(692f) Integrated Design and Operation of Low-Carbon District Heating Systems

Electrification has been identified as a major pathway for promoting deep sectoral decarbonization. This is particularly important for sectors historically difficult to decarbonize such as heat generation, and especially relevant under the recent energy insecurity issues related to fuel price and availability caused by political disruptions. For instance, industrial heating is estimated to comprise approximately 20% of global energy demand (IRENA, 2019), while in the US an estimated 2/3 of the industrial thermal demand is required at temperatures lower than 250 ºC, ideally suited to the application of renewable heat systems (McMillan et al., 2021). District heating plants centralize heat production and thus present a high potential for increasing energy efficiency and reducing emissions. In this work, we propose a formulation for the integrated design and operation of low-carbon district heating plants including electrical heat pumps, non-concentrating solar thermal collectors, and thermal energy storage tanks, augmented by natural gas boilers. A monolithic multistage modeling approach is adopted, considering both hourly and seasonal variations of ambient conditions and utility prices. The relationship between supply temperature and available heat transfer loads for each equipment is carefully analyzed and equipment models are judiciously selected to retain a linear framework, which is important to ensure that the large-scale integrated design and operation problem remains tractable. Results from a case study identify the potential of each low-carbon technology and highlight their synergistic behavior for different sites in the United States.

References

IRENA. 2019. Innovation landscape brief: Renewable power-to-heat, International Renewable Energy Agency, Abu Dhabi.

McMillan, C., Schoeneberger, C., Zhang, J., Kurup, P., Masanet, E., Margolis, R., Meyers, S., Bannister, M., Rosenlieb, E., Xi, W. 2021. Opportunities for Solar Industrial Process Heat in the United States. NREL/TP-6A20-77760. National Renewable Energy Laboratory, Golden, CO. Available at: https://www.nrel.gov/docs/fy21osti/77760.pdf.