What is the least-cost and most efficient solution for reducing both greenhouse gas emissions and primary energy demand in an increasingly urbanised world?
The development of ‘modern’ district energy (DE) systems is one of the best options, according to the United Nations Environment Programme (UNEP) in a new publication: District energy in cities – unlocking the potential of energy efficiency and renewable energy. Launched at the International District Energy Association’s (IDEA’s) annual conference last month, the report calls for the accelerated deployment of DE systems around the world.
At the same event, the US city of Boston won the IDEA system-of-the-year award for its investment in a steam pipeline extension from neighbouring Cambridge, which allows DE system operator Veolia to export more heat energy from a CHP plant there, increasing capacity, reliability and overall system efficiency.
But note the word ‘modern.’ UNEP is keen to see a new generation of DE schemes developed – systems that supply heating and cooling services from inherently efficient and green sources, using CHP, thermal storage, heat pumps and decentralized renewables. UNEP lists 45 ‘champion cities’ around the world that use such systems, from Aberdeen in the UK to Yervan in Armenia. Operators of a quarter of these systems have set targets for either carbon neutrality or a 100% renewable energy supply.
DE has come a long way from its inefficient, coal-fired roots in Eastern Europe and North America more than a century ago. UNEP quotes Port Louis in Mauritius, which is developing the first seawater district cooling system in Africa, and cities in China and Eastern Europe now integrating renewable energy sources and improved energy efficiency into well-established DE systems.
UNEP charts the development of DE from the first generation of systems – built in the US and based on coal and oil, and with high temperature steam distribution – to today’s schemes incorporating gas, waste fuels and geothermal energy, and with lower temperature distribution of hot water. The next generation will use even lower temperatures to distribute thermal energy from sources such as solar thermal plants, biomass and heat pumps to buildings with lower heat demands, and with increasingly smart metering and control.
In a world where more than half of the population already live in cities, a figure projected to increase to two-thirds by 2050, getting an efficient and low carbon energy supply to urban conurbations is vital.