Geothermal direct-use district energy system is developed in a place where low-temperature geothermal resources below 150 °C are available at affordable depth. In the United States, the geothermal direct-use (DU) applications have been developed in the western U.S. and limited outside of these areas due to relatively lower-grade geothermal resources. This study evaluated techno-economic potential of geothermal deep direct-use (DDU) systems for district-scale heating and cooling systems in southeastern New York and eastern Michigan. Regional geological formation, lithology, and bottomhole temperature data were collected through the literature review to characterize geothermal resource potential in the two study areas. The two study areas mainly consist of igneous and metamorphic rocks at target reservoir depth of 3 km to 4 km. Geothermal gradients in the New York and Michigan study areas were estimated as 19.7 °C/km and 21.2 °C/km, respectively. The characterized reservoir properties and temperature were incorporated in GEOPHIRES techno-economic model tool for the techno-economic analysis of direct-use heating at 3 km, direct-use heating and cooling at 4 km, and district heating coupled with peaking boiler at 3 km. Average heat production during 20-year lifetime in the New York site was 5.6 MWth at 3 km and 9.5 MWth at 4 km with average production temperatures of 67 °C and 85.2 °C, respectively. Similarly, the average heat production in the Michigan site was 6.5 MWth at 3 km and 10.6 MWth at 4 km with average temperatures of 71.3 °C and 90.8 °C, respectively. The reservoir thermal drawdown in the two study areas was approximately 7% to 8% after 20 years of operation. With the increase in production depth from 3 km to 4 km, the levelized cost of heat (LCOH) of direct-use applications was significantly decreased from $20/MMBtu to $12.5/MMBtu in New York and from $17.5/MMBtu to $11.2/MMBtu in Michigan, respectively. The levelized cost of cooling (LCOC) was generally higher than the LCOH due to additional capital and lifetime operational costs and 80% to 90% efficiency of absorption chiller for cooling. These results provide general backgrounds on the lifetime system performance, LCOH, and LCOC implying that DDU systems in the two study areas are techno-economically feasible and comparable.

Press the Back button in your browser, or search again.

Copyright 2024, Stanford Geothermal Program: Readers who download papers from this site should honor the copyright of the original authors and may not copy or distribute the work further without the permission of the original publisher.