Monday 1 October 2012

Environmental Benefits of Wood Burning

Peter Mintoft, Technical Director of Charlton & Jenrick Ltd, manufacturer of Fireline wood stoves takes a look at some common wood burning myths and actual eco-benefits of using wood to heat your home:

In recent times greater numbers of householders are turning to wood fuelled stoves as part of their over all heating strategy. With gas and electricity prices hovering around historic highs, this often makes sense financially as well as environmentally, not to mention enhancing the living space with a very tangible warm and homely ambience. However, there is often concern expressed about wood stoves and alleged pollution, plus cutting of wood to use as fuel, most of which is unfounded. To start with it is worth discussing some common myths about wood burning and revealing the actual facts:

“Surely if we cut down trees to burn them it is a bad thing and we will end up with less trees and less wood left?”

Not true – almost all firewood comes from thinning operations during forestry management and if demand for wood fuel is low then many areas of woodland can be neglected and not managed correctly. Increased demand for wood fuel will simply increase the amount of proper thinning and management that is done. Correctly managed woodland will increase its bulk and grow better than non-managed woodland. It is easy to forget that trees are constantly growing; they are not a static resource, a hardwood forest might accumulate up to 7 cubic metres (about 7 tonnes green) of new wood per hectare each year and softwood much more. When fully seasoned this is approximately 5 tonnes of useful fire wood per hectare per annum. There are 3.1 million hectares of woodland in the UK which has been increasing in recent years, so it can be seen that fully sustainable wood fuel potential is huge.

“Isn’t it just as environmentally friendly to burn logs in my open hearth?”

Definitely not – open fires are very inefficient because combustion cannot complete and lots of warm room air is lost up the chimney whether or not the fire is burning. Open fires burning wood, or any fuel, are very inefficient and smoky and must be avoided at all costs. A modern closed wood stove will produce around 4 times the heat from the same amount of wood as an open fire plus massively reduced smoke and particulate emissions. The best, most environmentally friendly way to burn wood logs is in a modern DEFRA compliant wood burner.

“I hear that all wood stoves produce dirty smoke, tar and soot don’t they?”

Not true – sure some older stoves are nothing more than a dirty burning metal box and they should definitely be replaced with modern, efficient clean burning stoves. Current clean burn and DEFRA exempt stoves have very clear exhaust. All Charlton & Jenrick Fireline stoves are DEFRA capable or already exempted for burning wood in UK smokeless zones and produce particulates and visible smoke levels 60% or more below DEFRA limits. DEFRA smoke particulate limits are actually tighter than some EU and Scandinavian limits. Just maintain flames above the logs at all times and the exhaust will remain clear.

“Although the stove has a glass panel won’t it soot up after a couple of hours so we can’t see the fire?”

Not true – Charlton & Jenrick Fireline stoves have a very well developed air wash system that operates as an integral part of the clean burn combustion system. Just maintain flames above the logs at all times and the glass will not soot up. Older stoves either did not have these or they were a poor add-on air wash box that did not work properly. With our modern designs and clean combustion usually the most that will be needed is a wipe over the glass with a dry cloth before lighting the stove next day.

“I hear that the ash will need taking out every day and it’s too much hassle.”

Aylesbury Fireplace & Stove Package
Not true – most wood burning stoves have ash capacity for many days burning within the firebox and ash pan. If only burning a stove for evenings and weekends it may only need emptying once every month or two. Modern wood stoves have a proper grate allowing a build up of ash bed to be achieved together with proper ash collection arrangements rather than the basic metal box requiring shovelling out that users used to be given. All Charlton & Jenrick Fireline stoves are provided with proper wood burning grates and stainless steel ash pans for ash management.

“Surely burning any fuel emits carbon dioxide and that is a bad thing?”

Partial truth – of course burning wood does emit carbon dioxide (CO2) like any other fuel but the big difference is the carbon cycle that is operating when using wood fuel. Coal, oil and gas are ‘fossil’ fuels so-called because the carbon inside them has been stored for millions of years underground – not in the atmosphere. When we burn these fossil fuels we release that old carbon back into the atmosphere as additional CO2. When burning seasoned logs we are still releasing carbon dioxide back into the atmosphere but that gas has been absorbed by the wood in recent years. So as we burn wood, a new or existing tree is growing and soaking up that CO2 from the atmosphere quickly. As long as woodland is correctly managed we are not adding to the over all burden of carbon in our atmosphere. Even if trees are left to rot in the forest they give up their carbon back to the atmosphere eventually.

“The new Fireline stove I want has a cast iron grate and I’m told it can’t possibly burn wood as well as a flat bottomed stove?”

Not true – This was often the case in the past for UK designed stoves but modern wood burners, particularly those from Europe or Scandinavia are equipped with properly designed wood burning grates for convenience and flexibility. Charlton & Jenrick Fireline stoves are all provided with our own specially designed grates to allow 78-81.5% efficiency, very clean combustion and ash building on the standard grate. We don’t believe that you should have to scrabble and shovel out ash from a stove just because it is a wood burner so we provide large ash storage capacity and a proper stainless steel ash pan to manage the wood ash.

“Cutting splitting and stacking logs is hard work and doesn’t it take up a lot of space?”

Not necessarily – Space is a big advantage for cutting, splitting, storing and seasoning wood at low cost but you don’t always need to do things the traditional way. One method of greatly reducing hard work and storage requirements is to buy in prepared logs, preferably kiln dried such as Certainly Wood’s environmentally sound and high quality products. These can be obtained just a few bags at a time from stockists or cheaper in bulk if a little space is available to store them. Be sure that your supplier uses their waste wood energy for the kiln drying process and is not employing oil or gas which impacts badly on the wood fuel’s carbon footprint.

“If we have to cut down trees shouldn’t we be using it for buildings or furniture instead of burning it?”

Not necessarily – As we have already identified almost all firewood comes from thinning operations during forestry management. The type of wood harvested during these operations is just not of the high quality required for construction or cabinet making. It could be left to rot in the forest – releasing carbon dioxide anyway – or we can use it as a carbon neutral fuel.

“Won’t we return to the bad old days of ‘London smogs’ if everyone burns wood?”

Not true – ‘London smog’ was mainly caused by the fall out from terribly inefficient (20%) dirty open fires incompletely burning filthy coal fossil fuel. Modern wood burners meeting strict emission rules must be encouraged and used to replace old stoves and open fires, particularly in built up areas and smokeless zones and no such issues will arise. Open fires burning wood are very inefficient and smoky and must be avoided at all costs.

“I have central heating so I can’t have a wood burning stove can I?”

Not true. All you need is a suitable chimney or flue – and these can be retro-fitted into a property or repaired easily where necessary. Most central heating systems should already have thermal radiator valves fitted (TRV’s) or zones so that if a stove is lit it will take over the thermal load from the central heating system in that room. If you do not have TRV’s then they are easily retro-fitted. A boiler stove can even be connected into almost any kind of wet central heating system and power the radiators and sometimes the hot water when it is lit. These types of mixed systems are improving rapidly and as a bonus greatly reduce dependence on gas or oil as a sole heat source.

“Aren’t heat pumps powered by electricity more environmentally sound than wood burners?”

Not true – the biggest flaw in this assumption is the fossil fuel used to generate electricity and the losses in distribution of that electricity. The vast majority of electricity comes from fossil fuels and then by the time the electricity is generated and transmitted to your home, often only about 40% of the original energy is available to be used. Heat pumps are very expensive in first cost and performance is often not as good as predicted, not least because the technology is not yet mature and lots of development remains to be completed. In comparison an 80% efficient DEFRA exempt wood burner using properly seasoned or kiln dried firewood from a sustainable source is carbon neutral technology available today. Besides – there is also no heat pump in the world which is as enjoyable to watch in operation as a wood stove!

Burning wood is definitely a very positive environmental move overall if it is from a  sustainable source, dry, burnt in a new clean burn stove and can displace oil, coal, electricity or gas use in the home. Fortunately these are easy issues to deal with today. Fuel supply from managed woodland replaces the trees and encourages maximum growth to re-absorb the CO2 released during stove operation giving a relatively short closed loop carbon cycle. There is little waste in heat loss from the chimney and wood ash can be mixed with topsoil in the garden to help plant growth. The heat we feel from the wood stove is the sun’s energy returned to us in a way that fits in with the natural cycle of the woodland environment.
Wood stoves with modern combustion chamber design can be found in many different aesthetic styles from traditional British freestanding type to fabulous European designer looks. Be sure to look for the essential air wash coupled with tertiary air systems which introduce air into the top of the combustion chamber and clean up otherwise unburned flue gases before they leave the firebox. DEFRA exemption is usually a very good guide to the quality of emissions from a wood burning stove. Stove CE marking is a requirement from 2013 and any stove worth its salt will be CE marked already. Proper upper firebox baffles help to elongate the flame path and maximise efficiency and proper ash handling facilities are a must if you prefer not to be shovelling ash out from a more basic stove.
There is also the unquantifiable ‘feel good’ factor in being able to absorb the comforting warmth from a wood stove whilst watching the exquisite flame picture through a large air-washed glass window. A good stove can be an extremely satisfying and valuable asset to your home whist not costing the earth.
Charlton & Jenrick are members of the national Stove Industry Alliance (SIA – ) and manufacture the CE marked Fireline range of cost-effective, modern, in-house designed clean burning wood stoves. Some have multi-fuel capability and all have maximum size ceramic glass panels. All but one of the range are DEFRA exempt for wood burning in smokeless zones and have fantastically effective window air wash meaning that combustion is full and complete so you, and your environment are getting the best value from your stove and fuel.
Why not visit Fireplace Megastore and see the Aylesbury Fireplace and Stove Package in all its glory, get a feel for the solid natural limestone surround and matching chamber, complete with DEFRA approved wood burning stove.

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