Optimal heat storage in district energy plants with heat pumps and electrolysers

Date: 12/04/2023

Elsevier's scientific journal Energy has accepted and published an article by Professor Poul Alberg Østergaard and Ph.D. Ext. Ass. Professor Anders N. Andersen about optimal heat storage in district energy plants with heat pumps and electrolyzers.


The article highlights

- Electrolyzers and heat pumps competing for low electricity prices

- Analyses of district energy plants using energyPRO

- Increased thermal storage is a no-regrets option in district energy plants.

- Little incentive for added electrolyzer capacity to improve flexibility.

- Incentive for added heat pump capacity to improve flexibility.

District energy (DE) plants are transitioning away from being providers of heat and electricity through the cogeneration of heat and power (CHP) to being heat providers consuming electricity for heat pumps (HPs) and electric boilers. Concurrently, hydrogen production for electro fuels may be combined with DEs to exploit thermal losses from electrolyzers and electro-fuel synthesis. Where CHP units favor high electricity prices and electric boilers or HPs favor low – thus providing incentive for operation at both high and low electricity prices - future DEs with HPs and electrolyzers both call for low electricity prices, increasing the need for thermal storage. Costly hydrogen storage could also enable flexible operation. In this article, energyPRO is applied to investigate optimal system compositions with a focus on storage capacities. Results show that added flexibility in the shape of more thermal storage is valuable. Storage costs are more than compensated by the improved performance in the electricity market. Added electrolyzer capacity and HP capacity also improve flexibility, but only added HP capacity pays off in business-economic terms. All the modeled ways of increasing flexibility enable the units to perform better on the electricity market – and thus give value to the overall energy system.