The heat under the street
They can cut carbon emissions, reduce energy bills and even attract scarce government subsidy. Jess McCabe reports on the landlords firing up district heating systems
Britain is a nation of gas boilers. More than eight in 10 homes are connected to our vast network of pipes pumping natural gas from stores in the North Sea, or as far away as Russia, each going into an individual furnace, where it is burned to heat the water which circulates through our central heating systems and hot water pipes.
In much of Europe, the development of central heating systems took a different turn in the middle of the last century. Instead of being connected to a gas grid, homes are connected to a heat grid: a hot water network, rather than a gas network.
Any means can be used to heat up this water - from the excess heat produced in a power plant or factory, to a traditional fossil fuel boiler, the waves of excess heat coming off data centres, or solar thermal panels. This system is known as district heating, a heating network or, on a smaller scale, as community heating.
The UK got caught up in the rush towards this type of heating system in the middle of the 20th century, with local authorities funding the schemes as they built new social housing, but take-up was limited.
While nearly 70 per cent of Danish homes get their heat through a network, less than 2 per cent of the UK’s heating demand is met in this way, according to the district heating industry. The Department of Energy and Climate Change says there are 2,000 heat networks in the UK, supplying 172,000 domestic buildings - mostly social housing, tower blocks and public buildings.
But the ground is being laid in many parts of the country for new district heating systems and the refurbishment of older systems. District heating could reduce the UK’s carbon emissions, and diversify its sources of heat. And, as it develops, it can easily switch to low carbon heat technologies or waste heat sources. If powered by biomass, as new systems increasingly are, district heating is eligible for the renewable heat incentive subsidy.
With this in mind, DECC published a new heating strategy in March, which said heat networks can be ‘core to the UK’s heat strategy and have the potential to play a critical role in helping buildings and industry decarbonise their heat supply out to 2050’.
After years of no subsidies, district heating is now a hot prospect again, and there are two reasons for this. First, Britain has a target to cut greenhouse gas emissions by 80 per cent from 1990 levels by 2050. Heating accounts for half of those emissions and it will be nearly impossible to meet the target without, to some extent, ‘decarbonising’ the heating system.
The second reason is energy prices, which are only expected to continue to rise. Southampton’s 20-year-old, 14 kilometre network, for example, saves 11,000 tonnes of CO2 a year, according to operator Cofely, and saves customers £600,000 a year on their energy bills. After looking at the rest of Europe, politicians have seen district heating as a possible answer to these two problems.
A brief history
To understand how district heating might work in future, we need to examine how it worked in the past, and also the part played by social landlords so far.
Birdsill Holly, an American engineer, invented district heating in the 19th century, and the first system was installed in New York City in the 1880s. But the concept didn’t take off in the UK until much later. Sustainable Housing visited one of the oldest systems in the country - the Pimlico District Heating Undertaking - which was almost closed in the 1990s when interest is such systems had plummeted.
But now district heating is cool, or rather, hot again. Earlier this year, the Treasury announced systems will also be able to apply for loan guarantees from a new £40 billion infrastructure fund.
It is also eligible for payment under the renewable heat incentive, and some biomass schemes can earn renewable obligation certificates.
Meanwhile, the Scottish Government set up a district heating loan fund to help overcome the barriers to setting up new systems. In November, it gave out £1.9 million of loans at 3.5 per cent interest from the fund to help communities in Scotland develop eight small district heating schemes, all using biomass.
Clusters of new district heating systems and smaller communal-scale systems have been announced along with plans to renovate ageing ones.
London’s Olympic village, and surrounding homes and businesses, are served by a £480,000 network installed by Cofely, one of the bigger district heating operators. Southwark Council, meanwhile, hopes a new network will be installed by 2013 which will pipe waste heat from the South East London Combined Heat and Power Plant in Deptford to boiler houses that heat around 3,000 homes across seven estates in the south London borough.
The cost of the scheme is still being finalised, with an announcement expected at the end of the year. The council hopes it will save 8,000 to 10,000 tonnes of CO2 and cut bills for council tenants and leaseholders.
Southampton, Sheffield, Leeds, Derby and Bradford are some of the other cities that have this year announced proposals for new or extended district heating systems, from a variety of heat sources.
Andy Nolan, director of sustainable development at Sheffield Council, explains: ‘We believe district heating networks have the potential to play a significant role in reducing the UK’s carbon emissions, particularly because of their ability to source heat from renewable and low carbon sources.’
Industry is responding too. In July, Rehau, a specialist manufacturer of pre-insulated pipes for use in district heating and biomass, opened the first such factory in the UK. Until now, developers have had to import the pipes.
Cofely says it now has the capacity to deliver 500 gigawatt hours of heating a year. And DECC says that 300 combined heat and power systems - one of the more popular technologies - were built in the UK in 2011, a 300 per cent increase from 2010.
Meanwhile, Richard Kirkman, head of technology at engineering company Veolia, explains that his firm is actively seeking ‘heat customers’ for the heat produced from its waste burning plants across the country. It already pumps 60 megawatts of steam a year from a waste-to-energy plant into Sheffield’s 44-kilometre network.
Planning rules have helped encourage district heating by requiring new developments to be ready to connect to heat networks, and encouraging the installation of combined heat and power systems - which could potentially connect up to a larger heat network in future. ‘Our experience in Sheffield is that over the past 10 years any new developments have, under the planning requirements, had to have connections made up so that they can connect to the district heating network,’ says Mr Kirkman.
It’s taken a while to get the critical mass to connect up to those places, he says, but this is now happening. ‘The most difficult thing is to put the pipework in,’ he adds.
Success is not just about pumping in subsidies to enable authorities to lay pipes, however. In June, the mayor of London’s energy team worked with all the boroughs to produce a map of the city’s heat demand and found that heating networks are best suited to dense, urban areas where lots of homes or businesses can be connected without installing lengthy pipes.
‘Our driver, really, is the mayor’s environmental policies and targets to reduce London’s carbon dioxide emissions,’ says Peter North, a senior manager of programme delivery at the GLA - London also has a target to meet 25 per cent of energy demand with decentralised systems by 2025.
Not everyone is a fan of district heating though. Fordham Consulting Engineers, for example, calls it ‘an unhelpful step to lowering our reliance on carbon emitting fuels’, because it diverts money that should be spent on better insulation and saving energy.
Others remain unconvinced that the government’s ambitions can be met without a radical increase in financial support. For example, William Orchard, an engineer and consultant who champions heat networks, says it would be ‘absurd’ for a private developer to invest in new heat networks under current subsidies and policy conditions, because they wouldn’t promise a high enough return.
David Wickersham, a champion of the Pimlico system in Westminster, which now has 3,256 homes and a handful of businesses and schools connected, has been trying since 2008 to build a connection between Pimlico and the nearby Whitehall district heating scheme, which is powered by gas. A connection would mean even more people could connect to the network, and would make better use of heat generated by the gas turbine running in the Ministry of Defence. When the plan was announced, it immediately attracted £3.5 million in government grants. The project was tendered and digging was poised to begin when the money was taken back - to help fund the Olympics.
Since then a new business case for the project showing that it can pay its way has been put together and is poised for approval by Westminster Council.
The sustainability arguments for district heating are sound, the government is engaged, but whether the idea of installing more systems is hot enough to go the distance is being questioned by some.
Given the trouble he’s had building the Pimlico system’s ‘no brainer’ of an extension, Mr Wickersham, for one, wonders, ‘What chance do projects have elsewhere?’
The Pimlico project
We’re here because of Battersea Power Station,’ explains David Wickersham (pictured), technical advisor to City West Homes, which runs the Pimlico district heating undertaking, as he shows us around the facility, which was renovated in 2006 to install a combined heat and power plant.
Construction started on Battersea Power Station on the south bank of the River Thames in 1928. The coal-burning electricity plant is an icon of the London skyline, but as a feat of engineering it left a lot to be desired. At its peak,it only had a thermal efficiency of 28 per cent.
‘All its waste heat was simply dumped into the Thames,’ Mr Wickersham explains. This heated the river to the point it was declared sterile.
In 1950, an opportunity came to do something about the unused heat. Work began on the north side of the Thames on Churchill Gardens, a 1,600-home social housing estate. A savvy decision was made to contain all the waste heat from Battersea Power Station, pump it under the Thames and use it to heat the estate. A 132-foot glass accumulator tower was built to store extra heat until it was needed.
The motivation for doing this was smog. By the time PDHU was was under construction, about 300 million tonnes of coal was being burned each year in London, producing a heavy, polluted smog that was a serious
‘The idea was you could build an estate without a single flue or chimney to add to pollution,’ Mr Wickersham says.
PDHU was, for the time, a massive success. From the 1950s onwards, the concept of the district heating network took off across the nation - built almost exclusively by local authorities and connecting to dense social housing, along with other big heat users such as universities and public buildings.
By the 1980s, however, district heating’s popularity began to wane. The discovery of massive natural gas stores under the North Sea created a cheaper heating option. And, explains William Orchard, an engineer and
consultant who champions heat networks, these original systems were beset by problems. ‘It was all very badly maintained by the local authorities,’ he says.
Although district heating systems have become more sophisticated since they were first installed, for example, adding thermostats in individual homes so residents have better control over the heat supply, Mr Orchard argues that these failures were ‘very little to do with engineering - and all to do with politics’.
As a result of these woes, ‘district heating has ended up with a reputation as being an inefficient, heavy carbon offering,’ adds Craig Dennett, research manager at the Combined Heat and Power Association, formerly the UK District Heating Association.
In Pimlico, the system was nearly shut down. In 1983, the inefficient Battersea Power Station was decommissioned, and the PDHU heat network switched to a boiler plant on a leased out corner of the old site. In the mid-1990s the PDHU was about to be decommissioned.
Residents were about to be switched to individual boilers, when Mr Wickersham, who joined Westminster Council in 1980 and had just been assigned to PDHU, made a last-ditch attempt to make the system work. It spent £50,000 working on some of the pumps to make the whole thing more efficient. It worked and the PDHU survived. ‘It just needed a champion,’ says Mr Wickersham. ‘It needed someone who’d love it, or at least understand it.’
Doreen Green has lived on the site of the estate for 82 years. She says the system is reliable and wouldn’t change it if she could, especially now it is on all year. ‘We didn’t have any heating in the summer months [originally],’ she remembers.
Now the system is flourishing, with 3,256 homes connected. In 2008, the pipes under the Thames were mothballed after a new gas boiler and an efficient combined heat and power system was added in 2006. The 3.2 megawatt CHP system also generates electricity to sell to the grid, which nets a profit of £500,000 per year.
City West is looking to expand its use of district heating in the future.
Communal heating in practice
Communal heating systems are the smaller-scale cousin of district heating. St Pauls in Preston is the first sheltered housing scheme in the country to install a biomass boiler. The 39-flat complex was built in 1986 and sits in the middle of the town centre.
A few years ago it became clear the old gas boiler needed to be replaced. ‘The efficiency had decreased to 55 per cent, so 45 per cent of the gas was dumped through the chimney,’ says Derek Watters, sustainable development manager at the 62,000-home housing association, Places for People.
The landlord decided to make St Pauls a prototype for replacing dated boiler rooms with a £120,000 outdoor energy centre, fitted out with a duel fuel system - new, more efficient gas boilers and a biomass system fed with locally sourced pellets.
PfP set up a joint venture with London supplier Font Energy, which entered into an energy performance contract with the association to supply heat to St Pauls residents.
PfP expects to save 1,781 tonnes of carbon dioxide over 25 years. It also expects to cut energy bills, although Mr Watters cautions that the joint venture is still looking at the numbers for the first year of operations to calculate the exact savings. Tenants, who pay a flat fee for heating via their service charge, have been promised no bill increases for three years.
Terry Harbon, 66, who has lived in St Pauls for four years, says there were no interruptions when the system was installed. ‘If you can save energy I think it’ll be quite good,’ he adds.
The housing association says 37 per cent of its 84 communal boilers need to be replaced. It is in the final stages of procuring a second joint venture energy services company - its partner cannot yet be announced. This will allow it to replace boilers and act as an energy company in around 200 social housing developments.