Offshore conversion of wind power to gaseous fuels: Feasibility study in a depleted gas field

A proof-of-concept study is presented of a Power-to-Gas system that is located fully offshore. This paper analyses how such a system would perform if based at the depleted Kinsale Gas Field in the Celtic Sea Basin off the south coast of Ireland. An offshore wind farm is proposed as the power source for the system. Several conversion technologies are examined in detail in terms of resource efficiency, technological maturity, and platform area footprint, the aim being to ascertain their overall applicability to an offshore Power-to-Gas system. The technologies include proton exchange membrane electrolysers for electrolysis of water to release H2. Bipolar membrane electro-dialysis and electronic cation exchange module processes are also considered for the extraction of CO2 from seawater. These technologies provide the feedstock for the Sabatier process for the production of CH4 from H2 and CO2. Simulations of the end-to-end systems were carried out using Simulink, and it was found that the conversion of offshore wind power to hydrogen or methane is a technically feasible option. Hydrogen production is much closer to market viability than methane production, but production costs are too high and conversion efficiencies too low in both cases with present-day technology to be competitive with current wholesale natural gas prices.