A revolution in biogas design
Appropriate Rural Technology Institute (ARTI), India
A revolutionary compact biogas system that uses food waste rather than dung to produce gas for cooking.
According to the World Health Organisation, every year, in India alone, 500,000 women and children die prematurely due to exposure to smoke from cooking on traditional stoves using wood or dung cakes as fuel. Aside from the health hazard, collecting fuel wood is time consuming and is directly linked to deforestation, soil erosion and climate change. Fossil fuel alternatives such as gas are increasingly expensive and they also produce carbon emissions.
Against this background using biogas as cooking fuel has been growing in popularity. There are a number of highly successful projects and technologies in place, several of which have won Ashden Awards in previous years. But they all rely on livestock and human waste as a feedstock for the biogas plant.
By contrast, ARTI’s new compact biogas technology developed by the inspirational Dr. Karve and his team of engineers, needs only vegetable residues, waste food and grain. Its daily consumption is just 1kg of feedstock (such as waste flour, leftover food, spoilt grain, spoilt milk, over-ripe fruit, green leaves and oil cakes) as opposed to the 40kg of cow dung needed for the traditional plants. From this small amount of feedstock it produces 500 litres of gas. The digestion process is also much quicker - taking place within 48 hours instead of the 40 days required when using dung.
The biogas plants are made from cut-down HDPE water tanks. The standard plant uses two tanks of incremental sizes (eg. 0.75 and 1m3) so the smaller fits inside the other. The smaller tank holds the gas and the larger contains the slurry. The basic water tanks, which are mass produced, often from recycled plastic, are adapted with the help of a heat gun and standard HDPE piping. The plant is filled with a starter mix, either cattle dung mixed with water and starch or effluent from an existing plant mixed with starch (waste flour). The feeding of the plant is built up over one or two weeks until it provides a steady supply of gas
With its moulded plastic construction and 1m3 capacity it takes only 2-3 hours to install, and is cheaper and easier to put in place than the dung based plant. Its relatively small size means it can be used in urban houses and even apartments, which is a break-through in the world of biogas production.
It has even attracted keen interest from the Pune urban administration who are keen to find an effective disposal system for the growing food waste in the area as they have recently stopped collecting food waste due to the shortage of landfill sites available.
So far, 700 units have been installed in the state of Maharashtra. The potential for rapid replication is vast. According to Dr. Ronald W. Larson, Chair of the American Solar Energy Society: "I predict that we will see a very large proportion of the world’s 2 billion poor, as well as the more affluent, seeing this as their technology of choice in the future".
Installing these systems and supplying feedstock to users also offers good business opportunities to rural enterprises - made possible by the fact that ARTI has decided not to patent its design, and so allow the rapid dissemination of this innovative and effective technology.
In the words of the users ..
“I use my waste food material to make biogas and ask my neighbours to give me theirs. The result is that the area is much cleaner as food waste is not thrown around; the street dogs do not scavenge and there are no flies” Mrs Salunkhe, a customer from the Warje District of Pune
"I live in the midst of Pune city and have no space around my house to install a biogas plant. I have no terrace as I have a sloping roof. But the compact biogas plant unit is so small, that I could install it on the concrete slab of the toilet block of my house. As feedstock, I use leftover food, peels of mango, papaya, musk melons, and vegetable waste that the household generates. Mr. Kate, Pune.
“I use only leftover food as feedstock for my biogas plant. The food comes not only from my own household but also from the households of my neighbours” Mr. Rajendra Yadav
“I have so far installed more than 200 of these biogas plants. Wherever I install one, five other householders in the vicinity want a similar biogas plant installed in their own houses” Mr. Rajendra Salunkhe
“I live in a village.Until now we were dependent on LPG that we had to obtain from the nearest town. Not only is LPG costly, but its ready availability is also not guaranteed. With the new biogas system, I have an independent fuel supply. As farmers, we can easily lay our hands on damaged grain and overripe and unmarketable fruits. I thus cook using gas which is absolutely free of cost” Mrs. Badve
“I earn almost 40% of my income by installing the compact biogas plants” Mr.Satish Raikar:
Ashden Award money would be used to help the design reach 500,000 potential users in the state of Maharashtra.
ARTI is an NGO based in Maharashtra, founded by a group of scientists and social workers. The mission of the organisation is to serve as an instrument of sustainable rural development through the application of scientific and technological knowledge.
Dr. Karve has won a number of awards for his innovative technologies including an Ashden Award in 2002 for the development of a system for making char briquettes using agricultural waste.
Dr. Karve will represent ARTI at the Ashden Awards ceremony in London.