As the world adds solar and wind energy capacity at an unprecedented scale, we are increasingly faced with an energy variability crisis. Solar panels only produce energy when the sun is shining, and wind turbines when the wind is blowing. Unfortunately, energy demand curves are often directly at odds with these production trends. This creates a major dilemma for the energy grid, as well as for energy markets. And market volatility, including record-breaking negative energy prices in places where renewables have been deployed at a massive scale, can scare off investors, thereby threatening the future of clean energy adoption when it’s never been more urgently needed.

The obvious solution to this problem is the massive expansion of grid-scale energy storage and the development of cost-effective and scalable long-term energy storage solutions. Scientists around the world are currently hard at work doing just this – but many researchers are also looking into new and novel forms of clean energy production that can produce around-the-clock, avoiding the variability issue altogether. 

Some of these solutions are so out-of-the-box and innovative that they sound ripped from the pages of science fiction, from “reverse solar panels” that create energy at night after capturing heat during the day, “anti-solar panels” that can create light from darkness, and sending solar panels to space, where the sun never sets. 

But those all sound relatively plausible compared to new findings out of China. Just last month, a team of researchers based in Yunnan published a study revealing that it has made a new form of solar energy system that can create energy even in darkness. And, craziest of all, it’s made of wood. “Our work presents a scalable and environmentally friendly wood-based platform for advanced solar thermal energy harvesting,” the researchers wrote in their paper, published in the scientific journal Advanced Energy Materials. 

Raw wood reflects sunlight and absorbs water, qualities which can be harnessed to create a kind of solar cell. Balsa wood, in particular, has the potential to work in a solar energy system due to its natural formation. The research team found that, thanks to its natural structure full of aligned microtubes, balsa wood is excellent for guiding heat and holding onto materials like a ‘natural scaffold.’ 

However, the wood is not useful for energy applications in its natural state. In essence, the method works by “rebuilding wood from the inside out,” as explained by Interesting Engineering. First, the natural lignin, which gives the wood its color and rigidity, must be removed to make the material extra porous, essentially turning the wood into a sponge. Then, all those internal channels are coated with black phosphorene, “a material that absorbs sunlight across ultraviolet, visible, and infrared wavelengths and converts it into heat.” Finally, those channels are filled with stearic acid, which melts and stores energy when heated. 

This, among other methodological details, is what makes the material useful as a component of a solar energy system. When sunlight hits the material, it heats up and melts the acid inside, which is then released gradually, meaning that the material continues to produce energy in the form of heat long after the source of sunlight is gone. “As a proof of concept, stable solar–thermal–electric conversion is demonstrated with an output voltage of up to 0.65 V under one-sun irradiation,” the paper went on to detail. 

“This work suggests a simple way to build a highly efficient solar system,” reports Interesting Engineering. “If successful, it could be adapted to other nanomaterials and biomass structures, giving rise to a new generation of solar power systems capable of capturing, storing, and managing energy on their own.”

By Haley Zaremba for Oilprice.com

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