This article was published by The Energy Mix on Feb. 23, 2024.
By Mitchell Beer
The push for hydrogen could increase near-term global warming by half compared to directly burning fossil fuels for the same purpose unless its proponents fully account for climate pollution at every stage of production and in the fuel itself, concludes a new paper this week in the journal Environmental Science & Technology.
And making the wrong choices on hydrogen could have serious implications for Canada’s climate performance, and for the fossil fuel industry costs borne by taxpayers, a leading hydrogen analyst warns.
“The climate impacts of hydrogen deployment can be far greater than expected when including the warming effects of hydrogen emissions, observed methane emissions intensities, and near-term time scales,” writes a team of authors from the U.S. Environmental Defense Fund and the University of Arizona. “This lowers the perceived climate benefits when replacing fossil fuel technologies.”
While some analyses show “blue” hydrogen derived from gas decreasing short-term warming by 70 per cent, a worst-case estimate would see warming increasing by 50 per cent, the paper says. For “green hydrogen”, the immediate benefits of producing the fuel from renewable electricity fall by 25 per cent after factoring in the climate impact of the hydrogen itself.
The stakes attached to the calculations are high: the paper says current plans call for governments, businesses, and investors around the world to pour more than US$500 billion into more than 1,000 hydrogen projects over the next decade.
Hydrogen’s Climate Impacts
The researchers say scientists have spent several decades documenting hydrogen’s climate impacts. The smallest molecule known to science “is a leak-prone gas with a potent indirect warming effect in the near-term due to the fact that its chemical oxidation in the atmosphere increases other short-lived greenhouse gases (GHGs) in the atmosphere—methane, tropospheric ozone, and stratospheric water vapour,” the paper explains.
There are no field measurements available for hydrogen leakage rates from industrial facilities or infrastructure, the research team reports, but estimates range from 1 per cent to 20 per cent with liquid hydrogen installations believed to come in on the high end. “Given the similarity between hydrogen and natural gas infrastructure, and that natural gas emissions have been shown to be higher than previously thought, it is reasonable to expect that hydrogen emissions may also be significant.”
Similarly, the methane emissions attributed to blue hydrogen projects in climate impact assessments (and to natural gas extraction in general) “are often not consistent with those actually observed across a diversity of facilities and supply chains,” and vary widely across jurisdictions and gas fields, the paper says. “Higher than anticipated methane emissions could undercut the climate benefits of deploying hydrogen technologies as a replacement for fossil fuels, especially in the near term.”
The EDF analysis was based on eight “hydrogen-to-end use pathways” published by the Brussels-based Hydrogen Council in 2021. The four for blue hydrogen included long distance passenger vehicles, ships, industrial heat, and power generation from ammonia. The green hydrogen pathways were fertilizer production, buses, heavy trucks, and steelmaking. For each of them, the Council estimated life cycle GHG emissions in 2030 and 2050 and came down in favour of hydrogen use at mid-century.
The new study adds carbon dioxide, methane, nitrous oxide, and other climate pollutants to the assessment, calculates a variety of emission rates for both hydrogen and methane, and shifts assumptions on carbon capture rates for blue hydrogen, and on renewable energy available to power utilities.
“It’s important to get the emissions accounting right, both to accurately assess climate impacts of hydrogen systems and to identify opportunities to reduce them,” said EDF climate scientist and lead author Tianyi Sun. “When we consider all climate warming emissions and their impacts over the near and long term, our analysis shows that hydrogen deployment can have far greater impacts than expected.”
Over-Optimistic Assumptions
For blue hydrogen, which depends on still-shaky carbon capture and storage (CCS) technologies to sequester the carbon dioxide emissions from gas, the EDF scientists assumed a 60 per cent capture rate, rather than the over-optimistic 98 per cent preferred by CCS and blue hydrogen boosters. With the more realistic calculation, “the climate benefits of blue hydrogen pathways are reduced by 15 to 50 per cent in the near-term, and 20 to 60 per cent in the long-term,” the organization says in a release.
For green hydrogen, the big question is whether new renewable energy capacity can come online fast enough to supply a new source of electricity demand while simultaneously allowing power grids to phase out their fossil-fuelled generating stations.
“Consistent with other studies, the EDF analysis found that adding renewable electricity to local systems is necessary to help ensure the climate benefits of green hydrogen development,” the release explains. “Otherwise, renewable electricity used to produce green hydrogen is likely replaced by natural gas or coal, resulting in full elimination of intended climate benefits to three times increase in emissions at the system level.”
Like many other recent research studies, the EDF authors also take issue with the common practice of estimating global warming potential over a 100-year scale, when the 20-year impact of methane and hydrogen emissions will matter most over the years when humanity is scrambling to get the climate emergency under control.
Placing Bad Bets
Chemical engineer Paul Martin, Toronto-based co-founder of the independent Hydrogen Science Coalition, said the study carries important implications for Canada.
The country “is betting big on blue hydrogen, a fossil fuel-derived chemical masquerading as an energy solution,” he said in a release. “This research should finally lay to rest the unfounded hope that creating incentives for fossil hydrogen production in Canada is any kind of solution for the climate, or for economic development. Instead, it will lock us into climate pollution worse than fossil fuels, at significant expense to Canadian taxpayers.”
He added that “the scientific evidence is undeniable—Canada must support green hydrogen made from renewables or fall behind in the global energy transition.”
The EDF team did a good job of showing “that it’s important to make green hydrogen truly green,” and that the more “convoluted and disconnected” use cases for hydrogen are likely to be more damaging from a climate perspective, Martin told The Energy Mix in an interview this week.
“It’s how to make this thing make sense,” he said. “The direct uses of hydrogen came out pretty okay. But when you start looking at making it into ammonia and then shipping it to a power plant, it starts to look pretty stupid. From my perspective, that’s obvious, but it isn’t to the industry that’s selling these concepts.”
Instead, “these sorts of things are attracting investor attention, tax credits, and the like,” Martin added. “So we really need a systematic way to evaluate global warming and mitigation potential.”
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