This book evaluates the potential of the combined use of district heating networks and cogeneration in the European Union (EU). It also proposes measures to remove barriers hindering their widespread implementation, formulates policies for their implementation, and evaluates their economic, energy, and environmental consequences. The book presents a preliminary assessment of the likely cost and the impact of widespread adoption of district heating networks and cogeneration carried out in three cities that represent the variety of climatic conditions in the EU. Based on this assessment, it is estimated that by undertaking the maximum economically feasible implementation across the EU, fuel savings of €95M/year would be achieved, representing energy savings of 6,400 petajoules (PJ), which is around 15% of the total final energy consumption in the EU in 2013 (46,214.5 PJ). Using simple and quick calculations and not specific software, the method used allows the evaluation of the potential benefits of retrofitting existing power plants into cogeneration plants and connecting them to nearby heating networks. In light of increasing energy costs and environmental concerns, the book is of interest to heating engineers, city planners, and policy-makers around the globe.

Conventional thermal power generating plants reject a large amount of energy every year. If this rejected heat were to be used through district heating networks, given prior energy valorisation, there would be a noticeable decrease in the amount of fossil fuels imported for heating. As a consequence, benefits would be experienced in the form of an increase in energy efficiency, an improvement in energy security, and a minimisation of emitted greenhouse gases. Given that heat demand is not expected to decrease significantly in the medium term, district heating networks show the greatest potential for the development of cogeneration. Due to their cost competitiveness, flexibility in terms of the ability to use renewable energy resources (such as geothermal or solar thermal) and fossil fuels (more specifically the residual heat from combustion), and the fact that, in some cases, losses to a country/region’s energy balance can be easily integrated into district heating networks (which would not be the case in a “fully electric” future), district heating (and cooling) networks and cogeneration could become a key element for a future with greater energy security, while being more sustainable, if appropriate measures were implemented. This book therefore seeks to propose an energy strategy for a number of cities/regions/countries by proposing appropriate measures supported by detailed case studies.

Heating and cooling consume half of the EU's energy. Today, the majority of heating and cooling is still generated from fossil fuels and almost all of the waste heat produced in the EU is currently not used. The IEA finds in its 2020 report on heating that the decarbonisation of the sector is not on track (https://www.iea.org/reports/heating). In order to fulfil the EU's climate and energy goals, the heating and cooling sector must not only urgently become more efficient, but carbon-neutral by using 100% renewable sources and waste heat. District Heating and Cooling (DHC) is a proven solution for delivering heating, hot water and cooling services through a network of insulated pipes, from a central point of generation to the end user. They are suited to feed in locally available, renewable and low-carbon energy sources, such as solar thermal and geothermal heat, waste heat from industry and commercial buildings, heat from combined heat and power plants. The ability to integrate diverse energy sources means customers are not dependent upon a single source of supply. District energy networks are inherently diverse and variable in terms of size and load; while employing similar operating principles, each network develops according to specific local circumstances and adapts to continuous innovation. Heat networks are based on economies of scale, as the generation of heat in one large plant can often be more efficient than production in multiple smaller ones.

A case study method has been retained to illustrate how renewable and waste heat or cold sources are being integrated into some of the most efficient DHC networks in Europe. This approach enables to illustrate the specific technical, economic, regulatory and operational enablers of ten DHC systems in operation within different geographies and contexts. It also displays strategic decisions made to reach a significant share of renewable and waste energies in their energy mix, as well as development paths followed towards decarbonisation, identifying replicable success factors.

Conventional thermal power generating plants reject a large amount of energy every year. If this rejected heat were to be used through district heating networks, given prior energy valorisation, there would be a noticeable decrease in the amount of fossil fuels imported for heating. As a consequence, benefits would be experienced in the form of an increase in energy efficiency, an improvement in energy security, and a minimisation of emitted greenhouse gases. Given that heat demand is not expected to decrease significantly in the medium term, district heating networks show the greatest potential for the development of cogeneration. Due to their cost competitiveness, flexibility in terms of the ability to use renewable energy resources (such as geothermal or solar thermal) and fossil fuels (more specifically the residual heat from combustion), and the fact that, in some cases, losses to a country/region's energy balance can be easily integrated into district heating networks (which would not be the case in a “fully electric” future), district heating (and cooling) networks and cogeneration could become a key element for a future with greater energy security, while being more sustainable, if appropriate measures were implemented. This book therefore seeks to propose an energy strategy for a number of cities/regions/countries by proposing appropriate measures supported by detailed case studies.

This is a background report designed to provide guidance on defining and accounting for efficient district heating and cooling networks under Article 14 of the Energy Efficiency Directive and Articles 23 and 24 of the Renewable Energy Directive. It also analyses the options for a future definition of efficient district heating and cooling that would support the net zero decarbonisation target of 2050.