Biomass briquettes and pellets
The area served by Barnsley Metropolitan Borough Council (MBC) used to be dominated by coal-mining: many residents were employed as miners and many public buildings are still heated by coal-fired boilers. But the Council also had a source of low-carbon fuel in the many tonnes of wood waste from its parks and gardens that it disposed of each year.
In June 2004, Barnsley MBC adopted a Biomass Implementation Policy, committing it to considering biomass heating systems for all new and refurbished buildings. It has already completed a 470 kW wood-fuelled district heating scheme for 166 flats, and a 500 kW scheme for the council depot. This work has enabled a small wood-chip supply business to start up, and Barnsley MBC is also starting its own wood-chip supply from Council waste.
In 2004, Barnsley MBC had 133 coal-fired boilers at 66 premises (mainly primary schools), including 26 district heating schemes, which jointly consumed 6,500 tonnes of coal per year. Barnsley had implemented a programme of efficiency measures for coal boilers, starting in the 1980s, which had reduced coal use by 20% and thus delayed a switch to gas heating which happened in many other places. However, by 2004 many coal boilers were due for replacement.
The first biomass boiler was installed in 2005 to replace an outdated coal boiler in the Sheffield Road Flats, a social housing complex of 166 flats in three seven-storey blocks. This was carried out as part of a major £1.7 million refurbishment to the complex, which also updated the heat mains in the building, installed double glazing and provided heat metering to individual flats. Two linked wood-chip boilers rated at 320 kW and 150 kW were installed. The smaller boiler is used alone to provide heat demands during the summer, thus avoiding the inefficiency of running a single large boiler at a small fraction of its rated output. Boilers made by the Austrian company Fröling were chosen due to their ability to cope with wood with up to 60% moisture content. A gas boiler plant with 100% back-up capacity was installed, to provide continuity during the change-over and to reassure residents about the risk of biomass supply interruption. A thermal storage vessel helps the boiler to manage peak loads.
A new, local wood-supply business Silva Power Ltd, has been started as a result of this development, and currently supplies 350 tonnes of wood-chip per year in weekly deliveries to a bunker with an automated feed to the boilers. Their wood is all sourced from local sawmill and forestry waste.
The second installation is a 500kW Fröling wood-chip boiler at the Smithies Lane Depot, which belongs to Barnsley Council. This boiler was installed in early 2006 to heat the depot and supply hot water to 450 council employees, in place of two coal boilers which were in urgent need of replacement. It will use an estimated 150 tonnes of wood-chip each year. An oil-fired back-up boiler was installed to maintain continuity of service during the installation.
One function of the depot in the past had been to handle large volumes of waste from council treemanagement. A small amount of this was used as a mulch in urban parks, but most was sent to landfill. Barnsley MBC has decided to convert this waste to wood-chip and a 700-tonne store has been constructed, which will allow storage and air-drying of the wood-chip for supply to different biomass heating systems.
Wood-chip boilers are also being installed in new buildings, instead of gas; including the highprofile 'Westgate Plaza One', which will become the Barnsley MBC civic headquarters and house about 700 employees. Under the first phase of this development, a 500kW boiler has been installed, which can use either wood-chip or wood pellets. The boiler will heat the Westgate complex by day and will supply heat to thermal storage vessels in the nearby central library by night. This will maintain an even load and will displace 275 kW of off-peak electrical heating. A further phase is planned, and this will link to a civic centre heating scheme which will supply the Town Hall as well. Barnsley MBC has convinced the private developers of the Westgate Centre to plan for continuing biomass use after the 25-year Council tenancy expires. They have therefore provided only a 50% back-up gas boiler, rather than 100% back-up which they originally planned.
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Another installation underway is a 320 kW wood-chip boiler to supply heat to 120 high-tech business units in the Digital Media Centre, which is due to be completed by September 2007. Barnsley MBC also plans to convert two more district heating schemes to wood when their boilers are renewed, and to install biomass boilers in 9 secondary schools to replace solid fuel boilers under the 'Building Schools for the Future' Scheme.
Econergy Ltd, an energy service company (ESCO), manages the boiler and heating systems at Sheffield Road Flats. They buy wood-chip at around £35 per tonne from Silva Power, and sell heat to Barnsley Council. Pre-payment heat meters have been installed in the flats as part of the refurbishment. Previously, tenants paid a flat rate fee for heating as part of their rent.
The boilers at Sheffield Road Flats and Smithies Lane Depot have a 25 year lifetime. Econergy coordinates servicing and maintenance of the boilers, and wood-chip supply.
Berneslai Homes, which manage the Sheffield Road Flats, have found that they need to spend about half an hour per week on regular maintenance of the biomass boilers, compared with about 3 hours a day previously in winter.
The biomass boilers are reducing energy consumption and carbon emissions. This is partly because they replace old, inefficient, coal boilers at Sheffield Road and Smithies Lane. However, the programme has also emphasised the efficient use of energy. This includes the use of heat metering at Sheffield Road, which has motivated tenants to reduce wastage.
Tenants at the Sheffield Road Flats have reduced heating bills (not yet formally surveyed, but thought to be about 50% reduction) and have more control over their heating. They are also pleased to be rid of the noise and dust of coal delivery.
Barnsley MBC estimates that, even at 2004 fuel prices, the 25-year lifecycle cost of the new Westgate biomass heating scheme is less than that of gas-fired heating. Although the capital cost of £150,000 for the 500 kW biomass heating system is much higher than £18,000 for a gas-fired equivalent, the 25-year running costs will be only about £300,000 rather than £1,200,000. These estimates were based on wood-chip being purchased, rather than using the Council's own supply which will soon be available at much lower cost. Also, since the estimates were made, the price of gas has nearly doubled. Barnsley MBC also saves by not having to pay landfill tax to dispose of surplus tree waste.
Econergy surveyed Barnsley for tree waste, and identified the potential for at least 1,000 tonnes of wood per year which could supply three 500 kW boilers. South Yorkshire Forest Partnership, which receives funding from four local authorities, believes that a further 45,000 tonnes of wood could be supplied from existing forestry each year. In addition, 1,300 hectares of short rotation coppice have been planted. The new demand for biomass created by Barnsley MBC has helped to form a wood fuel supply chain, supporting the active management of woodland and preventing wood from going to landfill. Barnsley MBC expect a total of 20 jobs to be created as a result of the projects at Sheffield Road, Smithies Lane and Westgate.