Decommissioning of Offshore Platforms and Conversion for Renewable Energy Production

During last decades, the consciousness about fossil fuels drawbacks emphasized the necessity of radically changing the energy generation paradigm towards the development and diffusion of renewable technologies. Both the gradually depletion of fossil resources and the change in energy generation paradigm make appear really interesting the possibility to couple existing traditional infrastructures with renewable energy systems. This thesis work analyzes the possibility to convert existing offshore Oil&Gas platforms at the end of their operational life, by exploiting their substructures for renewable energy systems installation. The idea to recover and convert offshore platforms seems currently very attractive to the energy community, mainly because it allows to avoid part of the costs associated with the decommissioning phase and to exploit offshore renewable resources in several forms (wind, solar, wave motion). After an introduction chapter, the state of the art of offshore Oil&Gas decommissioning sector is discussed, analyzing the technological and economic aspects and the different approaches currently followed worldwide. After that, the wind and solar resources of all offshore Italian facilities are analyzed to evaluate their conversion potential. As a result of the renewable potential assessment, a case-study is selected and a preliminary conversion is designed, by means of the WAsP software, in order to assess the energy performance of an offshore wind farm, assuming to install the generators exploiting the existing jackets of the selected Italian platforms.