Wood burning stoves are increasingly being used in winters to overcome chilly climate. They are in hot demand among Britons hoping to save money on energy bills. But Are they safe enough for environment? Let's get into the details to understand it.

Research shows levels of a particularly nasty form of pollution surge during winter when these stoves and open fires are lit.

A return to wood-burning is being seen in cities throughout western Europe, while in London, wood-burning is responsible for 10 per cent of air pollution in winter. In some British cities, wood-burning accounts for 13 per cent of particulates in the air.

Wood-burning stoves are fuelling air pollution in a big way. Worryingly, domestic wood-burning is now the UK's single largest source of PM2.5 emissions. Smoke also contains harmful pollutants such as benzene, formaldehyde, acrolein, nitrogen oxides and a class of nasty chemicals called PAHs. Plus, any burning of fuel produces carbon monoxide, the potentially deadly, colourless gas. They are fuelling rise in winter smog: Levels of one form of the pollution surge during colder months due to wood burning.

The wood-burning craze is posing a real danger not only to the environment, but also to our health. Burning wood generates particulates that can raise the risk of asthma.  Air quality experts say the stoves contribute to an ever-thickening cloud of smog engulfing our towns and cities, which is increasing the risk of cancer, lung disease, heart attack, stroke and even dementia. Wood smoke is a cocktail of gases and dangerous microscopic particles. Some of these blobs of soot, called PM2.5s, are 100 times smaller than the diameter of a human hair and can get deep into our lungs and into other organs.

Exacerbating the problem is the seemingly innocent habit people have of throwing open the doors of the stove to recreate the effects of an open fire or to warm up a room more quickly — thereby flooding the air with a deadly cocktail of noxious gases and toxic wood smoke particles.

Wood Heating and Environmental Sustainability

Sustainability is usually defined as ensuring that our actions today do not limit the ability of future generations to meet their own needs. The use of renewable energy sources is considered to be sustainable because they can be used forever without being depleted. The sustainability of solar, wind and hydroelectric power is easy to understand because as long as the sun shines, the wind blows, and water flows downhill, these sources can continue to supply our energy needs. Wood is also considered to be a renewable energy resource, but on the question of sustainability, the picture is not quite as simple.

Wood is a renewable energy source in the sense that a tree cut for fuel will naturally be replaced by a young tree that springs up in its place. This is certainly true, but there are conditions attached. The use of wood as a fuel is not sustainable if the trees are harvested in a way that damages the site. For example, if a stand of mature hardwood trees were clearcut the site could be damaged by erosion and the elimination of shade to such an extent that high value hardwoods would not re-grow there for many generations, if ever.

The use of wood fuel is also sustainable on the condition that it is converted to heat with reasonable efficiency. Wood that is burned in fireplaces at very low efficiency is wasted. On the other hand, if wood is burned in a modern EPA certified stove or fireplace, its use can immediately reduce the consumption of one of the other heating fuels like oil, natural gas or propane. This type of displacement is important because it is one of the ways we can reduce the carbon dioxide emissions that are linked to the problem of global climate change.

Oil, natural gas, propane and coal are fossil fuels, meaning that their formation has taken millions of years. They are not renewable fuels and their use is not sustainable because they will run out some time in the future. Of more immediate concern is the fact that the burning of fossil fuels results in the emission of carbon dioxide (CO2), the main greenhouse gas. When wood is burned CO2 is also emitted but this CO2 is just one part of a short-term natural process called the carbon cycle.

As trees grow, their leaves absorb carbon dioxide from the air in a process called photosynthesis. This carbon dioxide is converted to the carbon that is used in the tree to build its structure. Chemically, about half the dry weight of wood is carbon. The ability of trees to absorb carbon dioxide is the reason environmentalists promote tree-planting as a way to reduce net greenhouse gas emissions from human activities. In one sense it could be argued that burning wood for heating is a problem because it means fewer live trees are available to absorb CO2 from the atmosphere. However that argument does not take account of the second part of the natural carbon cycle.

After a tree reaches maturity it dies because of disease, rot and insect infestation and falls to the forest floor. There, it decomposes, a process of slow oxidation which emits CO2. In fact, whether a tree is processed into firewood and burned, or whether it dies and decomposes on the forest floor, the same amount of CO2 is emitted. In either case, the space the tree had occupied in the forest is now opened up to sunlight that spurs the growth of young trees on that site, increasing their absorption of CO2 from the atmosphere.

The process of CO2 absorption by trees and its emission back to the atmosphere during decomposition or burning of wood is the natural, renewable carbon cycle. The carbon cycle of the forest and the use of wood as fuel is sustainable provided the trees are harvested so the site is not damaged and the fuel is converted efficiently to heat energy.

Modern wood burning stoves are, undoubtedly, greener than their predecessors.

Modern wood burning stoves are far less polluting in the home than traditional fires, producing 90 per cent less pollution and 14 per cent less carbon dioxide. They are a genuinely green and carbon neutral way of heating our home, which can save us money and make us less dependent on the big energy companies.

Modern stoves are very efficient and clean, with about 14 milligrams of particulate per cubic metre of air. The compares to 100mg five years ago.

Advanced combustion stoves and fireplaces burn wood about 90 per cent cleaner and one-third more efficiently than older conventional appliances.  That means a lot less smoke outside and lower forest impacts because less wood is used. The same advanced appliance characteristics that result in lower outdoor emissions also result in less chance that smoke will be spilled inside the house.

When You Burn Garbage, You're Making Poison!

Many people get tempted to burn some household garbage in their wood burning stove, furnace or fireplace. Do you think burning it might be better than burying it in a land fill site? In fact, it is not. While it may seem harmless enough, burning garbage is damaging to the environment, to our family's and our community's health, and to our wood burning system.

Although there has been a tradition in rural areas of burning garbage in backyard barrels and in wood burning heaters, it is not wise. When you burn garbage, you're making poison.

Burning garbage produces unpredictable results because, unlike seasoned firewood, garbage contains a whole range of materials and chemicals that react when burned together. For example, household garbage contains various forms of paper and plastics. When paper and plastics are burned, you don't really destroy them, you just change their chemical form. The inks and dyes used for the coloring and printing of paper and plastics add to the chemical cocktail that is emitted when they are burned. The problem with burning any kind of garbage is that we just don't know what the resulting pollutants will be. One of the pollutants that results when paper, plastics and salt water driftwood are burned in a wood stove is dioxin, a highly toxic chemical that doesn't decompose and which builds up in the tissues of animals and humans. Airborne dioxin settles in soils and on vegetation, some of which may then be eaten by livestock. Dioxin builds up in fats in the body and is concentrated in cow milk and even in human mother's milk.

According to a World Health Organization fact sheet,

"Once dioxins have entered the environment or body, they are there to stay due to their uncanny ability to dissolve in fats and to their rock-solid chemical stability."

Certain kinds of toxic substances, including dioxin, can be destroyed using industrial-scale incinerators, but at the lower temperatures found in residential wood burners, dioxins and other pollutants are created, not destroyed. The dioxin produced in wood stoves when garbage is burned is not just emitted with the exhaust, but is also concentrated in the residual ashes. However, that ash is disposed of, its toxic legacy will remain. The burning of garbage at home or the cottage is the fifth largest known source of dioxins in Canada.

So, don't burn, just recycle your garbage. Recycling is far kinder to the environment than burning because it avoids the immediate air pollution and reduces the consumption of resources for new products. One of the best ways to cut your garbage output is to reduce the amount of packaging you buy. Since food preparation is one of the biggest sources of household garbage and because, in general, the more processed the food, the more packaging it has around it, buying less processed food is a good way to cut down on the amount of garbage your household creates. By reducing the packaging you buy, recycling as much waste as you can and burning only clean, uncoated wood, your household can contribute to a healthier environment.

 CONCLUSIONS

Those of us who heat homes with wood can do our part for sustainability by pressuring our firewood suppliers to prove that the wood they sell comes from a sustainable source. If many of their customers asked questions about sustainable forestry, firewood dealers would soon pressure their suppliers and the public will would be expressed within the firewood market.

Firewood should be cut, split and stacked in an open area in early spring to be ready to burn in the fall. Very hard woods like oak may take longer, and drying in damp maritime climates can also take longer than just the summer months.

One Final tip about sustainable firewood. Ugly wood piles that include wood from less desirable species tend to be more sustainable than perfect piles of maple or oak with regular pieces in the classic wedge shape. This is because straight lengths of these high value, slow growing species should be used for furniture, not wood heating.

Clean burning with no smoke is not rocket science, it just takes some extra awareness like most other acts of environmental responsibility.

The knowledge and skills needed to operate a wood burning system need to be learned and practiced to get them right.  

In sum, the environmental effect of wood burning depends very much on how it's done. Sustainably harvested wood burned in modern fireplaces and stoves can be a positive addition to our energy mix.

And no other way of heating our home adds as much beauty and comfort on a cold winter night as a wood burning fire.

Responsible wood heating should be promoted on environmental grounds. Responsible wood heating is so straightforward that its main requirements can be stated in a single sentence, like this one:

Burn sustainably harvested, properly processed and seasoned fuel in an advanced combustion stove or fireplace that is vented through a chimney that runs straight up through the building.

Burning wood produces environmental impacts. That is why it must be done responsibly.

Sources:

http://www.dailymail.co.uk/news/article-2873942/Wood-burning-stoves-fuelling-rise-winter-smog-Levels-one-form-pollution-surge-colder-months.html

http://woodheat.org/wood-burning-and-the-environment.html

http://woodheat.org/sustainability.html

http://www.dailymail.co.uk/news/article-3972966/Inconvenient-truth-wood-burning-stove-bad-environment-health.html

http://www.alternativeenergyprimer.com/Environmental-effects-of-wood-burning.html