Valorising agricultural waste and by-products for renewable energy: Sustainable technologies and pathways

Technological and industrial development, coupled with global population growth, has led to a rising demand for energy and resources, accompanied by uncontrolled waste production and increasingly severe environmental degradation. The agro-food sector contributes significantly to this issue, generating large amounts of liquid, solid, and gaseous waste, which contain high levels of organic material. Improper management of these wastes exacerbated environmental problems, facilitating the spread of contaminants in soil, air and water. Furthermore, greenhouse gas emissions from agricultural activity contribute to climate change. In alignment with the sustainability goals outlined in the 2015 Paris Agreement, this research aimed to explore ecological and sustainable approaches for managing agricultural waste and agro-industrial by-product. In this paper, a comprehensive literature review is presented. The primary objective of this study was to highlight and discuss the viability of different technologies for the processing of agricultural by-products and waste into valuable products, such as bioenergy, fertilizers or soil improvers. This review encompassed a wide range of technologies, including emerging and innovative methodologies, evaluating their sustainability based on environmental, economic, and social impacts. By synthesizing the latest research and advancements in the field, the review identified critical gaps requiring further investigation and proposed pathways for advancing and implementing these technologies. This was highlighted as an essential step toward the implementation of a circular economy model, where resources are continuously reused and repurposed, contributing to both environmental protection and sustainable development.