Hydrogen holds tremendous potential in reducing greenhouse gas emissions and combating the effects of climate change. Policymakers and industry are pouring tens of billions of dollars into various hydrogen energy technologies.
But hydrogen is a leak-prone gas with a potent warming effect of its own that is widely overlooked. Whether a hydrogen energy revolution helps the climate will depend on how it’s produced, managed and used.
Today, hydrogen is mainly used in specialized applications like fertilizer production and oil refining. But supporters envision it everywhere from transportation fuel to home heating and cooking, and augmenting wind and solar generation.
Estimates suggest demand could increase up to tenfold by mid-century.
If hydrogen is to achieve the environmental benefits that backers promise, measures are needed to keep it from escaping into the atmosphere.
Newly recognized warming power
Scientists have long known that hydrogen triggers indirect warming effects in the atmosphere. Based on the latest understanding of those effects, researchers at EDF and elsewhere say its warming power is much greater than previously recognized.
What’s more, standard scientific accounting used in treaties and reporting requirements systematically understate hydrogen’s powerful near-term warming effects.
That's because hydrogen doesn’t remain in the atmosphere long, and its warming effects disappear after about two decades. But climate impacts are nearly always calculated over a 100-year timeframe — masking damage caused by escaped hydrogen in the near term.
Applying the latest atmospheric science and measuring over a 20-year timeframe to better reflect its near-term warming impact, EDF climate scientists calculate that hydrogen has six times more warming power than is generally recognized today.
That means that it will be critical to keep hydrogen from escaping. And as the smallest molecule, hydrogen is particularly difficult to contain.
What is “clean” hydrogen?
Typical hydrogen production is energy-intensive and generates a lot of climate pollution. But it can also be made using renewable energy to peel away oxygen molecules from water (“green” hydrogen) or by extracting it from natural gas with the residual carbon captured and stored (“blue” hydrogen).
Neither blue nor green hydrogen is yet available at commercial scale. Both are more expensive than conventional fossil fuels, but massive investments now flowing into the sector will likely improve the picture.
Handled properly, they could bring real climate benefits. But if too much hydrogen escapes, those emissions could decrease the near-term warming benefits relative to fossil energy.
Benefits depend on leakage
In their recent study, EDF scientists compared the climate impact of blue and green hydrogen under high- and low-leakage scenarios.
With a low leak rate, they say that both blue hydrogen made from natural gas (with carbon capture plus minimal upstream methane emissions) and green hydrogen made with zero-emission electricity would reduce climate impact dramatically, compared with fossil fuels.
But if leakage of hydrogen and supply-chain methane is high, blue hydrogen could actually increase the 20-year warming impact. Green hydrogen would still be better for the climate than the fossil equivalent over 20 years, but far less so than the climate-neutral promise boosters claim.
Realizing the climate potential
Preventing hydrogen from leaking into the atmosphere will be crucial. Use-case also matters.
Hydrogen is most appropriately used for applications where other clean alternatives are lacking, such as steel and cement production, or as feedstock for low carbon fuels for ships and planes. And since transporting hydrogen is likely to increase the risk of leaks, it makes sense to produce it close to where it’s used.
Prior research suggests deployment of green hydrogen can require 2 to 14 times more energy than available alternatives that use direct electrification.
That means in most cases it won’t make sense to divert clean electricity from the grid to make hydrogen for use in cars, homes or commercial buildings, where clean electricity can serve these energy needs directly.
Sensible hydrogen strategy
Hydrogen remains a key strategy of reaching net-zero goals globally. Through thoughtful planning and research, we can safely secure a clean hydrogen future.
Additional research is needed to understand hydrogen’s effect in the atmosphere relative to other GHGs, taking a closer look at varying leakage rates in relation to the global deployment of hydrogen.
Accurately measuring hydrogen leakage and the likelihood of its associated impacts will help inform decisions about where and how to deploy hydrogen effectively.
Identifying leakage mitigation measures and best practices can prevent further climatic degradation in real time as further research is conducted into hydrogen’s overall atmospheric impact.
Taking a proactive and scientific approach to understanding the climate implications — and ability to mitigate hydrogen emissions — will ensure that the global rush to hydrogen delivers on its promise to benefit the climate significantly, no matter the time scale.