| Authors |
Jeff TESTER, Tim REBER, Koenraad BECKERS, Maciej LUKAWSKI, Erin CAMP, Andrea AGUIRRE, Terry JORDAN, and Frank HOROWITZ |
| Abstract |
Given that a large portion of the United States’ primary energy consumption goes into heating, cooling, and providing electricity to residential and commercial buildings, geothermal energy has significant potential to deliver and distribute both thermal and electrical energy on a community scale. Excluding a few exceptional cases in the U.S., the focus for development has been on producing electricity from high-grade hydrothermal systems located in various western U.S. states. By ignoring the potential to deliver thermal energy directly, a large portion of the U.S. geothermal resource is marginalized. In particular, lower grade, lower temperature hydrothermal and Enhanced Geothermal Systems (EGS) resources are more widespread and have sufficient temperatures ( more than 80ºC) that they are ideally suited for direct-use applications. By employing Geothermal District Heating (GDH) on a community scale, low grade hydrothermal and EGS in formations with poor permeability have the potential to supply a significant fraction of the thermal energy (temperatures less than 125ºC) throughout the U.S., used for heating buildings, supplying hot water, and for lower temperature process heating. A key objective of our study is to characterize a number of important geothermal resource types ranging from conduction-dominated EGS to permeable sedimentary aquifers, as well as technical and economic factors that influence the levelized cost of delivering geothermal heat and/or electric power to a range of communities in the Eastern U.S. from lower grade resources (temperatures less than 125ºC). To demonstrate the level of deployment possible, we developed a regional model to evaluate the potential for GDH in the states of New York and Pennsylvania. A GDH network was simulated at each population center within the study region and the levelized cost of heat (LCOH) was estimated from GDH for each community. LCOHs were then compiled into a supply curve from which several conclusions were drawn. Our evaluation revealed that geothermal resources have the potential to supply cost-effective energy for space and water heating in several New York and Pennsylvania communities in the near future. To realize wider deployment in NY, anticipated increases in conventional fuel prices, and/or more aggressive renewable energy policies and incentives along with modest improvements in EGS technology are needed to enable GDH to compete with other heating alternatives. In addition, creative implementation strategies would also help overcome the cost barriers that exist today for geothermal by focusing initially on developing the infrastructure needed for district heating and combined heat and power systems at a community scale. These district energy systems could be designed to initially utilize conventional fuels and waste biomass feedstocks and later transition to using geothermal energy as their primary energy source. |