The Task:

Tynedale Council was looking for a new energy supply for the remote village of Kielder and the use of local resources was strongly encouraged.

 

The Client:

Kielder is a forestry village in Northumberland of about 200 people, surrounded by Kielder Forest and located at the northern end of Kielder Water. There are several individual homes, a petrol station, village shop and pub, but also communal buildings such as the Youth Hostel and the visitor centre at Kielder Castle.

 

Before:

Buildings in the village were individually heated by oil or solid fuel stoves and open fires, but the Council wanted to make sure that while local resources should be used to heat a majority of buildings, it would be done in an energy-efficient way with low emissions.

 

Installation:

It was decided to install a form of central heating novel to the UK – a shared heat network fuelled by wood. Districk heating projects are commonplace in European countries such as Sweden and Austria, where forestry residues are often used as a fuel, but this is one of the first of its kind in Britain. A local fuel stockpile store was specially designed and built in the Forestry Enterprise Depot, this store is filled up three or four times a year with specially dried and chipped logs (wind-blow and low value timber). The woodchip delivery trailer holds about 16 cubic metres (two to three tonnes) of fuel, and has a 'push off' action to empty the chips into the boiler house fuel store. Inside the boiler house, a 'walking floor' moves the woodchips from the storage area to the augers, which then convey the wood chips into the boiler where they are burned. The A Köb PYROT boiler is made in Austria and was installed by Boiler Services. Its output is 300kW, with an efficiency of 87% (measured as heat output to woodfuel energy input). It has a special rotating firebox, designed to burn all kinds of dry and damp wood fuel (chips, sawdust, shavings, pellets, briquettes, forestry wood shavings). The hot water is piped to surrounding buildings, where heat exchangers transfer the energy into domestic heating and hot water systems. The boiler house also has a back-up system (an oil-fired burner) that can be used if the primary system requires maintenance.

Over 950 metres of super-insulated plastic heat pipe have been used at Kielder to connect the homes and other buildings to the boiler house. Various sizes of pipe are used, depending on the flow rate required – for example, the supply to the school buildings uses a 3-inch diameter pipe. The heat pipes are made in Europe by Flexalen, and have been used in district heating schemes in many European countries. The hot water leaves the boiler at 85%C and is circulated to all the buildings in the scheme through the buried heat pipes.

The water returns from the building a little cooler, and is reheated by the boiler before being pumped around the system again. The boiler produces very little noise, smoke or ash. Visitors sometimes cannot even tell when it is running! A heat meter measures the amount of energy used by each customer.

 

Operation and Pellet Fuel Consumption:

Annual wodchip consumption has fallen to between 250 to 450 tonnes. The mail fuel store can hold up to 450 cubic metres (between 80 and 120 tonnes) of woodchip from Kielder Forest. The locally grown wood is chipped and stores by Forest Enterprise at a specially designed fuel store in the village. Kielder Community Enterprise Ltd has been established as a community-owned energy service company or 'ESCo', providing a permanent source of local employment, and sends users monthly heating bills. Emissions from the chimney are mainly composed of water vapour: total emissions are less than a single household coal fire. The few wheelbarrow-loads of ash produced each year are used as a fertiliser to mix with compost for the village gardens and allotments.

 

After:

The heating scheme supplies heat and hot water to the Kielder Castle Visitor Centre, six new three-bedroom homes, Rivermead Workshoops, Kielder Community First School and the Youth Hostel. Compared with alternative fossil fuels (which in this case would be heating oil), the Kielder district heating system saves about 57 tonnes of carbon dioxide emissions per year, as wood fuel is a renewable resource. It does not contribute to greenhouse gas carbon emission, since the carbon emitted in burning is balanced by forest re-growth. The woodchip fuel supply also helps to secure local forestry jobs and contributes to the Kielder Regeneration Initiative, ensuring the viability of the village in the years to come.