Agriculture-stubble oil ideal for rural cooking

At the Clean Cooking Forum held in New Delhi in November, one of the panels discussed the use of alcohol for cooking. Use of alcohol for cooking is gaining traction in African and Latin American countries as it provides clean burning, drastically reducing household pollution.

Use of alcohol fuel for rural households was pioneered in India by a rural NGO in Phaltan in Maharashtra in the late 1980s. In 1985 it set up the world's first solar pilot plant to produce ethanol from sweet sorghum and used it in specially-designed lanterns for lighting and in stoves for cooking. Its pioneering efforts were recognised by the panel.

Presentations made to the panel showed that large-scale efforts are underway all over the world to use of ethanol for cooking. There are estimates (though the numbers are suspect) that China has close to four million ethanol stoves and Madagascar is shooting for 100,000 ethanol stoves a year in the coming decade.

Similarly, countries like Kenya, Nigeria, Ethiopia, Ghana and Haiti are embarking on a major programme of using alcohol as a cooking fuel for rural households.

But are alcohol fuels safe and available cheaply?

In quite a number of these national programmes, the fuel used is a mixture of ethanol and methanol. Ethanol is produced from plant-based materials like sugarcane, sweet sorghum, corn or any other starch- or sugar-producing plant, while methanol can be produced from natural gas, coal or via biomass gasification. Since India has a good supply of natural gas, Niti Aayog is pushing for a national programme of methanol as a substitute for diesel or gasoline for transportation. There is no programme at present for its use as cooking fuel in rural households.

Also, in all these programmes, the alcohol concentration used in stoves is between 90 and 95 per cent (on volume basis). Alcohol at such concentrations is inflammable and could cause kitchen accidents. Its flash point (the lower the flash point the more dangerous a fuel is for kitchen use) is ~170 C whereas for diesel and kerosene it is more than 500C.

This was the reason why the pioneering work in Phaltan in the 1980s was based on the use of 50 per cent concentration alcohol/water mixture in the stoves. This mixture with higher flash point resulted in a safe fuel for cooking.

Ethanol is an excellent material for chemical feedstock and is used in the pharmaceutical, perfumery and other chemical industries. Burning it either in cook stoves or automobiles is a waste of a precious, high-quality chemical. Besides, a large number of deaths in villages in India take place every year from drinking illicitly-distilled alcohol.

For cooking needs of the rural poor, the cost of ethanol becomes very important. Since it is produced from plant-based material, farmers should get adequate remuneration for growing it. Most of the alcohol produced in India is from molasses, which is a by-product of the sugar industry. That is the reason why alcohol prices are low.

Today the Indian government purchases alcohol from local distilleries at Rs 40 per litre. If it is produced directly from sugar-based plant material, the price will double or treble. With the calorific value of high-concentration alcohol around 60 per cent that of LPG, kerosene or diesel, the net alcohol cost becomes Rs 83/kg. This is costlier than diesel and kerosene.

In the US, alcohol is produced from corn and the corn farmers are heavily subsidised by the government -- close to $6 billion per year, about 60 per cent of the total cost of alcohol produced. That is why farmers can afford to produce alcohol. Any country in the world will produce alcohol with such heavy subsidies.

There are better fuels than alcohol for rural household cooking. Biogas, after cleaning and compressing, is equivalent to compressed natural gas (CNG). All over the world, CNG is used as a cooking and home-heating gas. It is safe and can easily be transported by pipelines over large distances.

Another technology for producing renewable liquid fuels from biomass is pyrolysis. Pyrolysis oil is a medium calorific value (CV) fuel with CV of 17 MJ/kg and can be produced from any biomass and agricultural residues via fast pyrolysis route (hence the name pyrolysis oil). Major work in this area is being done in the US and Europe where it is being used for power generation.

R&D is therefore needed to produce it economically and efficiently in India and in developing suitable cook-stoves. With 400 to 600 million tonnes a year of agricultural residue in the country, which is mostly burnt in the fields, pyrolysis oil can be an attractive alternate to petroleum products for household fuel. Not only will it save foreign exchange but will also provide large-scale employment in rural areas.
(The writer heads the Nimbkar Agricultural Research Institute in Phaltan)