Peanut Shell Waste Could Become a New Source of Graphene, and the Production Method Looks Surprisingly Practical

Researchers in Australia say discarded peanut shells could be turned into high-quality graphene-like carbon, offering a potential new use for a major stream of agricultural waste.

The team estimates global peanut production generates more than 10 million tons of shells each year, much of it currently sent to low-value recycling or disposal.

Graphene is prized for being exceptionally strong, light and conductive, but producing it at scale can be costly and energy intensive. That challenge has fueled a search for cheaper carbon sources and simpler manufacturing routes that could support broader use in electronics, energy storage and industrial materials.

How flash heating does the work?

The approach, led by engineers at the University of New South Wales, relies on a process known as flash Joule heating. It uses a brief electrical pulse to heat prepared biomass to temperatures above 3 000 °C for milliseconds, rapidly reorganizing carbon atoms into graphitic structures.

In this study, the crucial step came before the flash: the shells were pretreated to remove impurities and convert them into a more conductive char. The researchers report the staged pretreatment reduced defects and helped form few-layer, turbostratic graphene rather than more disordered carbon.

Why lignin makes shells useful?

Peanut shells contain lignin, a carbon-rich polymer common in plants, which can serve as a strong precursor for graphitic materials when handled correctly. The work suggests that controlling the precursor’s cleanliness and conductivity can be as important as the high-temperature step itself.

While similar peanut-shell experiments have been reported previously, the authors say their preparation method improves the consistency and quality of the resulting material. They add that the process avoids chemical additives, a factor that could reduce environmental impacts compared with some conventional routes.

What comes next for scaling?

The team cautions the material is typically not a perfect single-atom sheet, but a small stack of graphene layers with beneficial properties. They also estimate it could take 3 to 4 years to scale the technique beyond the lab, depending on engineering and cost hurdles.

Next, the researchers plan to test whether the same pretreatment and flash heating strategy can work with other biomass, including coffee grounds and banana peels. If successful, it could broaden the range of waste materials that can be upgraded into valuable carbon products.

The findings were published in Chemical Engineering Journal Advances.