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The International Council on Clean Transportation (ICCT) has released yet another report assessing road vehicle decarbonization in Europe, and once again, the analysis systematically misses the mark on hydrogen. The ICCT’s latest lifecycle assessment (LCA) positions hydrogen fuel cell electric vehicles (FCEVs) as a climate-friendly alternative, offering competitive emissions profiles relative to battery electric vehicles (BEVs).

This graph is worth assessing at face value. First, it’s assessment passenger cars in 2025, when fuel cell cars are a dead segment with no one considering them seriously any more in Europe. The question in Europe has moved on to buses and heavy goods vehicles, and is being answered with overwhelming purchases of electric buses and major economic councils and auditor courts saying hydrogen is dead for those segments too.

Why in 2025 is the ICCT bothering to include a dead end segment in an assessment? In 2024, only 11 Hyundai Nexos were sold in Europe. Toyota Mirai sales drove off of a cliff on the winding seaside roads of the Mediterranean too. What exactly is the ICCT trying to achieve by assessing a now clearly non-existent segment against the actual solution, battery electric vehicles?

The biggie however, is that this analysis neglects to accurately factor in the well-established challenge of hydrogen leakage along the entire supply chain, as well as the critical implications of using the 20-year global warming potential (GWP20) rather than the commonly used 100-year potential (GWP100). These oversights are significant, skewing comparisons and potentially misguiding policymakers toward technologies that may exacerbate, rather than mitigate, climate change.

Hydrogen’s indirect warming impacts occur when hydrogen molecules leak at various points along the production, distribution, and consumption chain. A growing body of scientific literature points to meaningful leakage rates throughout the hydrogen value chain. Recent analyses show hydrogen leakage from electrolysis plants at around 4 percent, with additional leakage at liquefaction facilities (another 4 percent), pipeline transmission (approximately 1 percent), trucking (up to 5 percent), refueling infrastructure (about 6 percent), and finally onboard vehicle systems, which leak around 0.5 to 2.6 percent per year. Aggregating these emissions leads to total hydrogen losses ranging between 5 percent and 15 percent across typical supply chains.

This isn’t just economically problematic, as if hydrogen needs yet another expense added to its pile of bling, but it’s also a climate problem. Hydrogen is a potent indirect greenhouse gas. It interferes with the breakdown of methane in the atmosphere, extending that high global warming potential gas’ residence. That gives hydrogen a global warming potential of 11 to 33, based on the most recent study which added factors to the couple of years old study that found 12 to 37. Hydrogen leaks and it causes global warming.

Further, that leakage isn’t remotely easy to fix. We store hydrogen at pressures equivalent to 3 to 7 kilometers under the surface of the ocean, or at temperatures only a few degrees above deep space, or both. It’s the smallest diatomic molecule in the universe. Tiny molecule, extreme pressures and temperatures and the engineering to contain it gets exotic. That’s why it leaks so much in empirical studies like the one linked above, and that’s why the problem isn’t going to go away.

Applying the correct global warming potential metric further amplifies the impact of this leakage. Traditionally, lifecycle analyses, including those by ICCT, use a 100-year global warming potential for gases like hydrogen and methane. Yet policymakers focused on urgent climate targets increasingly advocate for the use of GWP20, the global warming potential over a 20-year period, especially for short lived atmospheric forcers like methane and hydrogen. For hydrogen, the shift from GWP100 (approximately 13 times that of CO₂) to GWP20 (around 33 times that of CO₂) drastically increases the significance of hydrogen leakage in lifecycle emissions calculations.

Recalculating the ICCT’s latest hydrogen vehicle LCA with these corrections provides a sobering perspective. The original ICCT study assigns green hydrogen-powered vehicles around 50 grams of CO₂-equivalent per kilometer (g CO₂e/km). Introducing even a conservative 5 percent hydrogen leakage at GWP20 adds approximately 17 grams per kilometer, pushing total lifecycle emissions upward significantly. At a more realistic 10 percent leakage, lifecycle emissions increase by about 33 grams per kilometer, moving green hydrogen vehicles toward a range between 67 and 83 grams CO₂e/km. A 15 percent leakage scenario would add approximately 50 grams per kilometer, doubling the originally stated emissions for FCEVs using renewable hydrogen.

When the focus shifts to fossil-derived grey hydrogen, the miscalculations become even more pronounced. ICCT’s original analysis places grey hydrogen vehicles around 175 grams CO₂e/km, including upstream methane leakage at a conservative GWP100 value. Recalculating methane leakage using the GWP20 factor (around 84 times that of CO₂ over 20 years) raises lifecycle emissions substantially. The grey hydrogen lifecycle emissions jump from 175 grams to around 229 grams CO₂e/km. Add a moderate 10 percent hydrogen leakage rate at GWP20, and emissions soar to approximately 260 grams CO₂e/km. This puts hydrogen vehicles fueled by fossil-sourced hydrogen firmly in the territory of being worse than modern diesel vehicles in terms of lifecycle climate impact.

The absolute best cases for hydrogen cars are far higher GHG emissions than today’s battery electric vehicles.

These miscalculations are consistent with previous ICCT assessments that exhibited similarly optimistic assumptions about hydrogen across multiple sectors. In 2023, the ICCT released a trucking analysis that applied unfairly different electricity price assumptions for hydrogen refueling versus battery charging. ICCT assumed wholesale electricity pricing for hydrogen electrolyzers at refueling stations but applied significantly higher retail pricing assumptions for battery-electric trucks. These inconsistent assumptions artificially inflated the economic competitiveness of hydrogen for heavy trucking. The methodological inconsistencies, identified clearly at the time, were defended inadequately by ICCT, further undermining their credibility on hydrogen-related analyses.

A similar pattern emerged in ICCT’s aviation analysis later in 2023. That report assumed hydrogen could easily integrate into existing aviation infrastructure without significant consideration of challenges such as mass distribution, aircraft certification, and entirely new ground-handling infrastructure. These oversights led to unrealistically optimistic projections for hydrogen aviation and risked diverting valuable policy attention and investment away from more viable solutions like sustainable aviation fuels and regional battery-electric aviation.

In maritime shipping, ICCT repeated its optimistic errors, notably underestimating liquefaction costs, assuming remarkably low prices for liquid hydrogen, and glossing over the substantial infrastructure challenges inherent in scaling hydrogen as a shipping fuel. ICCT’s preference for niche technologies like liquid hydrogen and rigid sails further complicated their analyses, creating unrealistic scenarios that distorted comparative technology assessments. Once again, their approach misled policymakers about hydrogen’s potential to decarbonize maritime shipping realistically.

This recurring pattern of overly favorable hydrogen assessments by ICCT appears rooted in bias, methodological oversights, reliance on industry data without adequate skepticism, and neglect of real-world integration constraints. These persistent shortcomings matter because ICCT has substantial influence over global transport policy and investment decisions. Billions of dollars in infrastructure and R&D funding can follow the guidance provided by these analyses, highlighting the urgent need for greater accuracy and transparency.

My assessments of the ICCT’s published studies found that the organization had a strong history of referencing its own papers and clear errors in the use of data. Further, it had a clear history of only having internal review that clearly wasn’t rigorous. While I live and die by post-publication humiliation, I’m one analyst working independently. The ICCT should not be so consistently publishing humiliatingly wrong and incomplete studies. It’s a well funded organization with a big global team and can easily reach out to experts to ask if framing is correct and what external data they’ve excluded.

It’s not as if the ICCT overall was unaware of the literature on hydrogen’s indirect GWP. This ICCT paper from 2023 makes it clear that at least some ICCT affiliated researchers were aware of the literature on hydrogen’s indirect global warming potential. That’s two years ago, two years before this most recent botched study on ground transportation hit the internet. How could internal review have missed hydrogen’s GWP? How could it not at least present the GWP20 challenges of methane and hydrogen leakage as a sensitivity analysis?

It’s not as if a report published in July of 2025 had an excuse for not knowing about hydrogen’s leakage rates. Publications from the DOE date back years, and empirical studies related to leakage have been emerging in the peer reviewed literature in recent years as well. I published on the problem last year based on the literature, finding 1%+ leakage per touch point and 5–7 touch points in any extensive hydrogen supply chain, for example to refueling stations for hydrogen fuel cell vehicles.

There is no world in which hydrogen cars actually exist in the future, except as exhibits in a museum of bad ideas that lived long past the time they should have disappeared. There is no world in which hydrogen cars have lower lifecycle emissions than battery electric cars. There is no world in which the total cost of ownership of hydrogen vehicles is remotely close to battery electric vehicles. Yet the ICCT keeps finding hydrogen for transportation to be superior in some fictitious world where green hydrogen is favored over everything, all of battery electric vehicles negatives are counted and some or most of hydrogen’s negatives are carefully avoided. That’s cherry picking.

To avoid further distortions, ICCT must adopt rigorous internal methodological reviews and subject future hydrogen-related analyses to thorough external peer reviews. Clearly their current internal review process is superficial and their internal reviewers are either ignorant of the current literature or biased toward hydrogen.

Further, this is another study they should yank and redo. They didn’t yank and redo their hydrogen truck total cost of ownership study, but instead defended their biased analysis. Now they’ve repeated their failure with a biased analysis of ground vehicle lifecycle carbon emissions. Frankly, I’m not expecting them to fix their mistake this time either. They’ve proven that they don’t have the organizational guts to admit they are wrong, fix their mistakes and address the root causes that led to their failures.

Hydrogen leakage and the appropriate use of GWP20 as well as GWP100 must become standardized considerations in all LCAs. Sensitivity analyses must also be prominently displayed, ensuring policymakers understand the substantial impact of differing assumptions. Only through such improvements can ICCT fully regain credibility as a trusted guide in decarbonization strategies.

The stakes are high. As countries commit increasingly ambitious climate targets, accurate lifecycle assessments become critical for guiding policy toward the most effective, feasible, and timely solutions. Continuing to underestimate hydrogen’s climate impacts and costs risks prolonging dependence on fossil fuels and delaying meaningful climate action.

ICCT has another opportunity to lead by example, setting higher standards of rigor and transparency. However, they’ve failed multiple times, refused to accept responsibility and refused to fix the problem. If they don’t step up this time, they should be ignored going forward. The climate, and indeed policymakers worldwide, urgently require it.