Log burning

Ben84

While they're good for cutting carbon emissions (assuming you're burning relatively local and sustainable wood), burning wood also generates a lot of other pollutants, both inside the house and outside. Compared to mains gas (which given sufficient air emits almost nothing but water and carbon dioxide) it's a very dirty fuel.

Generally, burning plant matter of any types creates a long list of unhealthy break down products and particulate matter. The 4000 compounds in cigarette smoke aren't in fact in any way special to cigarettes, they're just the result of burning plant matter. If we swapped them all for dried privet hedge clippings rolled in paper they'd emit almost exactly the same stuff when burnt.

grahamc2003

Ben84 wrote: »

While they're good for cutting carbon emissions (assuming you're burning relatively local and sustainable wood), burning wood also generates a lot of other pollutants, both inside the house and outside. Compared to mains gas (which given sufficient air emits almost nothing but water and carbon dioxide) it's a very dirty fuel.

Generally, burning plant matter of any types creates a long list of unhealthy break down products and particulate matter. The 4000 compounds in cigarette smoke aren't in fact in any way special to cigarettes, they're just the result of burning plant matter. If we swapped them all for dried privet hedge clippings rolled in paper they'd emit almost exactly the same stuff when burnt.

Much of the crap from wood burning comes out as smoke - if you burn wood in such a way that it doesn't smoke, I'd expect any pollution to be minimal. The way to burn all the gasses given off the wood is to have a hot combustioin chamber in an airtight stove. and the correct amount of air delivering the correct amount of oxygen - too much air cools everything down, and not enough air results in unburnt fuel (smoke) going up the chimney.

More or less the same with gas (which of course is plant matter). Incorrect burning of gas also produces some nasties - carbon monoxide being the real killer. It's just that most gas burning is near optimal, but most wood burning is far from optimal - e.g. not in a stove, and when in a stove burning overnight/burning too cool, chocking off the air supply when the room gets too hot, or burning damp wood which can't get sufficiently hot.

Ben84

grahamc2003 wrote: »

Much of the crap from wood burning comes out as smoke - if you burn wood in such a way that it doesn't smoke, I'd expect any pollution to be minimal. The way to burn all the gasses given off the wood is to have a hot combustioin chamber in an airtight stove. and the correct amount of air delivering the correct amount of oxygen - too much air cools everything down, and not enough air results in unburnt fuel (smoke) going up the chimney.

More or less the same with gas (which of course is plant matter). Incorrect burning of gas also produces some nasties - carbon monoxide being the real killer. It's just that most gas burning is near optimal, but most wood burning is far from optimal - e.g. not in a stove, and when in a stove burning overnight/burning too cool, chocking off the air supply when the room gets too hot, or burning damp wood which can't get sufficiently hot.

The pollution from wood burning varies and can be reduced in some ways. However, even between ideal conditions for burning wood and using gas, the pollution is many orders of magnitude more. You still need to sweep the chimney with even the cleanest burning wood appliances to remove condensed tar and soot particles, while gas burns so cleanly many people use appliances like gas cookers that vent straight in to the house.

To put the difference in to perspective, I used to live next door to a 3,000 kW industrial gas boiler and never once noticed any smoke or odour. Meanwhile I do notice smoke and smells from domestic wood burners a lot and they're only rated at a few kW normally. Smoke tends to drift down in cold weather and hang around allowing it to build up over time, while gas fumes (when burnt with sufficient air) are just steam and carbon dioxide, the exact same stuff we breathe out, and seem to disperse very readily in even the coldest weather as they're gasses rather than small particles of smoke. Of course the carbon dioxide comes with some environmental problems on a global scale, but it's not hazardous on a local scale.

Overall, I suspect wood is best for the global environment, but gas is best for the local environment. However, this may change as methane gas can also be obtained from biodigesters that can be fed various materials, for example sewage (there's one in oxfordshire that feeds gas in to the mains) and other organic materials. So, I think in the future we will make renewable gas here in the UK from various sources and enjoy the benefits of biomass without any local pollution.

BobbinAlong

Remember timber needs to be seasoned and dried for a year or two before burning. We stack in log stores built from old pallets with a felted roof.
We've just started burning some of the timber we cut last year as well as that from the local supplier - grown within five miles and sold about one mile from the house!
The price of logs is rising just like other fuels though - £110 per ton last time we bought.

jamesingram

"Interesting “Material World” on Radio 4. A report this week issued by Greenpeace, Friends of the Earth and the RSPB suggests that crucial mistakes in our carbon accounting procedures make burning biomass in the form of wood appear a better idea than it really is. In fact, they go so far as to suggest we'd be better off sticking with coal."
Listen again on
http://www.bbc.co.uk/programmes/b01ntjpz

rogerblack

jamesingram wrote: »

"Interesting “Material World” on Radio 4. A report this week issued by Greenpeace, Friends of the Earth and the RSPB suggests

For power generation.
For in-home use, it differs markedly.
Because of the larger quantities required for powerstations, they are liable to ship it longer distances, taking fuel, and at the end of the day perhaps convert 30% of the fuel value into electricity.

Good woodstoves, fueled from comparatively locally grown wood, can get easily twice, some closing on three times the heat out, with much less transport.

marich

You MUST NOT , really should not , if being responsible as a neighbour (let alone a 'Greenie') burn 'board' wood (ply- , chip- , conti- , block- , OSB , hard_ , etc.) . All of these contain adhesives or other compounds that are poisonous .

Likewise - painted , stained , varnished and/or treated wood is noxious when burnt . Worst of all is the burning of telegraph poles (even just using power tools on them leave you open to the Copper-Chrome-Arsenic compounds they are soaked in for a year prior to use .

It is so tempting to use what is at hand , it will all burn and give heat . One has to consider neighbours (who will quickly let you know) and the passing public as well as the possibility of a COMPLAINT to the local Council . Stoves are specifically licensed by DEFRA for us in 'Smokeless Areas' , and if you live in one then you will have to comply with the fuel-type that has been approved for your specific appliance . You can find the information on their site (if you have not already done so prior to installing your chosen stove !) .

Stoves are great and quickly become the heart of your home . There is plenty of otherwise wasted energy hanging around for collection (trailers are good for this) , and with a bit of elbow-grease and enterprise you can save yourselves a load of money as well as delay the extinction of the Human Race !

jamesingram

Roger , fair point , but even a good wood stove is probably only rated at 70% efficient , and in use more likely 50%

Ectophile

jamesingram wrote: »

Roger , fair point , but even a good wood stove is probably only rated at 70% efficient , and in use more likely 50%

Actually, the better ones are rated at 80% efficient. Of course, this will be under ideal conditions.

rogerblack

jamesingram wrote: »

Roger , fair point , but even a good wood stove is probably only rated at 70% efficient , and in use more likely 50%

On actually listening to the program, I find it was raising a different point, that is actually debatably complete !!!!!!!!.

The argument is basically that if we clearcut all forests now, and then replant, then there will be a transient large spike in carbon output.

This does not apply to - for example - newly planted coppiced forests, or any place where new woods are planted at the same rate old ones are cut.