Sustainable design of Cornell University campus energy systems toward climate neutrality and 100% renewables

In this paper, the sustainable design of carbon-neutral energy systems is addressed, considering earth source heat, lake source cooling, on-site renewable electricity generation, and sustainable peak heating systems. The electricity is mainly purchased from the local electric grid with on-site generation from renewables. Deep geothermal energy serves as the base-load heat supplier due to its better economic performance over an electrified heating system based on heat pumps under the current electricity price. Lake source cooling meets most cooling demand due to its high coefficient of performance and low emissions. Conventional chillers handle the peak-load cooling demand on hot summer days. Peak-load heat demand can be met by introducing biomass or biogas heating, heat pumps, hot water tanks, and green hydrogen. A multi-period optimization model given a time horizon and a temporal resolution is built on the basis of the proposed superstructure for carbon-neutral energy systems to minimize the total annualized cost. The model aims to determine the optimal energy systems configuration, seasonal operations, energy mix, and corresponding capacity of technologies while fulfilling the seasonal demand for electricity, heat, and cooling. A set of case studies using the main campus of Cornell University as the living laboratory demonstrate the applicability of the optimization framework. Based on the current electric power mix, scope 1 and 2 emissions are substantially reduced to 8%-17% of the value in 2020. These numbers are further reduced to 1%-2% when the 2035 electric power mix is considered with higher penetration of low-carbon technologies. The results drawn from the Cornell case can be applied to other campuses, towns, cities, and regions with similar climate conditions, especially the temperature by modifying some case-specific dimensions, such as the local availability of renewable energy sources.