Solar and wind powered green hydrogen systems: A review

This review evaluates solar- and wind-powered green hydrogen pathways for decarbonizing energy systems, focusing on system design, electrolyser operation, storage, economics, environmental footprints, and policy alignment. A structured evidence map compiles input ranges for renewable generation, batteries, electrolysers, and storage and reconciles reported cost outcomes across case studies. Electrolyser efficiency spans 60–80%, water demand spans 9–15 L kgH₂⁻ 1 , and salt-cavern storage costs fall less than $1 kWh⁻ 1 . Hybrid photovoltaic–wind systems with battery buffering report curtailed renewable energy less than 15% in high-utilization designs. Across reviewed studies, the levelized cost of hydrogen commonly ranges from $3 to $13 kg⁻ 1 under present-day capital costs, financing, and capacity factors. Policy instruments such as tax credits, carbon contracts for difference, and concessional finance are reported to reduce costs by up to $3 kg⁻ 1 when paired with certification and procurement commitments. An integrated 2030–2040 roadmap aligns technical targets (electrolyser CAPEX 400–600 $ kW⁻ 1 , lifetime more than 80 000 h) with phased policy milestones to support a cost pathway toward less than $2.0 kg⁻ 1 by 2040 while managing land and water trade-offs. • Global hydrogen exceeds 95 Mt yearly, 96% fossil-based with 900 Mt CO₂ emissions. • PV-only systems face 30–40% curtailment, cut to less than 15% with storage. • Electrolyzers operate at 60–80% efficiency, CAPEX ranges $500–1400 kW⁻¹ . • Green hydrogen LCA shows 0.6–2.5 kg CO₂e kgH₂⁻¹ , grey reaches 12–14 kg CO₂e. • Roadmap targets $2 kgH₂⁻¹ cost, 15 GW scale, and 80% efficiency by 2040.