Techno-economic analysis of decarbonizing building heating in Upstate New York using seasonal borehole thermal energy storage

Abstract

On average, fossil fuel space heating constitutes 56% of a building’s total energy usage in Upstate New York due to the cold winter climate. Similar levels of fossil fuel heating pertain in at least 15 states in the U.S. northern tier. To meet aggressive carbon reduction goals in this tier, decarbonizing the heat supply in the residential and commercial sector must be pursued. Using Borehole Thermal Energy Storage (BTES) to seasonally store excess thermal energy in the subsurface for later heating use is an innovative way to increase heating efficiency and lower carbon emissions. This paper investigates the technical and economic feasibility of heating Snee Hall on Cornell campus with unused summer steam from Cornell’s Combined Heat and Power Plant stored in an optimized BTES array. Snee Hall is a 6855 m2 building with an annual total heating load of 3040 GJ. A standard 2-D transient subsurface conductive heat transfer model is coupled to a high temperature heat pump (delivering > 60 °C) that can supply Snee Hall’s existing radiators with 70 °C water. For local geological parameters, 94% of Snee Hall’s winter space heating demand can be supplied by a 37-borehole array (90 m depth, 3 m spacing) and a 250-kW high temperature heat pump capacity with average coefficient of performance of 3.85. The calculated storage efficiency is 68.7% and the system has a 30-year net present value of about $526,400, an internal rate of return of 13%, and a payback period of 10 to 11 years. The system offsets about 6900 MMBTU (7280 GJ) of natural gas combustion and saves 250 MT CO2 emissions annually. The results of the single building analysis can be applied to other buildings on campus or in similar geologic settings in the U.S northern tier.