District heating as a flexibility service: Challenges in sector coupling for increased solar and wind power production in Sweden

With expanding solar and wind power production, the topic of flexibility services attracts increased attention in the Swedish energy system. In this context, the potentials in using thermal storage capacities in district heating (DH) systems have been brought forward, primarily by academic scholars. Using a 'grounded' approach, this study investigates if professionals assigned to Swedish DH companies and electricity distribution system operators utilise, or plan to utilise, DH systems as flexibility services for the electricity grid. Original data was collected through semi-structured interviews, held with fourteen individuals affiliated to different actors in the Swedish energy system. These individuals were identified as being experts, or practically engaged, in using DH utilities as flexibility services for the electricity grid. The findings show that although technologies for coupling between DH systems and the electricity grid are already in place, initiatives for using DH systems as flexibility services for the electricity system are rare in Sweden. Coupling challenges stem from ownership and operation legislation frameworks, marginal incentives and a widespread focus on firm benefits rather than energy systems benefits. Identified initiatives for using DH systems for flexibility services are primarily run on a local scale, designed and propelled by small groups of engaged individuals.