Media release

From: Springer Nature

Generating electricity using salty ice

Salty ice can generate an electric charge 1,000 times greater than regular ice when strained, according to research published in Nature Materials. Further research could investigate how this phenomenon could enable sustainable energy generation at low temperatures where salt and ice mix, with implications for ice geologies, for example in glaciers or moons in the outer Solar System, such as Europa or Enceladus.

10% of the Earth’s surface is covered by ice, which can generate electricity upon bending, but its potential power remains untapped. This phenomenon — the ‘flexoelectric effect’ — depends on the material, and pure water ice has failed to generate a substantial enough current to power small electrical devices (with a current from pure ice of about 1-10 nanocoulombs per metre).

Xin Wen and colleagues show that by freezing salt and water together in various concentrations, the salty ice generates a flexoelectric coefficient — the relationship between a bending radius and the electric charge that's generated — that increases with salinity. More specifically, ice that was 25% salt by weight was found to reach a flexoelectric coefficient of 1-10 microcoulombs per metre, which was 1,000 times larger than ice consisting of only water, and a million times larger than salt alone. The authors hypothesized that this flexoelectric enhancement happens because saline forms around the edges of ice crystals before they fully melt. When the ice is bent, the salty water streams from the compressed side to the stretched surface, creating an electrical charge.

The authors note that further research is needed to determine how this energy generation could power electronics. However, these findings suggest that environmentally sustainable and cheap energy-harvesting and sensing devices could be implemented in cold locations. Similarly, the results may have implications for natural systems where salt ions and ice mix, such as in glaciers or outer Solar System moons.