Now wouldn't it be great if you could solve all these problems by creating one single device? Imagine an affordable three-in-one technology that consists of an efficient, low-cost refrigerator, combined with a safe and clean cooking stove, and an electric generator added to it. To make things better, imagine the device being powered by the very biomass rural people in the South already use on a daily basis, albeit in a wasteful manner.
Well, the SCORE project (Stove for Cooking, Refrigeration and Electricity) is developing exactly such a machine. What is more, the device will rely on the physics of thermoacoustic heating and cooling - a field of research that has resulted in such high-tech applications as devices to cool satellites, radars and to liquefy natural gas. The £2 million (€2.93/US$3.96 million) project brings together four major UK universities, the US Los Alamos National Laboratory, a multi-national electrical goods manufacturer, an international charity and numerous universities in Asia and Africa.
The consortium's goal is to reduce poverty in Africa and Asia by understanding the energy needs of rural communities and working with them to develop the affordable, versatile, domestic appliance. The collaboration will ensure the device is affordable, socially acceptable, and there is scope for communities to develop numerous businesses from the manufacture, repair and innovative usage.
The University of Manchester's Dr Artur Jaworski, an expert in thermoacoustic engineering in The School of Mechanical, Aerospace and Civil Engineering, will lead the vital research into the engine design for the SCORE device.
In simple terms, thermoacoustics refers to generation of sound waves due to the non-uniform heating of gas - a typical example being the 'singing' of hot glass vessels during glass blowing processes, a phenomenon known for centuries. The process works in reverse as well. The idea is to couple the heat generated by the biomass-powered thermoacoustic engine and cooking stove, to the resonator that contains pressurised gas which, when heated, generates soundwaves that power the thermoacoustic freezer and that is coupled back to the engine, while at the same time generating electricity (see diagram, click to enlarge). If you have some free time, why not make your own [*.pdf] tabletop thermoacoustic refrigerator to learn more about the science?
Using thermoacoustic technology is a more efficient way of using wood as a fuel than using an open fire to cook. It produces less pollutants. Like a Stirling engine, the device will also have fewer moving parts than ordinary engines and freezers, making it more reliable. The efficiency of thermoacoustic engines (40%) is considerably higher than that of ordinary combustion engines:
bioenergy :: biofuels :: energy :: sustainability :: biomass :: cooking :: heating :: refrigerator :: generator :: electricity :: thermoacoustics :: developing world ::
The concept of the device is based on the proven thermoacoustic Stirling engines and refrigerators developed by Los Alamos, NASA and the US military for applications including: cooling of satellite systems and radar arrays, gas liquefaction and cryogenics, use of waste heat for air conditioning, separation of binary gas mixtures and many others. There is a significant level of innovation in the proposed work in three respects:
- research into the combination of the thermoacoustic engine, linear alternator and cool box in a single device, powered by a biomass stove, which has not been attempted before
- design of a rugged and inexpensive linear alternator that could be easily mass-produced
- the overall system design from the viewpoint of low cost, application of indigenous materials, use of local manufacturing skills and simplicity of assembly, which are major research issues compared to the high-cost and high-tech thermoacoustic systems produced so far.
Within the overall 5-year duration, there will be two stages to the project: the first 3 years will mainly focus on conducting the necessary social and scientific research, while the last 2 years will broadly focus on technology hand-over, including representative field trials and a wide dissemination among target communities.
Dr Jaworski says: "A multi-purpose thermoacoustic device such as this, powered by biomass, has never been attempted before. Although we have wide experience of this technology and applying it in different ways, this new and exciting project will require plenty of ingenuity and innovation."
Making a difference
"With the depth of experience and expertise we have assembled as part of this international project, we are confident we can meet our aims, deliver a viable appliance and make a real difference to people living in the developing world."
"The benefits could be huge, ranging from better health due to the correct storage of medicines, to improved education through electricity for computers and lighting, to a higher standard of living through the creation of employment opportunities and associated businesses."
Researchers will need to look carefully at ways of ensuring any design can be assembled cheaply and easily using local labour and indigenous materials. Given the high cost and high-tech nature of current thermoacoustic systems, this represents a significant challenge.
Dr Jaworski, who is an EPSRC Advanced Research Fellow, will work closely with academics at The University of Nottingham, Imperial College London and Queen Mary, University of London.
Other partners are the international charity Practical Action, Los Alamos National Laboratory and GP Acoustics. Universities in developing countries in Africa and Asia will also assist with the design, development, production and introduction of the device.
The SCORE consortium is funded by grants from the Engineering and Physical Sciences Research Council (EPSRC) as part of its initiative on energy and international development.
The SCORE project website.
The Thermoacoustics web-server at the Los Alamos National Laboratory, with an overview of the physics.
Daniel A. Russell and Pontus Weibulla, "Tabletop thermoacoustic refrigerator for demonstrations" [*.pdf], American Association of Physics Teachers, 2002.
Steven L. Garrett, Scott Backhaus, "The Power of Sound", American Scientist, November-December 2000, Volume: 88 Number: 6 Page: 516 DOI: 10.1511/2000.6.516