Biogas Plants in the Sustainable Energy Transition: Environmental Performance, Public Health Implications and Socio-Economic Trade-Offs

Biogas plants can support decarbonisation, organic waste management and local energy security. Their contribution to a sustainable transition, however, cannot be judged by biogas production alone. The aim of this work was to assess biogas systems across the full value chain, from feedstock sourcing and transport through anaerobic digestion (AD) to energy use, emission control and digestate management. A narrative review was conducted using Scopus, Web of Science Core Collection and ScienceDirect. Google Scholar was used for supplementary searches, while additional information was obtained from institutional sources. The final evidence base comprised 182 references. Because the studies differed in plant type, methods, system boundaries and reported outcomes, the literature was synthesised thematically. The novelty of the review lies in integrating environmental performance, public and occupational health, and economic and social conditions within a single full-chain assessment, while examining whether benefits in one area create costs or risks elsewhere. The reviewed evidence indicates that waste- and residue-based systems can provide substantial benefits when methane losses are controlled, energy is used effectively and digestate is managed safely. Health assessment must distinguish potential hazards from actual exposure and confirmed health effects. Economic viability and social value, in turn, depend on financial conditions, local value retention and the distribution of benefits and burdens. A two-step integrated assessment framework is proposed, with minimum environmental, health and safety conditions assessed before broader sustainability performance and trade-offs are considered. Biogas sustainability is therefore best demonstrated by verified whole-system performance rather than by gas production or profitability alone.