Posted By: ringiA small amount of pollution is removed from the air by lots of nature systems, so provided we add pollution at a lower rate then it gets removed, we do not create too much damage

Except that you're using up natural reprocessing capacity that's sorely needed elsewhere.

You should pipe this clean air flue straight back indoors to reclaim the heat

Posted By: Peter_in_Hungary but so is the exhaust from gas boilers
Posted By: fostertom
Is it? I know you can often smell it (a sign of incorrect adjustment, like typical diesel vehicles) but at best natural gas produces near enough just pure CO2 and H20 - that's it's claim to fame.


I wouldn't want to be in the same room as a gas boiler with a open flue any more than a wood stove with an open flue. At least you can smell the smoke! Locally a family had new windows installed and inside 3 weeks there were 2 dead and 2 in hospital - CO poisoning. The gas regs should have prevented this but the new windows were fitted without reference to the gas regs. as the window fitters have no duty to check this!

Posted By: orangemannotQuite seriously I have never seen any smoke or vapours from our 11m high, well exposed flue, it is always perfectly clear, you really really cannot tell whether our wood stove is lit or not.

And, of course, 2.5 µm particles are easy to see from 11 metres, if you put your specs on.

Posted By: fostertom

Posted By: barneyNG isn't as benign as you would suggest

Wonder where I got that idea from? Makes a big difference to my attitude.

NG in a modem boiler gives a lot less pollution then anything else being burned at a domestic scale, it also has lower sulphur then coal even when the coal is burned as power station scale.

Older NG boilers can be a real issue, with a few boilers responsible for a considerable amount of the pollution in an area. (Hence a government pollution test on all boilers every few years may be a good option.)

Wood boilers can NEVER be trusted on a domestic scale, as you can't control how well seasoned the wood being burned is, along with paint etc on reclaimed wood.

The most dangerous particulates are the very small ones and the can't be seen by the naked eye

What's the evidence for that, Ringi?

Or your classic car (and mine)?

Attached chart claims about c20% of London NOx down to Gas.

(Caveat - No date, no source for data)

Posted By: orangemannotOops, I knew there was sommat else pertinent to the above debate.....The continued resurgence of interest in steam powered rail travel.
.....
Ditto for all unnecessary travel, by whatever means.

How much steam travel is there actually? In the scale of UK pollution I suspect it's irrelevant.

Define un-necessary travel. Everyone thinks their car journey is essential. 23% of trips under 1 mile are driven in the UK and 70% of car journeys are under 5 miles - a huge number of those could be walked or cycled.

Interesting discussion. I confess to selling logs for a living these days. It's a very rural area and very few customers have natural gas. I suspect the amount of particulates released from wood burners will vary vastly. Drove into town the other day and lots of wood smoke was hanging in the air. Looking closely you could see it was coming from just two chimneys. The difference in visual emissions from an open fire burning poorly dried logs V a modern high efficiency stove with dry logs is like chalk and cheese. A modern stove with dry logs and an educated user will produce almost no visual pollution but I freely admit have no idea how much invisible pollution there is. An open fire with damp logs will belch out smoke.

I see in the US catalytic stoves are common place and would be interesting to know how much cleaner they are. A link and quote "During third-party laboratory testing, the Catalyst achieved 0.2 grams per hour of particulate emissions. This is more than 20 times lower than new, more stringent, EPA emissions regulations and less than half the smoke produced by a single cigarette. These emissions were enough to win the Catalyst the Low Emissions Prize at the 2013 Wood Stove Design Challenge and the 2014 Grand Prize, besting its prior performance." http://mffire.com/catalyst/ . Obviously this is advertising blurb so probably take with a pinch of salt.

As an aside was at a farm this morning that was storing piles of chipped wood waste. Not nice clean fresh timber this was chipboard with melamine and god knows what in it. Asked the guys where it was destined for and was told it got shipped to Sweden to be burnt

I am not going to defend large scale biomass but feel small scale biomass in rural areas may have it's place and will undoubtedly continue for a long time. We aim to supply good dry wood and try to educate our customers how to burn it efficiently. It does have have a short C02 cycle and it is easy to store without loses in fact during the drying it's increasing potential output

Posted By: ringi

Posted By: BeauAs an aside was at a farm this morning that was storing piles of chipped wood waste. Not nice clean fresh timber this was chipboard with melamine and god knows what in it. Asked the guys where it was destined for and was told it got shipped to Sweden to be burnt

Provided it is burned in a licensed boiler, the emissions will be tested often. The power stations that are licence to burn post consumer waist timber (including chip board etc) have a gas burner heating up in the flue with additional air being pumped in, so that all the smoke is burned. Often there are also filters on the flue.

Very different from someone burning chipboard with melamine on an open fire……

I rather that such waist is burned on a controlled way then put in landfill......

Agreed but shipped from Devon to Sweden!

I expect it is being used for district heating, the shipping is not an issue, as very little energy is used for shipping. The question is how is it being got too and from the ship.....

Posted By: Beau293 miles from here to Sweden

I am further than that from Watford, are are you talking about the shortest route from the UK to Sweden (if there was a road).
Bit of info about fuel use by transport type here, no idea how accurate it is (just first google hit) and the units are US.
http://business.tenntom.org/why-use-the-waterway/shipping-comparisons/

A bit more googling and it seems that bunker fuel (as used in ships) has 40 MJ/kg, (https://people.hofstra.edu/geotrans/eng/ch8en/conc8en/energycontent.html), so that would be 11kWh/kg or 42 kWh/US gallon.

If a ship does the equivalent of 514 MPG/Ton of cargo, then to move 25 tonnes (24.6 ton), that will be 21 MPG/gallon equivalent.
21 US gallons has an energy content of 882 kWh.
25 tonnes of wood chip will have a usable energy content of around 112,500 kWh.
So less than 1% is lost to transport.

(not sure if that is right, but others can check)

So if we say that it is equivalent to 500 MPG to go by boat and it is 1500 miles, then to move a tonne will be about 3 gallons.
That is 33 kWh.
So 25 tonne of woodchip (112,500 kWh) will use 75 gallons, or 825 kWh (there are some rounding errors in there).
Let us call it 1000, kWh to move 100,000 kWh, still 1%.
I think we can discount "the amount of energy needed to ship wood chip half way around the world" as a bit of a red herring.
It would use 16% to do that or about double what total electricity losses are in the UK (most looses are in the last few miles and not from those large pylons, I seem to remember that they accounted for under 3% losses).