Wood Burning
Current energy and environmental issues are on all our minds. With gas and oil prices rising and stocks depleting the mention of renewable energy is no longer just the concern of the green ones among us. One answer lies in the sustainable management (coppicing) and replanting of our local indigenous woodlands in harmony with urban and rural society.
Coppice is an ancient woodland industry, mastered in the Tudor era. Sustainable sections of forest were harvested to produce a variety of products, from firewood to battleships. The coppice was regulated by a statute of Henry VIII, which required woods to be enclosed after cutting (to prevent browsing by animals) and 12 standards (mature uncut trees) to be left in each acre and be grown as structural timber.
Traditionally the coppice takes place on a 10-20 year rotation depending on the product needed. Young tree stems are cut down to the stump (stool), which re-grow producing multiple stems called poles. This process is especially beneficial for plant and wildlife as a wide variety of habitats unfold. The sunlight (previously blocked by dominant trees) reaches the woodland floor to release dormant flora such as bluebells and orchids. Trees that are well managed live longer, support local biodiversity and consume more carbon dioxide.
As a tree grows it absorbs carbon from the atmosphere, when the tree is burnt or left to rot, the same amount of carbon is released again. This is known as a carbon neutral cycle. The heat produced by burning wood can be seen as the warmth of the sun, stored in the trees through the process of photosynthesis. When the sun abandons us during the cold dark days of winter, we liberate the suns heat through reverse photosynthesis, like every other cycle in nature, every process has its opposite.
Our concept is to make woodlands self sufficient. We show daily that wood burning can be eased into modern lifestyles through the education of ours and our children's generation to use sustainable wood as a real and necessary carbon neutral alternative to fossil fuels. Heating your home with logs can mean that your energy bill incurs no standing charge and is paid directly to the local forest industry that manage our woodland, street and garden trees. In turn, local councils, farmers and land owners see tree planting more favourably.
Basic guide
Any type of wood will burn, however different types of wood can have significantly different energy values (calorific values). Hardwoods burn best and longest whereas softer wood burns quickly but hot. Waste wood is a good cheap form of fuel as most ends up in landfill and is left to rot, releasing its carbon. Care must be taken not to burn contaminated waste timber.
Local tree surgeons are a good source for timber, however across the industry a greater understanding of logs supplied to support a new generation of users is required.
The moisture content of freshly cut wood is between 50 and 80%. Wet logs such as these will give little heat as the energy is spent burning off the water. Stacking logs correctly and leaving for 1- 4 years (depending on species) will dry (season) the fuel and remove unwanted resins. To get the optimum heat and efficiency from burning wood, the fuel will need to hold less than 20% moisture. Keeping a few days' worth of wood inside, near the fire, will warm the fuel before use, further increasing efficiency.
Our ongoing research into processing coppice from our local woodland 'Belfairs' has given us a good insight into the potential of wood burning. We are surrounded by a variety of species such as Oak, Ash, Birch, Chestnut and Hornbeam.
Our results have shown that if wood is:
- Chopped by hand or using minimal machinery
- Left to dry (season) in the woodland or local compound
- Delivered to the end user locally from where it was processed in measured quantities
- Graded for specific wood performance (calorific value) and stacked
correctly - Burned in a well fitted, high efficiency stove, by a consumer educated in good user practice
Then we have the most carbon neutral form of heating available. Wood that is processed by large, oil dependant industrial machinery and delivered around the country in diesel lorries is not carbon-neutral.
