District heating systems are set to play an increasing role in the UK’s drive to force down both energy prices and greenhouse gas (GHG) emissions. The election focus, however, has been more on capping power bills and less on encouraging energy efficiency. But do low-energy bills create bad energy habits we can’t afford? Jon Herbert reports.
We once cooked and shared heat around communal camp fires. Cosy individual homes then tempted us in with coal fires, and later gas or oil-fired boilers, plus electric heat storage systems and AGAs. Foraging for camp fire wood had a social cost; today, household and business energy prices are a live economic issue.
One response is to use less — energy efficiency. Condensing boilers, low-energy appliances, lagged lofts and green light bulbs force down the watts.
Another answer traces its history back to the co-operative aspects of sharing camp fires. Well-run community energy schemes allow residents and small businesses to benefit from economies of scale associated with local power and heating plants of various types. Such schemes are very much on the Government’s sustainability agenda because of their low costs, energy efficiency and important contribution to national GHG emission reduction targets.
Last year, the Department of Energy and Climate Change held a consultation on the Heat Networks Investment Project (HNIP) with the aim of providing £320 million in capital support to stimulate the sector and create conditions for the development of a self-sustaining heat network market. A pilot funding project is going ahead as a result.
Are low energy prices good for us?
Meanwhile, politicians on the election “stump” have taken a different energy stance. They have been vying to promote their own particular prescription to end “rip-off energy prices” with caps and ceilings. The problem with prices restraints is that they can have a negative effect — encouraging bad energy habits. They are also temporary.
Low prices offer little incentive not to waste energy. With higher prices, lights get turned off, more is spent on A++ rated appliances and serious consideration is given to investing in energy-efficient condensation boilers.
Even so, it is generally agreed that energy efficiency is the best route to both keeping power bills and consumption low.
Ironically, 2015’s incoming government swiftly ended the flawed and criticised flagship Green Deal energy-efficiency programme but did not replace it. Its 2016 successor offered no alternative.
The Conservatives’ target is to insulate one million homes in the life of a Parliament; 2007 actually saw 2.5 million homes insulated in a single year. Labour wants to quadruple the current rate and has offered interest-free loans to improve home energy efficiency. Against this background, a well-run district energy strategy is a natural priority for any Downing Street tenant.
Made in America
Birdsill Holly invented the first district heating system in New York State in 1877. He realised that the urban environment is full of available thermal energy which can be recovered as a commercial secondary commodity. Soviet Russia took up the torch. Workers were entitled to warmth; reliability and efficiency were not high.
Modern systems are not restricted to any particular source, although sustainable, non-fossil fuel systems are naturally preferable. Combined heat and power (CHP) — also known as cogeneration — is a way to increase the efficiency of power plants. Standard power plants effectively use just 40% of their fuel to produce electricity. The rest is “wasted”.
Share and share alike
The drive today is to save wasted urban heat. The UK wants to involve millions of people in CHP projects accounting for 18–20% of energy production and use by 2050.
Communities around the northern hemisphere are investing in municipal-scale heating systems with industrial-sized boilers. Modern heat networks send heat and hot water to many different properties via a network of underground pipes fed by a central heat source.
Denmark leads the way. In the 1970s, 90% of its energy came from high-priced imported oil. The oil crisis forced factories to close. Danes shivered at home. Driving was banned on Sundays.
The county’s remedy was district heating from huge community boilers. Crucially, waste heat is recovered from power stations, factories, computer server farms and transport networks to be recycled. Forty years on, district heating provides heat for 63% of Danish households.
By one estimate, London’s waste heat would be sufficient to meet some 70% of the capital’s heating needs, offsetting high bills, fuel poverty, emissions and energy security. The remaining energy shortfall could be made up using CHP plants that are often twice as efficient as ordinary power stations which traditionally waste heat.
The hidden warmth of cold water
Norway has another lesson for the world. Using heat pump technology — refrigeration in reverse — it extracts large quantities of latent heat hidden in cold sea and river water.
One shared community scheme in the town of Drammen uses a sealed ammonia network turning liquid to gas which, when pressurised, heats water to 90°C. Water exits back to the river 4°C colder.
Heat pump technology may still have a carbon cost if it is not powered by renewable energy. At present, most UK district systems are coupled to gas-fired heat and power networks.
But more ground and water heat pump systems could be seen in the future. Essentially, once the basic system is built, advanced technologies can be added as they develop.
In Scotland, where more than half of the nation’s energy is used for heat, and surface water is much warmer than in Norway, there is even talk of taking heat from water trapped at 30°C in deep flooded mines. Ironic!
The Scottish Government has been called upon to use its Warm Homes Act to deliver affordable, renewable heat for homes and workplaces in line with the regulatory approach seen in Norway, Denmark, Sweden and the Netherlands.
A government spokesman described community energy as having the potential to “empower people and help tackle some of our most pressing issues, including fuel poverty, increasing costs and security of supply, while it can also support Scotland’s efforts to cut damaging greenhouse gas emissions”.
New York, New York
Across the Atlantic, rapid urbanisation and government initiatives are also promoting the use of sustainable energy from geothermal heat pump technology.
New York City Governor, Andrew Mark Cuomo, recently announced $15 million funding to encourage the development of a city renewable heating and cooling system. The initiative will also be designed to help reach the city’s target of reducing GHG emissions by 40% in 2030 from 1990 levels.
In the chilly northern UK, March 2017 saw the opening of the Gateshead District Energy Centre. This will generate heat and power distributed via a new 3km underground network of heat pipes and high voltage “private-wire” electricity cables. The scheme will supply public buildings at first, including the Gateshead Civic Centre, the Sage Gateshead, Baltic and Gateshead College plus homes managed by the Gateshead Housing Company.
However, it has been designed to meet the energy needs of future Gateshead town centre developments. These include commercial developments at Gateshead Quays and the Baltic Business Quarter. It will also serve major housing developments of up to 1000 new homes.
The centre uses two 2 megawatts (MW) gas-powered CHP plants capable of serving 5000 homes. Engine waste heat is recovered to provide hot water for heating. As a further bonus, the scheme will add 4MW of electricity generating capacity to the National Grid through a partnership with the demand response company, Flexitricity.
There is good and not so good news about existing community energy schemes.
The BBC has reported on heating systems intended to reduce bills that have increased fuel poverty. Costs, it is said, can be higher than with traditional heating and beset with problems. On one London project, smart meter failures are said to have produced monthly bills for vulnerable tenants totalling hundreds of pounds.
A residents’ association says residents too distressed to switch on their heating system have gone to bed early to keep warm. Intermittent service has been a problem; energy outages in some cases have lasted for months. Tenants also say that they are tied in to extremely long contracts, the BBC adds.
Clearly, district heating systems comes with opportunities and warnings. With diligence, the opportunities should be greater.