There are many challenges to overcome on the road to a renewable, non-fossil-fuel future for heat supply. The combination of district heating and cooling (DHC) with renewable energy sources has the potential to play an important role here, and can help meet growing urban energy needs, improve efficiency, reduce emissions and improve local air quality.
DHC offers a cost-effective and energy-efficient option for residential and commercial buildings. However, DHC supply is currently dominated by fossil fuels such as coal and natural gas. There is significant potential to upgrade existing systems and to create new networks using solid biofuels, solar and geothermal technologies — but today’s generation of district heating and cooling technologies needs to be developed further. The technology must evolve and be flexible enough to fit efficiently into the future smart energy system.
District heating and cooling are constantly changing and improving. While the first generation relied on distributing heat with steam, the second generation began to use water at temperatures above 100 °C, and the third generation improved efficiency with hot water at temperatures below 100 °C. The development of the 4th generation involves meeting the challenge of optimising the use of low-temperature water distribution and limiting installation costs and heat losses. In addition, it must harness renewable energy sources and waste heat in order to cut carbon emissions and reduce air pollution. Although some aspects of the 4th-generation concept are already being applied in existing DHC systems today, general adoption is expected to begin after the year 2020.