OneOak woodchip heats it up

One of the last parts of the OneOak tree waiting to be processed was a large pile of its branchwood. Ever since the tree was felled in January 2010 the branchwood has been stored at Blenheim where it has been drying slowly for the last 18 months.

Some of the OneOak branchwood waiting to be chipped

James Norman, from Oxford Renewables, has been waiting patiently for the wood to be ready for chipping. The resulting woodchip would be used by one of his clients to create heat for a large domestic boiler.

Last week the pile of branchwood was delivered by James Norman to Ed Mant of EJM Tree Services, who kindly chipped the material at no cost.

Ed Mant of EJM Tree Services chipping the OneOak branchwood

The first giant bag is nearly full of OneOak woodchip

The chipping operation was overseen by expert William Hamer of Hampshire Woodfuel Cooperative Ltd. William checked the quality of the woodchip that was produced. Its moisture content was 25% (making it officially ‘W30’) while the proportions of its particulates confirmed that it qualified as ‘G30’.

We were particularly pleased to be able to assist Sylva with the woodfuel element of the One Oak Project. We are keen to encourage the use of woodfuel and this was an excellent opportunity of demonstrating the understanding of its conversion and use, albeit at a rather smaller scale than we would normally work.

Braziers Park is one of the Cooperative’s regular customers and as we also supply other systems installed by Oxford Renewables, James Norman’s request for our help was one we were more than happy to accommodate. EJM Tree Services work regularly on Estates I manage for clients and Ed Mant was kind enough to agree to help as soon as I asked him.

William Hamer, Hampshire Woodfuel Cooperative Ltd

The different size particles on the OneOak woodchip. 17.9% greater than 16mm (foreground), 76.2% greater than 3mm, 4.2% greater than 1mm, and 1.7% less than 1mm (far end). Chip designation = 'G30'

James Norman delivered the woodchip weighing 610kg to his client Braziers Park. Using a standard figure of 3.8kWh per kg at 25% moisture content (Biomass Energy Centre), the estimated energy value of the OneOak woodchip was 2,318kWh. James explained that the OneOak woodchip was:

“enough to heat a four-bed house for about six weeks, or for one month in winter.”

The three bags of OneOak woodchip at the Braziers Park woodchip store

James Norman of Oxfordshire Renewables adjusts one of the boilers at Braziers Park

James explained more about the Braziers Park heat system that Oxford Renewables installed:

“The heating system at Braziers Park is based on a cascade of two SOLARFOCUS 60kW Therminators, which heat a pair of 3000 litre buffer tanks. The heat from these is drawn off as required through an underground “district heating” system, which supplies both the main house 80 metres away, and two cottages as well. The fuel is usually woodchip, although these boilers can also be run on logs. Having a pair of boilers has several technical advantages, leading to greater efficiency. For the community at Braziers, the new wood-fired system provided real warmth in the large old house for the first time while cutting their fuel bill by three-quarters, and above all giving them heating and hot water which is almost carbon neutral.”