A Review of Energy Pellet Production from Agricultural Waste for Reducing Fossil Fuel Consumption

Abstract

The global transition towards sustainable energy systems necessitates the exploration of renewable alternatives to fossil fuels. Agricultural waste represents a substantial yet underutilised resource for bioenergy production, with energy pellet manufacturing emerging as a promising pathway for converting these residues into standardised, high-energy-density solid fuels. This comprehensive review examines the current state of knowledge regarding energy pellet production from agricultural waste, encompassing feedstock characteristics, pelletisation technologies, pretreatment methods, quality parameters, environmental implications, and techno-economic considerations. This review was conducted through a comprehensive search of peer-reviewed literature using established academic databases, including Web of Science, Scopus, Google Scholar, and PubMed. Agricultural residues, including cereal straws, corn stover, rice husks, sugarcane bagasse, and various crop processing by-products, demonstrate considerable potential for pellet production when appropriately processed. The review critically analyses the influence of feedstock properties such as moisture content, particle size distribution, and chemical composition on pellet quality attributes including mechanical durability, bulk density, and calorific value. Advanced pretreatment technologies, particularly torrefaction and hydrothermal processing, are evaluated for their capacity to enhance pellet characteristics and combustion performance. Life cycle assessment studies indicate that agricultural waste-derived pellets can achieve substantial greenhouse gas emission reductions compared to fossil fuel alternatives, though the magnitude of these benefits depends significantly on supply chain configurations and processing methodologies. The co-firing of biomass pellets with coal in existing thermal power plants represents a pragmatic near-term strategy for emission mitigation whilst maintaining energy security. Despite promising developments, several challenges persist, including feedstock variability, seasonal availability constraints, logistical complexities, and the need for supportive policy frameworks. This review identifies research gaps and provides recommendations for advancing agricultural waste pelletisation as a viable contributor to global decarbonisation efforts.