Composite Score-Based Analysis of Carbon Capture Strategies for Sustainable Natural Gas-to-methanol: A Comprehensive Assessment

Methanol production from natural gas remains highly carbon-intensive. Previous studies have examined its energy, environmental, or economic dimensions in isolation, often neglecting the combined influence of carbon capture, syngas quality adjustment, and process heat substitution under consistent boundaries. This study presents the first integrated techno-economic and environmental assessment of methanol production via steam methane reforming (SMR) and autothermal reforming (ATR), developed as a case study for Alberta, Canada. The analysis integrates detailed Aspen HYSYS simulations to evaluate energy performance, environmental footprint, and cost using Alberta-specific utility prices and grid emission factors. Thirty-seven configurations were evaluated across varying stoichiometric numbers (SNs), carbon capture strategies, and process heat sources (natural gas or hydrogen). SMR with natural gas utility and pre-combustion CCS achieved the highest net energy ratio (0.77), whereas SMR with hydrogen utility and full CCS yielded the lowest GHG emissions (0.48 kg CO2/kg-MeOH). The lowest minimum selling price (MSP, $229.13/t) occurred for SMR with natural gas utility, pre-CCS, and hydrogen by-product revenue. Composite scoring identified SMR (SN = 2.91, pre-CCS) and ATR (SN = 1.77, full CCS) as the most balanced low-carbon pathways. Integrating carbon pricing and hydrogen revenue reduced breakeven prices to $10/t-CO2 (SMR) and $9/t-CO2 (ATR). Morris and Monte Carlo analyses revealed natural gas price, carbon price, discount rate, and hydrogen storage duration as dominant cost drivers, with uncertainties in cost estimates of +1.7 % for SMR and +1.5 % for ATR. This work establishes a comprehensive framework to evaluate conventional reforming with CCS and by-product valorization toward competitive, low-carbon methanol production in fossil-reliant regions.