Techno-economic analysis of current and emerging electrolysis technologies for green hydrogen production

Power-to-X technologies will play a key role in the future energy market, converting renewable electricity to chemicals. The first step in most Power-to-X schemes is the production of hydrogen. Several electrolysis technologies capable of producing hydrogen by water/steam splitting are currently available, each characterized by specific advantages and drawbacks and more are under development. This work presents a techno-economic analysis of green hydrogen production via alkaline electrolysis and solid oxide electrolysis technologies. Their current state of development and anticipated improvements are also considered; an alkaline electrolyzer operating at high pressure and temperature and a solid oxide electrolyzer operating at high pressure. The projected costs of electrolytic hydrogen via the different routes are compared to the cost of hydrogen derived from natural gas with and without CO₂ capture. Threshold CO₂ taxes needed for different electrolysis technologies to be cost-competitive are derived as a function of natural gas price and levelized cost of electricity. With the projected capital expenditure for solid oxide electrolyzers, reducing the levelized cost of electricity from 60 to 30 €/MWh would decrease the cost of hydrogen from 3.2 to 1.9 €/kg by 2050. With today’s capital expenditure, natural gas price of 30 €/MWh and electricity price of 30 €/MWh, a CO₂ tax of 90 €/tCO2 would make electrolytic hydrogen from alkaline electrolyzers cheaper than hydrogen derived from natural gas. It was found that feeding free steam increases the efficiency of the low-pressure solid oxide electrolyzer from 79 to 94%.