Hydrogen technology includes a number of applications that use hydrogen as an energy source. Hydrogen can potentially be used in place of conventional fossil fuels to power cars, heat buildings, and supply them with power, and also in newer developments like energy storage. Hydrogen gas is a clean-burning fuel that produces energy and water as the products of its combustion. More often, though, fuel cells make use of a chemical reaction between hydrogen and oxygen to produce electricity. Hydrogen technologies can include any of these applications or refer to broader fields such as hydrogen production, transportation, and delivery.
One type of hydrogen technology, called a fuel cell, can be used to power automobiles, public transit vehicles, and buildings. Fuel cells produce electricity as the main product and water and oxygen as by-products. Conventional fuels such as gasoline and coal generate heat energy, which drives an engine's pistons or a power plant's turbine. Fuel cells increase efficiency because they produce electricity directly and lose much less energy through heat loss. They also dramatically reduce the production of pollutants like carbon dioxide and particulate matter, which lower air quality.
A hydrogen fuel cell basically contains two chambers, one holding hydrogen and one holding oxygen. The chambers are divided by a membrane. The membrane diverts the hydrogen's electrons, which would otherwise cross the membrane, through an outside circuit. In the case of car, this circuit would run to an electric motor, supplying the car with electric power. The electrons then return to the other chamber and are eventually released in water molecules.
Hydrogen technology is also seen as an effective method of energy storage. It may be used in combination with conventional power sources, such as coal, or newer energy alternatives like wind or solar power. Hydrogen could be stored as gas to even out wind and solar power production, which can't be counted on to produce electricity on calm or cloudy days. Conventional power plants could use hydrogen technology to store power for days when the demand for electricity is highest.
Due to the potential of hydrogen technology to heat buildings and power homes as well as cars, some see the possibility of a hydrogen-based energy economy. Such a system would require newer methods of transportation and storage, as well as fueling stations for cars that use hydrogen as their power source. This is because, as a gas, hydrogen will likely need to be compressed or condensed in order for it to be stored or transported.