Pathways to carbon neutral energy systems at the University of California, Davis

Abstract

To achieve carbon neutrality by 2025 the University of California, Davis (UCD) seeks to eliminate its dependence on fossil energy sources. This study outlines a methodology to identify optimal equipment phase-in and capacities, and the major technical and economic drivers influencing the implementation of a carbon-neutral energy system. The analysis, focused on UCD, considers solar photovoltaic and thermal, biomass combined heat and power, biomass boiler, heat pump and electric boiler as replacement systems. Three cases besides the baseline are presented: 1) biomass-based system, 2) combination of biomass and electrification, and 3) electrification. Analysis period spans 2016–2035, with equipment phasing limited to the 2020–2025 period, and capacity limited to the peak campus loads of 40 MW e for electricity and 80 MW t for thermal. Results indicate that balancing the supply-demand mismatch is the greatest challenge for high renewable penetration at UCD, thus making thermal storage and generation systems which can modulate with variable loads crucial. The cost of carbon credits offset has negligible influence in the results due to its low value in the present market. Relative to the baseline 20-yr present cost of $634M, the 3 alternate cases are projected to incur between $629M (Case 1) and $704M (Case 3). • Supply-demand mismatch is the greatest technical challenge for the campus. • Thermal storage and generators that can modulate quickly based on load are crucial. • NPC of alternate systems ranges $629M-$704M, relative to the baseline $634M • Carbon cost need to exceed $170/ton CO 2 to break even on the costliest option.