18 August 2015
This month’s member story comes from Adam Potter, Head of Estates Maintenance at Thoresby Estate in the heart of Sherwood Forest, North Nottinghamshire. Adam tells us more about Thoresby’s sustainable wood fuel cycle, from restoring the estate’s native woodland to growing fuel for newly installed biomass boilers.
This month’s member story comes from Adam Potter, Head of Estates Maintenance at Thoresby Estate in the heart of Sherwood Forest, North Nottinghamshire. Adam tells us more about Thoresby’s sustainable wood fuel cycle, from restoring the estate’s native woodland to growing their own fuel.
Thoresby Estate was originally carved out of the ancient forest in the 16th Century. It now comprises over 700 hectares of mixed woodland, which falls into three main categories: commercial; landscape & amenity; nature conservation.
Thoresby’s woods play a vital role in biodiversity and carbon sequestration. The harvesting and marketing of timber is an important part of this process and will help ensure that the woodland can be enjoyed by visitors into the 3rd millennium and beyond. Within the woods team there are now nearly 200 years combined experience of the estates and their woodland. It is humbling to think that the Woods Foreman is now leading the felling of trees he planted as an apprentice!
Timber, restoration, and habitat conservation
The award-winning commercial woods, which are predominantly coniferous, are grown & managed sustainably to produce a regular supply of timber for sawmills around the country. In the woodland at the heart of the Estate, our task is to recruit new generations of oak, sweet chestnut, beech, yew and lime, as many of the established hardwood trees are approaching maturity. The internationally renowned southern woods contain a sizeable population of veteran oak trees, some of which have their origins in the 13th Century. The lack of disturbance has enabled many rare organisms to survive and prosper. Associated habitats of heath and acid grassland are also present, representing fragments of a landscape that would have been familiar to Robin and his band of outlaws!
Moving with the times
We are in the early stages of a 50-year programme aimed at gradually reducing the coniferous element of the woods, in favour of native hardwoods. The challenge for foresters will be to maintain a level of income for the Estate from the sale of quality timber.
Although a traditional wooded estate with its own forestry team, Thoresby has very much moved with the times. The process is highly mechanised and able to offer contract services with specialised equipment much in demand from foresters, land managers and owners across the East Midlands. As well as milling our own quality oak, beech, pine and fir for building restoration projects, we have developed our own woodfuel enterprise.
Between 300-500 tonnes is reserved from the annual thinning programme to supply this. Our contractors set aside the smaller diameter softwood (pine, larch, hemlock, western red cedar) that would otherwise go to the mills for chipboard production. It is stacked on bearers in open glades within the woods, where it air- & sun- dries for a minimum of 9 months. At that point (ideally at sub- 30% moisture content), it is forwarded to the barn where it is stacked in readiness for chipping. It is then chipped (using Jenz HEM 360Z fed by Kesla roof mounted loading crane) into the woodchip barn, and ideally sold or distributed to our biomass boilers.
Renewable heat projects
There is currently one biomass boiler in full time operation, which is supplying heating and hot water to 8 holiday lodges (with plans to attach a further 8 lodges in 2015). Given the isolated nature of the site and the density of use, a district heating system is ideal. The estate’s desire to move to ecologically sound fuel sources led to the decision to trial woodchip biomass.
We will also be installing a new 110KW boiler with 5000L buffer facility to provide heating and hot water to a range of office spaces planned for Thoresby Home Farm. This site is a grade II listed 19th Century model farmstead which will eventually house up to 16 office units and the existing farmhouse. Again this is a relatively compact site where district heating makes a great deal of sense. Given that the site is only a mile from our woodchip storage facilities it seemed ridiculous not to utilise a readily available fuel source.
Towards the end of 2015 it is hoped that (subject to planning) a third woodchip boiler will be installed on the estate as we convert a derelict, unlisted farmhouse into a residential home and school facility in association with one of the estates partners. Woodchip supplied by the estate will provide a sustainable and reliable heat source at a competitive cost.
Challenges and next steps
Moving forward with the drop in RHI we face the very real financial problem that biomass (and specifically woodchip) boilers are becoming less cost effective. That said, I believe it is highly unlikely that oil and gas prices will return to the prices of 15 years ago or even 5 years ago. In addition the estates are actively investigating the possibility of installing district heating systems based on woodchip biomass to provide heating and hotwater to multiple properties.
If you would like to find out more about the sustainable wood fuel cycle at Thoresby, contact us, as a site visit will take place later in the year. We regularly publish our members story to the website. Read about Church of England’s sustainable sleep-over pods, or tune in to our monthly good news feed.