Fuel Cell Electric Vehicles
Fuel cell electric vehicles, also known as FCEVs, are powered by hydrogen and have the potential to revolutionize our transportation system. They are more efficient than conventional internal combustion engine vehicles and produce no harmful tailpipe exhaust—they emit water vapor and warm air. Fuel cell vehicles and the hydrogen infrastructure to fuel them are in an early stage of deployment. The U.S. Department of Energy is leading government and industry efforts to make hydrogen-powered vehicles an affordable, environmentally friendly, and safe transportation option. Hydrogen is considered an alternative fuel under the Energy Policy Act of 1992 and qualifies for alternative fuel vehicle tax credits.
What is a fuel cell electric vehicle?
FCEVs use a completely different propulsion system than conventional vehicles and can be two to three times more efficient. Unlike conventional vehicles, they produce no harmful exhaust emissions. Other benefits include increasing U.S. energy security and strengthening the economy.
FCEVs are fueled with pure hydrogen gas stored directly on the vehicle. The vehicles can be fueled with pure hydrogen and they emit no pollutants, only water and heat. Similar to conventional vehicles, they can fuel in less than 10 minutes and have a driving range of around 300 miles. FCEVs can be equipped with other advanced technologies to increase efficiency, such as regenerative braking systems, which capture the energy lost during braking and store it in a battery. Major auto original equipment manufacturers are offering production vehicles to the public in certain markets starting in 2014 and 2015.
How Fuel Cell Vehicles Work
Like battery electric vehicles, fuel cell electric vehicles use electricity to power a motor located near the vehicle's wheels. In contrast to other electric vehicles, fuel cell vehicles produce their primary electricity using a fuel cell powered by hydrogen, rather than drawing electricity from a battery. During the vehicle design process, the vehicle manufacturer controls the power of the vehicle by changing the fuel cell size and controls the amount of energy stored on board by changing the hydrogen fuel tank size. This is different than a battery electric vehicle where the amount of power and energy available are both closely tied to the battery size.
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 (usually from air) to the cathode. The hydrogen molecules break apart into protons and electrons because of an electrochemical reaction in the fuel cell catalyst. Protons, travel through the membrane to the cathode.
The electrons are forced to travel through an external circuit to perform work (providing power to the car) then recombine with the protons on the cathode side, where the protons, electrons, and oxygen molecules combine to form water. See the fuel cell animation to learn more about the process.