What do the cities of Amsterdam in the Netherlands, Anshan in China and Arlington in the US have in common? Or Christchurch in New Zealand, Copenhagen in Denmark and Cyberjaya in Malaysia? They are each ‘champion cities’ among 45 around the world that use district energy (DE) systems, named as such by the United Nations Environment Programme (UNEP) in its latest publication, District energy for cities – unlocking the potential of energy efficiency and renewable energy.
It’s not exactly news to COSPP readers, but UNEP describes the latest generation of DE systems as one of the most efficient and least-cost solutions for reducing both greenhouse gas emissions and primary energy demand in towns and cities around the world. DE systems usually provide lower-cost energy too, making use of a variety of locally-available energy sources via energy distribution networks (for heat, cooling and, sometimes, power) to supply whole communities.
But UNEP is talking about modern DE systems that employ inherently efficient and green energy sources – CHP, heat pumps, decentralised renewables and thermal storage – to provide heating and cooling services. The 45 champion cities are in the forefront of developing such systems, which deliver a whole range of benefits, depending on how they are set up.
Want to cut greenhouse gas emissions? In Copenhagen, recycling of otherwise wasted heat displaces the burning over a million and a half barrels of oil annually. Concerned about air pollution? The Chinese city of Anshan is to reduce its use of heavily-polluting coal by more than a million tonnes per year through connecting previously separate DE networks and capturing waste heat from a steel plant in the city.
Need to integrate large volumes of renewable energy into local systems? Several countries with high shares of wind and solar power – such as China, Germany and Denmark – have begun using district heating systems to use excess renewably-generated electricity during periods of oversupply.
Is the local electricity system struggling to cope with demand and in need of greater resilience? In Kuwait City, where air conditioning accounts for more than 70% of peak power demand, the use of district cooling is set to reduce this proportion by half, and cut annual electricity consumption by 40%.
Finally, is investment capital tight and authorities are looking for ways to finance a shift to a green energy economy? In Toronto, Canada, an innovative scheme to extract lake water for district cooling has earned the city $90 million in revenue from selling a stake in its district energy systems.
UNEP is supporting the efforts of its champion cities to move DE beyond the original concept merely to connect many buildings to one efficient heat or cooling source. Operators of a quarter of these systems have set targets for either carbon neutrality or a 100% renewable energy supply.
For heat, a myriad of sources are being used alongside more traditional boilers: geothermal plants, waste-to-energy-plants, waste heat recovery from industrial sites, heat pumps and large-scale solar thermal systems. For cooling, sources of ‘free’ cooling are available in lakes, rivers and absorption chillers driven by waste heat. Thermal storage, both heat and cold, helps to maximise the use of available energy sources to maximum effect.
UNEP has gathered together some truly groundbreaking efforts from around the world to make its point on the advantages of district energy – local energy for an increasingly urbanised world.