Highly Renewable District Heat for Espoo Utilizing Waste Heat Sources

The district heating operator Fortum and the city of Espoo have set a goal to abandon the use of coal in district heating production and increase the share of renewable sources to 95% by the year 2029. Among renewable fuels and heat pumps, waste heat utilization has an important role in Fortum's plans for the decarbonization of district heating production, and Fortum is considering the possibility of utilizing waste heat from a large data center in its district heating network. The goal of this paper is to investigate the feasibility and required amount of waste heat to achieve this goal. Two different operation strategies are introduced-an operation strategy based on marginal costs and an operation strategy prioritizing waste heat utilization. Each strategy is modeled with three different electricity price scenarios. Because the low temperature waste heat from a data center must be primed by heat pumps, the electricity price has a significant impact on the feasibility of waste heat utilization. Prioritizing waste heat utilization leads to higher production costs, but a lower waste heat capacity is needed to reach the goal of 95% renewables in production. The higher electricity price emphasizes the differences between the two operation strategies. Waste heat utilization also leads to significant reductions of CO(2)emissions.