Supercapacitors are commonly used in solar panels to rapidly capture the generated energy so that it can then be stored. However, the material they use, activated carbon, is unsustainable and expensive. Biochar, on the other hand, represents a cheap, green alternative. It is the byproduct of the pyrolysis process used to produce biofuels, and as the use of biofuels increases so will biochar production.

The Stevens Institute of Technology Chemical Engineering Senior Design team of Rachel Kenion, Liana Vaccari, and Katie Van Strander designed, fabricated, and tested biochar electrodes for supercapacitors. The group is advised by Dr. Woo Lee, the George Meade Bond Professor of Chemical Engineering and Materials Science.

The team was able to demonstrate biochar's feasibility as an alternative to activated carbon for electrodes. "While the team's findings are preliminary, the approach taken by us represents a small, but potentially very important step in realizing sustainable energy future over the next few decades," says Dr. Lee.

The supply of biochar comes from goldenrod, and through an IP-protected process, most organics, metals, and other impurities are removed. “It is a more sustainable method of production than activated carbon," Vaccari says. Another significant advantage is that biochar is nontoxic and won’t pollute the soil when disposed. The team estimates that biochar costs almost half as much as activated carbon, and is more sustainable because it reuses the waste from biofuel production.

"Using this technology, we can reduce the cost of manufacturing supercapacitors by lowering the cost of the electrodes," Van Strander says. "Our goal is eventually to manufacture these electrodes and sell them to a company that already makes supercapacitors."

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