The 2016 Toyota Mirai hydrogen fuel cell car has gone on sale in California but faces stiff odds odds against it’s success, particularly over the few number of outlets where it can refuel and the cost of providing hydrogen infrastructure.
But few doubt the green credentials of the car, at least with respect to what comes out of the exhaust pipe.
The Mirai is basically an electric vehicle with the fuel cell charging the battery.
Electricity is generated in a fuel cell through a chemical reaction between the hydrogen fuel and oxygen. Hydrogen is supplied to the anode, or negative, electrode and ambient air to the cathode.
Toyota explains the technology on its UK blog
The fuel cell as a whole is made up of individual cells within a membrane electrode assembly (MEA) that are sandwiched between separators. The MEA consists of a polymer electrolyte membrane with positive and negative catalyst layers on either side. Each cell produces less than one volt of electricity, so hundreds of cells are connected in series to produce the required output voltage. As a whole, the combined body of cells is called a stack, or more commonly, the fuel cell unit.
A fuel cell can use almost any hydrocarbon but hydrogen’s advantage is its high energy efficiency, with the potential to convert 83% of the energy in a hydrogen molecule into electricity.
The hydrogen hydrogen reacts within the fuel cell to produce electricity to charge the battery. Leftover hydrogen ions combine with oxygen to produce water, – the Mirai’s only exhaust, which Toyota brags is safe to drink.
The video below explains in more how the system works.
The Mirai has a range of just over 500 kilometres on a full tank of hydrogen.
California is the only US state where individuals can purchase the vehicle and Toyota has sold just sold 34 units there, but has big plans.
“Our goal is to produce 30,000 units annually by 2020,” said Mirai’s chief engineer Yoshikazu Tanaka in an interview. “Further cost reduction is necessary to make the technology affordable and accessible.”
Bill Condie is a science journalist based in Adelaide, Australia.
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