[Greenbuilding] Wood-burning Cooking, Central Heating, & Hot Water: Advice Needed

[Corwyn]

On Feb 20, 2007, at 23:42, Rob Tom wrote:

> The reason willow grows so fast is because it, like bamboo, sucks up a 
> lot
> of water and for that reason, willow isn't a very good choice as a fuel
> wood IMO.
>
> That opinion seems to be confirmed by the btu output per unit weight
> numbers as compared to other wood species, willow having the lowest of 
> all
> the wood species (hardwood and softwood) listed , at 13.15 million Btus
> per cord. (Compare this to 21.59 milion Btu/cord for maple, 26.39 for 
> r/w
> oak).(source: in "Handyman in~your-pocket" by Young & Glover))

I am going to have to disagree with Rob here.  Cord is a measurement of 
volume NOT weight (128 ft^3).  In fact, different species of trees 
produce wood of very similar BTU per (dry) WEIGHT.  Thus, although 
willow will take up more room in your basement for equivalent heating, 
it won't be any less heat per pound.  Moreover, a less dense wood will 
burn faster and hotter, making it more suited to cookstove heating.  
Traditionally, wood burning cookstoves were fed with small pieces of 
low density woods.

> Aside from the fact that you'd have to burn twice the volume of wood to
> get the same heat output as about 1/2 the volume of a "good" firewood 
> (and
> presumably with twice the emissions),

I can't imagine why you would get twice the emissions.  The air between 
the cellulose molecules isn't producing any pollution.  Faster, hotter 
burning will actually produce less pollution.

> with high water content woods like
> willow, there's the risk that impatience and/or improper drying will
> result in too-wet wood being burned and that results in more wood than
> necessary being consumed (ie to cook off the excess moisture), dirtier
> emissions and higher risk of creosote formation and attendant higher 
> risk
> of chimney fires.

True enough,  wet wood, is the bane of all wood burning, however 
coppised willow will be small diameter, and thus dry much faster than 
large chunks of oak.

Thank You Kindly,

Corwyn

-- 
Corwyn
Kermit didn't know the half of it...
http://www.greenfret.com/
corwyn at greenfret.com