Valorization of brewer’s spent grains through hydrothermal carbonization

Increasing global energy demand, which is currently supplied predominantly by fossil fuel, and its associated climate impacts necessitate the search for more sustainable sources of energy. Moreover, the growing global population and coincidental food consumption will create a surplus of agricultural and food waste. Over the last few decades, valorization of these agricultural and food residues through different treatments (e.g. biological, thermal) has been intensively investigated. One technology, the production of the hydrochar, is very promising within the framework of a biorefinery concept as an alternative to solid fossil fuels like coal. Hydrochar is CO2-neutral, sustainable, and can be used as starting material for other processes such as the production of activated carbon. This study illustrates the potential of using brewer’s spent grains for high-value protein extraction and solid fuel production in the form of hydrochar. In addition, the successful recirculation of process water illustrated one method to reduce operating cost and net energy.