How do fuel cell cars work?

Fuel cell vehicles use a completely different propulsion system compared to conventional vehicles, and are generally two to three times more efficient. Unlike conventional vehicles, the fuel cell vehicles produce zero harmful exhaust emissions. The only emission is water through the exhaust and are powered with hydrogen which is abundant in our nature. Also, these vehicles qualify for alternative fuel tax credits though there are not many commercial models on the market just as yet. It is expected that in the next few years, the fuel cell vehicles will be commercially available on the market.

How do they work?

Just like electric vehicles, fuel cell vehicles use electricity to power motors located near the vehicle’s wheels. However, the difference is that fuel cell vehicles produce their primary electricity using a fuel cell which in turn is powered by hydrogen filled tanks.

The most common type of fuel cell for vehicle applications is the polymer electrolyte membrane (PEM) fuel cell. In a PEM fuel cell, an electrolyte membrane is sandwiched between a positive electrode (cathode) and a negative electrode (anode). Hydrogen is introduced to the anode and oxygen to the cathode. The hydrogen molecules travel through the membrane to the cathode but not before the membrane strips the electrons off the hydrogen molecules.

The electrons are forced to travel through an external circuit to recombine with the hydrogen ions on the cathode side, where the hydrogen ions, electrons, and oxygen molecules combine to form water. The flow of electrons through the external circuit forms the electrical current needed to power a vehicle. The water is a by product and can be emitted from the vehicle exhaust.

In terms of the hydrogen supply to power the fuel cell vehicles, the gas can be stored directly on the vehicle or extracted from a secondary source such as methanol, ethanol, or natural gas. These secondary fuels must first be converted into hydrogen gas by an onboard device called a reformer. Fuel cell vehicles fueled with pure hydrogen emit no pollutants, only water and heat. Vehicles that use secondary fuels and a reformer produce only small amounts of air pollutants.

Fuel cell vehicles can be equipped with other advanced technologies to increase efficiency, such as regenerative braking systems (such as those in hybrid cars), which capture the energy lost during braking and store it in a large battery.

In addition to lower or zero emissions, other benefits include increasing U.S. energy security and strengthening the economy. As these vehicles get cheaper to manufacture, the cost of owning one should also drop significantly. Honda has a fuel cell vehicle called FCX which is currently available only for fleets though there is talk that soon it will be commercially available for individuals. One of the barriers to the fuel cell cars is that most gas stations are ill equipped to handle the refilling of hydrogen tanks.