Technoeconomic analysis of offshore green hydrogen production re-using oil and gas infrastructure

Abstract

With more industries realising the decarbonisation potential of green hydrogen, and more countries introducing their future hydrogen strategies, large scale hydrogen production will soon become a number one priority to meet growing hydrogen demand. For this reason, offshore wind farms are being proposed for large scale hydrogen production.

There are two routes to transfer energy generated by offshore wind farms to shore. A more conventional way through cables in the form of electricity, and a more novel route, by building new or re-using existing gas pipelines to transfer renewable electricity in the form of green hydrogen. This work compares the two approaches for energy transfer and provides a technoeconomic assessment of a large scale offshore green hydrogen production for non-grid connected wind farms. With over 6000km of existing oil and gas pipelines in the UK continental shelf of the North Sea to be decommissioned in the next 10 years, the methodology developed within this work has been applied to a case study in the Northern part of the North Sea.

The methodology firstly identifies and maps areas of interest that match offshore renewable resource and oil and gas infrastructure. Once the area has been identified, the wind resource can be assessed in this area and the energy yield determined for a particular floating wind farm size. The volume of green hydrogen that can be produced from the floating wind farm can then be determined and consequently the requirements for the hydrogen pipeline infrastructure can be calculated. The final stage in the methodology is to conduct a techno-economic assessment to allow realistic and informed decisions to be made regarding the use of hydrogen as an energy vector at the chosen location.

This work demonstrates that it is possible to re-use oil and gas pipelines from a thermo-hydraulic perspective even without requiring the use of a compressor on the platform. However, substantial summer and winter hydrogen production differences cause efficiency issues, leading to significant storage requirements. It also shows that building new pipelines to shore only adds 2% to LCOH and might be preferred from pipeline integrity perspective. It was established that using pipelines is cheaper than using cables in low and central cost scenarios, when the cost for building a new topside is not included.

The methodology presented within can be applied to any future large scale non-grid connected windfarms enabling countries to reach their 2050 net zero goals.