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Nottinghamshire - United Kingdom.

Nottinghamshire replaces coal with wood-fuel for schools’ heating


Nottinghamshire has a history of coal mining, and many schools have traditionally used coal-fired heating systems. In the past few decades many mines have closed, and coal is no longer such a locally available fuel as in the past, but fortunately Nottinghamshire has a significant area of forest, and land to grow energy crops that can provide a sustainable alternative fuel.

As part of its Local Public Service Agreement (PSA) to reduce CO2 emissions, Nottinghamshire County Council started a programme of replacing coal with wood-fuel in schools throughout the county, either by installing new boilers or converting existing coal-fired boilers to handle wood pellets (note : PSAs set out aims and objectives for public sector organisations and describe how these targets will be achieved). The conversions have been particularly cost-effective, increasing efficiency whilst making use of much of the existing equipment. Wood pellets have been chosen over wood chips for all installations because of the relative ease of delivery and storage, and they will soon be supplied from a pellet mill within the county. The Council has worked hard to build up the infrastructure for the supply and use of wood-fuel, which includes local manufacturers and installers, and also a not-for-profit company dedicated to developing renewable energy solutions and supplying sustainable fuels.

A total of 21 boilers have already been installed in 17 schools, with a combined heat capacity of 7MW. CO2 savings are 2,400 tonnes/year, and have helped the Council meet its 3,500 tonnes/year PSA target. The schools have benefited from a reduction in pollution and soot, and from the knowledge that they are helping to reduce the county’s CO2 emissions. The Council has a strategy to achieve zero net emissions by 2050, and converting more schools to wood-fuel is part of this. A further 27 schools will have been converted by the end of 2008, and funding is currently being sourced to cover a further 35.

Building details

Type of building : Schools
Heating and cooling / measures installed Some schools have had new wood-pellet boilers installed and others have had their existing coal-fired boilers converted to handle wood pellets.
Energy/CO2/Water label (before and after improvements if possible) Total CO2 savings are 2,400 tonnes/year

Project Description

Aim The aim of this programme is to replace coal with wood-fuel in schools throughout Nottinghamshire County, because wood is a more sustainable fuel, that, over the lifecycle of the fuel, produces less net CO2 and pollution when burned.
Key points Technology used

_ Two approaches have been taken in converting Nottinghamshire schools from coal to wood heating.
Some schools had old boilers that had reached the end of their lifetimes, and these were replaced with new wood-fuelled boilers. However, other schools had more modern coal-fired boilers and in these cases the boilers were modified to allow them to burn wood and to improve their efficiency.

_ A conversion is the preferred choice if the existing coal-fuelled boiler is in good working order and still has at least 10 years life left - even a customised conversion costs only about one fifth of the price of a completely new system. The conversions carried out so far by the local company Instatherm have typically involved modifications to the fuel bunker and the control system. The fuel bunker and feed mechanism are modified to allow them to use wood pellets instead of coal, while the control system is upgraded to measure the oxygen content of the flue gases and vary the air flow and pellet feed rate accordingly. The results are typically an increase in boiler efficiency from 55% to 87%, and more reliable operation.

Alan Allsopp, Principal Energy Officer who set up the Nottinghamshire Wood-heat Programme, at West Bridgford School, one of 17 schools in the region to have their boilers converted from coal to wood fuel.

_ Installations to-date

_ The first trial installations of new wood-fuelled heating systems took place in 2003, and used equipment from Binder. However, local boiler manufacturers Hoval and Ashwell were improving their designs over this period, and all subsequent installations have used equipment from them. Because they are local they are easily available for site visits and installations, and close to hand if any advice or maintenance is required. The new boilers have an expected lifetime of 15-20 years and run at efficiencies of over 90% at their design output. Their efficiency is still high when they are running at only 30% of design capacity in mild conditions or to supply hot water. This is important because the demand on the boiler varies greatly throughout the year. All installations are in locked boiler houses, and access is controlled very carefully.

_ By April 2007, the Wood-heat Programme had resulted in the installation of :

- Nine new wood-pellet fuelled boilers at seven schools, totalling over 2 MW of heat capacity.
- Four conversions of conventional coal-fuelled boilers at two schools to wood-pellet use, totalling close to 4 MW.
- Eight conversions of boilers using coalflow pearls, a manufactured product similar to anthracite, which has now been phased out, at eight schools to wood-pellet use, totalling over 1 MW.

Use of wood pellets

The Council decided to use wood pellets rather than wood chips for the fuel supply. There are several reasons for this :

- Wood pellets have a higher energy density than wood chips and therefore take up less space, which allows schools to continue using their existing coal bunkers for storage, rather than having to install extra storage for wood chips.
- Wood pellets are more consistent in size and moisture content than wood chips, leading to more predictable boiler operation.
- Several schools had boilers designed to use coal formed into small coalflow pearls similar to wood pellets, so conversion to wood pellets was very straightforward.
- Pellets can easily be delivered in tankers, using a pneumatic system to blow them into the fuel bunker through a hose, reducing dust and also allowing delivery at sites where access is difficult. It is particularly important that deliveries to schools are carried out as quickly and safely as possible, because of the large numbers of children on the sites.

The County Council helped to set up Renewable Nottinghamshire Utilities Limited (ReNU), a not-for-profit company dedicated to developing renewable energy solutions, including supplying wood fuel in Nottinghamshire. ReNU had the initial contract for supplying wood pellets to schools. To start with, ReNU had to obtain UK manufactured or imported pellets from wherever they were available, and most pellets were imported from Sweden. Now, however, ReNU has two pellet mills located in Nottinghamshire. By 2007 the wood pellet contract had grown to a value where it was subject to EU procurement regulations, and a new pellet supplier has now been awarded the contract. They have been involved in a partnership with local energy crop growers to establish a new 10,000 tonnes/year pellet mill in Nottinghamshire that will source all its material locally.

Year 5 children holding wood pellets at Mornington Primary School, which has recently had a new boiler installed.

Training, support and quality control

When a boiler is converted or a new one installed, the school site manager is trained by the company doing the installation. However, as most site managers in Nottinghamshire are already familiar with operating a coal-fuelled boiler, they find it fairly simple to learn how to operate one using wood-fuel.

_ The school will normally have a maintenance contract with the installation company, who will provide advice over the telephone and come to visit if a problem requires their attention. The company will also handle communications with any third parties for spare parts when they are required. Using local manufacturers and installers is therefore a significant advantage for maintenance and support, as they are able to respond quickly and are keen to maintain their reputation.

_ In the larger schools there are usually multiple independent boilers so that there is some backup capacity in the event of one boiler failing. In smaller schools with a single boiler there is provision to use portable heaters if the boiler fails. The Council also has a portable oil-fired boiler that is used to maintain supply during conversions, and is also available as a back-up boiler should this ever be required.

_ The experience of using wood pellets as a fuel has generally been very positive. There was one short period when pellets had an elevated dust content, but this was a national and international problem because of a very severe winter and pressure on supplies.

Reason for inclusion as Shining Example Through their Wood-heat Programme, Nottinghamshire County Council has reduced CO2 emissions and pollution by switching schools’ heating fuel from coal to wood. In addition, this programme has helped to create a local infrastructure for the supply and use of wood-fuel, in particular wood pellets, which has resulted in the creation of new jobs in the County.


Costs &


The Wood-heat Programme has been funded from several sources. Schools in Nottinghamshire pay one third of the cost of replacing a boiler, no matter what type of fuel it burns, and the Council pays the remainder. The Council has access to the Bio-energy Capital Grants Scheme funding to reduce the cost of installing wood-fuelled heating systems (note : the Bio-energy Capital Grants Scheme is a government scheme that aims to support the installation of biomass-fuelled heat and combined heat and power projects in the industrial, commercial and community sectors in England). This enables schools to have a new wood-fuelled boiler at no additional capital cost to a gas-fuelled boiler.

_ The costs of new installations range from about €573/kW (£400/kW) for 150 kW boilers in small primary schools down to less than €430/kW (£300/kW) for an 800 kW boiler in a secondary school. Conversions are considerably cheaper, typically €72/kW (£50/kW) for small boilers and as low as €29/kW (£20/kW) for the 2 MW schemes in very large secondary schools.

_ Each school is responsible for paying for fuel and boiler maintenance from its own budget. Wood pellets currently cost €186/tonne (£130/tonne) delivered, and work out more expensive than coal. However, operational and maintenance costs are lower, and most schools have been willing to absorb a small increase in overall cost because they believe that the environmental benefits are worth it.

_ Only one school has opted to return to coal after a trial period of having the conversion done, because of severe financial difficulties, but they hope to switch back to wood-fuel as soon as possible.
Benefits The schools are enthusiastic about using wood-fuel for a variety of reasons, most importantly the environmental benefit of using a sustainable fuel. They also appreciate the lack of smoke and soot when using wood-fuel – one site manager commented that the old coal-fuelled boiler sometimes looked like a ship setting off from the docks ! The schools’ neighbours are also pleased with the reduction in local pollution – there had been several complaints in the past, but these have stopped completely since the switch from coal to wood-fuel.

_ The schools and the Council are also pleased to be able to use local manufacturers, installers and infrastructure. For example, the businesses and drivers that used to deliver coal to the schools are now delivering wood pellets, so jobs in the region have been protected. As the fuel supply becomes increasingly localised, further employment opportunities will be created in the county, especially in rural areas.

_ Primary schools in particular have been able to use their new wood-fuel boiler as an educational resource, in lessons on sustainability and climate change.

Year 8 pupils at West Bridgford School look into their boiler converted to run on wood-fuel.

_ The use of wood pellet boilers in schools has resulted in a significant reduction in CO2 emissions of 2,400 tonnes/year. This has helped the Council meet its PSA target reduction of 3,500 tonnes/year, resulting in a reward grant that covered the costs of the Wood-heat Programme.

_ The county as a whole has also benefited, as the Council’s work has helped create an infrastructure for the supply and use of wood-fuel, in particular wood pellets. About seven jobs have been created or secured through the programme to date. New suppliers and users will be able to enter an established and growing market.

Partnership details

Partners & role The schools’ Wood-heat Programme has been managed by the Council, but has required the cooperation of many other organisations, in particular the schools themselves. Other key partners in the programme are ReNU, and a range of installers and manufacturers such as Hoval & Ashwells the boiler manufacturers, Instatherm the installers and Browns Biomass who deliver pellets. A recent partnership has been formed with The Energy Crops Co. and Biojoule to supply locally produced pellets.


Achievements Nottinghamshire County Council keeps records of all of the boiler installations and monitors their performance.

_ The Council’s Wood-heat programme won second prize in the UK division of the Ashden Awards for Renewable Energy 2007. This award is for organisations such as NGOs, non-profit groups, commercial organisations, Local Authorities and Energy Agencies which have carried out projects or programmes to increase the supply of renewable electricity and/or heat at a local level.
Growth and replication Nottinghamshire County Council now has a strategy for zero net emissions from all council activities by 2050. The council is also to pilot a scheme which puts strict requirements on emissions from any buildings which are constructed on land which it sells. Extending the use of wood for heat in schools is an important part of this strategy. The Council has already secured €716,307 (£500,000) from the Bio-energy Capital Grant scheme to convert a further 27 school sites totalling 10 MW by 2008. The next stage will convert 35 sites totalling 11 MW, and the council is currently awaiting the outcome of a further €1,432,600 (£1 million) bid to cover this.

_ To ensure continued support from the schools, the council is actively promoting the programme, and communicating the benefits to the schools. The result is that schools are choosing wood-fuel over the alternatives, even if it is not always the cheapest option, because of the environmental benefits and the resulting local employment that is generated.

To know more



Nottinghamshire County Council
Contact Alan Allsopp
Phone +44 115 9773571

Useful info

Publications Ashden Award Technical Report 2007, Alan Allsopp : “Using wood heating in schools to reduce carbon emissions, and help build local wood-fuel infrastructure”.
Arrangements to visit Contact Alan Allsopp

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