Many of us live in apartments that are warmed by district heating. In our daily lives, it doesn’t necessarily occur to us how effortlessly our apartments are warmed and that breaks in heating are rare, brief and barely affect our comfort. Radiators and thermostatic radiator valves, which we don’t even need to touch to maintain a pleasant indoor temperature, are all that remind us of heating. However, district heating will most likely undergo major changes over the next decade.
District heating has a long history. The world’s first systems were implemented at the end of the 1800s. In Finland, the distribution of district heating began in places such as Helsinki and Espoo in the 1950s. Most district heating is still produced by either combined heat and power plants, or separate heating plants. However, the trend is shifting from the current third-generation district heating towards fourth-generation district heating systems. The long-term trend has seen improvements in the energy efficiency of district heating and a fall in water temperature levels during the transition to the next generation.
District heating is more and more often being produced from renewable energy sources and various types of waste heat, which would otherwise remain unused. For example, several data centres have recently been built whose facilities generate a great deal of heat. Waste heat of this kind is already being used as a source of district heating. In the sample calculations for the EFEU research project, carbon dioxide emissions were reduced by half, while a fifth of the district heating produced for the studied area comprised waste heat from the data centre.
Towards changing markets
The district heating markets are also changing. An open, two-way district heating network means one that both distributes district heating to consumers and enables customers or individual heat producers to sell their surplus or other generated heat to the network. This could mean a major increase in the share of, say, solar power or large thermal heat pumps in district heat production. In the EFEU project, it was observed that, since solar and geothermal heat saw the biggest increase during the twenty-year study period, the need for centrally produced heat fell by 34%.
In an open district heating production structure, the operators will also change. Someone must take responsibility for the trade in heat and the related production and demand management. It must be decided under what terms and with what technical solutions trade can be made possible, how demand during peak consumption can be met in all circumstances and how investments will be made.
As the temperature levels of district heating water fall, household heating systems will have to be upgraded. The latest systems are so-called low-temperature systems, whose radiators – for example – are bigger than the current ones. Changes can be implemented during other renovations, which makes them cheaper than when done separately. A building’s heating distribution system would then be ready for either the person’s own renewable energy system, or for the new network – freedom to choose is a blessing.
In the future, network operators may also encourage customers (by using tariffs, for example) to prepare for connection to a low-temperature network. For network operators, lowering the network temperature will open up new markets, such as the possibility to buy and utilise cheap waste heat. In addition, energy-renovated buildings previously disconnected from the network in an ‘old district heating network’ area could reconnect, or new buildings with their own heat production could be connected for the first time. In practice, however, changes in buildings’ systems will occur in stages and only in new district heating areas to begin with.
EFEU research project
Energy system scenarios were created via the Efficient Energy Use (EFEU) programme coordinated by CLIC Innovation Ltd. The scenarios involved research on increasing the use of solar heat and geothermal heat pumps, industrial waste heat recovery, and the impact on energy and emissions of small-scale producers selling heat to consumers. These options were explored in a case study of the Central Uusimaa district heating network.
The publication, ”Visions for future energy efficient district energy systems”, is available online at: http://www.vtt.fi/inf/pdf/technology/2016/T277.pdf
The report sets out visions of the energy systems of the future and the current status of systems connectible to district heating in Finland. The publication describes the challenges, needs and scenarios related to future business activities and services.
Satu Paiho, Senior Scientist
Rinat Abdurafikov, Research Scientist