A comparison of the most promising low-carbon hydrogen production technologies

The energy transition to be successful requires an increasing share of renewable electricity and large amounts of low-carbon hydrogen. This paper presents a comparison of the following promising low-carbon hydrogen production technologies. Typical electrolyzer technologies, namely alkaline electrolysis (AEL), polymer electrolyte membrane electrolysis (PEMEL), and high-temperature electrolysis (HTEL), as well as methane pyrolysis systems based on thermal, plasma and catalytic decomposition along with steam methane reforming (SMR) with carbon capture utilization or storage (CCUS) are discussed and evaluated. These hydrogen technologies are then compared on the basis of assessment criteria such as the technology readiness level (TRL), scalability, levelized cost of hydrogen (LCOH), the impact of by-products and their carbon footprint. Compared to the other two lowcarbon hydrogen production technologies mentioned in this paper, methane pyrolysis performed well and was found to be a promising alternative. Using exclusively renewable electricity for the required process heat yields lower CO2 emissions than currently operating SMR-CCUS systems can achieve and shows competitive LCOH. Moreover, in the course of decarbonization and due to its inadequate CO2 capture rates, the SMR-CCS technology should serve exclusively as an interim solution to the rapid market ramp-up of the low-carbon hydrogen economy. With respect to the ambitious green hydrogen targets, it was determined that electrolysis is indispensable, but still needs to be scaled up as it currently does not produce sufficient amounts of hydrogen. Furthermore, the LCOH of methane pyrolysis was lower than the one of electrolysis using renewable electricity. Therefore, methane decomposition is considered a promising low-carbon hydrogen production technology that needs to be implemented alongside green and blue hydrogen to contribute to a successful energy transition.