Geothermal Direct Use for Decarbonization - Progress Towards Demonstrating Earth Source Heat at Cornell



Key Words:

district heating, low enthalpy, direct use, decarbonization


Stanford Geothermal Workshop




Direct Use



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Space and water heating in residential and commercial buildings and low-temperature industrial process heat in New York State are provided primarily by the combustion of fossil fuels (natural gas, fuel oil and propane) in furnaces and boilers. As a result, heating currently accounts for about 40% of the State’s carbon footprint. To reach New York’s aspirational goal of achieving carbon-neutrality by 2050, a transformation of its heating systems is necessary. In addition, other heating–dominated states in the Northern Tier of the U.S. face similar challenges. Geothermally-heated fluids at temperatures below 100oC could provide an affordable low-carbon alternative for meeting a majority of these heating demands. In fact, direct use geothermal energy is a key component of Cornell University’s overall strategy to reach carbon neutrality by 2035. Since 2010, Cornell has been evaluating using Earth Source Heat (ESH) for heating its campus. The basic idea of Cornell’s ESH project is to circulate water thru fractured regions of deep hot rock containing naturally-stored heat at temperatures high enough to be used directly to supply thermal energy to the campus district energy network. With its high baseload winter heating demand of about 50 MW(thermal), a successful demonstration of geothermal heating at Cornell would also serve as a representative and scalable model for carbon neutral heating in many rural and urban communities located elsewhere. This past summer, Cornell’s Earth Source Heat (ESH) project took an important step forward. Starting in June through August, 2022, an exploration well was drilled to a depth of 3 km (TD = 9790.5 ft). The exploration well is formally called the Cornell University Borehole Observatory or CUBO. The main function of CUBO is to identify and characterize target rock regions having temperatures of 80oC or higher that have the potential to be used as ESH reservoirs. Additionally, CUBO will be used for monitoring reservoir performance during the stimulation and heat extraction phases of the ESH well field contained by a set of injection and production wells. CUBO data allow identification of preliminary target regions in sedimentary rock (e.g., 8600-8750 ft [2.6-2.7 km]), in the basal sedimentary, contact zone, and shallowest weathered (?) basement rock (9350-9500 ft [2.85-2.9 km]), and deeper in the high grade metamorphic basement (9600-9720 ft [2.93-2.96 km]). Data collected during drilling and testing and analyses performed will be summarized. Topics include: 1. Well and casing designs, 2. Drilling performance results, 3. Lithology based on mud logging, drill cuttings analysis, image logs and side wall cores, 4. Stress magnitude and direction from mini-frack tests, caliper logs, and image logs, 5. Mechanical properties based analyses of side wall cores, 6. Temperature and pressure based logs, and 7. Preliminary flow testing to determine target formation permeability. Several other papers will also be presented by the Cornell ESH research team at this meeting to provide additional details regarding the analysis of CUBO results.

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