Archive for August, 2010

Woodfuel Excursions by Sophie Nash

Friday, August 13th, 2010

We have been considering using woodfuel at the Arboretum for a while, but as it’s such a complex subject area with lots of new technology involved (mainly Austrian and German), we decided to venture away from the Arboretum to look at working woodfuel systems for inspiration and guidance.
Mark Ballard and I recently visited Blaise Nursery in Bristol, which chips arboricultural leftovers and logs for their woodfuel boiler which in turn heats large polytunnels for the Nursery. The wood waste is sorted using a large sieve which splits out the different size pieces of wood, which are then stored in a large open shed to allow the chips to dry (you could see it steaming like a compost heap) This is then scooped into the boiler and burnt, producing potash and heat at the end of the process.
We also visited Star College in Cheltenham with Simon Toomer to view a different system. The woodchip was lorry loaded in and stored in a large underground chamber. In a room alongside the chamber were two large corkscrews, which moved when the boiler requested fuel. However just before we arrived, the sensors which control the level of woodchip requested, stopped working and the whole room filled with 5 feet of wood chip which then had to be bucketed out! In the boiler room were two large boilers, like huge wood burning stoves, three large water tanks and a huge amount of pipes which fed hot water into the radiators and underfloor heating around the site. 
Both visits were incredibly useful, as with such new technology almost every system has experienced some problems, but it was good to see how each site had resolved them.