Thermodynamic assessment of a novel liquid direct air capture system integrated with natural gas reforming for synergistic methanol production

[Geoengineering News]

https://www.sciencedirect.com/science/article/abs/pii/S0196890426009386

Authors: Mohammad Moosazadeh, Hamin Kim, Shadfar Davoodi, Wafa Suwaileh, Jinwoo Park

Abstract 

This study encompassed the development and evaluation of an integrated steam methane reforming (SMR)–direct air capture (DAC)–methanol system, wherein reformer-derived heat and gas streams are utilized to intensify DAC regeneration and enhance carbon supply for methanol synthesis. Four configurations, SMR–methanol, sweep gas–assisted SMR–DAC (SG–DAC), thermally coupled SMR–DAC (TC–DAC), and dual-mode SMR–DAC (DM–DAC), were assessed using a coupled thermodynamic and techno-economic framework, with reformer temperature and steam-to-carbon ratio identified as key operating variables. DAC integration was found to increase carbon throughput and methanol production from 275.7 mol/s in the baseline SMR–methanol case to over 371.1, 375.2, and 397.4 mol/s in the SG–DAC, TC–DAC, and DM–DAC configurations, respectively. This corresponds to production increases of 34.6%, 36.1%, and 44.1%. However, this gain shifted the system from hydrogen-surplus to hydrogen-deficient operation. Consequently, external hydrogen demand reached 25.6 mol/s in SG–DAC, 37.9 mol/s in TC-DAC, and 104.4 mol/s in DM-DAC, reflecting the increasing stoichiometric requirement associated with elevated CO 2 incorporation. These process-level effects are directly reflected in the economic performance of the systems. The baseline SMR–methanol configuration remained the most favorable, with an NPV 25 of $398.78 million and a TAC of $86.26 million/year, whereas the DAC-integrated systems exhibited reduced profitability, with NPVs between $88.54 and $210.73 million. Overall, DAC integration shifts the governing constraint from carbon availability to hydrogen supply, indicating that optimal system design requires balancing carbon utilization, hydrogen provision, thermal integration, and economic viability.

Source: ScienceDirect