Green hydrogen electrolyzer and hydrogen-methane CCGT power plant in NEOM City

Abstract

The Royal Society recently highlighted the huge energy storage needs for the United Kingdom to make stable a grid only fed by solar and wind energy, which must come mostly from hydrogen energy storage. Similar results are obtained for NEOM City modeling the operation of a 50/50 wind and solar energy production, adopting an efficiency for green hydrogen production of 0.75, and an efficiency for power generation from the hydrogen of 0.55. The analysis for NEOM City suggests that with an evenly distributed combined wind and solar generating capacity of 30 GW, a dispatchable annual energy contribution of 60 TWh to the grid is attainable. This presupposes the availability of hydrogen energy storage amounting to no less than 8 TWh and electrolyzers with a power capacity of 22 GW. Ideally, the hydrogen power generation facility should have a nominal power of 13.5 GW. Integrating an intermediate high-efficiency energy storage system, such as flow batteries, between wind and solar generators and electrolyzers can significantly cut the power of the electrolyzers by up to 80 %. A high-efficiency combined cycle gas turbine power plant is then proposed to feed back the grid burning a mixture of green hydrogen and natural gas. By using an almost off-the-shelf technology, gradually shifting towards higher hydrogen contents as green hydrogen becomes more readily available, this solution delivers the lowest possible life cycle CO2 emission at any time during the progress of the project.