Wood has been burned by mankind since first we harnessed fire. It has been the fuel behind the provision of heat, cooking, defence and craft to name but a few things. Nowadays, as we watch our fossil fuel reserves dwindle, we are seeking a ‘sustainable resource'. Fossil fuels, such as coal, oil and gas have been consumed at an alarming rate since the dawn of the industrial revolution.

 

The ‘Black Gold’ and its two cohorts have also been responsible for the increased pressure on our planet through its release of carbon dioxide. The production of fossil fuels takes millions of year’s worth of heat and pressure applied to fossilised remains of organic material. Being non-renewable we are depleting the resource before it has time to replace what has been removed. Like its name, fossil fuel, the carbon which is released is also ancient.

 

This addition of this ‘fossilised’ carbon dioxide back overloads the atmosphere, causing global warming via the greenhouse effect. Wood fuel, if managed properly can be ‘carbon neutral’, unlike fossil fuels. The carbon dioxide emitted from wood when it is burned does escape into our atmosphere, that much is granted.

 

However this carbon dioxide can be reabsorbed by plantations of trees as they grow. Provided plantations of wood resources designated for woodfuel use are replaced and managed as they are utilised, there will be a continuous cycle of growing trees to absorb the carbon dioxide released as it is burned. Throughout Scotland, especially in the Highlands, there is a vast resource of mature woodlands. These huge resources of woodland do not have a strong market value, and as such it does not make fi nancial sense to harvest them.

 

If the woodfuel market became stronger in Scotland, this resource would have a market, being harvested and used as one of three sources of wood fuel.

 

1) Logs The image of a log burning on a fi re is enough to make me turn to jelly with relaxation. It's beautiful, cosy and an environmentally guilt free indulgence. If you harvest it yourself and do not transport it using a vehicle then the only carbon released into the environment is offset by that which is absorbed by the growing trees. If you are chopping the tree with nothing but an axe then you can bask in the warm glow of your log fi re coupled with a sense of environmental wellbeing.

 

2) Woodchips Woodchips are used widely throughout Northern and Central Europe as well as several large installations in Scotland. Harvested stems are sent through a multi-bladed chipping machine before being dried so that their moisture content is between 15% and 30% (larger boilers can burn chips with larger moisture contents, perhaps as high as 50%). Reduced moisture content means the boiler will burn the chips with greater effi ciency, as well as releasing larger amounts of energy. A chip boiler can vary in size, even being so large as to heat a district. In Finland there are many wood chip fuelled boilers which can provide heating and hot water for hundreds of homes. However, there is a ‘carbon cost’ attributed to harvesting, transport, chipping, and drying of the chips, although this is miniscule compared to that of fossil fuels.

 

3) Wood Pellets Wood Pellets are the most effi cient of all the types of wood fuel. They are produced through a process which applies huge pressures to sawdust, forcing it into a small pellet shape. These pellets can be burned, much like wood chip, in a small domestic sized boiler or in a larger boiler, capable of heating many homes. The benefi t of the pellet comes from its burning effi ciency (approximately 97% effi ciency), its small size (a small amount will produce a lot of energy, with perhaps a dozen producing enough energy to boil enough water for a cup of tea), and the need for minimal maintenance. As it burns so effi ciently it will produce virtually no ash or smoke, making it a realistic option for homes in ‘smoke free zones’.

 

It is fair to say that wood can be utilised to provide us with clean, green energy. It will not be the sole replacement for fossil fuels, but combined with other renewable and sustainable fuel resources, it will certainly go a long way to doing this. Through raising awareness and availability of woodfuel, we can manage our own woodland resources effi ciently and heat signifi cant amounts of Scottish homes with wood fuel.

 

Dominick Murray