How A Hydrogen Filling Station Works

Turns out, it's just like a gas pump. Except for the parts where it isn't.

The funny thing about future tech, it turns out, is how remarkable it looks to present tech. Drive into a hydrogen filling station, and you'll be forgiven for noting just how normal it looks. Fuel pump. Touch-screen. Nozzle. Overhead lights under a canopy. In some cases, even a familiar Shell logo. The only thing that's missing is a guy selling cigarillos and bottles of Mountain Dew Baja Blast. With more stations coming online every year, and more hydrogen cars on the road, such as the Toyota Mirai, it's worth taking a look at how hydrogen gets into a fuel cell vehicle and out on the road.

Hydrogen usually arrives at a filling station the same way gasoline does: on a truck. But unlike gasoline, it can also be generated on site, by separating the element from water or natural gas. Hydrogen can also be transported via pipes, such as the 700 miles of pipeline that already exist in America.

If the hydrogen arrives in liquid form, it must first be converted into a gas before it can be used. Here, it passes through vaporizer towers that heat the liquid until it turns into gas.

Before hydrogen goes into your car, it must be compressed to high pressures—up to 10,000 pounds per square inch, or 700 bar. There are two standards for hydrogen compression: half-pressure H35 and full-pressure H70. Higher pressure translates into higher range: On a modern fuel cell vehicle such as the Toyota Mirai, for example, a full fill at H70 equals 312 miles of range,* which is on par with gasoline-powered vehicles.

*2017 EPA-estimated 67 city/67 highway/67 combined MPGe for Mirai and 312-mile driving range. Actual mileage will vary. Range measurement pursuant to SAE J2601 standards (ambient temperature: 20°C; hydrogen tank pressure when fueled: 70 MPa). Fueling time varies with hydrogen fueling pressure and ambient temperature.

The hydrogen sits in storage tanks, just like gasoline. The main difference here, however, is that these tanks are above ground, while gasoline is stored below ground, to the tune of thousands of gallons. (Funny, that—a University of Miami study showed that a gasoline leak and fire are far more devastating to a vehicle than a hydrogen leak.) Any leak in a storage tank means that hydrogen, which is lighter than air, simply vents away before it has the chance to combust.

To prevent expansion, and to maintain energy density while being pumped in at high pressures, hydrogen must be cooled through a heat exchanger before it passes through a pump. The cooling prevents the vehicle's onboarding tanks from overheating, speeding up fueling.

Finally, the hydrogen goes to your pump. This pump is just like your average gas station pump, except light-years ahead in computing power: With the ability to communicate with your fuel cell vehicle's onboard computer, it can determine temperature, tank pressure and fuel levels, then it does the rest by itself. All you have to do is lock the nozzle into place and wait. Fuel is measured in kilograms instead of gallons, which may take some time to wrap one's internally combusting head around. It takes just three to five minutes to fill up a car's hydrogen tank,* and all this time, your hydrogen driver won't realize all of the science, technology and engineering that have gone into delivering this hydrogen into your tank.

*Fueling time varies with hydrogen fueling pressure and ambient temperature.

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