Life cycle assessment of hydrogen production pathways to support hydrogen decarbonization policies in a Canadian context

As the global community strides toward carbon neutrality, hydrogen has emerged as a pivotal energy carrier to help nations achieve their net-zero goals—including Canada's target of 2050. However, ambiguous regulatory frameworks and inconsistent quantification methodologies for carbon intensity have become major bottlenecks hindering international hydrogen trade and investment. While life cycle assessment (LCA) is widely recognized as a standardized tool for measuring hydrogen's carbon footprint, existing certification schemes lack harmonization in key aspects such as system boundaries, data quality criteria, and co-product allocation. In Canada, the introduction of the Clean Hydrogen Investment Tax Credit (CHITC) has further highlighted the urgency of a robust, unified LCA methodology to accurately evaluate which hydrogen production pathways qualify for policy incentives. This study aims to address this gap by validating a harmonized LCA approach tailored to the Canadian context.

The research team from Canada's National Research Council and Natural Resources Canada adopted a harmonized LCA methodology aligned with ISO standards (e.g., ISO/TS 19870:2023) to evaluate six mainstream hydrogen production pathways. The study defined a "well-to-gate" system boundary, focusing on 1 kg of gaseous hydrogen with a minimum purity of 99.9% as the functional unit. The assessed pathways included steam methane reforming (SMR) with and without carbon capture (CC), autothermal reforming (ATR) of natural gas with CC, alkaline (AE) and proton exchange membrane (PEM) electrolysis using grid electricity, and biomass gasification (wood chips) with CC. To ensure data reliability, researchers combined primary data from process modeling (using Aspen© and ProSim© software) with secondary data from the EcoInvent© database, supplemented by rigorous data quality assessments covering completeness, reliability, and geographical representativeness. Additionally, the team developed an open-source LCA database (hosted on openLCA) to enhance transparency and accessibility.

1. Carbon Intensity Spectrum: The well-to-gate carbon intensities of the six pathways ranged significantly from 0.26 to 10.07 kg CO₂ₑ/kg H₂. Biomass gasification with CC achieved the lowest carbon intensity (0.26 kg CO₂ₑ/kg H₂) due to biogenic carbon properties and co-product allocation of liquid CO₂. In contrast, SMR without CC had the highest intensity (10.07 kg CO₂ₑ/kg H₂), exceeding Canada's CHITC threshold.

1. Policy Incentive Eligibility: Alkaline and PEM electrolysis (using Quebec's grid electricity) achieved intensities of 1.23 and 1.34 kg CO₂ₑ/kg H₂ respectively, qualifying for the 25% CHITC. With economic allocation of co-products, SMR with CC (2.02 kg CO₂ₑ/kg H₂) and ATR with CC (1.01 kg CO₂ₑ/kg H₂) became eligible for 15% and 25% credits, while biomass gasification with CC met the 40% maximum credit threshold (intensity <0.75 kg CO₂ₑ/kg H₂).

1. Sensitivity Factors: Electricity source and consumption were critical variables. For PEM electrolysis, switching from Quebec's grid to 100% wind power could push it into the 40% credit tier, while increasing electricity consumption from 55.3 to 83 kWh/kg H₂ raised intensity by 54%. For biomass gasification, using Alberta's grid (higher fossil fuel share) increased intensity from 0.26 to 2.12 kg CO₂ₑ/kg H₂.

1. Broader Environmental Impacts: Beyond carbon intensity, electrolysis pathways had higher water consumption (~1.1 m³/kg H₂) and freshwater ecotoxicity. Biomass gasification with CC, despite low carbon emissions, exhibited the highest land use impact due to biomass feedstock cultivation requirements.

This study fills a critical gap in harmonized LCA methodologies for hydrogen production, providing authoritative data to support Canada's decarbonization policies. The validated framework ensures consistent carbon intensity quantification, addressing a key barrier to international hydrogen trade by aligning with global standards like the UK Low Carbon Hydrogen Standard and Argonne's GREET model. The open-source LCA database enhances transparency for investors and policymakers, while the identification of pathway-specific optimization levers (e.g., electricity source for electrolysis, CC efficiency for SMR) offers actionable guidance for industry. By linking LCA results directly to the CHITC incentive structure, the research accelerates the commercialization of low-carbon hydrogen in Canada. Moreover, the analysis of multiple environmental impacts promotes a holistic sustainability approach, supporting the global transition to carbon-neutral energy systems beyond just greenhouse gas reduction.