The carbon LCA included detailed assessment of the manufacture, fabrication and installation process for mooring system components. The study found that steel chain is currently the most commonly used mooring line component with the greatest associated carbon emissions. It was found that steel chain accounts for 88% of the carbon emissions in a typical 3-line catenary mooring system using drag embedment anchors. The main contributors to the carbon emissions of steel mooring chain suitable for FOW were found to be the manufacturing processes and transportation emissions.
Despite having relatively high manufacturing carbon emissions per unit mass, synthetic rope was found to have significantly lower carbon emissions when used in the mooring system compared to steel chain, due to the reduction in mooring line material mass required. The additional ancillary equipment required in taut and semi-taut mooring configurations add their own carbon emissions to the system, but enable greater emission savings in the system as a whole. The potential use of more novel anchors and ancillaries have been identified as areas that could offer significant reductions in carbon emissions. Using technologies such as LRDs can allow the length of mooring line to be shorter or the steel chain diameter to be reduced, therefore resulting in a decrease in material and emissions.
The development and commercialisation of mooring solutions using synthetic rope and enabling ancillaries has been identified as a key opportunity to reduce mooring system carbon emissions. Other opportunities in mooring system design to reduce carbon emissions include reduction in ground chain diameter development of novel anchor solutions and standardisation of components. Opportunities for carbon emission reduction were also identified within life cycle processes, such as raw material production for mooring system components. Carbon emissions produced by the manufacture of steel mooring components can be reduced using clean electricity and a green heat source.
The recycling of steel presents the opportunity to reduce carbon emissions from raw material extraction, however current recycling processes and facilities are not capable of recycling steel at this scale in an energy efficient manner. Manufacturing processes for synthetic rope are novel in comparison to steel, and the opportunity for carbon reduction should be explored through the use of bio-based synthetics and through the recycling and reuse of materials.
While raw material and manufacture has been found to be the greatest contributor to mooring system life cycle carbon emissions, further assessment of O&M and end of life considerations in the LCA should be investigated as FOW development in the Celtic Sea reaches commercial maturity. From the findings of the carbon LCA study performed, and the carbon reduction opportunities discussed, mooring system carbon reduction opportunities for the Cornwall area are identified to support the development of commercial FOW in the Celtic Sea.
The Celtic Sea, Floating Wind and Hydrogen
