How do Fuel-cell Vehicles Work?

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When the Honda Clarity won the 2018 Green Car of the Year Award, it had an important advantage over the other candidates. Instead of offering one or two high-efficiency powertrains, the Clarity has three. Naturally, these include hybrid and plug-in hybrid systems. But the difference maker is the Clarity’s available fuel-cell powertrain.

According to Honda, “Vehicles like the Clarity Fuel Cell are potential game changers because they offer an uncompromising, zero emissions customer experience, with utility, range and refueling times on par with today’s gasoline-powered cars.”

And Honda isn’t the only automaker putting its support behind fuel-cell vehicles. The Toyota Mirai is on the road in certain California markets. General Motors also recently showed off a fuel-cell concept truck for military use. GM made it clear that fuel cells would be part of the electric future for everyday vehicles, too.

Before that happens, however, let’s take a quick look at some of the details behind fuel-cell technology.

Who Invented the Fuel Cell?

Welsh scientist William Robert Grove developed the first modern fuel cell in 1842. Although formally trained as a lawyer, Grove put his legal career on hold after passing the bar and followed his passion for physics. This included a particular interest in electricity. He invented a fluid-based battery in 1839 that directly led to the creation of the fuel cell.

Known as a “gas battery,” Grove’s fuel cell was a direct outcome of lab work: Imagine two popsicle sticks, each with one end dipped in the same container of liquid. The ends sticking out of the liquid are then enclosed in separate tubes. In Grove’s first gas battery, those sticks were platinum electrodes, the liquid was sulfuric acid, and the tubes contained hydrogen and oxygen. More importantly, the result was a constant flow of electricity between the electrodes.

Scientists of the time didn’t understand why that happened, though. That occurred some 50 years later.

(As for Grove, he also went on to invent one of the world’s first incandescent light bulbs. He eventually returned to law as well, serving as a judge on England’s Court of Common Pleas for more than 15 years.)

How Do Fuel-cell Vehicles Work?

It was Friedrich Wilhelm Ostwald who first worked out how fuel cells produce electricity. A pioneering German chemist, Ostwald revealed his findings in 1893. Basically, in both Grove’s gas battery and modern-day automotive fuel cells, hydrogen is the fuel.

The process begins when that fuel goes through the first electrode, or the “anode.” There, it meets with another chemical, called the “catalyst.” The catalyst affects the individual atoms of hydrogen. More specifically, it causes a reaction that separate electrons from the hydrogen atoms. The hydrogen atoms continue moving through the cell, but the electrons flow into the vehicle’s electrical system as electricity. Since the electrical system is a closed circuit, the electrons continue traveling until they’re back at the fuel cell.

(Also, it’s worth pointing out that each cell makes a fairly limited amount of electricity. Fuel cell vehicles actually rely on hundreds of small cells working together.)

Now, the hydrogen atoms are traveling on their path through the cell at the same time, and the system also is drawing in oxygen from the air. All three ingredients (hydrogen atoms, electrons and oxygen atoms) next come together with a second catalyst. At this point, a new chemical reaction occurs. It binds together all the separate particles into one molecule of hydrogen and oxygen. In other words, water.

The bottom line is that fuel-cell vehicles operate much like all-electric vehicles. What sets them apart is where the electricity comes from.

What are the Advantages and Disadvantages of Fuel-cell Vehicles?

With that in mind, the key benefits of both fuel-cell vehicles and electric vehicles are the same. Namely, they don’t burn fossil fuels, and they don’t release any harmful exhaust gases. Fuel-cell vehicles also match traditional cars in important ways for drivers. For example, the Clarity and the Mirai have EPA ranges of 366 and 312 miles, while they both can be completely refueled in about five minutes. The Chevrolet Bolt EV, by contrast, has a range of 238 miles. Then, to recharge the Bolt, it takes 30 minutes for 90 miles’ worth of range.

Yet cars such as the Bolt are more efficient than fuel-cell vehicles. Chevy’s new EV is rated at the equivalent of 128/110 mpg city/highway. The Clarity and Bolt compare at the equivalent of 66/68 and 66/66 mpg city/highway. Nor can you fill up fuel-cell vehicles by plugging them in at home, like you can with electric vehicles.

In fact, the lack of hydrogen filling stations might be the biggest hurdle for fuel cell vehicles to overcome. Consider: There are currently more than 16,500 public EV charging stations in the United States, but only about 50 locations for hydrogen fill-ups.

Just remember that both EVs and fuel-cell vehicles are only as green as the ultimate source of their power. For EVs, electricity often still comes from burning coal and other fossil fuels. With fuel cells, well, hydrogen may be the most common element in the universe, but it’s rarely found alone. Again, companies today usually rely on fossil fuels to separate hydrogen for cars such as the Clarity and Mirai.

By | 2018-06-19T15:49:27+00:00 April 9th, 2018|Technology|0 Comments

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