Willow power comes
of age at last
Energy crops are on the
back burner as far as many
growers are concerned. In
this special focus we
examine progress on
three large-scale biomass-
burning projects which aim
to change that. We also
review the latest findings
on coppice management.
Charles Abel sets the scene
with a look at how one
grower has succeeded in
turning power generation
plans into reality. Edited by
EUROPES first on-farm willow-fired heat and power plant is up and running and is set to provide the best return of any crop on the Northern Ireland farm where it is based.
"The net margin after all costs is £150-170/acre and I can tell you there is no other crop on the farm that has done that this year," comments project pioneer John Gilliland.
Earlier this week the willow-powered combined heat and power (CHP) unit at Brook Hall Estate, Londonderry, was formally switched on, offering up to 100kW of electricity to the national grid and heat for grain drying and heating on the 260ha (650-acre) farm.
"This is a great step for the technology," says Mr Gilliland. "It finally shows that it is commercially viable to grow coppice willow and burn it for electricity and heat in the UK."
Mr Gilliland, who won a joint Ulster Arable Society/farmers weekly/Avonmore Foods scholarship to study coppice power in Sweden, admits there were numerous teething problems getting the Brook Hall unit operational.
"The local electricity board wanted extra protection to prevent power surges and the monitoring equipment we installed has not been working 100%. But anyone following in our footsteps is going to find it much easier."
Half a years fuel supply is already in store – 250t of hardwood tree toppings were chipped and dried on the farm, since Brook Halls willow is not yet ready for coppicing. "Next year well take the first five acres and the year after 35 acres, at a dry yield equivalent to 3.6t/acre/year. That means well just about be able to meet our own requirements in winter 1999."
Willow plantings at Brook Hall Estate amount to 30ha (75acres), with the final 14ha (35 acres) due for planting next year. Once coppice enters its second rotation dry chip yield is expected to rise to the equivalent of 12t/ha/year (4.8t/acre/year).
Key to the projects success is gasification which converts dried wood chip into methane, hydrogen and carbon monoxide. That mix is cleaned and fed into a diesel engine to power a generator. Each 1kg of dry wood chip produces 1kWh of electricity, plus heat for drying and farm heating.
Mr Gillilands NFFO contract gives him a preferential electricity price of 6.95p/kWh, equivalent to £618/ha/year (£250/acre/year). Heat output is valued at £6000/year or £135/ha (£54.50/acre), giving a total output of £753/ha (£304.50/acre).
Capital costs of £140,000 are partly offset by a 50% grant from the EUs Energy Demonstration Scheme and depreciated to give overheads of £107/ha (£43.50/acre). Add growing costs of £200/ha/year (£81/acre/year) and total cost is £307/ha (£124.50/acre).
That leaves a net return of £446/ha (£180/acre).
"Other growers can now follow in our footsteps. But I would urge them to seek a direct market rather than go the NFFO route. NFFO is fine for larger farms or co-operatives that can spend the time on the paperwork. For smaller producers it makes sense to target a rural energy user and arrange to supply direct. Not only does it avoid the bureaucracy, it also offers the scope for higher rural energy prices."
A bright idea…John Gillilands on-farm heat and power plant uses 1kg of wood chips to generate 1kWh of electricity worth 6.95p plus useful heat, giving a net margin from the crop of more than £440/ha.
• Electricity for grid at 6.95p/kWh and heat for farm.
• Hardwood chip fuel now, all home-grown willow in 1999.
• £446/ha+ net margin beats all other crops.
Brook Hall CHP
1kg dry chip 1kWh
Electricity price 6.95p/kWh
8900kg dry chip/ha
8900kWh x 6.95p
£6000/year divided by 44.5ha £135/ha
£140,000 capital cost divided by 44.5ha of willow and offset by 50% grant £1573/ha
After depreciation £107/ha/year
Willow production costs £200/ha
NET MARGIN £446/ha