[Gasification] Wood heating in the UK - whole log gasification

Rex Zietsman rex at whitfieldfarm.co.za
Thu Jan 2 03:11:32 CST 2014

Having spent a lot of time in rondavel huts (round huts with conical thatch
roof) as a kid growing up on a farm, I can also attest to some benefits of
wood smoke in such huts - the smoke keeps mosquitoes at bay! Also, the trick
is how the top of the roof is made. In the older traditional huts there was
a gap at the top of the roof to allow smoke to leave. Modern designs close
this off with a cement cap on the top of the cone - no smoke release. It is
this type of design where the smoke is retained inside the building that is
a problem. 




From: David [mailto:david at h4c.org] 
Sent: 28 December 2013 06:29 PM
To: Discussion of biomass pyrolysis and gasification
Subject: Re: [Gasification] Wood heating in the UK - whole log gasification



On 12/28/2013 12:57 AM, Jason wrote:

PS. I have one aquaintance in New Zealand that is challenging the science
around respiratory disease and emissions from wood smoke. He says the link
is tenuous and the early bogus studies keep getting repeated and used as
justification to ban wood stoves. 

Water is necessary for life and too much can drown you. Similarly with some
things, a little can be of benefit. I recall a study of woodcutters that
showed they had increased resistance to colds, and this was attributed to
intermittent exposure to wood smoke. On the other hand, the WHO says that
1.6 million people die every year from exposure to indoor air pollution,
i.e. also (for the most part) wood smoke. (Coal smoke is far more deadly.)
The epidemiology is pretty well established.

The term of art is hormesis, for which wikipedia offers the definition:

Hormesis is the generally favorable biological response to low exposures to
toxins and other stressors. A pollutant or toxin showing hormesis thus has
the opposite effect in small doses as in large doses. ...


As far as the most common contributors to air pollution, it may end up that
airborne particulate matter of a certain size range, particularly where the
makeup of the particles includes irritants leading to inflammation, will be
seen to be most at fault for negative impacts on health. Not wood smoke,
exactly, in other words, but some things found in wood smoke, may well be
identified as the key bad actors. That would be my current best guess, where
I am solidly grounded in nearly perfect ignorance.

It may be hard to get around the better safe than sorry approach that many
might be inclined to take. The future promises to have more regulation, from
almost any point of view.



David William House

"The Complete Biogas Handbook" www.completebiogas.com 
Vahid Biogas , an alternative energy consultancy www.vahidbiogas.com 

"Make no search for water.       But find thirst,
And water from the very ground will burst." 

(Rumi, a Persian mystic poet, quoted in Delight of Hearts , p. 77) 




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