alt.energy.homepower

On Fri, 03 Aug 2007 13:36:11 -0400, Neon John wrote:

>On Fri, 03 Aug 2007 11:54:21 +0200, Trygve Lillefosse
>wrote:
>
>
>>>You'll be surprised at how little fuel that condenses down to. I recently had three
>>>large white pines removed from near my house. I shot the largest with my laser
>>>rangefinder and measured 145 ft. The tree guy brought in a whole tree chipper
>>>(powered by a 235 hp Cat turbodiesel!) and chipped the trees. The resulting pile is
>>>barely 5 ft tall and maybe 10 ft diameter at its base. I'm not sure what I'm going
>>>to do with this pile (probably spread it out as mulch) but I can't imagine it lasting
>>>long when burned.
>>
>>Depending on its shape, the pile should be somewhere between 3,5 m3
>>and 4m3,

The pile dimensions are too vague, the shape unknowable, and John is
much more definitive about the tree size. Here's a cone calculator, a
crude but better method I think to estimate the trunk volume at least.
/~fto/tools/vol/

R1: R2: .1 H: 145 = 258 cubic ft, or cubic meters for one
trunk alone.

>> if it contains 30% air, it should at least amount to 2500
>>kWh. With 70% efficiency in the oven, this is about 1750 kWh of heat,
>>In my house, i assume that it would probarbly last for 3 months
>>(19kWh/day).
>
>Converting back to useful units, 1750 KWh is about 5,971,248 BTU.

That doesn't seem very useful... How about 8 cords for the trunks,
including the limbs perhaps >10 cords total, at 14 million btu per
cord. /

> My 3 ton heat pump
>can move (12,000 * 3 * 24) = 864,000 BTU per day if it ran continuously. It runs
>about a third of the time in the coldest weather. Make that 285,000 BTU/day. 6
>million BTU would last about 21 days.

After adjusting for a more accurate volume, many times more days of
heating, no? I think the average homeowner who heats with wood, after
looking up at 3 such large trees would think "this is going to be a
whole lot of work, and it's low-value wood, but it should last an
entire winter".

>If I already had the equipment on hand to dry, store and burn the chips then it would
>seem worthwhile. Otherwise not.

No need to chip it if it was going to be burned in a stove. Just
chop, split, and stack.

Wayne