Economic assessment of membrane-assisted autothermal reforming for cost effective hydrogen production with CO 2 capture

Abstract

A recent techno-economic study (Spallina et al., Energy Conversion and Management 120: p. 257–273) showed that the membrane assisted chemical looping reforming (MA-CLR) technology can produce H2 with integrated CO2 capture at costs below that of conventional steam methane reforming. A key technical challenge related to MA-CLR is the achievement of reliable solids circulation between the air and fuel reactors at large scale under the high (>50 bar) operating pressures required for optimal performance. This work therefore presents process modelling and economic assessments of a simplified alternative; membrane assisted autothermal reforming (MA-ATR), that inherently avoids this technical challenge. The novelty of MA-ATR lies in replacing the MA-CLR air reactor with an air separation unit (ASU), thus avoiding the need for oxygen carrier circulation. The economic assessment found that H2 production from MA-ATR is only 1.5% more expensive than MA-CLR in the base case. The calculated cost of hydrogen (compressed to 150 bar) in the base case was 1.55 €/kg with a natural gas price of €6/GJ and an electricity price of €60/MWh. Both concepts show continued performance improvements with an increase in reactor pressure and temperature, while an optimum cost is achieved at about 2 bar H2 permeate pressure. Sensitivities to other variables such as financing costs, membrane costs, fuel and electricity prices are similar between MA-ATR and MA-CLR. Natural gas prices represent the most important sensitivity, while the sensitivity to membrane costs is relatively small at high reactor pressures. MA-ATR therefore appears to be a promising alternative to achieve competitive H2 production with CO2 capture if technical challenges significantly delay scale-up and deployment of MA-CLR technology. The key technical demonstration required before further MA-ATR scale-up is membrane longevity under the high reactor pressures and temperatures required to minimize the cost of hydrogen.