As far as we are aware bracken has not been harvested in the UK for use as a fuel until now. It has been considered in some theoretical studies, one or two going back 25 years.
Bracken has been harvested for the production of organic compost for some time in relatively low volume. One of our Directors, local farmer Ian Reid, has been responsible for harvesting bracken from the Mendip Hills for 5 years. It was as a result of Ian's experience with bracken from the Mendips and discussions about its possible other uses with Les Davies of the Mendip Hills AONB Service that led to the idea to investigate its use as a biomass fuel.
Ian discussed this with others (now Directors) and it was agreed to launch a project to investigate the feasibility and viability of harvesting bracken to produce a biomass fuel in the form of pellets, briquettes and cobs to market to local consumers and public sector & commercial users.
A large (€200,000) grant from the EU offered through DEFRA was considered but we realised that we had much to do at a 'grass roots' level before we would be confident that such investment would be worthwhile.
An application was submitted instead for a much more modest £12,040 to Mendip AONB who had the responsibility of allocating monies from the Sustainable Development Fund supported by Natural England.
The application was successful and the funding was matched with monies invested by the Directors. Work commenced in late summer 2008 and almost 50 tons was harvested using contractors during October 2008. This was considerably later than would normally be expected (late August to mid-September should be the normal time for bracken harvesting) due to the abnormally wet season. Contractors were still bringing in the grain harvest as late as the first week or two of October 2008.
As part of the Feasibility Project, we have established a pilot production facility where we are able to produce bracken pellets in low volumes. We sent off samples to two independent laboratories and now have all the results back. We are very pleased to say that our Bracken Biomass Fuel has a clean bill of health and is an excellent source of energy.
So far, all results point to our ability to produce a high performance biomass fuel from bracken economically.
Of particular importance is the need to ensure there is no presence of carcinogens in the bracken we harvest. Comprehensive analysis was undertaken by staff at the Forestry Commission Research Station in Hampshire in 1994 (see list of References below). This showed that provided bracken is harvested once dead (in other words when brown) then there is no likelihood of the presence of Ptaquiloside or its analogues as there can be when bracken is green and particularly when it is sporing. This is, of course, as important to those people harvesting and producing bracken pellets as it is for those using them. We are anxious to ensure there is no presence of these carcinogens either in the raw material or in our final product so we are using the very same accredited chemical testing laboratory (and, indeed, the same expert, Dr David Potter) to test samples of our bracken as was used in the original studies in 1994. From all our research thus far, we are confident of the safety of our products to date and intend to undertake regular expert testing of each harvest to ensure continued safety into the future.
As we have mentioned elsewhere on this website, we have found over the past few months that moisture content is extremely important for several key reasons and our target is now 15% for final product. Up to 20% would be acceptable and is a common figure for wood pellets, for example. Clearly, with such an exceptionally wet harvest last autumn, we needed to find economical and eco-friendly ways of drying the bracken in order to produce a high performance biomass fuel. This work is on-going and is more complex than it first appears.
We have also discovered that long term storage of bracken pellets needs careful planning since they will easily absorb moisture if stored in bulk in damp conditions.
We continue to optimise the production process. Broadly speaking the key stages are:
For 2008 we used contractors using conventional equipment with tractors pulling cutters and balers. We tried bales of approximately 400Kg and 700Kg. Baling is necessary to bring the harvest in to storage efficiently and economically, minimising the carbon footprint.
We have tried two different methods - using a large agricultural shredder that takes a bale at a time and a chipper normally used to chip branches, hedges, etc. The chipper produces better results but requires more labour - it is our preferred option at this time.
Although it is possible to produce pellets directly from bracken that has been shredded, it seems we can provide better quality pellets by passing the shredded material through a grinder that turns it into quite a fine powder.
Our pelleter has been set up to produce 6mm diameter pellets, one of the most common sizes for pellet boilers. Producing consistently high quality, high performance pellets is as much an art as it is a science or technology. We continue to work on an optimal pellet, which is directly impacted by the previous processes (above), moisture content and the possible addition of small quantities of other organic compounds.
We are currently geared up to produce bracken pellets in bulk using ½ ton 'dumpy' bags and sealed 15Kg bags. Storage is a big issue especially for bulk product since bracken like wood pellets will absorb moisture from the atmosphere. Sealed bags are far less of a problem.
This stage is only at the planning stage at this time since we have not entered full production, which we hope to do from October 2009 following the harvest this season. Our key aim here is to absolutely minimise our carbon footprint by focusing on the embodied energy and carbon on a true 'end-to-end' basis i.e. from harvest to boiler. We are also seeking to provide a service that as closely matches the experience of users of oil-fuelled boilers today, where a pellet tanks is used instead of an oil tank and pellets are blown into the tank from a delivery lorry and fed automatically from the tank to the pellet boiler. These systems are already in operation and we intend to work with boiler manufacturers, suppliers, installers and fuel dealers to establish s full service.
Of course, there is no direct experience for us to turn to - hence this feasibility project. Somewhat to our surprise and confirmed to us by others who have looked at the pelleting of wood, what we are attempting to do is as much an art as it is a science (and technology). It is going to take most of our time for the next few months to perfect the production of bracken pellets to the high standards we have set ourselves. We shall also be investigating the production of briquettes and cobs, larger formats particularly useful for larger scale operations such as factories, office buildings, schools, hospitals, town halls and other public buildings.
Our belief still is that we can produce totally sustainable local high performance biomass fuels more cost effectively utilising naturally occurring bracken harvested from land otherwise unavailable to agriculture, without taking land out of food production. The management of bracken is very much encouraged by DEFRA since it leads to significant improvements in biodiversity, enabling new flora and fauna to flourish and extended grazing opportunities for animals. On the Mendips, this includes ponies, goats, deer and cows.
With a local operation and local distribution, we are hoping to create a local social venture business that provides new employment, direct investment in the local economy and some measure of independence from globalisation for customers and the business. Unlike some other sources of biomass fuels currently available on the market in the UK, we won't be importing raw materials from continental Europe, Asia, China or South America, all of which challenges the essence of sustainability.
We have learned a great deal from the feasibility project and gathered considerable background information on biomass fuels, boilers and sustainability. We intend to make this information available through these pages of our website and provide links to others sites of potential interest.