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Scientists harvest electricity from wood soaking in water

According to a new study led by the KTH Royal Institute of Technology in Sweden, wood and water may be one day all that is needed to provide enough electrical power for a household. By focusing on what naturally happens after wood is placed in water and the water evaporates – a process known as “transpiration,” in which water moves through a plant – the experts found that small amounts of electricity can be produced.

The scientists discovered that, with some nanoengineering of wood, together with pH tuning, small but promising amounts of electricity can now be harvested.

“At the moment we can run small devices such as an LED lamp or a calculator,” said study senior author Yuanyuan Li, an expert in Biocomposites at KTH. “If we wanted to power a laptop, we would need about one square meter of wood about one centimeter thick, and about two liters of water. For a normal household we’d need far more material and water than that, so more research is needed.”

By modifying the nanoscale composition of wood, the scientists improved its properties in terms of surface area, surface charge, porosity, how easily water can pass through the material, and the water solution itself – all of which are crucial factors influencing electricity generation in wood.

“We compared the porous structure in regular wood with the material we improved with regard to surface, porosity, surface charge, and water transportation. Our measurements showed electricity generation that’s 10 times higher than with natural wood,” Li explained.

Moreover, the scientists found that further tuning the pH difference between wood and water – due to an ion concentration gradient – can achieve a potential of up to one volt and a remarkable power output of 1.35 microwatts per square centimeter. Until now, the wood has managed to deliver high voltage for approximately two to three hours, before beginning to wane.

“The great advantage of this technology is that the wood can readily be used for other purposes once it’s depleted as an energy source, such as transparent paper, wood-based foam, and different biocomposites,” Li concluded.

The study is published in the journal Advanced Functional Materials.


By Andrei Ionescu, Staff Writer

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