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Earth Day is April 22, and the usual message – taking care of our planet – has become even more urgent due to the challenges highlighted in the latest IPCC report. This year, Ars looks at the technologies we normally cover, from cars to making chips, and find out how we can increase their sustainability and minimize their impact on the climate.
You understand why the idea of a hydrogen-powered car is attractive. People aren’t very good at accepting change, but we do find comfort in the familiar. Being told that our transportation needs to become low-carbon means more change. While electric vehicles are better at: almost everything, even the world’s greatest EV evangelist has to admit that charging a car takes longer than filling a fuel tank. Hydrogen can be pressurized and pumped, and hydrogen can be clean, which is why hydrogen-powered cars make sense, the argument goes.
That’s probably the only question any regular Ars Technica reader needs to list the reasons hydrogen is a no-starter. Like mammals after the Chicxulub asteroid, battery-powered electric vehicles are poised to fill the niches soon to be left by the dinosaurs, in this case fossil-fuel vehicles, vaporizing alternative fuels like hydrogen into the air.
But don’t count the simplest molecule in the universe just yet. While it is unlikely to catch on for light passenger cars in the near future, there are commercial applications such as trucks, trains and other heavy equipment where it makes sense. (For this entire article we are talking about green hydrogen, made from wind or solar energy; using fossil fuels to make hydrogen – even with carbon capture – offers little to no benefit. Unfortunately, the vast majority of the hydrogen is currently produced derived from from hydrocarbons.)
Forget hydrogen cars – at least for now
There are two ways to use hydrogen to power a vehicle. You can burn hydrogen under pressure in an internal combustion engine or use the hydrogen in a fuel cell to generate electricity to power electric motors.
Burning hydrogen in an internal combustion engine is probably the simplest in terms of existing technology – after modifications to the engine and fuel system, the rest of the car’s powertrain remains the same. And the only exhaust product is water. But hydrogen has a low energy density, with only a single covalent bond between two atoms that must be broken. Hydrogen combustion engines also provide little power and are very inefficient compared to a comparable engine that burns gasoline.
So, BMW’s 2006 Hydrogen 7 used a modified version of the company’s V12 engine that, by burning hydrogen, generated about 60 percent as much power as the gasoline-burning V12 and required five times the fuel to do so.
Hydrogen fuel cells have a longer automotive history: the first was the General Motors Electrovan in 1966, which had a curb weight that would put even a Hummer EV to shame and used real space-age technology. By the mid-2010s, automakers’ interest in fuel cells was on the rise, with Audi, BMW, GM, Genesis, Honda, Mercedes-Benz, Toyota and others forecasting fuel cell EVs in the coming years.
Some even went into production: Ars tested two generations of Toyota Mirai and the Hyundai Nexo, all of which use hydrogen fuel cells to power their electric motors. But Mirai and Nexo are not common on the roads. Here in the US, neither is viable outside of California, which remains the only state with any level of public hydrogen refueling infrastructure.
Hydrogen’s fast refueling times (vs. fast charging an EV) don’t count if you can’t find a gas station, creating a chicken-and-egg problem. Without hydrogen fuel cell EVs on the roads, there is no demand to build the infrastructure. And there is no demand for a car or SUV that you have nowhere to refuel.
“The challenge of doing this for retail customers who have very different needs than, say, commercial customers in the aerospace sector or the truck sector or the rail sector, is that they want hydrogen everywhere. They don’t know where to go. .” We’ll want it, but they want it there when they need it, and they don’t want the inconvenience or the range fear of trying to hunt for hydrogen. And that means putting in a lot of stations if you don’t. There are a lot of vehicles on the road and those stations don’t work efficiently,” explains Charlie Freese, head of GM’s fuel cell program.
