Effect of the use of industrial excess heat in district heating on greenhouse gas emissions: A systems perspective

• EU policy promote EH in DH, Swedish policy neither promote nor steer away from it.
• Swedish policy does not differentiate between different DH production technologies.
• EH in DH based on boilers is positive from a GHG-emission perspective.
• GHG emission reductions from EH in CHP based DH requires a strengthened EU policy.
• Measures towards use of biomass where it has most favorable effects are needed.

European policy promotes increased use of excess heat as a means to increase the efficiency of resource use. By studying possible effects on greenhouse gases, this article aims to analyze and discuss system aspects of the use of industrial excess heat in district heating. Effects on greenhouse gas emissions are studied by applying different energy market conditions with different system boundaries in time and space. First, life cycle assessment is used to assess the introduction of excess heat in district heating in a contemporary system with different geographical system boundaries. Thereafter, future energy market scenarios for Europe are investigated to explore possible future outcomes. This study concludes that both the heat production system and the energy market conditions affect the system emission effects of using excess heat in district heating. Industrial excess heat in district heating can be beneficial even if it leads to reduced local electricity production when unused biomass can be used to replace fossil fuels. It is recommended that a strengthened EU policy should encourage the use of biomass where it has the most favorable effects from a systems perspective to ensure emission reductions when industrial excess heat is used in district heating.