Green Energy Sources and Their Effects on the Environment: A Critical Review of Recent Advances, Environmental Impacts, and Future Perspectives

Abstract

Background. The simultaneous escalation of energy demand and climate disruption has made the transition from fossil to green energy one of the defining scientific and policy challenges of the twenty-first century. Global energy-related carbon dioxide emissions reached an all-time high of 37.8 Gt in 2024, yet renewable power capacity additions also set successive records, with 692 GW added in 2025 to reach a cumulative 5,149 GW. Understanding whether and under what conditions  green energy delivers net environmental benefit is therefore urgent.

Objective. This review critically synthesises the recent (2022–2026) literature on the principal green energy sources  solar, wind, hydropower, biomass, geothermal, ocean, and green hydrogen, together with emerging technologies  and evaluates their full environmental footprint rather than their carbon benefits alone.

Methodology. A structured search of Scopus, Web of Science, ScienceDirect, SpringerLink, and IEEE Xplore was combined with authoritative grey literature from the IEA, IRENA, IPCC, and UNEP. Records were screened following the PRISMA 2020 framework, and a bibliometric analysis characterised publication and thematic trends across the review window.

Major findings. Across life-cycle metrics, wind and solar photovoltaics consistently emerge as the lowest-impact sources, with life-cycle carbon intensities roughly one to two orders of magnitude below those of fossil generation and energy payback times now below two years. However, every source carries non-trivial and frequently overlooked burdens  land-use and habitat change, water consumption, critical-material demand, biodiversity disturbance, and end-of-life waste  that are unevenly distributed across technologies and geographies. The review identifies persistent controversies, including the climate footprint of hydropower reservoirs, the carbon neutrality of biomass, and the material and recycling bottlenecks of the solar–storage–hydrogen value chain.

Research gaps. Key gaps include regionally disaggregated and harmonised life-cycle assessments, integrated water–energy–land nexus modelling, biodiversity-explicit impact metrics, and credible circular-economy pathways for end-of-life renewable infrastructure.

Future prospects. Realising a genuinely sustainable energy system will require co-optimising decarbonisation with biodiversity, water security, material circularity, and social equity, supported by artificial-intelligence-enabled system integration, robust storage, and policy frameworks that internalise full life-cycle externalities.

Keywords: renewable energy; environmental impact; life-cycle assessment; energy transition; sustainability; green hydrogen; decarbonisation; circular economy.