Sustainable hydrogen production via carbon black: Direct carbon fuel cell application for turquoise hydrogen

• A novel process integrating turquoise hydrogen, DCFC, and SOEC is proposed. • Strategies for using carbon black by-product from turquoise hydrogen are outlined. • An economic feasibility study for DCFC is presented for the first time. • DCFC achieves price competitiveness with gray hydrogen below $1,200/kW. • Resulting greenhouse gas emissions are 48.6% below the green hydrogen threshold. If the large-scale commercialization of turquoise hydrogen progresses, the market value of carbon black is likely to decline due to oversupply. Therefore, it is necessary to explore strategies for the efficient utilization of carbon black. This study proposes a novel hydrogen production strategy by integrating turquoise hydrogen, the direct carbon fuel cell (DCFC), and the solid oxide electrolysis cell (SOEC) to enhance both economic feasibility and environmental sustainability. The integrated process utilizes carbon black as a fuel for DCFC, and the electricity generated by the DCFC is then supplied to an SOEC to maximize hydrogen production. This study conducts a comprehensive analysis using various methodologies. The analysis results indicate that the proposed integration not only enhances hydrogen production by 78% but also achieves a 48.6% reduction in greenhouse gas emissions. The energy analysis reveals the overall energy efficiency of 64.54 %. Techno-economic analysis indicates that the proposed process can achieve economic competitiveness with gray hydrogen if the DCFC cost is reduced below $1,200/kW, and with blue hydrogen if the cost falls below $1,800/kW. An uncertainty analysis shows a 54.8% and 75.9% probability of being cost-competitive with gray and blue hydrogen, respectively, while the probability of falling within the cost range of green hydrogen is only a 4.2%. These findings serve as a guideline for addressing market uncertainties associated with carbon black while emphasizing the significance of DCFC costs. Furthermore, the proposed process is presented as a sustainable hydrogen production solution with economic competitiveness compared to conventional hydrogen production methods.