Many governments are planning to utilise low-carbon hydrogen as part of their strategies for reducing greenhouse gas (GHG) emissions. Hydrogen can be reacted with oxygen/air to produce energy without carbon dioxide (CO2) at the point of use, making it attractive for mitigating a wide range of GHG sources such as transportation, industry, electricity, and building heat. Today, hydrogen is commonly used as an industrial feedstock in processes such as fertilizer manufacturing and petrochemical refining.

Virtually all existing hydrogen production is derived from fossil fuels using processes that create significant GHG emissions – the most prevalent is steam reformation of natural gas. Using renewable energy to split water molecules via electrolysis is frequently proposed as a low-carbon alternative. However, renewable-powered electrolysis is significantly more expensive than conventional hydrogen production (US$3-8/kgH2 vs. US$1-2/kgH2) and technologies are commercially available which could capture CO2 from fossil fuel-based processes. For example, regenerative amine-absorption is widely used to remove CO2 during natural gas processing and hydrogen production (e.g., CO2 must be removed upstream of ammonia synthesis to prevent catalyst deactivation). Furthermore, fossil fuels are expected to provide a dominant share of world energy supply until at least 2050 based on current government policies.

I was lead author of a research paper recently published in the International Journal of Hydrogen Energy which explored the impact of process design decisions on life cycle GHG emission intensity and cost of producing hydrogen via steam reformation of natural gas with carbon capture and storage. We found that existing technologies, low-carbon electricity supply, and low-emission natural gas production could be configured to produce hydrogen with GHG emissions similar to renewable-powered electrolysis but with significantly lower cost. Below, I share some of the key findings from our study.

Process design choices dramatically affect life cycle emissions

Our study assessed four process configurations with different combinations of CO2 capture location and burner fuel. In all configurations, life cycle GHG emissions varied significantly with process design conditions (figure below). While cost of producing hydrogen (LCOH) increased for lower emission intensity process designs, 99% fossil-CO2 capture was found to be achievable with less than US$125/tCO2e marginal abatement cost.

Impact of process design conditions on cost of producing hydrogen (LCOH) and cradle-to-gate GHG emission intensity for four configurations of steam reformation of natural gas. Fossil-CO2 capture rates of selected points noted. Source: Cownden et al (2023).

Life cycle emissions can be comparable to renewable-powered electrolysis

Our study considered three scenarios for natural gas supply chain emissions: a peer-reviewed study of demonstrated low-emission production practices in western Canada, average natural gas production emissions in British Columbia, and average BC emissions with fugitive methane rates increased 80% above reported values. The results of our study are consistent with prior studies (figure below); however, while prior studies assumed a fixed fossil-CO2 capture rate, our study demonstrates a range of potential fossil-CO2 capture rates (76-99.9%) depending on process design assumptions. In all natural gas supply chain scenarios in our study, hydrogen life cycle GHG emission intensity is within the range of published estimates for renewable-powered electrolysis. Low natural gas supply chain emissions combined with steam reformation process design for high fossil-CO2 capture was shown to have life cycle GHG emissions comparable to wind-powered electrolysis.

Comparison of cradle-to-gate emission intensity in our study (green area) compared to prior studies of steam reformation of natural gas and renewable-powered electrolysis. Fossil-CO2 capture rates of each study are noted. Source: Cownden et al (2023).

Low-carbon steam reformation of natural gas costs significantly less than renewable-powered electrolysis

Our study considered a range of natural gas prices with the 10-year historical average price in western Canada (US$2.04/GJ) as the baseline. The cost of producing hydrogen (LCOH) in our study varied depending on the process design and natural gas price, but in all scenarios is within the range of prior studies (figure below). LCOH in the scenarios in our study is well below the estimated current cost of producing hydrogen by renewable-powered electrolysis (US$3-8/kgH2) and at the low end of the range of future projections (US$1-3/kgH2). Further, the LCOH in our study is near the US Department of Energy research goal for low-carbon hydrogen – US$1/kgH2 by 2031 – a price point which is expected to make hydrogen viable for a wide range of applications.

Comparison of cost of producing hydrogen (LCOH) in our study (green area) compared to prior studies of steam reformation of natural gas. Assumed base year of each study is noted. Source: Cownden et al (2023).

Life cycle emissions are dominated by upstream CO2 in deep decarbonization scenarios

Previous studies have shown that natural gas production with low fugitive methane emissions is required for hydrogen produced from natural gas to have net benefit for GHG mitigation. Our baseline analysis used low-emission natural gas production practices that have been demonstrated commercially at industrial scale in western Canada. In deep decarbonization scenarios assessed in our study, direct CO2 emissions from the process were near zero (figure below) and life cycle emissions were dominated by indirect emissions from upstream natural gas production – primarily CO2 emissions during natural gas processing. Thus, in addition to reducing fugitive methane emissions, there is also a significant opportunity to reduce life cycle emissions of hydrogen from natural gas by reducing upstream CO2 emissions.

Breakdown of life cycle emission sources for hydrogen from steam reformation of natural gas with different process design assumptions. Source: Cownden et al (2023).

Looking forward to low-carbon hydrogen

Life cycle GHG emissions of hydrogen from steam reformation of natural gas in our study were within the range of renewable-powered electrolysis while cost was significantly lower than current estimates and at the low end of the range of future projections. This important finding shows that steam reformation of natural gas with carbon capture and storage could be a long-term energy solution consistent with climate stabilization. Having a diverse range of viable emission abatement options to achieve net zero GHG emissions is essential to ensure that the social, economic, political, and energy security needs of different jurisdictions can be met.