Despite few fueling stations to support a fuel cell vehicle, Toyota is scheduled to release its Mirai FCV this fall. Will hydrogen cars hit the highways or remain a (tail)pipe dream?
Driving an electric vehicle (EV) has advantages over a regular gasoline-engine car. EVs are quiet and smooth and they deliver more torque. But battery-powered cars present a greater ideal: You can fuel them from household current, ideally supplied by an on-site PV array, to allow you to “dump the pump.”
A major drawback to pure EVs is their relatively limited driving range—about 85 miles per charge for the most popular electric cars like the Nissan Leaf. (Note: Upcoming models, like the Tesla Model 3 and the Chevrolet Bolt, are expected to get up to 200 miles per charge.) Despite the fact that the average U.S. motorist travels less than 40 miles a day, limited range keeps some consumers on the sidelines. And many apartment dwellers and others without a dedicated 240 V supply of electricity at their residence likely wouldn’t even consider an EV. These obstacles have pushed several car companies to pursue a different approach to tailpipe-emissions-free electric driving—cars powered by fuel cells.
From the outside, there’s no difference between a hydrogen fuel vehicle and a gas-powered car. But most hydrogen-powered cars toss away an internal combustion engine and replace it with electric-chemical components—a fuel cell and an electric motor, plus (usually) a high-output battery that can provide supplemental power to the motor.
Think of a fuel cell as a different kind of battery—one that is fed with reactants and spits out electricity. An internal combustion engine is similarly fed with gasoline or diesel, which gets burned or combusted. But with a fuel cell, nothing is burned. That’s why it’s more efficient. There are no combustion losses or wasted heat. Instead, it transforms a chemical form of energy (hydrogen and oxygen) into electrical energy.
Hydrogen gas stored in a tank travels through the fuel cell’s channel (or plates) until it hits a membrane covered with a platinum catalyst. It then splits apart into protons and electrons. The protons pass through, but due to the properties of the catalyst, the electrons can’t advance from the hydrogen side (the anode) to another plate on the other side containing oxygen (the cathode). So an electrical path is provided for them, handily routing them as electrical current to a motor. Meanwhile, on the cathode side, protons and electrons are reunited and, together with the oxygen, form water.
Hydrogen cars are essentially a different type of electric vehicle—one that uses electricity from the fuel cell for power. These vehicles are often considered hybrids, because they also have a small battery pack. That’s part of the vehicle’s efficiency strategy—like a Prius that uses a combination of gas and battery-derived energy, a car like the Toyota Mirai uses a blend of energy from both fuel cells and a battery pack.
Understanding what happens under the hood is less important than the driving experience. Fill up the tanks with about 300 miles’ worth of gaseous hydrogen. Jump behind the wheel, step on the accelerator, and the car quietly zips forward like an electric car, emitting only water vapor from its tailpipe.