[Terrapreta] Response to Farm Scale Batch Charcoal Furnace on the Terra Preta bioenergy list

[AJH]

On Mon, 7 Apr 2008 07:26:30 -0500, David Stewart wrote:

>Andrew,
>
>No problem about the 4000 miles, I'll just pop onto a plane and be
>right over! Hah.

That'll increase the carbon footprint somewhat!
>
>Thanks so much for your reply.  It sounds like you've been down this
>path.  My entire project involves a greenhouse and furnace which will
>have some other attributes for using or storing heat in water tanks.
>It is my intention to use a hydronic system.  I'll post a sketch on my
>google group page sometime that will reveal the full depth of my
>delusional state.

Greenhouse heating is ideal but I would have thought we were talking
about a few hundred kW(t), the thing is with hydronic underfloor
heating you only need low temperatures.
>
>Regarding the offgas, I have some drawings from Mother Jones Magazine
>from the 70s that show a device for capturing offgas which was then
>used to power a truck.  Not sure how far they went on a load of 2x4s,
>but it seems to have been enough to drive it around a bit.  This made
>me think that it might be enough to run a generator.  I do also have
>the ability to generate methane from cow manure, so maybe a
>combination of the two would be enough to keep a generator going.

Digester (bio)gas to a generator will be easier than gasifer running
wood to generator, you'll really need to go to [gasification] if you
are wanting to go that route. One thing I will say is that gasifying
charcoal takes less cleaning up of the offgas, though it is a poorer
offgas for performance.
>
>I was hoping to avoid the idea of shoveling out a furnace full of
>coals to get char.  Seemed like hot and messy work, but it could be
>done if the other concepts don't pan out.

Shoveling out ring kilns was hot and dusty work, definitely to be
avoided.
>
>Do you have any further info on Yury from Russia?  I'll check the stoves list.

Tom Miles links this page:
http://www.repp.org/discussiongroups/resources/stoves/Yudkevitch/charcoal/index.html


They're much bigger than you require.

>Thanks again for your reply and if you're ever in Epsom (a good UK
>town name if ever there was one) NH, USA, stop by.

I'm 20km from Epsom, Surrey and was last in NH in 2002.

AJH