Flexibility through power-to-heat in local integrated energy systems with renewable electricity generation and seasonal thermal energy storage

In heating dominated regions, the flexibility obtained through coupling heating and power sectors is particularly beneficial for the integration of high shares of variable renewable energy sources. This study concerns the design of an energy system for a new neighborhood in Norway, including a seasonal thermal energy storage storing excess heat from waste incineration, a seawater heat pump, and local power generation. Two supply temperature scenarios are considered for the local heating network: medium-temperature (70 °C), where all heating demands are covered through the network; and low-temperature (45 °C), where booster heat pumps are applied for hot water production. Both scenarios are more cost-effective than if heat demands were to be met through import from the district heating network, however, the difference between the two scenarios is small. The low-temperature scenario has the highest degree of self-sufficiency, and the advantage of additional flexibility gained through the local heat pumps with hot water storage. Cost-optimal charging strategy for the seasonal storage was highly dependent on the pricing of excess heat with respect to the electricity prices. Unlimited sharing of electricity among all users in the neighborhood should be promoted to gain full benefits of local flexibility.