What wood can I burn?
People often ask what is the best type of tree to use for firewood? Should it be hardwood or softwood? Should it be oak or ash or pine? The truth is that all types of wood contain calories - cellulose cells (or carbon) - that have captured the energy from the sun during the lifetime of that tree (or if it is coppiced then only part of the lifetime of that tree).
You might ask: won't I still be adding carbon dioxide to the atmosphere? Yes, that's true as carbon makes up about half the weight of firewood and is released as carbon dioxide when the wood is burned. However it is part of a 'present' rather than 'ancient' carbon life cycle, as a tree absorbs carbon dioxide from the air as it grows and uses this carbon to build its structure. When the tree is processed into firewood and burned, the carbon is released again into the atmosphere. This cycle can be repeated forever without increasing atmospheric carbon. Heating with wood, therefore, does not contribute to greenhouse gas emissions. Whereas fossil fuels such as coal and oil are 'ancient' sunlight captured in times long gone, when we release their stored carbon we are making a net contribution to the CO2 in the world.
So now that our conscience is clear back to "what wood can I burn?" The most important factor in getting good firewood is the Calorific Value' (CV). The two things that affect CV and are the 'moisture content' and 'wood density'. Look here for more information on how to reduce the moisture content of your wood.
Different types of trees have differing wood density - according to whether the wood is 'hardwood' or 'softwood'. Hardwoods come from broadleaved trees such as oak, ash and beech. Softwoods come from coniferous trees like pine, fir, spruce and larch.
Generally speaking hardwoods burn hotter and longer than softwood, but that doesn't mean that 'hardwood' is necessarily better than softwood, as weight for weight the wood contains the same energy. However some species of trees dry better than others and some have the tendency to spit when burned. If you have limited storage storage space then hardwood may be your preferred choice. Softwood is often in plentiful supply and will serve you just as well if you're burning it in a stove, provided that it is well-seasoned.
All trees have their different character and their suitability as firewood has been the topic of many a fireside chat. Have a look at this document for a good summary of what each species can offer.
The firewood poem was written by Celia Congreve, is believed to be first published in
THE TIMES newspaper on March 2nd 1930.
11 December 2012
|per kWH||per Year|
|Woodfuel - Logs||£0.023||£690|
|Woodfuel - Pellets||£0.052||£1560|
|Woodfuel - Chips||£0.026||£780|
|Oil - Kerosene||£0.07||£2100|