Energy-efficient distributed carbon capture in hydrogen production from natural gas

Lowering the energy penalty associated with CO2 capture is one of the key issues of Carbon Capture and Storage (CCS) technologies. The efficiency of carbon capture must be improved to reduce the energy penalty because capture stage is the most energy-consuming stage in the entire process of CCS.Energy-efficient distributed carbon capture in hydrogen production has been demonstrated with an advanced membrane reformer system. We have already developed and operated an advanced 40 Nm3/h-class membrane reformer system and demonstrated its high hydrogen production efficiency of 81.4% (HHV), which is the world highest efficiency in terms of hydrogen production from natural gas. The system has another significant feature that the CO2 concentration in the reactor off-gas is as high as 70∼90% and CO2 can be liquefied and separated easily with little energy loss. An apparatus for CO2 capture was combined to the membrane reformer system and over 90% of CO2 in the reactor off-gas was captured by cryogenic separation. The total energy efficiency of hydrogen production even with CO2 capture was still as high as 78.6% (HHV), which is 5∼10% higher than the conventional reforming technologies.The total CO2 emission from hydrogen production was decreased by 50% with only a 3% energy loss. A sensitivity analysis was also carried out to evaluate the effects of the operating conditions of the system on hydrogen production efficiency and CO2 reduction rate.