Abstract
To address climate change and energy security issues associated with fossil fuels, new power generation methods such as renewable energy sources as a sustainable alternative for electricity generation are introduced. One of the most available and environmentally friendly renewable energy sources is wind power. Wind energy is expected to grow ninefold by 2050, accounting for 11% of total primary energy consumption worldwide. Within the domain of wind energy, offshore wind energy appears to be the most promising in the years ahead due to higher and steadier wind speeds in open seas. However, despite producing clean electricity during operation, offshore wind turbines have environmental impacts throughout upstream and downstream life cycle stages such as manufacturing, installation, and decommissioning. Offshore wind technology's environmental impact and energy performance can be measured, and the most commonly used assessment method is life cycle assessment (LCA). Nevertheless, after performing a scoping literature review method, it was observed that comprehensive assessments of the environmental impacts of different offshore wind technologies are limited. This study aims to bridge this gap by conducting a comprehensive cradle-to-grave LCA of two real case scenarios: floating (FOWF) and bottom fixed offshore wind farms (BFOWF), specifically Hywind Tampen and Dogger Bank. It encompasses all stages from manufacturing, transportation, installation, operation, and maintenance (O&M), and decommissioning. The methodology employed utilizes openLCA® software and ecoinvent 3.9 databases, with the ReCiPe 2016 v1.03 midpoint (H) impact assessment method. Key findings indicate that the environmental impact of Hywind Tampen FOWF is higher compared to Dogger Bank BFOWF, with sensitivity analysis revealing significant influences of capacity factor and lifetime of the wind farm. Among the life cycle stages analyzed, manufacturing emerges as the primary contributor to total emissions, with the O&M stage following closely behind. Consequently, this study underscores the critical need for the implementation of more sustainable manufacturing methods. One solution could be designing turbines with greater generation capacity to minimize material usage. Maintaining material usage at current levels for larger wind turbines could result in a significant decrease in emissions. Finally, the reliability of wind turbines needs to increase to reduce the share of O&M. Having said that this study also compares the emissions from the two studied offshore wind farms with other renewable and non-renewable energy sources, and although there are some environmental impacts associated with the offshore wind farms, they still could be one of the best alternatives for fossil fuels and some other renewable energy sources.