Local councils are showing an increasing interest in promoting renewable energy. Some have begun to develop micro-renewable generators of heat and power on their own estates, for example by replacing gas-fired boilers with biomass ones. This month Nottinghamshire County Council announced that 17 schools will shortly be heated with biomass made from locally-grown energy crops, while Essex County Council revealed plans to establish “clusters” of biomass boilers in schools and other buildings over the next two years.
Another way councils can develop such micro-renewables is by applying for a grant under “stream two” of the government’s low carbon buildings programme (ENDS Report 375, pp 44-45 ). This is aimed at public bodies and community groups. So far, 215 applications have been allocated over £3.1 million.
The vast majority of these grants are for solar photovoltaic installations – 137 applications receiving £2.5 million – although applications for solar thermal systems, ground source heat pumps and wind turbines have all reached double figures.
However, all these approaches lack one thing: size. They are aimed at developing renewables below one megawatt (MW) – hardly the scale needed if local authorities aim to contribute significantly to meeting the UK’s renewables targets. The EU has proposed that 20% of its total energy should come from renewables by 2020 (ENDS Report 389, p 41 ).
The Carbon Trust’s Partnership for Renewables is aiming to build over 100 3-5MW wind turbines on public land (ENDS Report 381, p 15 ), but will not say how many of these will involve local authorities.
One type of renewable energy source seems to be held back by the small size of local authority projects more than others: biomass. If local authorities are not going to rely on imported pellets or wood chip for biomass to fire their boilers, they need to develop supply chains for wood and energy crops, and these can only come with a large enough market. This problem was highlighted by the government’s biomass task force in 2005 (ENDS Report 370, p 18-19 ) and this year’s biomass strategy (ENDS Report 389, p 41 ).
Several utilities have, or are in the process of developing dedicated biomass power plants that will help. For example, Eon is currently commissioning its £90 million 44MW Steven’s Croft plant in Lockerbie, and has submitted a scoping statement for a 25MW plant in Blackburn Meadows, Sheffield. Others, notably Drax, are burning large quantities of biomass in existing power stations. But these are few and far between.
“We’re seeing biomass falling behind the rest of the renewables market in that sense,” says James Beal, managing director of Renewables East, which is drafting a biomass strategy for the east of England. “Councils have focused on small installations like boilers, and utilities are investing in large units, but the 1-10MW projects have been overlooked. And they’re a good investment.”
Of the 831 biomass schemes identified by consultancy Enviros in a 2005 study for Renewables East, 696 were heating systems – the majority boilers between 100 and 500kW in output. Another 120 were electricity-generating; the majority of these involved sewage sludge. Only 15 were combined heat and power (CHP) projects, and four of those were “suspended”. The Enviros report found a “significant and growing deployment of biomass heating systems based heavily on waste wood” but did not offer encouragement for CHP in spite of its cost advantages. According to Enviros, a typical 1.1MW biomass CHP scheme has a four-year payback, compared to eight years for a 350kW biomass boiler.
However, one county council has emerged as the leader in trying to buck this trend. Worcestershire plans to build 25 MW of biomass CHP plants over the next five years, most likely ten plants each 2.5MW in size. All will use locally sourced biomass, including a growing proportion of material from managed woodlands and energy crops.
The council will take a 19% share in each project, leaving developers to find the rest of the funding. It is a model that others may well follow.
Best way to cut carbon
Worcestershire’s moves into biomass began with the publication of its carbon management plan in 2004, according to the council’s environment manager Simon Hartley. He was recruited specially for the post at the time of the plan from an energy consultancy.
The carbon management plan included baseline data for the council’s major sources of greenhouse gas emissions, unusually including landfill, and set reduction targets for each of them to achieve by 2009/10. However, the plan also required that the remaining emissions be offset. This amounts to 77,222 tonnes of CO2 equivalent per year, including 43,245 from landfill.
“We decided we couldn’t really claim an offset for ourselves confidently unless we had an equity stake in the project,” said Mr Hartley, explaining why the council did not simply buy carbon offsets off the shelf. “When we saw the costs we realised it would be better to offset the emissions ourselves locally and try to tie it in with economic regeneration. That seemed to be the only way we could justify the use of public money.” Several other councils have recently taken this approach to offsetting (ENDS Report 387, pp 36-39 ).
Following discussions with regional development agency Advantage West Midlands, Worcestershire looked at investing in anaerobic digestion facilities similar to Summerleaze’s 80,000 tonne facility in Holsworthy, Devon. These would have processed commercial waste from farms in the region, reducing waste to landfill and its associated emissions. However, “the economics didn’t stack up”, says Mr Hartley.
The waste that would have been treated was wet, meaning the council would either have had to transport large volumes of it to a central site or invest in on-site decantering equipment for individual farms to remove water. Both options were prohibitively expensive.
In light of this, the council turned to biomass CHP. According to Mr Hartley, it was the only other form of renewable energy that had the potential to offset 77,000 tonnes of carbon in the county. Worcestershire “simply did not have enough buildings” to achieve the reduction by installing biomass boilers on its own estate.
It was a logical step for Worcestershire, for the council had been a pioneer of biomass since the late 1990s. It installed the UK’s first wood-fuel boiler in a school at Weobley, Herefordshire, in 1997 when the two counties were joined. This was followed by the UK’s largest biomass boiler – 700kW – at its headquarters in 2002. The latter uses 600 tonnes of wood a year sourced from the Telford-based Marches Wood Energy Network.
The plan the council has since drawn up with developers to offset its emissions involves building 25MW of biomass CHP plants. This will most likely take the form of 10 plants all providing around 2.5MW electricity for export to the grid and 8MW heat for local use. Each plant will produce a saving of 7,000-8,000 tonnes CO2 e. In total, it is just enough to meet the offset target.
Tenbury Biomass Power – the council, along with Oxfordshire-based CJ Day Associates – is submitting a planning application for the first plant in Tenbury Wells to Malvern Hills District Council in the next few weeks. Worcester County Council hopes the plant will be operational by the end of 2008.
A second application will follow “shortly after the first”, said Mr Hartley. He would not name the developer for this project. In all, the council hopes to build five plants by the end of 2010. Feasibility studies have already been undertaken for the plants.
The Tenbury plant will use “combined steam-cycle technology”. This involves burning the biomass at 1,300°C to provide steam, which is then passed through a turbine at high pressure to generate electricity. The steam is then used to produce hot water.
The Tenbury plant will use 40% of the heat on-site to dry the wood chip fuel before it is burned – increasing its calorific value – as well as to operate a pelletiser to provide fuel for 10 biomass boilers that will be locally installed. The rest of the heat will likely be used by the area’s industry. It will cost £5 million – not including the cost of the feasibility study and efforts needed to develop the supply chain or the feedstock itself. This is roughly double the cost of a gas-fired CHP plant, assuming that costs £1,000 per kW.
An investment of that size is out of the reach of many local authorities. The council is able to go ahead with it because it is only taking a 19% stake in each plant as allowed under the Local Government Finance Act. C J Day Associates will secure the rest of the equity for Tenbury. Worcestershire estimates it will get a six to eight-year payback on its investment.
The county’s plan is admittedly similar to the energy service companies (ESCOs) that have been set up by several authorities – most notably Woking (ENDS Report 380, pp 10-11 ). These have used public-private financing to develop CHP and district heating systems. However, none have focused on biomass. Southampton’s scheme – probably the closest to Worcestershire’s – will run on imported palm oil (ENDS Report 376, p 15 ).
Developing a supply chain
One of the main aims of Worcestershire’s plan is to create a biomass supply chain in the region.
The Tenbury plant will need 25,000 tonnes of biomass a year. All of it will be sourced from within 30 kilometres of the plant and the majority will consist of wood chip from saw mills, says Mr Hartley. “There’s a significant limit on what feedstock you can use once you deal with a bank [as a financer] because they require a main supplier. That means you can only really go to saw mills.”
However, up to 2,000 tonnes will come from farmers and managed woodland in the area. This will include short-rotation willow, “possibly alder and maybe even miscanthus”, Mr Hartley says. That figure could grow after talks with the developer, he adds: “As an investor, we are making sure that there will be an increasing percentage of material sourced from woodland and farmers so we can develop supply chains. At the moment if we go to farmers and say we need 100 tonnes of material, they shake their heads and say they can’t do it. So we’re hoping the secure contracts we can offer will give them more confidence to act.”
Contracts will also need to be flexible so farmers are not afraid of penalties if supply dips.
Mr Hartley says that as the feedstock has been arranged, the only hurdle remaining for Tenbury is the planning process. The council and developer have already consulted residents on the project. According to Mr Hartley, the main concerns raised were “what potential is there for burning waste and what emissions will come out of the stack.” Most of the concerns, he says, “are based around misunderstandings” and the council does not feel they will stall the planning application.
The council is hoping to co-locate anaerobic digestion plants alongside “two to three” of the biomass plants from 2009 to deal with wet waste from farms or waste from food processors in the region. Each would be 2MW in size and take 100,000 tonnes of wet waste. Mr Hartley says these will have more problems with planning, so he is reluctant to provide more details.
The Worcestershire model already appears to be attracting interest from other councils. For example, Advantage West Midlands’s biomass strategy will encourage such projects when it is issued next year, according to Ian Baker, head of rural renaissance policy. “Tenbury may not work for other areas,” he says. “We won’t necessarily be able to use the same financial backing or the same feedstock. But it is an early example of what we hope can lead to a better use of resources and production of energy.”
Councils in the east of England also have “similar projects” in development, according to Renewables East. These will use the 1.5 million tonnes of waste wood going to landfill in the region.
But more definite signs of interest are expected to arise in the next six months, according to the Combined Heat and Power Association and the Renewable Energy Association. Both told ENDS that the government’s proposed “banding” of the renewables obligation (RO) had made dedicated biomass plants “very attractive”.
Under the detailed proposals announced in June, dedicated biomass plant will get 1.5 renewable obligation certificates (ROCs) per MWh of electricity they generate – up from 1 ROC (CHECK ENDS Report 389, pp 42-43 ). “It’s already having an impact on the market,” said Michael King, associate at the CHPA.
The development of gasification equipment for biomass CHP plant below 5MW should also increase interest, said Mr King. Firms like Biomass Engineering in Warrington and ITI Energy in Rotherham are working on technologies that can gasify biomass – burning it in partial oxygen to make a ‘syngas’ that can be put through gas turbines – for systems as small as 250kW. Gasifying the biomass, rather than burning it, produces efficiency gains as more carbon is transferred to the syngas. These gains differ for each gasification plant, according to Joe Schwager of energy and waste consultancy Juniper. He was unwilling to talk about the increased costs of gasifying biomass, compared to combustion, due to the wide variations in available technology.
Whether these advances in policy and technology will be enough for many councils to investigate large-scale use of biomass is questionable. “The lack of knowledge about and experience with biomass among many authorities puts them off,” said Mr Hartley. “Our forethought ten years ago is leading to benefits now.”
This was echoed by James Beal of Renewables East who said the East of England was “15 months ahead” of other areas in its plans even though most of its projects only concern biomass boilers such as a 150kW facility in Lowestoft. “The biomass task force report used the word ‘ignorance’ and there is still a lack of understanding about the opportunities biomass offers,” he says.
In short, other authorities will probably have to see Worcestershire’s CHP plants operating successfully before they make a commitment.