MODULE 10.1: District Energy in Cities
District energy is a proven energy solution that has been deployed for many years in a growing number of cities worldwide. It represents a diversity of technologies that seek to develop synergies between the production and supply of heat, cooling, domestic hot water and electricity. See Figure 1.7 of UNEP's District Energy in Cities for an overview of a complete district energy system. See also Figure 1.3 for the historical development of district energy.
District Heating enables the use of a variety of heat sources that are often wasted, as well as of renewable heat. Additionally, it can allow consumers to supply excess heat. Through heat storage, smart systems and flexible supply, these systems are an inexpensive solution for creating the flixibility required to integrate hight levels of variable renewable energy into the electricity grid.
District cooling systems supply cold water through pipes in combination with cold storage. Cold water can be produced from waste heat (such as from power generation or industry) through the use of steam turbine-driven or absorption chillers; from free cooling sources such as lakes, rivers or seas; and via electric chillers. District cooling can be more than twice as efficient as traditional decentralized chillers such as air-conditioning units and can reduce electricity use significantly during peak demand periods through reduced power consumption and the use of thermal storage.
Why should local governments (LGs) consider district energy?
Europe consumes half of its energy for heating and cooling purposes. Most of the thermal energy is used in buildings and industry. Heating and cooling efficiency and decarbonisation in buildings and industry hold the key to Europe's energy transition towards a sustainable low carbon future. Here are a few reasons why:
- Greenhouse gas emissions reductions. District energy allows for a transition away from fossil fuel use and can result in a 30-50 percent reduction in primary energy consumption.
- Air pollution reductions. By reducing fossil fuel use, district energy systems can lead to reductions in indoor and outdoor air pollution and the associated health impacts.
- Energy efficiency improvements. Linking the heat and electricity sectors through district energy infrastructure and utilizing low-grade energy sources, such as waste heat or free cooling, can greatly improve the operational efficiency of new or existing buildings.
- Use of local and renewable resources. Through economies of scale and the use of thermal storage, district energy systems are one of the most effective means for integrating renewable energy sources into the heating and cooling sectors.
- Resilience and energy access. District energy systems can boost resilience and energy access through their ability to improve the management of electricity demand, reduce the risk of brownouts and adapt to pressures such as fuel price shocks (for example, through cost-effective decarbonization, centralized fuel-switching and affordable energy services).
- Green economy. District energy systems can contribute to the transition to a green economy through cost savings from avoided or deferred investment in power generation infrastructure and peak capacity; wealth creation through reduced fossil fuel expenditure and generation of local tax revenue; and employment from jobs created in system design, construction, equipment menufacturing, and operation and maintenance.
- For more information on benefits of district energy, see pages 29 and 30 of UNEP's District Energy in Cities
Note: Information presented on this page was based on the UNEP's District Energy in Cities publication