Comparison of Commercial, State-of-the-Art, Fossil-Based Hydrogen Production Technologies

Hydrogen Life-Cycle Analysis in Support of Clean Hydrogen Production

“…Similarly, the electrolysis pathways (SOEC and PEM) considered in this study are powered by either nuclear or renewable electricity, both of which do not depend on the upstream NG emissions. GREET SMR and SMR-CCS WTG GHG emissions differ from those in Lewis et al 13 , despite using the same inventory data (Table 5). The difference arises largely because of the differences in the NG upstream supply chain GHG emissions.…”

“…10 The SMR GHG emissions in GREET 2022 have been updated using a recent National Energy Technology Laboratory report that provided mass and energy balance from SMR modeling. 13 Case 1 in Lewis et al modeled a 480-ton-per-day SMR plant with steam export to populate SMR parameters in GREET 2022. 13 In general, NG consumption and on-site CO2 emissions per unit of produced H2 in an SMR facility vary with process design and configuration, operation conditions (e.g., steam to carbon ratio), feedstock property (e.g., NG composition, carbon content, and heating value), and other process design and control parameters, such as methane slip and the production of steam for export.…”

“…The Lewis et al SMR study presented a case for SMR with CO2 capture from conversion and combustion processes, and compression for CO2 transportation and storage (case 2). 13 The modeled case assumed all by-product steam is used for the CO2 capture process, and thus no steam is available for export. Slightly more NG was required compared with Case 1 (without CCS), and 96% of the CO2 produced on-site was captured and delivered by pipeline for underground storage 62 km away in a deep saline formation (US Midwest).…”

“…We used the Lewis 2022 SMR-CCS energy inventory to compute emissions in GREET 2022 for the SMR with CCS pathway. 13…”

“…H2 may be produced via coal gasification. Cases 4 and 5 in Lewis et al 13 , which are coal gasification without CCS and coal gasification with CCS, were used to establish process energy input data for these pathways in GREET 2022. Based on Lewis et al, coal gasification w/o CCS has an overall energy efficiency (LHV basis) of 58.9%, with energy share of coal (as feedstock and process fuel) 99.1% and electricity the remaining 0.9%.…”