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Here's why hydrogen-fueled cars aren't little Hindenburgs

Lucas Mearian | Nov. 27, 2014
Hydrogen is explosive, but supply is a bigger issue for the nascent industry.

In fact, in the case of the hydrogen-filled Hindenburg, most of the fire and resulting devastation was the result of diesel fuel for the airship's engines and a flammable lacquer coating on the outside of the dirigible.

Today's hydrogen fuel tanks are also made from highly durable carbon fiber that is not only crash tested but shot at with bullets.

Toyota reached back to its roots as a loom manufacturer in the early 20th century to create its triple-layer, carbon fiber woven hydrogen tanks.

The tanks, which are plastic lined internally, underwent "extreme" crash and ballistics testing "to the tune of being shot with bullets that actually bounced off," Hartline said.

"They had to move to high-caliber armor piercing rounds to pierce the tank, and even then it had to be shot in the exact same spot twice with an armor piercing bullet," Hartline said.

The Mirai has other safeguards, including structural integrity to protect the tanks and electronic systems that are programed to shut down any hydrogen lines in the car if a leak is detected. "So there are redundancies upon redundancies," Hartline said. "We're not going to put anything on the road that doesn't meet our safety, quality and durability standards."

Hydrogen is the simplest and most common molecule known to exist, and because of that is almost part of another substance, such as water and hydrocarbons. Hydrogen is also found in biomass, which includes all plants and animals.

There are several methods for creating hydrogen fuel, but the most common nowadays is via steam-methane reformation, a process by which high-temperature steam (1,000 degrees Celsius) creates a reaction with methane gas in the presence of a catalyst to produce hydrogen, carbon monoxide, and a relatively small amount of carbon dioxide. The carbon dioxide and other impurities are then removed through a process called "pressure-swing adsorption," leaving essentially pure hydrogen. Steam reformation can also be used with ethanol, propane, or even gasoline to produce hydrogen.

Steam-methane reformation is most commonly used by oil refineries, which then use the remaining hydrogen to remove impurities, such as sulfur, from petroleum and diesel fuels.

Hydrogen can also be produced through electrolysis, or using electricity and a catalyst to create a chemical reaction that separates the hydrogen molecules from oxygen. Solar power can also be used in combination with water and a catalyst (typically a metal) to generate hydrogen fuel by splitting hydrogen molecules from oxygen. Most often, the catalystd are expensive metals, such as platinum (iridium).

"Making hydrogen from natural gas can be done relatively inexpensively," Kopasz said. "Hydrogen made from water electrolysis is a process we've known about for a very long time, but they're still working to bring the cost of that process down. The main cost now is the electricity, but the catalysts are expensive too."


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