Pollution from woodburners

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Pollution from woodburners
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Treacodactyl
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Joined: 28 Oct 2004
Posts: 25795
Location: Jumping on the bandwagon of opportunism

Posted: Mon Jul 04, 05 6:05 pm Post subject:

tahir wrote:

Treacodactyl wrote:

Depending on the method of growing the wood I actually thought coppice was carbon negative as the roots of the tree lock away carbon from the atmosphere and as they are not harvested the carbon stays locked away.

Must be quite marginal over the life of a coppice I'd have thought.

Depends, I've always been taught that the roots of a tree are the same size as the top. So assuming the trunk is about a third then the roots would be about a third. When a tree is cut down if it's coppiced then that third will carry on living and the carbon locked away for a few thousand years and if the stool is allowed to die then as the roots decompose I would think most of the carbon stays in the soil.

Either way, it's still better than digging up coal or extracting gas.

dougal

Joined: 15 Jan 2005
Posts: 7184
Location: South Kent

Posted: Mon Jul 04, 05 7:04 pm Post subject:

tahir wrote:

it's more about how clean the combustion is from all theses new woodburning stoves and boliers and how it compares to a modern gas boiler.

Modern boiler inovations are more about collecting more energy than further reducing pollutants. More energy efficiency of course means less CO2 for a given amount of heat. A gas boiler produces very little indeed apart from CO2 and water. There's very little NOx produced, the temperature being much lower than the combustion in a car engine. And the "Natural Gas" fuel is very (chemically) pure Methane, (which is a very simple compound, CH4). There's precious little sulphur - even the famous smell is a deliberate trace addition. There's practically no particulates. The purpose of annual "servicing" is largely to ensure that combustion is 'complete' and as little CO as possible is produced.
Its *very* clean-burning.
But mains gas supplies are fossil carbon.
However, it is perfectly possible (if not entirely practical for most folk) to bio-generate your own Methane, from renewable sources. Judyofthewoods has already provided pointers to the french guru Jean Pain.

In contrast, woodburners have a much more chemically complex fuel, with a variety of long-chain carbohydrates and some "aromatics" with ring-based structures. Consequently, combustion is much more difficult to complete.
When smoking food we are trying to use the active chemical products of very incomplete combustion. And those same chemical products of incomplete combustion are the "dangerous" pollutants!
Slightly more complete combustion gives sooty deposits. But, IIRC, wood gives larger (and so less harmful) sooty particles than coal.

Fossil fuels are essentially the remains of prehistoric vegetation. The sulphur in coal (and that extracted from liquid and gas petrochemicals) originated in the vegetation.
Modern wood is going to contain sulphur, but its not as concentrated as it becomes in coal.

We know that excessive use of raw coal produced fearsome pollution - the London "peasoupers" from Dickens to the 1950's. And ISTR that woodsmoke produces similar problems in some "third world" cities.
However, I would expect a modern, controlled domestic burner (especially those using chipped fuel) to be able to burn much more completely than those open fires, but never as cleanly as a gas boiler.
Apart from air pollution, the ash, in quantity would also be of concern.

The energy used in creating the stove wouldn't be massive, and the product lifetime should be very long.

One catch is "locally produced" fuel. The energy density is relatively low, so transport cost is relatively high...

So, while avoiding fossil carbon usage, with woodburning there is some price to pay in terms of pollution. I think the real question becomes whether that is a price worth paying.

So, not quite perfect, and not for everyone, but with local access to fuel, much better than most.

dougal

Joined: 15 Jan 2005
Posts: 7184
Location: South Kent

Posted: Mon Jul 04, 05 7:08 pm Post subject:

Treacodactyl wrote:

.... I've always been taught that the roots of a tree are the same size as the top.

One rule of thumb is to expect the roots to spread as wide as the crown - but it does vary dramatically with the species.
Seeing trees toppled by the "great hurricane" showed that the roots represent a pretty tiny fraction of the biomass...

Treacodactyl
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 25795
Location: Jumping on the bandwagon of opportunism

Posted: Mon Jul 04, 05 8:07 pm Post subject:

One thing that could be done to reduce a huge amount of pollution from burning stuff is to stop the vast amounts of bonfires people have. People round here seem to cut their hedges, trim trees and remove overgrown plants and just light a huge smoking bonfire the same day. Not a thought about drying the material off, composting some of it or even seasoning some of the wood for a bbq or inside fire.

In theory the council tells people not to have bonfires but in reality they do absolutely nothing about them.

Bugs

Joined: 28 Oct 2004
Posts: 10744

Posted: Mon Jul 04, 05 8:36 pm Post subject:

Treacodactyl wrote:

trim trees and remove overgrown plants and just light a huge smoking bonfire the same day....Not a thought about...seasoning some of the wood for a bbq or inside fire

Perhaps its because when you do that, even offer to take spare wood from them rather than have them drive it to the tip, and keep it to season and burn, you wind up with the desert-loving neighbours either side having conversations across your garden over the musical tones of the weed sprayer while they say "I like a nice easy maintenance garden I do". I'll give you an easy maintenance garden - the council runs scores of them on your behalf. Go and get a flat and let someone else actually appreciate and maybe even GARDEN in your garden. Grrr.

Sorry, were we talking about something else?

NL's point about the other good stuff from wood as well as just the fuel rings bells with me. I don't know that it is perfect, but I am happier with it than any other fuel, I would love to have an efficient burner rather than a gas boiler.

dougal

Joined: 15 Jan 2005
Posts: 7184
Location: South Kent

Posted: Mon Jul 04, 05 9:00 pm Post subject:

Treacodactyl wrote:

One thing that could be done to reduce a huge amount of pollution from burning stuff is to stop the vast amounts of bonfires people have.

I remember hearing that *barbecue* smoke (and grease!) is a significant contributor to Los Angeles' smog...

Environmental impact?
Sling on another burger, y'all!

sean
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 42219
Location: North Devon

Posted: Mon Jul 04, 05 9:29 pm Post subject:

dougal wrote:

Treacodactyl wrote:

One thing that could be done to reduce a huge amount of pollution from burning stuff is to stop the vast amounts of bonfires people have.

I remember hearing that *barbecue* smoke (and grease!) is a significant contributor to Los Angeles' smog...

Environmental impact?
Sling on another burger, y'all!

Hmm, that sounds a bit of a: "It's all right for me to drive a Hummer, it's those pesky barbecuers causing all the problems." type argument.
Doesn't everyone in LA only eat raw food nowadays anyway?

Jonnyboy

Joined: 29 Oct 2004
Posts: 23956
Location: under some rain.

Posted: Mon Jul 04, 05 9:38 pm Post subject:
July 12th & 13th celebrations coming up here, there'll be a fair few bonfires going on .....luckily I'm out of the country for it all

dougal

Joined: 15 Jan 2005
Posts: 7184
Location: South Kent

Posted: Mon Jul 04, 05 9:58 pm Post subject:

Smog and barbecues.
There's two stories at least. Which I may have minced together. Made a burger of actually.

1/ "Take Houston, Texas, where 'cuing is practically a way of life. Researchers at Rice University have found that fatty acids in the meat smoke wafting up from the city's grills (including those at restaurants) contribute a small but signiflcant amount of lung-harming particles to Houston's already hazy skies."
https://www.sierraclub.org/sierra/200507/hearth.asp

2/ Home chemicals including Barbecue Lighters as a major source of smog in LA.
"Ordinary household products such as cleansers, cosmetics and paints are now the Los Angeles region's second-leading source of air pollution, after auto tailpipe emissions, air quality officials say."
...
"A backlash against some of California's existing regulations is fresh in the minds of officials too. No pollution control measure in the Los Angeles region has drawn more litigation than rules requiring low-solvent paints. A 1990 measure requiring low-polluting charcoal lighter fluid infuriated political conservatives, who rallied around the slogan "use a barbecue, go to jail" and charged that air-quality officials were engaged in social engineering.
Home pollutants:
Consumer products now rank as a major source of air pollution in the Southland. All figures are in tons of hydrocarbons emitted daily:
178 -- cars and light trucks
108 -- consumer products
48 -- industrial paints and coatings
43 -- off-road equipment
36 -- recreational boats
28 -- commercial paints and coatings
22 -- petroleum marketing "
https://www.ecolivingcenter.com/articles/chemicalsinthehome.html

mochyn

Joined: 21 Dec 2004
Posts: 24585
Location: mid-Wales

Posted: Tue Jul 05, 05 12:51 pm Post subject:

We have a woodburner (Clearview) in the parlour which we put in last autumn when the oil burner conked out. It's wonderful, and the fuel could hardly be more local: all from our own land. We could use bottled gas, but we'd ahve to collect it or have it depivered. Sadly, the old chap uses a petrol chain saw to hoarvest the wood, but I don't think he's strong enough to do it by hand! (Don't tell him I said that!)

We do still use coal in the Rayburn though: I'm not sure if it would stay in over night on wood. Has anyone tried? If it's possible, I'd like to change over after cleaning the chimneys. Anyone got a set of chimney brushes?

sean
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 42219
Location: North Devon

Posted: Tue Jul 05, 05 1:30 pm Post subject:
Finally found the site I was looking for: https://www.woodheat.org/index.htm

oldhibberd

Joined: 09 Mar 2005
Posts: 118

Posted: Fri Jul 08, 05 6:38 am Post subject:

Am intending to Install a Clearview Stove in the lounge in a few weeks.

Should be fairly self sufficient in wood.

I do wonder however what effect on the whole 'Carbon Neutral Cycle' thing chopping it all up with a gas guzzling chain saw would have.

Just as I decided against the strimmer in favour of a decent scythe, I'm chopping most of my wood with a bow saw. But then I'm still youngish and fitish. Can't guarantee I'll still be able to in thirty years time!

Incidentally the old Rayburn in the kitchen which leaks like a Sieve spewed coal dust all over Kitchen (And presumably likewise straight up the Chimney) last winter. Burning on wood did seem to be a lot cleaner. Seemed to me to create only a fraction of the dust. I Just need to get round to having a really good go at sealing up all the cracks so am able to control the temperature properly.

farmwoody

Joined: 19 Mar 2005
Posts: 98

Posted: Fri Jul 08, 05 7:50 am Post subject:

My OH Martin is a chimney engineer. He installs woodburners, lines chinmeys, replaces flues and runs a consultancy advising historical (& new!) buildings.
I'm NOT an expert but he would say several things about woodburners.
1. The burner is only as efficient as the flue. On 99% of occasions a chimney needs to be lined.
2. Clearview stoves are in his experience the most efficient stove manufactured in the UK. (He is self employed, so no bias. We have two clearviews here at upperwood)
3. Something to consider if you install your own stove or have a builder install for you. Unless the installer is HETAS certified your garauntees and house insurances are invalid should something go wrong or when you come to sell your house.
About 30 % of Martins consultancy work is taken with cases where builders have incorrectly installed stoves and flues and litigation proceeds .
4. Your stove needs to be correctly installed. Burning wood causes carbon monoxide just the same as coal. If a stove or flue is 'leaky' due to sloppy installation, it CAN kill.

Bugs

Joined: 28 Oct 2004
Posts: 10744

Posted: Fri Jul 08, 05 8:03 am Post subject:
Sean, shall I add that link to your article on installing a woodburner or do you want to develop it yourself? https://www.downsizer.net/index.php?option=com_content&task=view&id=52

Nanny

Joined: 17 Feb 2005
Posts: 4520
Location: carms in wales

Posted: Fri Jul 08, 05 8:14 am Post subject: woodburners

the only problem we had with our woodburner was that in a house our size, it was too efficient and in the end we removed it and went back to open log fires because we couldn't actually sit in the front room while it was running, it was too hot and using up all the oxygen in the room..

i think they are marvelous things but in a 12 ft square room with low ceilings just too big

we had to have the window open so far that it was just a nonsense using it at all

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