New alloy turns waste heat into electricity, say US engineers

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Researchers in the US have demonstrated that a new alloy can be used to convert heat directly into electricity.

The energy conversion method is in the early stages of development, but it could potentially be used to create environmentally friendly electricity from waste heat sources.

Professor Richard James and his team from the University of Minnesota say that the new “multiferroic” alloy - which combines nickel, cobalt, manganese and tin - undergoes a reversible transformation from a nonmagnetic structural form to a magnetic one when its temperature is raised by a small amount.

When the material goes from a solid nonmagnetic “martensite” phase to a strongly ferromagnetic solid “austenite” phase, it absorbs heat and can spontaneously produce electricity in a surrounding coil.

The researchers claim waste heat from a car’s exhaust could be used to heat the material and produce electricity for charging the battery in a hybrid car.

The team is working with University of Minnesota chemical engineering and materials science professor Christopher Leighton to create a thin film of the material that could be used, for example, to convert some of the waste heat from computers into electricity.

Other possible uses include capturing rejected heat from industrial and power plants or exploiting the temperature differences in the ocean to create electricity.

The research team is looking into possible commercialisation of the technology.