Life cycle carbon footprint accounting of an offshore wind farm in Southeast China—Simplified models and carbon benchmarks for typhoons

Abstract

Offshore wind farms are fast-spreading off the southeast coast of China to achieve carbon neutrality by 2060. However, unfavorable weather conditions in Southeast China (e.g. frequent typhoons and severe wind intermittency) may increase the carbon footprint of offshore wind energy. But typhoons have never been considered in carbon accounting before, which may affect the design decisions of stakeholders and research priority setting for academicians. (i) To determine the effect of typhoons on carbon footprint, a life cycle assessment was performed on a typical offshore wind farm using real data. The results demonstrate that typhoons can be the largest contributor to carbon footprint, and the maximum wind speed of typhoons is the most critical parameter to carbon footprint. (ii) To quantify the carbon emissions caused by typhoons, simplified models estimating carbon emission intensity under different maximum wind speeds of typhoons are established, using Monte Carlo method based on 51 historical typhoons. The models imply that wind turbines with Permanent Magnet Synchronous Generator (PMSG) are highly recommended in typhoon-prone area, because their carbon footprint is smaller than those with Doubly-Fed Induction Generator (DFIG). (iii) To set carbon benchmarks for typhoons, statistic analysis was conducted based on the simulated samples generated by Monte Carlo method. The carbon benchmarks of typhoons show that gearbox has the highest carbon emission intensity (mean=4.35g/kW, 95th percentile=7.00g/kW) among all components, resulting DFIG with gearbox not suitable in typhoon-areas. The site selection of offshore wind farms in Southeast China should avoid areas where the maximum wind speed of typhoons exceeds 44.5 m/s. This study emphasizes the importance of typhoons in carbon footprint accounting for offshore wind farms in Southeast China. More significantly, the proposed simplified models and carbon benchmarks of typhoons can be applied to feasibility studies in early design stage for engineers and stakeholders.