Low-carbon and cost-efficient hydrogen optimisation through a grid-connected electrolyser: The case of GreenLab skive

Abstract

Power-to-X technologies are a promising means to achieve Denmark's carbon emission reduction targets. Water electrolysis can potentially generate carbon-neutral fuels if powered with renewable electricity. However, the high variability of renewable sources threatens the Power-to-X plant's cost-efficiency, instead favouring high and constant operation rates. Therefore, a diversified electricity supply is often an option to maximise the load factor of the Power-to-X systems. This paper analyses the impact of using different power sources on the cost of production and the carbon intensity of hydrogen produced by a Power-to-X system. GreenLab Skive, the world's first industrial facility with Power-to-X integrated into an industrial symbiosis network, has been used as a case study. Results show that the wind/PV/grid-connected electrolyser for hydrogen and electricity production can reduce operational costs and emissions, saving 30.6 × 107 kgCO2 and having a Net Present Value twice higher than a grid-connected electrolyser. In addition, the carbon emission coefficient for this configuration is 3.5 × 10−2 kgH2/kgCO2 against 7.0 gH2/gCO2 produced by Steam Methane Reforming. A sensitivity analysis detects the optimal capacity ratio between the renewables and the electrolyser. A plateau is reached for carbon emission performances, suggesting a wind/grid-connected electrolyser setup with a wind farm three times the size of the electrolyser. Results demonstrate that hydrogen cost is not competitive yet with the electricity, suggesting an investment cost reduction but can be competitive with the current hydrogen price if the wind capacity is less than three times the electrolyser capacity.