CHRISTMAS LIGHTS ARE INCIPIENT:

The concept is called hydrovoltaic energy. "A big issue with hydrovoltaic energy harvesting from organic materials is the extremely low power output which it is difficult to power practical devices," says Jonas Garemark, a doctoral student and co-author of the work published in Advanced Functional Materials. "In our work, we can reach microwatts per square centimeter, which provides useful power outputs."

Natural wood contains long, empty channels called lumen that conduct water. These channels can be micrometers to millimeters wide. There has been a lot of research on nanoengineering wood to change its chemical makeup and nanostructure, which impart unique properties such as elasticity,  pliability and transparency. But, says Garemark, "no one has so far attempted to utilize the empty spaces within natural wood.

 

The KTH researchers decided to fill these voids with even smaller porous structures. The thought was that this would speed up the flow of water through the structure and increase the effective surface area between water and wood.

Making the efficient wood-based generator involved a one-step chemical treatment. The researchers immersed a piece of balsa wood in a water-sodium hydroxide solution for 48 hours at -6°C. This causes the cell walls in wood to partly break apart, causing a dense jumble of tiny cellulose fibers to collect in the lumen.

The dense network of fibers creates many smaller pores, which boosts water uptake and surface area charge, just as the researchers predicted. Their measurements showed that the modified wood produced 10 times more electricity than natural wood when soaked in pure water.

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