Offshore wind farms decommissioning. A simulation-based study of the impact of the vessel characteristics in the decommissioning process

The offshore windmills have a lifespan of 20-25 years, owing to that, a significant amount of wind farms will be decommissioned over the next years. The decommissioning of offshore wind farms has still an important lack of knowledge on the decommissioning time and costs. The vessels play a major role in the decommissioning process being used to carry the dismantling operations as well as the transportation. Therefore, in this research a simulation model has been developed to analyse the impact that the vessels characteristics, have on the time and cost following a quantitative model based research methodology. To simulate the weather conditions a Markovian model with weather windows and weather persistence has been implemented. It has been found that the loading capacity has a relevant trade off with the decommissioning time and costs being able to decrease the time in more than a 22%. A sensitivity analysis conducted, has revealed the different wind farm factors that have an influence on the vessel selection, as well as the optimal loading capacity and number of vessels for two different cases