Honda FCX Clarity
You know all about hybrids
. They’re everywhere. Nearly every manufacturer has at least one to offer, but there are other alternative fuel sources available today that are nearly as viable, and we're not just talking about electric cars. While compressed natural gas, biodiesel
and liquid petroleum gas are all options, hydrogen fuel cell vehicles are already cruising around in fleet service right now. That doesn’t mean they don’t have their drawbacks, but it does mean we may see more and more of these rigs on the street as time goes on and gas prices go up (again).
Germany's hydrogen bus
Honda's hydrogen fuel
Very soon there’s going to be a whole new encyclopedia of knowledge to brush up on when it comes to hydrogen fuel cell cars and the fuel itself. Fortunately, DriverSide is here to help. There’s some basic chemistry to muddle through, but we promise there won’t be a pop quiz afterward.
The Science of It All
As you may or may not remember from high school chemistry classes, hydrogen is the single most abundant element in the universe. It’s everywhere. Our sun is powered by hydrogen, as is just about every other star in the night sky. The element is also the most simple on the periodic table, comprised of just one proton and one electron. It’s also incredibly light when it’s by itself, which is why it is difficult to find hydrogen by its lonesome in our neck of the woods (it tends to float off and hang out in the upper reaches of our atmosphere). The good news is it bonds easily with all kinds of other elements, which means you can source hydrogen from everything from water to methane gas.
With three-quarters of the globe covered in water, it would be easy to surmise that this would be the best source of hydrogen around. It’s true that hydrogen can be separated from oxygen in water molecules through a process known as electrolysis, but the amount of energy required is substantial compared to the end result. Using electricity to generate hydrogen is costly, especially compared to a more popular method called steam reforming. In this method, steam reacts with methane gas to release hydrogen molecules from their carbon bonds in the methane. It’s cheap and easy, so it’s no surprise that steam reforming is responsible for most of the world’s hydrogen production.
Once on its own, hydrogen can be stored either as compressed gas or as a liquid, though for fuel cell purposes, compressed gas is the most common. Stored in a pressurized tank, hydrogen is usually measured in kilograms, where one kilogram is equated to around one gallon of gasoline, energy-wise. Once the fuel is on board a vehicle, it’s used to generate electricity. How? We’re glad you asked.
Typically, hydrogen is flows through channels near a negatively charged plate (called an anode) in the fuel cell. On the other side, air flows near a positively charged plate (called a cathode). In the middle, a polymer electrolyte membrane separates the two. Flowing through this set up causes the hydrogen molecules to lose their electrons and join with oxygen molecules, thereby creating electricity and water. The power goes either straight to a hydrogen fuel cell vehicle’s electric motor
, or gets stored in a battery – like in a normal gasoline-powered hybrid – while the water goes out of the car’s tail pipe. Just like that, you’ve got electricity from hydrogen.
Why Aren’t We Driving Hydrogen-Powered Cars?
Like we said earlier, hydrogen isn’t without its drawbacks. For one, fuel cells themselves are pretty pricey to generate. Also, vehicles are typically burdened by the same sort of battery restrictions current hybrids shoulder. Then there’s the issue of generating hydrogen. While the steam reforming method is cheap and easy, it also generates greenhouse gasses just like gasoline. The good news is that from the source straight to your car, hydrogen produces about half the emissions of its petrol brethren.
Aside from the price, hydrogen faces the hurdle of refueling stations. Right now there are fewer than 70 locations to top off your hydrogen tank nationwide. Compare that to 120,000 gas stations in America and you can see the problem. Currently, manufacturers are shy about building cars with no infrastructure to support them and filling stations aren’t interested in installing pumps no one will use. It’s the Catch-22 of new-age fuel.
That doesn’t mean hydrogen will pass the way of the dinosaur. There are several public transportation fleets nationwide that use the fuel as well as private fleets. Honda
released the FCX Clarity a few years ago, a hydrogen vehicle available for lease
in California for $600 for month. Will hydrogen take off as the next big fuel source or will electric cars grow to dominate the market? That depends on if other manufacturers will be willing to take the leap and build cars that rely on it.
Read more about green cars.