Cheap biomass stove can turn sound into electricity

Researchers are testing a biomass-burning cooking stove that also converts heat into acoustic energy, and then into electricity — all in a single unit. The low-cost generator, they say, has the potential to transform lives in the world’s poorest communities.

Led by the University of Nottingham, the £2 million Score (Stove for Cooking, Refrigeration and Electricity) project has brought together experts from across the world to develop an affordable, versatile domestic appliance for rural communities in Africa and Asia where access to power is extremely limited.

Researchers in the Department of Electrical and Electronic Engineering at the University of Nottingham are working on the stove’s linear alternator, the part which turns sound energy into electricity. The system uses special configurations of magnets to generate electrical energy from sound. Computer simulations of the linear alternator have proved successful, and test models are currently being constructed in the department’s workshops.

Nottingham researchers are working with Dai-ichi, one of Malaysia’s largest loudspeaker manufacturers, to bring down production costs through good design practice. Though the Score unit does not physically resemble the average loudspeaker, it is compatible with the Dai-ichi manufacturing process.

Score has been invited by Dai-ichi to exhibit at the “Better City Better Life” EXPO 2010 in Shanghai China from May to October 2010 to showcase its new advanced technology to 70 million expected visitors.

The aim of the Score project is to make a low-cost, high efficiency generator that can be used in the world’s poorest countries. The generator has a cost target of £20 per household, based on the production of a million units. The generator will weigh between 10 and 20 kilograms. The target is to generate an hour’s use per kilogram of fuel, which could be wood, dung or any other locally-available biomass material.

“The current linear alternator design is very exciting for me as it solves many of the problems we had with using loudspeakers as alternators, but can still be made cheaply,” said Chitta Saha, a research assistant at Nottingham. “My mum lives in Bangladesh — she is so proud that I am working on such a worthwhile project that she can see will help her community.”

The University of Manchester, City University London and Queen Mary, University of London and the Charity Practical Action are all partners in the Score project. The project will work with governments, universities and civil organisations across Africa and Asia, many of whom have already offered support. This collaboration aims to ensure the device is affordable, socially acceptable and that there is scope for communities to develop businesses to manufacture and repair the stoves locally.

The Score team is now looking for sponsorship to fund testing in the countries in which the generator will eventually be deployed. In fact, Germany’s Department of International Development (GTZ South Africa) has already signed a memorandum of understanding to provide funding to test the stove in southern Africa.

Practical Action, a charity which promotes the development of sustainable technology to tackle poverty in developing countries, is already leading field trials in Nepal and Kenya. The charity will expand the test sites when more units are made available.

Score community member Mark Loweth works in Tajikistan, one of the poorer countries in Central Asia. He has adapted a variation of a Score stove to ensure it is suitable for the communities it is aimed at.

Other members of the international Score community are investigating how a Score stove could best be adapted for their local environments.

“We are adapting a Score stove to work with paraffin (kerosene) as many rural communities in South Africa are still highly dependent on it as a major fuel source for cooking,” said South African Score community member Rynier Ferreira. “Adapting a Score stove for paraffin will increase not only the safety aspect for stoves using this type of fuel, but will give the people in these rural communities the additional advantage of electricity and refrigeration.”

More units are expected to be available for testing in field trials at the start of next year, with full production of the Score generator set to take place after 2012.