Short rotation coppice production may be a potential non-fossil fuel for the future but
expansion is being hampered by uncertainties over financial support. Mike Williams reports
FARMERS and contractors are still waiting for the go-ahead for a big expansion of short rotation coppice (SRC) production.
The prospect of producing willow or poplar chippings for use as a power station fuel has attracted plenty of interest, both from farmers who would like to grow the trees and from contractors who would operate the specialised planting and harvesting machinery.
This enthusiasm is not, so far, reflected in a rapid expansion of the SRC acreage due to uncertainties over financial support, the development of new biomass burning power stations and the development of specialised machinery to suit UK conditions.
Short rotation coppice has already been selected as one of the potential non-fossil fuel resources for the future. The UK government has made a firm commitment to supply more of our energy needs from environmentally friendly renewable sources instead of traditional fossil fuels such as oil and coal, and SRC has already been singled out as one of the energy sources the government favours.
In the current economic climate many farmers would welcome the opportunity to add SRC to the list of cropping options, and a big expansion of the trees-for-fuel acreage would provide extra work for contractors, but one of the problems is that SRC is an expensive crop to grow.
Cultivations start with deep ploughing and two passes with a power harrow are usually needed to provide a tilth that ensures close contact between soil particles and the stick-like cuttings to encourage early growth.
Typical planting rates are from 10,000 to 12,500 of the 10-15cm cuttings per hectare, and with prices between 10p and 12p per cutting this accounts for a big slice of the start-up costs. There are further costs for herbicide sprays to control weeds until the trees are established, and in some cases fertiliser may also be needed, but meanwhile there is no income from the crop until the first harvest three or four years after planting.
Financial prospects for the crop are bleak without grant aid and growers in England are entitled to a subsidy amounting to between £1000 and £1600 per hectare. The subsidy, available under the Energy Crops Scheme, is intended as a contribution towards establishment costs, with the amount paid depending on the type of land involved.
The grant, which is not at this stage available in Wales or Scotland, is paid only to growers who hold a contract to supply wood chips to a biomass burning power station or other energy producer, and this can cause problems, explains Dr Rebecca Heaton.
Dr Heaton runs the Salix Project at Cardiff Universitys Llysdinan Field Centre, New-bridge on Wye, Powys, where willow is growing as part of an investigation into the potential for biomass production on Welsh farms.
"The economic viability of SRC is strongly influenced by its high initial investment and hence the availability of grant assistance, but at this stage no support scheme has been proposed outside England, although similar schemes are likely to be introduced in Wales and Scotland," she says.
The fact that the English grant scheme depends on an existing fuel-for-energy contract ensures crops such as SRC are geared to the energy market, but it also creates a chicken-and-egg situation.
Very few UK growers have access to a suitable power station and those who have no immediate outlet for wood-fuel are discouraged from planting speculatively in anticipation that markets will develop in the future.
Although a number of new power stations have been proposed, planning permission problems have put the prospects for some of them in doubt, including the only two biomass power stations currently proposed for Wales.
As well as the question marks over grant aid for growers and the future development of power station outlets for the chippings, contractors who hope to service the SRC crops face additional uncertainties about the type of machinery needed to plant and harvest SRC grown under UK conditions.
Harvest time for SRC is late autumn or winter and the usual method is borrowed from Scandinavia where SRC production is well established. A special saw-action header on a self-propelled forage harvester is employed and rods cut by the header are reduced to chips in the forager and blown into a trailer, but Damian Culshaw, the energy crops development manager for Border Biofuels, believes a different technique will be needed in the UK.
The ground is frozen during much of the SRC harvesting season in Sweden, allowing heavy equipment such as self-propelled foragers to be used, he explains, but British crops are more likely to be harvested in wet, muddy conditions and a much lighter machine may be more suitable.
"Another problem is that chips from freshly harvested coppice have 50-60% moisture content and they deteriorate if they are not burned immediately," he says. "In Sweden most of the wood chippings are for winter heating and are used immediately, but British produced SRC will be used for electricity production and that means long term storage is essential. Wood chips are expensive to dry and store and it is easier to harvest and store the wood as complete rods and chip them later."
With no ideal harvester available, Border Biofuels, a company established to develop biomass burning power stations, has developed a machine it believes suits UK conditions. It is designed as a complete harvesting system, cutting, carting and stacking whole stems of willow coppice.
The weight of the self-propelled machine is 10t and it is mounted on rubber tracks to reduce the ground pressure and improve mobility in difficult ground conditions. A trailed version is also available.
One of the big advantages is that the complete harvesting operation from cutting to stacking is handled by one operator without additional support vehicles. Performance figures from initial trials in mature willow coppice produced a cutting rate of more than 1ha/hour.
Approximate prices are £200,000 for the self-propelled version powered by a 130hp engine and £40,000 for the trailed model. For further details call 0131-7184388. *