District heating warms cities without fossil fuels. Many cities which endure cold winters are adapting district heating schemes to keep people warm without the use of fossil fuels. As a way of providing warmth for thousands of homes, typically in multi-storey apartment buildings, district heating has a long history in eastern Europe and Russia. But the hot water it distributes typically comes from power stations burning coal or gas, which means more greenhouse gas emissions. Tapping into other forms of producing hot water, from renewable energy, bio-gas or capturing waste heat from industrial production, supermarkets or IT systems, provides alternative sources of large scale heating without adding to the carbon dioxide in the atmosphere. Sweden has pioneered the switch from fossil fuels to other ways of heating water. The Swedish Environmental Protection Agency says the country has gone from almost exclusively relying on fossil fuels to being 90% powered by renewable and recycled heat in 2017. Today Stockholm, the capital, which needs heating for nine months of the year, contains 2,800 km of underground pipes connecting to more than 10,000 buildings, says Erik Rylander from Fortum, an energy company active in Nordic and Baltic countries. “As long as you have a water-based heating circuit in your building (which basically all bigger buildings in Sweden have), the connection is easy,” he explains. “A heat exchanger is placed in the basement which connects the district heating system to the building’s heating system.” The system uses biofuels – wood chips, wood pellets and bio-oil – as well as household waste and recovered heat from the city’s data centres and industries. It also draws energy from the sea using large heat pumps, Rylander said. Further south in Spain, where heating is mostly required only in the winter months, winning public acceptance for the need to install district systems has been more difficult. The involvement of citizens is a key issue for smart city initiatives, said José Ramón Martín-Sanz García, energy efficiency engineer at Veolia, a partner in a Spanish project near Valladolid. “One of the biggest challenges was convincing homeowners that it was necessary. It required a communication plan,” he said. About 31 buildings, a total of 1,488 dwellings with more than 4,000 residents, have been retrofitted since 2014 to decrease buildings’ energy demands by 40%. While many district heating schemes are quite large-scale others can be much smaller, using waste heat from one building to heat another nearby. The strategy is that heat will be supplied from local sources of waste heat such as retail outlets, buildings and IT server rooms, as well as from renewable sources such as solar power and heat pumps – and often in combination with thermal storage.
Climate News Network 15th Jan 2018 read more »