Advancing SDG-7 for affordable and clean energy: decentralized energy access pathways, policy–finance barriers, and AI-enabled transition strategies

Sustainable Development Goal 7 (SDG-7) seeks universal access to affordable, reliable, and modern energy by 2030, yet progress remains uneven and structurally constrained. Despite declining renewable energy costs, around 685 million people lack electricity and more than 2 billion depend on traditional biomass for cooking. This review moves beyond descriptive assessments by providing a systematic, decision-oriented synthesis of SDG-7 pathways. Using a replicable PRISMA-informed protocol, it integrates peer-reviewed studies and authoritative international datasets published between 2015 and 2025. Centralized, decentralized, and hybrid energy systems are evaluated in terms of technical maturity, affordability, governance feasibility, and socio-environmental impacts. A structured barrier-to-intervention framework identifies context-specific challenges, including intermittency, financing risk, institutional capacity, infrastructure gaps, and climatic and geopolitical exposure, alongside viable technological and policy responses. Comparative case studies from India, Sub-Saharan Africa, Southeast Asia, and Latin America explain divergent outcomes of similar technologies across institutional and market contexts, and development pathways globally.