[Stoves] Jatropha fruit as fuel?

[Bjarne Laustsen]

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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