Hybrid systems design for blue and green hydrogen co-production: Integration of autothermal reforming with solid oxide electrolysis

Hydrogen is a clean and sustainable energy alternative to fossil fuels. Current hydrogen production methods are carbon intensive; hence, developing low-carbon hydrogen production methods is important. Among various production technologies, autothermal reforming (ATR) and solid oxide electrolysis (SOEC) are considered promising in terms of energy efficiency. However, there are several limitations: (i) ATR requires an air separation unit that consumes a large amount of energy, and (ii) SOEC, high-temperature steam electrolysis requires an electric resistance heater. To address these limitations, this study proposes a hybrid system of ATR integrated with SOEC. In the hybrid system, waste steam and heat in the ATR process are provided for the SOEC process, whereas the oxygen by-product in the SOEC process is supplied to the ATR process. In particular, the hybrid system where SOEC-generated oxygen completely satisfies the ATR reaction's oxygen demand exhibits the best thermodynamic and economic performance. This system represents a 28.6% reduction in power consumption compared to a stand-alone system that independently produces blue and green hydrogen. In addition, it exhibits enhanced economic performance with a levelized cost of hydrogen of 5.28 $/kg, which is 1.22 $/kg lower than that of the stand-alone system.