SCORE: Stove for Cooking, Refrigeration, and Electricity

BrianWangInformation about an interesting approach to small scale heat and electricity co-generation comes from a NextBigFuture posting. This thermo-acoustic device can burn any carbonaceous fuel -- even dried cow dung -- to produce the heat, which is converted to electricity via a linear generator.

BrianWang

* Target of 100-150 Watts electrical thermo-acoustic generator (stove, fridge, electricity) for £20 in 1 million quantities with half the wood and no smoke
* weight: 10-20kg
* 1.6 kWth for cooking and 0.75 kWth for simmering.
- Fuel: consumption 1 kg/hour, wood, dung and other bio-mass.
* fuel is placed inside the stove and burned. The fire heats compressed air that has been pumped into specially shaped pipes located inside the stove's chimney and behind the stove. The heated air begins to vibrate and produce sound waves. Inside the pipes, the noise is 100 times louder than a jet taking off. But because the pipes are stiff and do no vibrate, the sound waves have nowhere to go. So outside the pipe, people hear only a faint hum.

* The sound waves vibrate a diaphragm located at the end of the pipe. The diaphragm is attached to a coil of metal wires that sit inside a magnet. As the wire coil vibrates — about 50 times per second — it generates an electrical current, which is captured by wires and converted to the proper voltage.
* The stove has electrical sockets, where the homeowner can plug in, for example, a mobile phone for charging. Or she can sell the electricity as a phone-charging service.
* For refrigeration, the heated, compressed air is sent through a different part of the pipe, where sound waves cause the air to expand. As it expands, it cools to a temperature that can produce ice. It takes about two hours of stove use to produce enough ice that will keep the fridge cold for 24 hours. But homeowners have the option of producing more ice to sell for income. _NextBigFuture

Research innovation:
- Research into the combination of the thermo-acoustic engine, linear alternator and cool
box in a single device, powered by a biomass stove.
- Design of a rugged and inexpensive linear alternator that could be easily mass-produced.
- Overall system design from the view point of low cost, application of indigenous materials,
use of local manufacturing skills and simplicity of assembly, which are major research issues
compared to the current high-cost and thermo-acoustic systems.
Standing wave thermo-acoustic engine:
- Fractional wave length design.
- Combustor: wood burning, high efficiency, low emissions and used for cooking.
- Hot heat exchanger (1): 500 C gas temperature.
- Stack: heats and cools gas packets.
- Ambient Heat Exchanger (2): water cooled, also used for cooking. _SCORE.UK_PDF

This is one of many attempts to provide efficient cooking, heating, refrigeration, and small-scale power to the third world. Besides the need for clean water, inexpensive shelter, and abundant, nutritious food, the third world most needs practical sources of cooking fuel, refrigeration, and small power. Inexpensive, practical level medical and dental care would also score high on the list.

The challenge for the advanced world is to not allow itself to turn into the impoverished third world before it is able to solve the most pressing problems of the third world.