There is no perfect energy source, nothing that will power our vehicles without some kind of catch. Consider hydrogen. For decades it’s been propped up as a worthy alternative to oil, even if infrastructure-related hiccups seem to always hold it back from reaching its full potential. Nevertheless, there seems to be a bit of space left for hydrogen-powered vehicles even in a battery electric-dominated world. But new research indicates that hydrogen buildup could have adverse effects on the climate, not terribly unlike the fuel it’s meant to replace.
The study was conducted by Princeton University and the National Oceanic and Atmospheric Association. Hydrogen reacts with another molecule called hydroxyl radical (OH) that, on its own, typically reduces the buildup of greenhouse gases in the atmosphere. The researchers found that once a certain threshold of hydrogen emissions is surpassed, OH cannot do its job, leading to an overabundance of methane. From Sci Tech Daily:
The hydroxyl radical also reacts with hydrogen gas in the atmosphere. And since a limited amount of OH is generated each day, any spike in hydrogen emissions means that more OH would be used to break down hydrogen, leaving less OH available to break down methane. As a consequence, methane would stay longer in the atmosphere, extending its warming impacts.
According to Bertagni, the effects of a hydrogen spike that might occur as government incentives for hydrogen production expand could have decades-long climate consequences for the planet.
“If you emit some hydrogen into the atmosphere now, it will lead to a progressive build-up of methane in the following years,” [postdoctoral researcher at High Meadows Environmental Institute Matteo] Bertagni said. “Even though hydrogen only has a lifespan of around two years in the atmosphere, you’ll still have the methane feedback from that hydrogen in 30 years from now.”
In the study, the researchers identified the tipping point at which hydrogen emissions would lead to an increase in atmospheric methane and thereby undermine some of the near-term benefits of hydrogen as a clean fuel. By identifying that threshold, the researchers established targets for managing hydrogen emissions.
It’s critical that hydrogen emissions are kept below that tipping point, even if it’s being used to broadly replace fossil fuels. Hydrogen fuel-cell vehicles emit only water vapour of course, but the key here is that there are always leaks in the production and transport process. And if enough methane and hydrogen are leaked together, well — you may as well have just burned gasoline.
“Managing leakage rates of hydrogen and methane will be critical,” Bertagni said. “If you have just a small amount of methane leakage and a bit of hydrogen leakage, then the blue hydrogen that you produce really might not be much better than using fossil fuels, at least for the next 20 to 30 years.”
So maybe it’s good that automakers aren’t hurrying to pump out hydrogen fuel-cell cars in droves. Maybe. Lithium production will have to increase six-fold by 2035 to support the number of EVs manufacturers plan to build, electricity is likely to get real pricey at night and battery-powered big rigs will need charging stations supplied with a small town’s worth of energy to stay on the road. Meanwhile, synthetic e-fuels are still exorbitantly inexpensive because the process to create them is remarkably inefficient — and even if that weren’t true, they’d still pollute city air as badly the real stuff. There are no easy answers here.