Field generators

In a pioneering biomass energy project, Londonderry farmer John Gilliland is harvesting a power source for the National Grid. Paul Carslake looks at how such schemes fit into the Government’s call for greater use of renewable energy

As cottage industries go, power generation would seem an unlikely candidate. But government incentives aimed at cutting fossil fuel use and boosting the uptake of renewable energy has led to a handful of small-scale generators setting up grid connections in rural areas.

`I’m doing it for the good of my pocket, not for my good health,’ says John Gilliland, an arable farmer based half a mile from Londonderry in Northern Ireland. He has set up a wood-burning generator producing 100kW at his 260-hectare farm, which from the end of this year will burn coppice willow grown on his own land and turn it into electricity.

This is the first such generator to be connected to the UK’s national electricity grid, in this case at a rate of 6.95p per kWh – a `green’ premium rate which is more than double the electricity pool price paid to conventional generators.

The figures back the suggestion that his pocket will not suffer: once the £70,000 capital costs of the gasifier are paid off (in about two years) he expects to earn a better return per hectare than the set-aside land subsidy he would otherwise have had under the European Common Agricultural Policy.

Such biomass projects, using locally sourced crops such as fast-growing willow for fuel, could have an appeal in rural areas. But so far, few organisations have taken them up, and those that have relied on government aid under the Non-Fossil Fuel Obligation, which gave £130m of support for renewables in 1998/99. Private-sector investment in renewable energy sources has been running at about twice this rate.

Wider commercialisation, though, remains slow. Last month, the Government launched its consultation paper on new and renewable energy sources for the next century, restating its ambition for renewables to make up around 10% of UK electricity supplies by 2010. Depending on how development of wind energy and wave power turns out, projects that rely on energy crops could account for up to a fifth of the total renewable energy supplies.

The commercial growing of crops for such power generators has yet to be proven, though new projects are being monitored closely – with the process run for the DTI’s New and Renewable Energy Programme by ETSU, part of AEA Technology. Official projections for the longer term costs for this technology suggest it could become competitive.

Jim Birse, spokesman for British Biogen, the trade association for the biomass energy industry, believes the rate of growth of biomass is in the hands of the DTI, the electricity regulators and the European Commission. `It will definitely get a lot further in the next 15 to 20 years. It depends on getting the proper support – both in terms of the electricity market and incentives to grow energy crops.’

The technology remains relatively unknown to some of the local authorities whose backing will be essential to get such projects to spread. Burning waste to create heat to drive steam turbines is well understood. Biomass, however, often relies on more sophisticated chemical processes such as gasification, which turns fuels such as woodchip into gas, or pyrolysis, which turns it into liquid fuel.

The gasification route is not new: it was used in Sweden during the Second World War as a response to shortages of conventional fossil fuels. Gilliland’s system dries woodchip to 10% moisture content and feeds it to a downdraft gasifier, which burns the wood with a shortage of oxygen. Carbon monoxide, hydrogen and methane are collected, cleaned up and cooled, and fed into the air intake of a diesel engine, which uses a fuel-gas mix of 10% diesel to 90% gas. This drives the generator. This requires about an hour a day of labour to refuel and clean up.

Viability to be proved

Gilliland’s system has been developed from the Northern Ireland Department of Agriculture’s research gasifier at Enniskellen. It has run for about 2,000 hours, but will need another 5,000 hours before its commercial viability is proven.

Other small-scale projects are also getting under way in rural areas. In Larne, County Antrim, a wind energy firm called B9 has diversified into biomass power generation, with a £250,000 fully automated gasifier system generating 200kW, currently fuelled by woodchip.

Debra Jenkins, B9’s biomass managing director, estimates the payback period will be closer to seven years, but is working in a joint venture with her Swedish equipment suppliers to win contracts elsewhere in Europe. `At the moment, biomass is small, but so too is wind energy. It’s a drop in the ocean, but it is definitely the future,’ she says.

Not all biomass projects are small-scale. Yorkshire Water’s wood-burning Arbre project in Eggborough will supply 8MW when it comes on stream in November. The long-term plan is to supply the plant with locally grown coppice willow. In the meantime, though, woodchip will be used. Border Biofuels will next week be seeking planning consent for a 20MW pyrolysis plant on a derelict industrial site in Carlisle.