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Low Temperature Thermal Energy Demand in the U.S.

Researcher: Daniel Sutter, Don Fox
Principle Investigator: Professor Jefferson Tester

In regards to geothermal energy, electricity generation gets most of the attention over direct use. Given the low enthalpy/temperature resource, power generation is significantly limited by the 2nd law of thermodynamics. Omitting the electricity conversion by using the thermal energy directly in heating applications is a viable option for geothermal energy.

To understand the potential of direct use of geothermal energy, we must quantify the U.S. thermal energy demand and its distribution with respect to temperature. In other words, determine how much thermal energy is used at different temperature ranges. In the low temperature range, direct use of geothermal energy can replace conventional energy sources. Apart from the geothermal aspect, the distribution is also of importance for the use of waste heat from power plants or industrial processes.

Additionally, we realize that our energy use scheme is not the most efficient because high enthalpy/temperature fuels are often used for processes that require low temperatures. Such an example is space heating where combustion fuels can generate temperatures as high as 2,000 °C but only to be used to heat air between 40-60 °C. Thus, a more logical and efficient energy use scheme closes the disparity between source temperature and required process temperature. The energy source used should be chosen with the end use process in mind.

Thermal Spectrum