Blue, green, and turquoise pathways for minimizing hydrogen production costs from steam methane reforming with CO2 capture

•Steam methane reforming (SMR) with pre-combustion CO2 capture is a viable solution for near-term blue hydrogen production.•Almost 80% of CO2 emissions can be avoided cheaply (35 €/ton), but the remaining 20% is expensive (>150 €/ton).•Electrically heated reforming (blue-green hydrogen) can achieve similar costs to blue hydrogen if steady clean electricity is available at 60 €/MWh.•Molten salt pyrolysis replacing the pre-reformer (blue-turquoise hydrogen) can significantly reduce costs, depending on the price of pure carbon. Rising climate change ambitions require large-scale clean hydrogen production in the near term. “Blue” hydrogen from conventional steam methane reforming (SMR) with pre-combustion CO2 capture can fulfil this role. This study therefore presents techno-economic assessments of a range of SMR process configurations to minimize hydrogen production costs. Results showed that pre-combustion capture can avoid up to 80% of CO2 emissions cheaply at 35 €/ton, but the final 20% of CO2 capture is much more expensive at a marginal CO2 avoidance cost around 150 €/ton. Thus, post-combustion CO2 capture should be a better solution for avoiding the final 20% of CO2. Furthermore, an advanced heat integration scheme that recovers most of the steam condensation enthalpy before the CO2 capture unit can reduce hydrogen production costs by about 6%. Two hybrid hydrogen production options were also assessed. First, a “blue-green” hydrogen plant that uses clean electricity to heat the reformer achieved similar hydrogen production costs to the pure blue configuration. Second, a “blue-turquoise” configuration that replaces the pre-reformer with molten salt pyrolysis for converting higher hydrocarbons to a pure carbon product can significantly reduce costs if carbon has a similar value to hydrogen. In conclusion, conventional pre-combustion CO2 capture from SMR is confirmed as a good solution for kickstarting the hydrogen economy, and it can be tailored to various market conditions with respect to CO2, electricity, and pure carbon prices.