Hey Jonathan
The issue of incomplete combustion of Jatropha seeds in a TLUD gasifier
stove has in my opinion very much to do with that you by heating up the
seeds in the stove gets two different types of gasses. Pyrolysis gasses
and vaporized Jatropha oil. The last ones is much more difficult to
crack and burn, they will therefore require higher temperatures and more
secondary air for full combustion. But it will also require much more
control on the burning rates in the stove.
That is one of the reasons why we have changed our initial Jiko Mbono
gasifier cookstove to our new Jiko Bomba cookstove that use pellets as fuel.
That brings me to another issue you bring up. Why make pellets when
farmers just can burn their Jatropha seeds.
I find that there are several good reasons for that.
First, Jatropha seeds are in many part of Tanzania today a cash crop for
farmers. They can sell the seeds at good prices to companies that press
Jatropha seeds for getting Jatropha oil. So most farmers will never burn
a cash crop, they will sell it. He will rather sell it for cash he can
spend and then ask his wife to collect firewood for fuel, than burn the
seeds up in a stove.
Secondly, I agree with you that there are good quantities of Jatropha
seeds, however these quantities are still relative small. It will only
be few farmers that will be able to collect the 800 kg to 900 kg of
Jatropha seeds that will be required for a household's yearly demand for
fuel. This will then not leave anything for meeting other households
needs for fuel.
However there are big quantities of agricultural residues that are not
utilized efficiently. These agricultural residues can be turned into
efficient fuel if they are pelletised. Calculations shows that if 30% of
available agricultural residues in Tanzania are turned into pellets and
burned in efficient gasification stoves, they would be able to cover all
Tanzania's households demand for fuel.
Many of these agricultural residues requires a binder and lubricator for
pelletizing. This is especially the case for rice husk. 10% to 20% of
jatropha press cake mixed into agricultural residues works very good.
Such smaller amount of Jatroha press cake and less amount of jatropha
oil does not represent a problem for full combustion. Our Jiko Bomba
cookstove and its pellets burns very clean and efficient when operated
in the right way.
Thirdly. Using These kind of pellets in our stove is very economical.
Household that use our stove an pellets can save over 50% on there
energy bill compared to when they use charcoal, at least here in Tanzania.
Besides that by using pellets made form agricultural residues households
will use only renewable energy sources. This will contribute to reducing
the alarming deforestation rates here in Tanzania.
You can find more information on our stove on this link:
_www.treetanz.com <http://www.treetanz.com/>_
The site is in Kiswahili, but I believe you can read it.
Bjarne Laustsen
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