coppice

Oct 112012
 
15sep12 015

Why Grow your own firewood?

Wood is the natural sustainable choice of fuel for many domestic fires – in use since the first fire thousands of years ago. When we warm our homes with wood, we participate in a natural cycle that we share with ancient ancestors.

The ability to burn wood for heat in our homes gives us more control and options for fuel. We are no longer dependent on large energy utilities and multinational corporations whose charges only ever increase. Even if we have to buy in our logs at least we are supporting our local economy.

Unlike the burning of fossil fuels like coal, gas or oil, burning firewood releases no more greenhouse gases (carbon dioxide) than would be produced were the wood to simply rot on the forest floor. If we are responsible in the ways we grow, cut, and burn our firewood, wood burning can actually be a good choice for the environment.

When sourcing wood you have three choices, buy in, buy a mature woodland, or grow your own.  This article will focus on the latter, check out this other article about sourcing wood away from the smallholding.

What trees are the best to grow for firewood?

Note that all woods burn better when seasoned and some burn better when split rather than as whole logs.  In general the better woods for burning that you are most likely to come by are:

  • Apple and pear – burn slowly and steadily with little flame but good heat.  The scent is also pleasing.
  • Ash – the best burning wood providing plenty of heat (will also burn green)
  • Beech and hornbeam – good when well seasoned
  • Birch – good heat and bright flame, burns quickly
  • Blackthorn and hawthorn – very good, burns slowly but with good heat
  • Cherry – also burns slowly with good heat and a pleasant scent
  • Cypress – burns well but fast when seasoned, and may spit
  • Hazel – good
  • Holly – good when well seasoned
  • Horse Chestnut – good flame and heating power but spits a lot
  • Larch – fairly good for heat but crackles and spits
  • Maple – good
  • Oak – very old dry seasoned oak is excellent, burning slowly with a good heat
  • Pine – burns well with a bright flame but crackles and spits
  • Poplar – burns very slowly with little heat
  • Willow – good if seasoned well

If the tree you are looking for is not here then try this link.

Timescale for harvesting wood as fuel

If starting from scratch then the quickest tree to plant and harvest is willow.  It can be grown on damp unusable ground, and if properly undertaken, will produce wood of a size that is manageable by a smallholder without specialist equipment.

Willow as firewood

Pros

Super fast growing varieties can produce logs up to 3 inches or more thick in only 5 years.  It is best to cut or coppice in the dormant season from late autumn to late winter.  This ensures there is the least quantity of water within the coppice poles, which reduces the time taken to season the firewood to a minimum.

To get reasonably sized logs you will have to coppice your willow every 4-5 years.  The advantage of short rotation coppicing has always been the small diameter of the trees which enabled them to be worked with hand tools.  The production of firewood is best carried out using the coppice system  because a felling licence is not required to cut coppice poles with a diameter at breast height (1.3m from the ground) of 15cm or less.

Cons

Willow wood is mostly water and takes a long time to dry out.  Some other woods will dry all on their own, simply as a function of time, but the willow dries best with good access to a breeze. Otherwise it can rot or start to grow again before it drys out.  If it sits outside and get’s rained on, it will soak up water like a sponge even if it was previously “dry”. Willow has to be kept dry- in other words, kept under cover. It should dry for a minimum of six months, but letting it dry for two to three years improves its performance slightly.

Willow is very soft wood and it burns very quickly so mix it in with your other firewood because it won’t last long.

Click here for more information on the benefits of willow, planting willow, and willow types for sale.

Coppicing trees 

Many species of tree can be coppiced (e.g. hazel). This involves regularly cutting the tree down to a stump called a stool. Multiple new shoots (known as poles) regrow from the stool. The cutting is done on cycle so to keep a consistent supply you need to plan ahead and have sets of trees which you cut each year. The interval between cutting depends on the species of tree. The trees are cut during the winter before the sap has risen, and the branches are all cut low to the ground. By repeatedly cutting the trees their lifespan can be greatly increased. One of the advantages of coppicing is that you do not need to replant the trees every time you cut.

The new growth is fairly straight and manageable, and can grow very fast. Because the wood from coppicing is relatively small it also takes less time than large logs to season and you should easily be able to season it over one summer. Coppiced firewood can be burnt in a wood stove and is ideal for use in gasification / batch boilers – these boilers have very larger fireboxes which can take long length logs. You fill up the firebox and the boiler burns the fuel transferring the heat to a heat storage or accumulator tank for use when needed.

Many types of deciduous tree can be coppiced: Alder, Ash, Beech, Birch (3-4 year cycle), Hazel (7 year cycle), Hornbeam, Oak (50 year cycle), Sycamore Sweet Chestnut (15-20 year cycle), Willow, Sweet Chestnut, Hazel (7 year cycle), and Hornbeam. 

Turning trees into firewood

Once you have harvested your wood you must split any logs that are more than 6 inches in diameter.  This increases the surface area of the wood exposed to the elements and therefore enhances drying.  You can get mechanical splitters, and attachments for a tractor, when you have large quantities to split, but they are not cheap.

For the average user or smallholder a maul is the tool needed.  It is a type of axe with a heavy wide head especially for splitting logs.  A maul does not need to be particularly sharp – unlike a narrow felling axe which slices at wood and needs to be sharpened regularly.  You can use a felling axe for splitting logs but it is much harder work than a maul.  The trick with a maul is to let the weight of the head do the work – swing the maul over your shoulder and let the head fall on to the log without forcing it down.  The wide head will force the log apart.  It’s also important to have the log you are splitting at a good height – on a tree stump or larger log about 18 inches to 2 feet off the ground is ideal – this makes the job easier and avoids back damage.

Kindling

Trees and shrubs suitable for kindling include:

  • The older wood or prunings of Buddleia
  • Gorse -as a fuel it has a high concentration of oil in its leaves and branches, and so catches fire easily and burns well, giving off a heat almost equal to that of charcoal.
  • Lilac: Thinner branches make good kindling, whilst the thicker burn well with a clear flame and a very pleasant smell.
  • Rhododendron: Old thick and tough stems burn well.


More articles on firewood can be found here


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