A tool to simulate decommissioning offshore wind farms

Decommissioning is an emerging practice for the offshore wind industry. To date, the Yttre Stengrund and Vindeby Offshore Wind Farms are the only installations to have been fully dismantled. While every project requires a decommissioning plan to gain consent; they are high-level estimates of the expected strategy, time required and costs. This is due to the lack of reliable data or experience. However; if underestimated, decommissioning may result in significant and unexpected outgoings at the end of a farm lifecycle. Simulation is an effective way to test a plan is both executable and cost-effective, as well as optimising activities for an individual site. Therefore, a stochastic tool was developed to simulate a wide range of decommissioning methods, considering the impact of uncertain factors such as weather and costs on time and expenditure. It is the first detailed simulation model developed for this crucial project phase. This paper describes the scope of the model; documents the validation activities undertaken; and demonstrates the model's capabilities. It was found that while further validation against real-case scenarios is necessary, the model can indicatively forecast costs and time for a given strategy as well as optimise scenarios and mitigate risks. (paper)