Repurposing of Offshore Oil and Gas Cables for Renewable Generation: Feasibility and Conceptual Qualification

Wind farms are expected to be deployed in the North Sea in increasing numbers and at ever greater distances from land, over the coming decades. Many nearby oil and gas fields have reached or are near the end of their lifespans, and their operators are eager to explore innovative ways to reduce decommissioning costs. One possibility would be to repurpose some of their infrastructures for use by wind farms, which would both delay decommissioning and reduce the wind farm capital costs. This paper investigates the potential for repurposing existing submarine power cores in decommissioned oil and gas fields as transmission cables for offshore renewables. Offshore power cables generally have longer lifetimes than are needed to deplete hydrocarbon reservoirs. Cable transmission capacity could be too low to provide the main connection to wind farms, but there is scope to increase capacity or use cables as auxiliary connections. A qualification methodology is proposed to assess whether existing cables might be usefully repurposed. Repurposing cables has an impact on renewable project capital expenditure (CAPEX) and levelised cost of energy (LCOE), it also positively affects decommissioning cost and the environment. The qualification methodology provides a cost-effective initial appraisal prior to field testing.