UC Berkeley

There is an urgent need for building energy services that are not only low-carbon but reliable. District energy systems (DES) have the potential to meet building power, heating and cooling needs efficiently and reliably, but further research is needed to understand their coupling with local renewable energy sources such as biomass. Here we assess the cost and greenhouse gas implications of using bioenergy from local organic waste to power DES in California communities. We describe a set of possible scenarios for bioenergy integration into DES, including fuel switching and retrofitting of existing systems and DES expansion through new projects. In all locations, DES have higher combined capital and operating expenses (ranging from $5–12 million) than conventional fossil fuel building thermal systems. However, the net amortized annual cost of DES can reach as low as 70% that of the conventional system from the sale of excess electricity. Bioenergy-powered DES can offer a cost of carbon abatement on par with distributed solar-powered building thermal systems (50% less to 34% more). Furthermore, upgrading existing DES from fossil to renewable natural gas represents an immediate economical path to decarbonize buildings.