There are many challenges that need to be faced on the way to reaching a future of renewable non-fossil heat supply. District heating and cooling (DHC) combined...

There are many challenges that need to be faced on the way to reaching a future of renewable non-fossil heat supply. District heating and cooling (DHC) combined with renewable energy sources has the potential to play an important role in it and can help meet the rising 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 gas. There is significant potential to upgrade existing systems and create new networks using solid biofuels, solar and geothermal technologies but the present generation of district heating and cooling technologies will have to be developed further into a new generation. The technology of DH must develop and be flexible to effectively position DHC into the future smart energy system.

DHC changes and improves constantly - whereas the first generation was based on heat distribution by steam, the second generation started implementing water with temperatures above 100°C and the third generation improved efficiency with hot water at temperatures below 100°C. The development of 4th generation DHC involves meeting the challenge of optimizing the utilization of low temperature water distribution and limiting installation costs and heat losses. In addition to that it has to exploit renewable energy and waste heat in order to limit carbon emissions and reduce air pollution. Even though some aspects of the 4th generation DHC concept are applied in existing DHC systems today, the general implementation is expected to start after year 2020.