Nishant / Developing and selling cooking stoves fuelled by biomass residues

How does it work?

The Sanjha Chulha is a large stove permanently installed in the kitchen. It is designed for use throughout the day, and sized to provide full meals for up to 650 people. At one end of the stove the briquettes are fed by hand into the combustion chamber, at a rate of about 15kg per hour: this can easily be varied to suit cooking needs. The hotplates, which hold two large (250 litre) cooking pots, can also be used for making chapattis, which are familiar home food and very popular in boarding schools. The exhaust gases flow out of a chimney through the roof of the kitchen. A 400 litre water tank around the chimney absorbs heat from the exhaust gases, and provides water at up to 90oC for cooking and making tea.

How much does it cost and how do users pay?

US$1 = Rs 44 (Indian Rupees) [June 2005]

The stove costs about US$3,090 (Rs 136,000) and users must pay this cost, plus the cost of the briquettes, in full. The main obstacle for schools is finding the initial capital for the stove. Many residential schools in India are providing education to poor students: they do not have large capital budgets and they are not allowed to take out bank loans. Nishant Bioenergy therefore provides credit, so that users pay in instalments from the savings they make in their fuel costs.

Environmental benefits

Using briquettes instead of LPG gives both local and global environmental benefits. The

residues used for briquettes would normally be burned in the field to allow a second crop to
be planted. Briquetting avoids the local pollution and fire risk of burning in this way.

There are some concerns about using agricultural residues in domestic-scale stoves, because they tend to produce more particulates and gaseous pollutants than wood or LPG, particularly if the stoves are lit and extinguished several times during a day. However, the design of the Sanja Chulha and the fact that the stove is used for extended times ensures efficient, clean combustion.

Each stove saves about 43 kg per day of LPG and thus avoids the emission of about 26 tonnes/year of CO₂. The electricity used to make the briquettes and run the fans producesan estimated 1 tonne/year of CO₂, so the net annual saving is about 25 tonnes/year of CO₂per stove.

Social benefits

The stoves are popular with schools. Cooks find them convenient to operate, they can use them for different types of cooking and the food tastes good.

Ashden guides

Biomass briquettes and pellets

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Economic benefits

The stoves save money for schools – around US$3,000/year (Rs 140,000/year) and offer a secure fuel supply. The savings will become more significant if the price of oil increases and government subsidies are reduced.

Briquetting plants typically earn 40% more from selling briquettes to schools than to industrial users, with the additional benefit of a guaranteed market. The benefits go along the supply chain. A typical smallholder with 2 hectares produces about 5 tonnes of waste per year, which can earn about US$50 (Rs 2,200), increasing the annual farm income by about 10%

The future

There is potential for replicating this work, throughout India and in many other countries. There is a plentiful supply of field waste to make briquettes, and many large institutions that need to provide cooked meals. The stove could also be adapted for small-scale industries such as soap-making and dyeing.