The Member States of EU27 need to accelerate the integration of energy efficient technology solutions to reach the 20% energy efficiency target set for 2020. At current pace, projections indicate that only half of expected primary energy reductions will be reached. To meet the energy demands of growing populations and a vibrant economy, while simultaneously reducing primary energy supplies, the European continent faces a new kind of challenge never previously encountered. The identification and application of feasible, competitive, and comprehensive solutions to this problem are of highest priority if the remaining gap is to be closed in time. How is this multi-dimensional and complex dilemma to be dissolved? In this work, expanded use of district heating technology is conceived as a possible solution to substantially reduce future primary energy demands in Europe. By extended recovery and utilisation of vast volumes of currently disregarded excess heat from energy and industry sector fuel transformation processes, district heating systems and combined generation of heat and power can improve the general efficiency of the European energy balance. To investigate the possible range of this solution, this thesis introduces a set of methodologies, theoretical concepts, and model tools, by which a plausible future excess heat utilisation potential, by means of district heat deliveries to residential and service sectors, is estimated. At current conditions and compared to current levels, this potential correspond to a threefold expansion possibility for directly feasible district heating systems in European urban areas and a fourfold increase of European excess heat utilisation.

This thesis presents a set of methodologies and approaches to investigate and determine the extent by which district heating can contribute to improved energy system efficiency and reduced carbon dioxide emissions in future Europe. The main motivation for suggesting large-scale implementation of district heating as a structural energy efficiency measure to obtain these objectives originates essentially in the predicament that a majority of European buildings today remain highly dependent on fossil fuels to provide energy needed for space heating and hot water preparation. In parallel, vast annual volumes of rejected excess heat from European power plants and industries are mainly neglected and lost unutilised to the ambient surroundings, why extended recovery and utilisation of such secondary energy assets realistically could replace significant shares of current inefficient supplies by fuel substitution. A prerequisite, however, for the viability of this logical prospect, is that infrastructures by which to facilitate excess heat recovery and subsequent network heat distribution are in place, which by no means is the average case in contemporary Europe.

Hereby, the investigation is structured orderly by first establishing whether district heating can be a competitive alternative on current urban European heat markets, facilitated by a distribution capital cost model, where after the energy systemic benefits of expanding district heating are characterised and used to estimate a plausible expansion potential based on comparative analysis. Next, energy system modelling of continental EU27 by the year 2050, with district heating expanded in alignment with this potential, is performed to assess the total energy system cost benefits relative an alternative scenario focusing mainly on individual energy efficiency measures. Finally, spatial mapping to identify current primary target regions from which large-scale implementation of district heating could emanate is conceived and performed by use of a geographical information systems interface.

The findings are generally supportive of a realisation of the objectives, mainly so by establishing a three-fold directly feasible expansion potential for district heating in city areas, but recognise also several additional, mainly non-technical, issues and challenges necessary to address in a successful transition to more energy efficient supply structures in future Europe.