Environmental impacts of optimal designs of community energy systems under different CO2 footprints of electric grids

This work determines optimal energy system configurations that minimize CO2 emissions under three typical grid electricity generation sources: (a) mostly nuclear and hydro; (b) natural gas; (c) coal. Benefits of implementing ground source heat pump (GSHP) and air source heat pump (ASHP) are compared to using combined cooling-heating-power (CCHP) system considering meeting cooling, heating, and electricity demands of consumers. GSHP is modeled via a novel multilayer model of borehole field heat transfer. Results from case studies show that for regions using mainly renewable energy technologies, configuration anchored on GSHP + ASHP has the lowest emissions, while configurations anchored on ASHP or ASHP + CCHP emit 5% more. When electricity is generated from natural gas or coal, relative to the configuration with the lowest emissions (all equipment), configurations anchored on GSHP + CCHP emits 1% and 2% more, while configurations anchored on ASHP + CCHP emit 3% and 19% more, respectively.