A Review of District Heating in Denmark: Technical Diversity, Fuel Diversity and Flexibility Potential

This review paper discusses the state of the district heating sector in Denmark. Supplying approximately 65% of the Danish building mass heating, these extensive underground district heating networks integrate a diverse mix of fuels into the Danish energy system, for example bio-fuels, household waste, waste heat from industrial production, as well as natural gas and other fossil fuels, and the district heating infrastructures comprise a variety of innovative technical solutions and combinations. Much of the district heating in Denmark is supplied by the highly energy efficient combined heat and power plants (CHPs), strategically integrated into nationwide district heating networks from the early days. This paper discusses the role and importance of these historical and nationwide large-scale heat infrastructure planning processes and strategies; it discusses the role and importance of the rich technical diversity, the fuel use- and supply area characteristics, and overall bricolage-like character of what may be referred to as the Danish district heating landscape. Energy policy ambitions in Denmark are broadly captured by the notions of affordability for all, sustainability and stability of supplies. Taking these into account, this this paper also discusses the future challenges - and potentials - of the Danish district heating sector. It does so based on mixed literature and empirics collected from among a wide range of district heating sector stakeholders. Lessons learnt and policy implications from within this historical account are discussed.