(347a) Techno-Economic Analysis and Life Cycle Assessment for Carbon Black and Hydrogen Co-Production from Arc Plasma Methane Pyrolysis

Hydrogen is a versatile energy carrier that can enhance energy security by utilizing diverse domestic resources and facilitate renewable energy integration through storage solutions. Currently, the most common pathway for hydrogen production is steam methane reforming (SMR) of natural gas, which is energy efficient and low cost due to low-cost natural gas feedstock in the United States but emits significant of CO₂ emissions near 9 kgCO₂/kg H₂. Water electrolysis offers a carbon-free alternative when powered by renewable energy, but it is energy-intensive, requiring 50–65 kWh/kg H2 at a higher cost (~$4–$7/kg H2), limiting its widespread use for large-scale production in the near term. Methane pyrolysis (MP) emerges as a promising alternative, which can serve as a near term ‘bridge’ solution for hydrogen production since it decomposes natural gas into H₂ and solid carbon, thus avoiding CO₂ emissions associated with reforming process. Various technologies provide pyrolysis energy, including fuel combustion, electrical heating, high-temperature molten metal/salt media, and plasma by electricity. Among those technologies, arc plasma methane pyrolysis has the highest TRL and recently has been successfully commercialized by companies, including Monolith in the United States.

In this process, preheated natural gas enters an arc plasma reactor, where it is decomposed by hydrogen plasma. After a series of heat recovery and cooling operations, a solid carbon and hydrogen rich gas are separated. The hydrogen-rich gas is compressed and purified, while carbon solids undergo degassing, pelletizing, and drying to produce carbon black pellets. Currently, few open-to-public studies have accurately assessed the energy consumption, economic performance, and life cycle emissions of this process. This study addresses this gap by developing a detailed process model validated with plant operation data, followed by techno-economic analysis (TEA) and life cycle analysis (LCA). TEA results show that this technology is cost competitive while producing hydrogen without CO₂ emissions, meanwhile, electricity and carbon black prices are the two key cost drivers influencing the hydrogen production cost. LCA results show that electricity and NG upstream emissions are the two key drivers of GHG emissions of the methane pyrolysis process.