Hydrogen is the most abundant element on the earth. It is a prime component in water, and can be found in almost every natural compound on the planet. Furthermore, hydrogen has the potential to release impressive amounts of energy. In fact, one of the most destructive weapons ever created—the hydrogen bomb—has a blast equivalent of up to 12,500 tons of TNT!
Thankfully, the energy harnessed from hydrogen can do more than just lay cities to waste. Hydrogen fuel cell technology is gradually becoming more than just a theoretical form of eco-friendly, fuel-efficient transportation. Many experts agree that hydrogen powered cars will be available to the general population within the next 20 years or so.
To get a better idea of how a hydrogen fuel cell works, you need to know a little chemistry, as well as some mechanics.
The Hydrogen Atom
Composed of one proton and one electron, hydrogen is the simplest element on the earth. Consequently, hydrogen is very easy to manipulate, pull apart, or combine with other elements and compounds, making it both plentiful and useful for fuel cell technology. When hydrogen is run through a fuel cell, the fuel cell effectively breaks apart hydrogen molecules into 2 positively charged hydrogen ions, and a negatively charged electron stream. This steady stream of electrons is what produces electricity and powers the car.
A fuel cell is essentially a hydrogen powered battery: it contains a positive port, a negative port, and a fuel that, under the right circumstances, produces electricity. While there are several different kinds of fuel cells in development, the type of fuel cell used in cars is called a polymer exchange membrane, or PEM. This compact fuel cell is composed of four main components:
- Anode: The anode is negatively charged and conducts electrons through the car’s circuitry system.
- Cathode: The cathode is the positively charged electrode involved with combining the electrons and hydrogen ions with oxygen molecules to form water.
- Membrane/Electrolyte: Resembling plastic wrap, this special material only conducts positively charged ions; it allows hydrogen ions to pass through the fuel cell but forces the electrons to go around.
- Catalyst: Often composed of platinum particles on a very thin cloth, the catalyst is responsible for initiating the chemical reaction between the newly formed hydrogen molecules (H2) with the oxygen molecules (O2) found in the cathode.
- H2 molecules are pumped into the anode, while O2 molecules are pumped into cathode.
- The fuel cell’s membrane then separates the H2 molecules’ electrons from the protons, creating hydrogen ions and the electron stream.
- While the hydrogen ions are permitted to pass through the membrane and directly into the cathode, the electrons are forced around the membrane and into the car’s electric system.
- The electrons reunite with the hydrogen ions in the cathode to form H2 molecules.
- The catalyst then sparks a chemical reaction between the newly formed H2 molecules and the O2 molecules already in the cathode to produce water, which then exits the fuel cell in the form of steam.
While many hydrogen powered cars are still in the concept phase, manufacturers are confident that fuel cell technology will provide an efficient alternative to fossil fuels in the near future. As fuel cells become more streamlined and dependable, and less costly, they will help lower America’s dependence on foreign oil. And because hydrogen powered cars release steam as exhaust, fuel cell technology can also help the environment by cutting down on harmful airborne toxins, such as carbon monoxide.
The idea that a fuel cell can run on hydrogen, produce electricity, and emit only steam seems like something straight from a futuristic science fiction novel. But take a look at the simple chemistry and mechanics behind the technology and you’ll see that the future is not all that distant.
Image credits: Fallschirmjäger/Wikimedia Commons.