The search for abundant, inexpensive materials for energy storage applications can drive engineers to drink. In the case of researchers from Friedrich Schiller University Jena (Germany), Basque Research and Technology Alliance (Spain) and Basque Foundation for Science (Spain), this quest might be quenched by the exploitation of a brewery waste product for capacitor electrode design.

Carbonaceous materials suitable for such use were produced from brewer's spent grains (BSG). After drying the material at 80° C for 48 hours, BSG samples were ground to sizes in the 0.2 mm to 4 mm and analyzed, revealing a lignin content between 35% to 45%, cellulose and hemicellulose of 40% to 50%, and 5% of ash content.

Activated carbon and hard carbon electrodes prepared from the processed BSG were tested in electrical double layer capacitors (EDLCs) and lithium-ion capacitors. As reported in Electrochimica Acta, a high capacitance retention and specific capacitance 46 Farads/g was documented for the EDLCs, while the lithium-ion units demonstrated very high energy and power densities and 85% capacitance retention after 200 hours of float testing.

An additional application for BSG has previously been demonstrated by researchers Queen's University Belfast, Ireland: the material was used to synthesize activated carbon and carbon nanotubes for use in water remediation.