senate, and Rep. Betty McCollum (D-MN), with Reps. Jay Inslee (D-WA) and Paul Tonko (D-NY) as original co-sponsors, in the House.


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On September 16, 2010, the Environmental and Energy Study Institute (EESI) held a briefing on how district energy systems can tap into local renewable thermal resources and waste heat to reduce our use of fossil fuels, and proposed legislation to encourage the implementation of thermal energy infrastructure. More than 30 percent of all U.S. energy consumption is used for thermal purposes – heating and cooling buildings and industrial processes – and the majority of this energy comes from fossil fuels. However, some communities are instead using local renewable sources of thermal energy, as well as power plant and industrial “waste” heat. District energy systems connect these thermal resources to energy consumers by piping water and/or steam to buildings for space heating, domestic hot water, air conditioning and industrial process energy.

  • District energy systems provide a cleaner way to heat and cool communities, by capturing waste heat that would otherwise be unused, or using renewable resources such as geothermal, water, solar, or biomass.
  • District energy aggregates thermal loads to a scale that makes it possible to use thermal energy sources that would not make sense on a single-building basis.
  • District energy systems can help strengthen energy security by reducing the need for imported foreign oil and improve economic development by keeping energy dollars in the local economy.
  • There are district energy systems in all 50 states, but there are many opportunities to expand existing systems or build new ones. Under-utilization of district energy in the United Sates is not a technology issue, it’s a policy issue.
  • In Denmark, 80 percent of heating and cooling is drawn from district energy systems.
  • District Energy St. Paul has built the largest district energy system in the United States, serving 85 percent of downtown buildings. Its thermal energy comes from 70 percent renewable sources, with the hope of achieving 100 percent renewable in the future. It has plans to incorporate a large solar-thermal energy project, the first of its kind in the United States.
  • District energy has the potential to draw waste heat not only from power plants, but from industry as well. For example, District Energy St. Paul hopes to capture heat from a paper recycling plant a few miles from downtown.
  • To cool its campus, Cornell University pulls cold water from the bottom of Cayuga Lake through a district energy system, reducing the use of cooling electricity by 87 percent campus wide, cutting carbon dioxide emissions by 56 million lbs per year, and eliminating 40,000 lbs of CFCs.
  • A Seattle district energy system uses waste wood to serve approximately 200 downtown buildings, reducing carbon dioxide emissions by 55,000 tons per year.
  • Buildings that use district energy have more leasable space because boilers, chillers, chimneys, and other heating and cooling equipment can be removed.
  • The Thermal Renewable Energy and Efficiency Act of 2010 (TREEA) is intended to stimulate investments in low-carbon thermal energy infrastructure, focusing on use of renewable energy sources to supply heating and cooling. Major provisions include a renewable thermal production tax credit, expanded availability of tax-exempt bonds for district energy infrastructure, and modified authorization for institutional sustainable infrastructure.
  • If passed, TREEA will act as a foundation and set important precedence for future energy policy. Several other bills have been introduced to address other thermal energy policy gaps.

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