A least-cost path algorithm utilizing directional graphs and shape optimization techniques for offshore wind farm cost modelling in the North and Central Aegean Sea, Greece

Least-cost paths (LCPs) delineation is an important function of raster-based Geographic Information Systems (GIS). However, the integration of multiple criteria, straightness and smoothness for an optimal path is not always fully controlled, guaranteed, and assessed. As a result, GIS-based LCP algorithms need to be further improved to consider a more accurate demonstration of real-world problems. This study focuses on different LCP implementations for Offshore Wind Farm (OWF) cost estimation and assessment, considering subsea export cables (Transmission lines) and Operation and Maintenance (O&M) path delineation and cost approximation. During the first stage, a dual-graph Dijkstra algorithm using multiple cost surfaces and controlling the straightness optimality of a path upon raster surfaces was applied. Next, line smoothing and obstacle avoidance techniques were employed using Chaikin’s corner-cutting algorithm and the Bézier curves to achieve smoother path trajectories. Finally, the lengths of the optimal paths were assessed in terms of straightness control using a novel straightness metric (Sinuosity Index). Results indicated optimized paths with mean sinuosity values ranging from 1.08 to 1.11 and a mean cost reduction of approximately 0.3% to 1.13% for the transmission paths and 0.1% to 0.44% for the O&M paths, respectively, when smoothing techniques were applied, compared to the initial Dijkstra paths. These cost reductions highlight the potential for considerable savings, making the deployment of OWFs more financially attractive by lowering both upfront investment and long-term O&M costs in preliminary studies. Finally, the resulting cost surfaces can be utilized in multiple-criteria decision-making approaches for OWF site-prospecting studies in the Aegean Sea, and the methodology itself can be replicated in various marine regions worldwide. • A multi-criteria optimization scheme for optimal least cost transmission paths and shipping routes is applied; • Customized Least-Cost Path (LCP) algorithms with dual-graph representation for controlling path straightness as an objective; • Path-smoothing techniques are introduced by applying Chaikin’s corner-cutting algorithm and Bézier curves for more realistic, cost-effective results. • Introduction of a Weighted Sinuosity Index ( WSI ) to assess path straightness and angle control, improving on traditional Dijkstra implementations; • Results indicate a mean reduction of approximately 1.8% and 6.5% for the transmission cables and O&M costs.