Influence of grain size on the energy properties of briquettes made from grape stalks: a sustainable approach for Brazilian viticulture

Abstract

This study proposes a sustainable approach to meeting growing global energy demands, which are mainly made up of fossil fuels. In this context, grape stalks, an abundant waste product from viticulture, have emerged as a promising alternative for generating bioenergy. Initially, the chemical properties of the raw material were determined, such as the content of total extractives and holocellulose. Subsequently, briquettes were produced in a laboratory briquetting machine with four different grain sizes (2, 3, 5 and 8 mm). The energy quality of the briquettes produced and the impact of particle size on their physical and mechanical properties were evaluated. Detailed analyses of the briquettes' physical and mechanical properties, including bulk, apparent and energy density, compressive strength and volumetric expansion was realized. The size of the grape pomace particles had a significant influence on the physical, mechanical and energy properties of the briquettes. Remarkably, the smallest grain size (2 mm) provided more effective material accommodation, resulting in higher strength and density. The results achieved in terms of physical and mechanical properties show that briquettes made from residual biomass from viticulture emerge as compacted materials of high energy quality. Furthermore, this study goes beyond the technical dimension by presenting itself as a proposal that can be adapted to other production chains in which lignocellulosic waste is still little used. By integrating technological innovation, environmental sustainability and socio-economic inclusion, the research outlines a viable strategy towards carbon neutrality, especially in areas with an agricultural vocation, thus contributing to the goals of sustainable development.