Farmers in India, as elsewhere around the world, have long had a problem disposing of the agricultural waste left after harvesting. To get the ground clear in time to sow pre-monsoon crops, the most common method is to burn it in their open fields, causing air pollution. An Indian mechanical engineer, Ramesh Nibhoria, has developed a large-scale institutional stove, the Sanjha Chulha, which uses biomass briquettes in large-scale institutional stoves. The advantage of these stoves is the way they make use of a waste agricultural product of no economic value to farmers, and turns it into a cash income for them. In 2005, Ramesh’s company, Nishant Bioenergy, won a prestigious Ashden Climate Care award for this innovative stove project.
Briquettes of Biomass
Biomass briquetting is the process of converting high bulk, low density biomass into high density, energy concentrated fuel briquettes. The process of converting biomass to solid fuel involves drying, cutting, grinding and pressing briquettes into cylindrical shapes, with or without the help of binder. By compressing the wastes into briquettes they become easier to transport, store and burn. They give much higher boiler efficiency because of their low moisture and higher density. They do not contain sulphur, which as it burns pollutes the environment. Biomass briquettes cut to size
- However, there are some drawbacks with briquettes:
they cannot withstand direct contact with water, so a covered storage facility is required.
- the maximum attainable temperature is 1000° C due to their low carbon content. However this temperature is more than adequate for cooking purposes
- the burning capacity per unit volume is low compared to coal so a larger storage area is required.
Production plants that compress farm waste into biomass briquettes are not new in India. There are more than 250 plants in operation making fuel briquettes from a variety of agricultural wastes, such as peanut (groundnut) shell, coffee husk, mustard husk, coconut coir, cotton stalk, sawdust, etc. About 300 million tonnes of crop waste are produced in India every year and every year more plants are being set up to convert these wastes.
Demand for Briquettes
Most biomass briquettes are used to fuel kilns for firing bricks. Demand is variable and the price which brickmakers are willing to pay is low because the alternative is cheap coal. However, briquettes are cheaper than liquid petroleum gas (LPG) for cooking, and the Sanjha Chulha thus solves two problems – it allows schools to use a cheaper, sustainable fuel, and provides the briquetting industry with a more regular and higher-price market. Production of one tonne of briquettes needs about one day of labour, so supplying six schools would generate an extra full-time job. The benefits go along the supply chain. Farmers are paid about 500 rupees (£6) per tonne for field waste, and a typical smallholding of 2 hectares (5 acres) produces about 5 tonnes of waste per year, which brings in the equivalent of an extra month’s income to the farm.
The demand for biomass briquettes has rocketed and both the plant and farmers are benefiting financially. There is a huge potential market from thousands of institutions such as army bases, hospitals, colleges, temples, prisons and plantations that need large-scale cooking facilities.
The Briquette Stove
Nishant Bioenergy, a small business run by Ramesh Nibhoria, along with his brother Rakesh Nibhoria in Chandigarh, has developed the Sanjha Chulha stove, literally a combined cook stove. It is specially designed to cater for institutionalscale cooking using biomass briquettes. An installed Sanjha Chulha stove – the chimney removes smoke from the kitchen
The stove is made of steel, lined with fire brick and high temperature ceramic insulation to improve energy efficiency and keep the outside of the stove at a safe temperature. At one end of the stove the briquettes are fed by hand into the combustion chamber, at a rate of about 15 kg per hour, but this can easily be varied to suit the cooking needs. Cooking chapattis on the Sanjha Chulha stove
Three small (180 W) electric fans blow air through the combustion chamber, feeding the briquettes with a constant supply of oxygen and ensuring maximum smoke free combustion. The stove still works if there is an electric power cut, but with lower efficiency. The hot gases flow under hotplates, designed to provide uniform heat to the base of two large (250 litre) cooking pots. The hotplates can also be used for making chapattis, which are familiar home food and very popular in the schools.
Ash collects in a trap under the combustion chamber and can be removed when necessary. The stove has an overhead hood with in-built exhaust fan to take away the smoke and cooking fumes through a chimney. A 400 litre water tank around the chimney absorbs heat from the exhaust gases, and provides hot water on tap.
Care has been taken to provide a clean, safe working environment for the cooks: the hotplates are at a comfortable height; there is an electric control panel consisting of operating switches and timer; and an electric light is provided for better working over the stove.
Four different models have been designed to cater for the cooking needs of between 35 and 1000 people.
There are many advantages to using these briquettes:
- Briquettes are relatively cheap. Schools save around 40-50% of their fuel bill by switching from subsidised LPG to briquettes.
- The briquette stove provides a more constant, controllable heat, over a wider base of the pan than the LPG gas burner.
- The food tastes better, according to both teachers and children who are using it.
- Cooking is cleaner and safer – the fuel is burned more efficiently and any smoke is drawn away through the chimney. It replaces LPG and kerosene, which are more fire hazardous and accident-prone.
- It reduces dependency on imported fossil fuels such as LPG, replacing it with a locally produced fuel.
- It is less polluting: it stops emissions from the burning fields. Biomass is a carbon neutral source of energy. A Sanjha Chulha that replaces the use of around 42.6 kg LPG per day, offsets 26 tonnes of CO2 equivalent per year. The use of electricity for from briquetting the residue and running the fans produces only about 1 tonne of CO2, so the net annual saving is 25 tonnes of CO2 equivalent per stove.
India has many schools and other institutions that provide meals for large numbers of people. LPG is widely used for cooking, and is currently subsidised by the Government. However, with this subsidy being phased out over the next five years and rising oil prices, the cost of cooking is set to increase.
Many Sanjha Chulha have been installed in residential schools in rural areas of India. Users pay Nishant Bioenergy the full cost of the stove, which is about 136,000 rupees, (£1,700) and pay the briquette suppliers for the fuel. This capital outlay is a problem for the schools, which are providing education to poor students: they do not have large capital budgets and they are not allowed to take out bank loans. Nishant therefore provides credit so that users can pay in instalments from the savings that they make in their fuel costs.
A typical example is a residential school catering three meals per day for 450 people, which previously used three cylinders (42.6 kg) of LPG each day. With current Government subsidies, the LPG costs 900 rupees (£11) per day or 27,000 rupees per month. With the Sanjha Chulha, the school needs 150 kg of briquettes each day, costing 375 rupees (£4.70) per day or 11,000 per month. From the monthly savings of 16,000 rupees, Nishant Bioenergy takes 15 payments of 10,000 rupees (£125) to cover the cost of the stove. These payments are collected over a period of about 18 months, to allow for school holidays.
For added confidence staff from Nishant Bioenergy install each stove and provide three days’ training for users. During this training period the number of briquettes used is monitored, so that the monthly cost of running the stove can be estimated and compared with the previous cost of LPG. In this way users can see that the monthly payments are affordable. Nishant offers a maintenance contract for 7,500 rupees (£94) per year.
The stoves installed to date have worked very reliably, and their success has encourage the local education authority to make a deal with Nishant to replace the old LPG stoves.
At present Ramesh has funded the development himself, but he is using the Ashden award money to help produce and install more stoves under the repayment programme.
There is enormous potential for replicating this work as rural areas have a plentiful supply of field waste to make into 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.
The challenge is to match fuel supply with demand. Ramesh Nibhoria would like to franchise the technology and business model of the Sanjha Chulha under licence to manufacturers in other parts of India.
In India, the Prime Minister’s office has also taken a keen interest in spreading this technology and a large-scale installation of Sanjha Chulha is planned.
Hands On would like to thank Ramesh Nibhoria for his help in putting together this case study.
Nishant Bioenergy Private Limited www.nishantbioenergy.net
The Ashden Awards reward outstanding, inspirational and innovative local sustainable energy schemes that both protect the environment, tackle climate change and make real improvements to people’s quality of life. They are designed to encourage wider take-up of local energy solutions worldwide – proving to the public and policy makers alike that such schemes offer viable, practical ways of tackling poverty, resource shortages and climate change.
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