Honda’s guide to how the technology in its hydrogen fuel cell production vehicle – the FCX Clarity – works.
“Fuel cell cars, which run on electricity produced from compressed Hydrogen, emit zero harmful emissions and could be the future of motoring. They can be just as fast, practical, and can travel as far as a conventional petrol or diesel engine car, but the technology is very different. And importantly, the only thing that comes out of the exhaust is water vapor.
Rather than having a petrol or diesel tank like a conventional car, the fuel cell car has a tank that stores compressed Hydrogen as a gas. Hydrogen is used as an energy carrier, so that the fuel cell car can produce its own electricity on-board, rather than storing it in batteries.
This compressed Hydrogen is expanded and then fed into the fuel cell stack. The fuel cell stack is like a tiny electric power station. Inside it, the Hydrogen combines with Oxygen from the air to generate electricity and water as a byproduct. Water vapor is the fuel cell car’s only emission.
The electricity created inside the fuel cell stack is used to power the electric motor, which is, in turn, used to drive the car. The fuel cell stack is made up of hundreds of individual cells stacked together like a loaf of bread. In fact, each cell is like a sandwich, with a Membrane Electrode Assembly (or MEA) between two separators (or Bi-Polar plates). The MEA is made up of a Proton Exchange Membrane, or PEM, which sits between Hydrogen and Oxygen electrode layers and gas diffusion layers.
In each cell, Hydrogen gas passes over the Hydrogen electrode. Each Hydrogen atom is converted into a Hydrogen ion in a catalytic reaction, releasing an electron in the process. The Hydrogen ions then pass through the electrolytic membrane, where they bond with Oxygen ions straight from the atmosphere. The previously emitted electrons from the Hydrogen molecules arrive at the Oxygen electrode via an external circuit. The released electrons create a flow of direct electrical current in the external circuit, and water is generated at the Oxygen electrode as a byproduct. This water is drained from the system and exits the car as water vapor via the exhaust.
Because the electricity is generated from Hydrogen and Oxygen, no Carbon Dioxide or other pollutants are emitted from the car. It’s the ultimate in clean performance.
Honda’s FCX Clarity is the world’s first production fuel cell car and is already on sale in the US and Japan.”