ARTI Charcoal Kilns and Briquettes
AD Karve November 2002
Dear Tom and Paul,
I spent the last four days at Phaltan, looking at the charring kilns installed by ARTI at various sites. The operators in most cases are unemployed rural youth. After demonstrating the process to them on our own kiln they were provided with a kiln of their own, and they were asked to char sugarcane leaves in their own villages. In all the cases, they had unofficial advisers, who had already made charcoal using the traditional kilns. In the traditional process, the biomass to be charred is loaded into a kiln and ignited. One has to regulate the air supply very judiciously in order to have the right temperature to cause the biomass to char, but at the same time not provide so much oxygen that the biomass burns down completely to produce ash. In our oven and retort model, the biomass to be charred is enclosed in barrels and it never comes in contact with oxygen. We therefore keep all the airholes fully open, so that the biomass surrounding the barrels burns intensely to pyrolyse the biomass inside the barrels. Our entrepreneurs unfortunately followed the advice of the traditional charcoal burners in their villages and contrary to our advice, closed all the air vents, resulting in a very slow burn of the biomass surrounding the barrels. This not only increased the batch time but also in producing biomass which was just roasted and not charred.
Most of them were totally discouraged, firstly because of low output and also because of its poor quality. The correct process had to be demonstrated again at each site. We thought that we had developed a fooproof process, but it turned out that we were the fools believing that the villagers would easily be able to produce char using our technology. Our technology, if correctly employed, would yield about 50 kg char per 8 hour shift.
The char is sold in the form of briquettes. We started out with the extrusion process to convert the char into cylindrical briquettes. But in the field, there are problems with electric supply (either too low voltage or no electricity at all). So, during my stay at Phaltan we took the decision to provide the entrepreneurs with molds to produce the so called honeycomb briquettes manually. These briquettes look like mud pies, they weigh 100 grams each and each briquette has a set of 13 holes. So when it is ignited, the pot is hit by 13 flames. I myself produced these briquettes at the rate of one per minute. Thus by using our mold, a person can produce 50 kg dry briquettes per day. If the entire family works on this process, they can earn Rs. 250 per day (US$ 5), which is more than what an average industrial worker earns in a city.
We have developed a stove-and-cooker system for using the char briquettes most rationally. Through using a very scientific design, we achieve 70% efficiency with our stove-and-cooker. Just 100 grams of briquettes can cook rice, beans and vegetables for a family of family. We tested various prototypes and have now given orders to a stainless steel pots manufacturer to mass produce this cooker. We expect to get the first batch of cookers in about a fortnight and then see how we can market them. We shall sell them very cheaply (at practically no profit), because the user of a cooker is the potential buyer of the briquettes.
Appropriate Rural Technology Institute