Scientists produce electricity from wood

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Published 29 November 2022 at 12.01

Domestic. Researchers at KTH have managed to extract electricity by letting water pass through treated wood. The work has just been published in the scientific journal Advanced Functional Materials.

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What happens if wood is put in water and the water then evaporates? Transpiration. This process, that liquid travels through vegetation, occurs everywhere in nature. In connection with that, small amounts of electricity are also produced, something called bioelectricity in English.

The researchers at KTH have taken note of this. But in order to increase the amount of electricity that is generated and that the researchers collect, they have improved the wood's properties through nanotechnology. Electricity production in wood is affected by several factors such as area, porosity (density), surface charge, how easily water can pass through the material and the water solution as such.

– We have compared the porous structure of ordinary wood with that material which we improved regarding surface, porosity, surface charge and water transport. We have measured an electricity production that is ten times higher than natural wood, says Yuanyuan Li, senior lecturer in the department of biocomposites at KTH, in a statement.

A further adjustment of the pH difference between wood and water has, due to the so-called ion concentration gradient, a potential of up to one volt more electrical voltage. According to the researchers, this leads to a remarkable effect of 1.35 microwatts per square centimeter.

– Currently, we can operate smaller technologies such as LED lights and calculators. If we were to supply a laptop with electricity, we would need about one square meter of wood with a thickness of one centimeter, and around two liters of water. For a normal household, we need much more than that, and more research is needed there.

Yuanyuan Li says that so far the wood has been able to deliver high voltage for around 2-3 hours, before it subsides. According to the researchers, the wood has so far managed ten cycles of water without any reduction in the material's performance.

– The big advantage of this technology is that you can use the wood for other purposes without any problems, such as transparent paper, wood-based foam and different biocomposites, when it is consumed as an energy source.