Cost-Benefit Analysis (CBA) for offshore grids evaluates the economic viability of interconnected offshore transmission systems that support large-scale renewable energy, particularly offshore wind. The methodology compares total lifecycle costs—including seabed cables, substations, installation, operation and maintenance, and environmental impacts—against system-wide benefits. Key benefits include reduced generation costs through resource optimization, improved cross-border electricity trade, enhanced security of supply, and lower emissions. The analysis adopts a long-term horizon (often 30–50 years) and applies discounting to estimate Net Present Value, Economic Internal Rate of Return, and Benefit-Cost Ratio. It incorporates market and welfare impacts, such as price convergence and congestion reduction. Scenario and sensitivity analyses address uncertainties in demand, technology costs, and policy frameworks. Projects are considered viable if overall socio-economic benefits outweigh costs and meet defined economic thresholds.
