Why hydrogen Cannot be replaced as fuel
Do hydrogen haters have a molecule to stand on? We asked an expert
On the face of it, they seem to have a point. Hydrogen is difficult to produce, hard to store, and, with current extraction processes, not all that efficient. Meanwhile, electric cars are improving every day and appear to be serious competitors to internal combustion.
Actual production of fuel cell vehicles is less energy intensive than that of EVs.
So if all that were the case, companies would have to be crazy to pursue hydrogen fuel cells. But major automakers like Toyota and Honda have devoted tons of time and treasure to fuel cell-powered vehicles. If the rep at Honda with whom we spoke is to be believed, theyre not crazy; fuel cell detractors are just looking at the technology in the wrong way.
Not ones to take Musks word as gospel, we decide for this weeks Road Rave to explore the potential of hydrogen technology, as well as its future for ourselves.
What the heck is a hydrogen fuel cell?
For all of the attention that gets paid to hydrogen, the technology is actually not well understood. As it turns out, that is a problem because that misunderstanding gives people the wrong idea about the technologys purpose and benefits. So, with that in mind, lets look at how it works.
In a lot of important ways, hydrogen fuel-cell vehicles (FCV) work just like electric vehicles (EVs). The wheels on Hondas Clarityand Toyotas Mirai FCVare both turned entirely by electric motors. Further bridging the gap between EVs, FCVs even feature battery packs and regenerative braking. The differences between the two breeds start in the battery pack itself, which is on par with those found in gasoline hybrids rather than the massive chassis-breakers found in EVs.
Toyota Mirai FCV
That size difference is down to the fact that, while hydrogen cars are driven by electric motors, that electricity is generated by the onboard fuel cell rather than fed in from an electric grid-connected wall outlet. On the face of it, fuel cells seem like black magic; hydrogen and oxygen go in and electricity and water come out. As it turns out, the process of turning hydrogen into electricity is a deceptively simple one that involves no warlocks at all at least according to Honda.
Though there are many kinds of hydrogen fuel cell, automotive fuel cells are almost exclusively the Proton Exchange Membrane (PEM) type. These PEM fuel cells consist of a stack of extremely thin membranes. Each membrane has flow channels on either sides, one for hydrogen and the other for air.
The membrane uses a catalyst typically platinum to strip protons from the hydrogen, which then pass through the membrane creating electric current. The protons then bind with oxygen in the air to form a fuel cells only exhaust: water vapor.
The more of these membranes there are, the more electricity is produced. The beauty of this design is that it is almost infinitely scalable and requires no moving parts.
The criticism
Fuel cells themselves are brilliant. However, they come with more baggage than a crazy sex partner. The big problem is hydrogen.
Hondas next-gen fuel-cell vehicle will offer a fuel cell that is not only a third smaller but also 60 percent more powerful.
Yes, it is the most common element in the universe. It, however, is almost never found in its pure state. This means that any hydrogen that goes into cars must first be refined from a natural source before it is pumped into the onboard tank.
The most common method is steam reformation of natural gas, a process by which extremely high temperature steam is added to natural gas in the presence of a metal catalyst. The subsequent reaction breaks natural gas into hydrogen and carbon monoxide.
This method is already a big business, but it has problems. For starters, it requires natural gas, which slightly defeats the purpose of moving away from fossil fuel-powered vehicles. Further, it isnt actually that efficient. While Hondas representatives told me that it beats out internal combustion in terms of efficiency, other sources estimate more conservative efficiency figures.
The main alternative production method is hydrolysis of seawater. There is a plethora of different ways to do this and, while each is fascinating in its own right, I dont have the 10,000 words needed to describe them in detail. Suffice it to say that current methods require either high temperatures or high pressures to operate and thus a great deal of energy.
These factors make the criticism of hydrogen seem reasonable, even unapproachable. After all, why spend all that energy and money on hydrogen when you could just generate electricity directly, which could be used to power an EV?
Barking up the wrong tree
According to Steve Ellis, the head of fuel cell vehicle marketing for Honda, the criticisms of hydrogen are missing the point. Hydrogen isnt an alternative to battery powered EVs, it is a complement.
As it stands, battery-powered vehicles are still subject to the vicious cycle of energy density. The more range required, the bigger the batteries need to be, which in turn increases the weight, further increasing the battery demand. The only company to even partially address this has been Tesla. And it has done it at the cost of, well, cost.
Honda itself has developed a solar-powered home station that is capable of generating hydrogen for use in cars.
Hydrogen cars already in production, like the Honda Clarityor the Toyota Miraialready offer range competitive with gas-powered vehicles, as well as similar refueling times. The latter comes as a result of industry standard fuel pressures and the increasing use of carbon fiber composite hydrogen tanks, which are at least as safe as the tanks on gasoline- and diesel-powered vehicles.
There is another hidden advantage to hydrogen technology. While the production of hydrogen creates its own pollution footprint, the actual production of fuel cell vehicles is less energy intensive than that of EVs, thanks to the reduced need for battery capacity. As we have explored in the past, EVs have large hidden energy costs in production especially the toxic and costly nature of lithium refining and battery production. Toyotas Mirai is able to use cheaper, less environmentally problematic nickel hydride batteries.
These factors may not make hydrogen vehicles a replacement for EVs in a city setting, especially where small vehicles are concerned. However, hydrogen is a far more viable for larger, long-distance vehicles akin to gas vehicles. Hydrogen vehicles also have simple architecture, which can be easily shared with other types of powertrains. In theory, this should make it easy for automakers to offer hydrogen power in models alongside traditional hybrid drive, or even pure battery EVs.
Honda Solar Hydrogen Station
Speaking of batteries, advances in battery and electric drive technology wont so much leave hydrogen in the dust as bring it along for the ride. Because hydrogen vehicles use electric motors and small battery packs, they benefit from any advances made in those technologies, too. In fact, Ellis acknowledged that plug-in hybrid hydrogen cars could happen in the future.
The technology for fuel cells is also improving at a more rapid pace than battery tech. According Ellis, the next-generation Honda fuel-cell vehiclewill offer a fuel cell that is not only a third smaller but also 60 percent more powerful. This will translate to better efficiency and range.
These developments are happening in parallel with new hydrogen refining techniques. Honda itself has developed a solar-powered home station that is capable of generating hydrogen for use in cars. There are also interesting developments in using algae to break water into hydrogen and oxygen that could be commercially viable in the next five to ten years.
Conclusion
In some respects, hydrogen fuel-cell advocates have done themselves and the technology a disservice by claiming that it is a silver bullet that will provide the world with pollution-free transportation. The stance taken by Honda and other companies currently trying to make money from fuel cells is far more sensible, in that it acknowledges the technologys limitations as well as its potential.
Hydrogen may not be a substitute for EVs, but, by the same token, EV advocates would do well to acknowledge that the technology they champion isnt a silver bullet either. There may well be room for, as Steve Ellis says, everyone to get along.
Whatever we may think now, the next decade will do a lot to determine which technology will succeed and in what ways.
Editors' Recommendations
Hydrogen Benefits and Considerations
Hydrogen Benefits and Considerations
Hydrogen can be produced from diverse domestic resources with the potential for near-zero greenhouse gas emissions. Once produced, hydrogen generates electrical power in a fuel cell, emitting only water vapor and warm air. It holds promise for growth in both the stationary and transportation energy sectors.
Energy Security
The United States became a net exporter of petroleum in 2020 with exports surpassing imports, although imports of 8.47 million barrels per day in 2021 remained an important part of balancing supply and demand for domestic and international markets. Overall, the transportation sector accounts for approximately 30% of total U.S. energy needs and 70% of U.S. petroleum consumption. Hydrogen can be produced domestically from resources like natural gas, coal, solar energy, wind, and biomass. When used to power highly efficient fuel cell electric vehicles, hydrogen holds the promise of helping strengthen national energy security, conserve petroleum, and diversify our transportation energy options for a more resilient system.
Public Health and Environment
About half of the U.S. population lives in areas where air pollution levels are high enough to negatively impact public health and the environment. Emissions from gasoline and diesel vehiclessuch as nitrogen oxides, hydrocarbons, and particulate matterare a major source of this pollution. Hydrogen-powered fuel cell electric vehicles emit none of these harmful substancesonly water (H2O) and warm air.
The environmental and health benefits are also seen at the source of hydrogen production if derived from low- or zero-emission sources, such as solar, wind, and nuclear energy and fossil fuels with advanced emission controls and carbon sequestration. Because the transportation sector accounts for about one-third of U.S. carbon dioxide emissions, using these sources to produce hydrogen for transportation can cut greenhouse gas emissions. Learn more about hydrogen emissions.
Fuel Storage
Hydrogen's energy content by volume is low. This makes storing hydrogen a challenge because it requires high pressures, low temperatures, or chemical processes to be stored compactly. Overcoming this challenge is important for light-duty vehicles because they often have limited size and weight capacity for fuel storage.
Typically, the storage capacity for hydrogen in light-duty vehicles should enable a driving range of more than 300 miles to meet consumer needs. Because hydrogen has a lower volumetric energy density than that of gasoline, storing this much hydrogen on a vehicle currently requires a larger tank at higher pressure than other gaseous fuels. Medium- and heavy-duty vehicles have more space for larger tanks but could face weight limitations that reduce the total load potential to stay within U.S. Department of Transportation restrictions. Learn more about hydrogen storage challenges from the Hydrogen and Fuel Cell Technologies Office.
Production Costs
To be competitive in the marketplace, the cost of fuel cells will have to decrease substantially without compromising performance. According to at least one original equipment manufacturer, the predicted cost of mass-produced fuel cell electric vehicles could be similar to the cost of their hybrid counterparts by 2025. Unlike a battery, where most of the cost comes from the raw materials used to make it, the most expensive part of a fuel cell is manufacturing the fuel cell stack itselfnot the materials to produce it. The cost to build and maintain hydrogen stations also needs to decrease for the market to support a hydrogen economy.
More Information
Learn more about the benefits of hydrogen from the Hydrogen Interagency Task Force and the Hydrogen and Fuel Cell Technologies Office.
