A new UK electricity plant running on biomass has found the perfect partner in a New Holland header specially designed to harvest coppice willow. Joe Spencer reports.
New Holland’s brand new specialist willow header was put through its paces at a special demonstration in March, harvesting willow, a renewable biomass crop, which will be used to feed the groundbreaking Stevens Croft power station in Lockerbie, Scotland.
The largest wood-fired power station in the UK, Stevens Croft has a 44MW capacity and will burn a mixture of forest residue and specially grown short-rotation coppice willow. A biomass-powered station on this scale could power up to 70 000 homes, and create up to 340 jobs at the station itself and in forestry, sawmilling and agriculture. Almost all the fuel will be sourced from within a 100km radius of the plant.
The New Holland header is an attachment for the FR9000 range of forage harvesters. It’s claimed the combination has a harvesting capacity of over 8ha/day, double that of competitive machines.
New Holland’s Symon Bradney says their header has several distinct advantages. “The new header attaches very easily to the forage harvester, like the New Holland maize, grass and whole crop headers, so it doesn’t take hours to modify the machine,” he says. “It’s also very reliable, which means very little downtime. Heavy-duty forestry feed rolls have been developed so the machine can cope effectively with the tough material.
“The nett result is the contractor gets more use out of the harvester, spreading the cost of ownership and increasing profit margins.”
Short rotation coppice willow
As an energy crop, short rotation coppice willow (SRC) (Salix viminalis) had vigorous juvenile growth thanks to its ability to coppice, or resprout, from the stump remaining after harvest, according to a paper compiled by Michael Dawson in 2007 for Omagh College.
The crop is established from cuttings produced by specialist nurseries, planted in the spring and cut to ground level at the end of the first year to promote the development of multi-stemmed stump.
Growth is extremely fast after cutback, as high as 4m in the first year. In UK conditions it grows to 6m or 7m in three years.
SRC can be harvested on a three-year cycle and has a viable life of 19 to 25 years. Yields vary depending on the site, weather and other factors, but can be expected to be in the range of 21t to 36t drymatter per harvest or 7t/ha to 12t/ha drymatter per year.
SCR drymatter has an energy content of roughly 19MJ/kg, or 45% of the energy in an equivalent volume of light fuel oil. This gives a mean annual energy production equivalent to 3 300/ha to 5 700/ha of oil. |fw