What Is a Hydrogen Fuel Cell?

A hydrogen fuel cell converts chemical energy stored by hydrogen fuel into electricity.

In many ways, fuel cells are like regular batteries that you might find in a car or in a portable electronic device like an MP3 player. However, there are some important differences between batteries and fuel cells. The first fuel cells were invented in 1838. The first commercial use of fuel cells came more than a century later, in the National Aeronautics and Space Administration (NASA) space programs to generate power for satellites and space capsules. Since then, fuel cells have been used in many other applications.

Like a battery, a fuel cell with a supply of hydrogen and oxygen can be used to power devices that use electricity. While both batteries and fuel cells convert chemical energy into electrical energy, batteries store this chemical energy inside the battery itself. This means that a battery will run down, or need recharging, when there is no longer enough stored chemical energy available to produce sufficient electricity to power the device connected to the battery.

Rather than storing chemical energy inside itself, a hydrogen fuel cell receives a supply of chemical energy from outside the fuel cell itself. This chemical energy is stored in the hydrogen that is supplied to the fuel cell. This hydrogen can come from water or from splitting hydrogen cells from carbon-based fuels. A hydrogen fuel cell essentially consumes hydrogen and oxygen. When a fuel cell is continuously supplied with hydrogen and oxygen, and the water that is produced in the reaction is removed, the fuel cell can generate electricity.

Hydrogen fuel cells and batteries are both electrochemical cells. They each have two electrodes in contact with a material that can conduct ions, called an electrolyte. One electrode is the anode and the other is the cathode. In a hydrogen fuel cell, electrons are released from the hydrogen that is supplied to the anode, which differs from a battery where the electrons are released from the material in the anode itself. In a regular battery, the battery electrodes actively participate in the conversion of chemical energy to electrical energy; over time this can have a damaging effect on the electrodes and on the effectiveness of the battery. However, unlike in regular batteries, the electrodes in hydrogen fuel cells are relatively stable since they act as catalysts in the release or acceptance of electrons and are not chemically changed during this process.

When pure hydrogen is used as fuel, the only by-products generated from the fuel cell are pure water and heat. This makes fuel cells potentially very efficient devices with minimal environmental impact. Often both by-products can be used. For example, the heat can be used wherever a heat supply is needed. Fuel cells have been used in NASA spacecraft since the Gemini program in the 1960s, and even today they provide electricity and drinking water for astronauts on space shuttle flights.

Because hydrogen does not occur naturally in the environment, hydrogen fuel must be derived from other substances that contain hydrogen, such as methanol, gasoline, natural gas, and water. Most hydrogen that is produced today comes from natural gas.

If hydrogen is made from water, the only byproduct is pure water. If fossil fuels are used as the original source of hydrogen, there will be more by-products, such as carbon dioxide. When hydrogen is produced from water, electricity is used to split the water molecule. If that electricity comes from a renewable energy source such as wind or solar power, then the resulting hydrogen is a renewable, zero-emission fuel.

To learn more about Hydrogen Fuel Cell Safety visit our Hydrogen Fuel Cell Safety Online Training web page.