Sustainable Transportation Energy Pathways (STEPS), National Center for Sustainable Transportation
Miller, Marshall, Arun S.K. Raju, Partho Sarothi Roy (2017) NCST Research Report: The Development of Lifecycle Data for Hydrogen Fuel Production and Delivery. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-17-46
An evaluation of renewable hydrogen production technologies anticipated to be available in the short, mid- and long-term timeframes was conducted. Renewable conversion pathways often rely on a combination of renewable and fossil energy sources, with the primary conversion step relying on a completely renewable source and the auxiliary steps using a more readily available energy mix such as grid electricity.
The conversion technologies can be broadly classified into four categories based on the primary conversion mechanism: thermal processes, electrolytic processes, photolytic processes, and biochemical processes. Based on anticipated technology readiness, water electrolysis and biogas reforming pathways will be available in the near term whereas biomass gasification and bio-derived liquids reforming pathways are expected to be available in the mid-term. Photolytic and dark fermentation approaches are still in the research stage and must go through significant development and demonstration.
Life Cycle Analysis using the CA-GREET Tier 2 model was conducted for select centralized and distributed hydrogen production pathways. Fossil natural gas reforming, the dominant industrial hydrogen production technology, is used as the baseline against which renewable hydrogen production technologies are compared. Electrolysis using renewable power from a solar PV facility results in the lowest GHG emissions among centralized production pathways. The grid electricity-based hydrogen production uses the highest amount of total and fossil energy and results in significantly higher GHG emissions compared to the baseline.
An economic analysis of select pathways was also conducted using the H2A model. Fossil natural gas reforming offers the most cost-effective production option through central & distributed production. Electrolysis using renewable electricity (solar PV) results in the highest production costs through a centralized pathway whereas centralized biomass gasification offers the most cost-effective production method using a renewable feedstock. Based on the life cycle GHG emissions and cost performance, centralized biomass gasification pathway offers the most cost-effective option to reduce GHG emissions.
A review of studies focused on blending hydrogen into natural gas pipelines was conducted. The review focused on issues that impact the viability of blending. Those issues include effects on public safety, potential gas leakage from pipelines, durability of the pipeline networks, and effects on end-use equipment such as stoves or boilers.