In the quest for sustainable solutions, a team of researchers has uncovered a promising pathway to transform brewery waste into a valuable resource, potentially revolutionizing the energy and agricultural sectors. The study, led by Federica Barontini, explores the application of hydrothermal carbonization (HTC) to convert brewer’s spent grains (BSG), the primary byproduct of beer production, into hydrochar—a versatile carbonaceous material.
Brewer’s spent grains, typically used as animal feed, have long been overlooked for their potential in sustainable valorisation. However, this research, published in the journal *Chemical Engineering Transactions* (translated to English as *Chemical Engineering Proceedings*), sheds light on the untapped possibilities of this abundant byproduct. “The HTC process offers a sustainable and efficient method to convert high-moisture BSG into hydrochar, which can be used in various applications, including energy production and soil amendment,” Barontini explains.
The study employed a Design of Experiments – Response Surface Methodology (DoE-RSM) to analyze the combined effects of process operating conditions on hydrochar yields and properties. HTC experiments were conducted at various temperatures (200–260 °C), times (30–210 min), and solid contents (5–25 wt %). The results were promising: rising temperatures and extended reaction times enhanced carbonization, reducing the H/C and O/C ratios while enriching the energy content of the hydrochar.
“Hydrochars with carbon contents up to 72 wt % and higher heating values up to 30.8 MJ/kg were obtained,” Barontini reveals. “Optimization studies identified specific HTC conditions to maximize selected properties and process yields. Processing at 215°C with 23.5 wt % solids for 30 minutes ensured maximum carbon yield, leading to a hydrochar with properties comparable to lignite.”
The potential commercial impacts of this research are significant. The energy sector, in particular, stands to benefit from the conversion of brewery waste into a valuable carbonaceous material. Hydrochar can be used as a solid fuel, offering a sustainable alternative to traditional fossil fuels. Moreover, bioassay tests confirmed the potential agricultural utility of BSG-derived hydrochar as a soil amendment, enhancing soil fertility and promoting sustainable agriculture.
This research not only aids in waste reduction but also contributes to circular economy models by transforming brewery byproducts into a valuable resource. As the world grapples with the challenges of climate change and resource depletion, innovative solutions like HTC offer a glimmer of hope. “The HTC process can assume an important role in the valorisation of BSG, aiding in waste reduction and contributing to a more sustainable future,” Barontini concludes.
The findings of this study pave the way for future developments in the field of sustainable waste management and energy production. As the world shifts towards a more circular economy, the valorisation of brewery waste through HTC could become a cornerstone of sustainable practices, benefiting both the environment and the economy.