Lloyd
Crispin is right this time. We used grass (Hyperrenia rufa) as fuel in the
Adjumani refuge camp in North of Uganda in the early 90ties tree times per
day for about two years into TLUDs PekoPe and had no problem rather
opposite. The advantage by using grass as fuel into a TLUD is the simmering
effect caused by the fact the glowing mass, after the flame is over, doesn't
collapse like wood fuel and by that it will be giving good simmering
temperature close under the pot for quite a long time.
.Paal W [email protected]
----- Original Message -----
From: "Lloyd Helferty" <[email protected]>
To: "Discussion of biomass cooking stoves" <[email protected]>
Cc: "Crispin Pemberton-Pigott" <[email protected]>
Sent: Sunday, September 26, 2010 4:10 AM
Subject: Re: [Stoves] The Biochar myth..another stovers myth
Crispin,
You say right at the end that "Pelletized grass can be used in
/*any*/ pellet stove or furnace."
I do not believe that this is generally true. High ash grass pellets
could be a big problem. Many stoves cannot handle high ash content
fuels, and more ash means much more maintenance**.
Clinkers are where the combustion temperature of the fire exceeds the
melting point of the ash in the fuel pellet (esp. with chlorine and
potassium), and the silicates within the ash will bind together to form
a glass like mass.
When ash melts it forms a glob of sticky material that cools hard. If
a fuel has a lot of ash with a low melting point a clinker will form,
and this will have to be manually removed, which increases
maintenance**. ("Slag" is the name used for a similar material which
collects around the heat exchanger pipes, and reduces heat exchange, and
thus performance.)
**You might end up having to give it a serious cleaning every 6 hours or
so, in order for the stove to continue functioning.
Ash clinker formations are usually associated with biomass pellet
fuels such as grass and straw pellets. If the ash content of these
pellets is too high and the ash melts and form clinkers you could be
looking at a big loss on fuel -- as well as a big mess inside your
stove. Clinkers can end up blocking the air holes of the incoming air
which can upset the mixture of air and fuel. Incorrect adjustment of the
air to fuel ratio can then greatly increase the likelihood of more
clinker formation. This is due to the stoves inability to adequately
burn the excess fuel and remove the excess ash that is building up in
the burn pot.
Not very many simple stoves that I know of that can correctly handle
very high ash fuel pellets. Even most of the more expensive commercially
available pellet stoves in North America and Europe (designed to burn
wood pellets) have no means of dealing with high ash content (except
Perhaps a for Harman corn stoves, Dell-Point Industries Europa stoves or
the Country Flame Technologies Harvester stoves).
A simple TLUD with its "flaming pyrolysis" should not create clinkers
and will result in a biochar residue that should also not be too
alkaline (and so hopefully can be placed directly into soil or compost
without worrying too much about changes to the pH).
Lloyd Helferty, Engineering Technologist
Principal, Biochar Consulting (Canada)
www.biochar-consulting.ca
603-48 Suncrest Blvd, Thornhill, ON, Canada
905-707-8754; 647-886-8754 (cell)
Skype: lloyd.helferty
Steering Committee member, Canadian Biochar Initiative
President, Co-founder& CBI Liaison, Biochar-Ontario
Advisory Committee Member, IBI
http://www.linkedin.com/groups?gid=1404717
http://www.facebook.com/group.php?gid=42237506675
http://groups.google.com/group/biochar-ontario
http://www.meetup.com/biocharontario/
http://grassrootsintelligence.blogspot.com
www.biochar.ca
Biochar Offsets Group: http://www.linkedin.com/groups?home=&gid=2446475
On 9/15/2010 6:32 PM, Crispin Pemberton-Pigott wrote:
Dear Friends
First a tip of the hat to Dean for pointing out that stoves can be
designed to produce char or not.
I remind everyone to please look at the whole equation of a problem , not
just a part and then make claims. In some cases one might want to create
char and some not, for example when cooking at a low heat for a long
time.
RWL - Crispin, being a climate denier, should not be taken as the final
word on these issues. Biochar in many places is giving a doubling of
soil
productivity for centuries not just the first year, when there is a need
for twice as much fuel.
I agree with Ron on this: there is a lot of support for the idea that
char increases growth of plants. Alex English and I had a long
conversation a couple of weeks ago and he report that some plant diseases
are limited by an increased ability of the plant to cope with infections
if there is char in the soil. Personally I think it has to be in the form
of char, not carbon in general. I know some Permaculture stalwarts who
think the answer lies in composting done correctly.
The point I was making is that claims are being made for char making
stoves to simultaneously save fuel, save trees and produce significant
amounts of char. The energy and efficiency math does not support this,
interesting as char is as a soil amendment.
I have already pointed out that in order to get 'meaningful' (as promoted
in the literature) quantities of char from a stove means fertilising a
potted plant, not a field.
But as Nathan Mulcahy has been emphasizing, the fuels for pyrolyzing
stoves need not be wood at all. And for charcoal consuming stoves -
almost certainly obtained from wood, the gain of pyrolyzing stoves is
even greater.
As AD Karve has shown, charcoal fuels can easily be made from
agricultural waste and the whole system creates employment as well -
basically out of nothing. Let us not toss that system aside too easily.
RWL The last part is indeed true - but I am pretty sure that trees
generally produce more than grasses on an annual basis.
It is Roger who has conclusively shown that grasses significantly
outperform trees.
Melting permafrost allows for a huge increase in biomass per sq metre and
the tree line used to be much farther north than it is now only 6000
years ago. One expects that this can also grow grasses for biofuel. Right
Roger??
But grasses are pretty hard to use in all but pyrolyzing stoves.
Pelletized grass can be used in any pellet stove or furnace. It is also
worth the energy to create the pellets which is harder to say about wood.
Regards
Crispin
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