What is hydrogen?
Did you know?
Hydrogen is the lightest element. Hydrogen is a gas at normal temperature and pressure, but hydrogen condenses to a liquid at -423° Fahrenheit
Hydrogen is the simplest element. Each atom of hydrogen has only one proton. Hydrogen is also the most plentiful gas in the universe. Stars like the sun consist primarily of hydrogen.
The sun is basically a giant ball of hydrogen and helium gases. In the sun's core, hydrogen atoms combine to form helium atoms. This process—called fusion—gives off radiant energy.
The radiant energy from the sun gives earth light and helps plants grow. Radiant energy is stored as chemical energy in fossil fuels. Most of the energy people use today originally came from the sun's radiant energy.
Hydrogen gas is much lighter than air, and it rises fast and is quickly ejected from the atmosphere. This is why hydrogen as a gas (H2) is not found by itself on earth. Hydrogen gas is found only in compound form with other elements. Hydrogen combined with oxygen, is water (H2O). Hydrogen combined with carbon forms different compounds like methane (CH4), coal, and petroleum. Hydrogen is found in all growing things. Hydrogen is also an abundant element in the earth's crust.
Hydrogen has the highest energy content of any common fuel by weight (about three times more than gasoline), but it has the lowest energy content by volume (about four times less than gasoline).
Hydrogen is an energy carrier
Energy carriers move energy in a useable form from one place to another. Electricity is the most well-known energy carrier. People use electricity to move the energy produced from coal, uranium, natural gas, and renewable energy sources in power plants to homes and businesses. For many energy needs, it is easier to use electricity than it is to use the energy sources themselves.
Hydrogen is an energy carrier like electricity, and it must be produced from another substance. Hydrogen can be produced from a variety of resources (water, fossil fuels, or biomass), and it is a byproduct of other chemical processes. Hydrogen is not widely used as a fuel now, but it has the potential for greater use in the future.
How is hydrogen made?
Because hydrogen doesn't exist on earth as a gas, it must be separated from other elements. Hydrogen atoms can be separated from water, natural gas molecules, or biomass.
The two most common methods used to produce hydrogen are steam reforming and electrolysis (water splitting).
Steam reforming is a widely used method of hydrogen production
Steam reforming is currently the least expensive method of producing hydrogen, and it accounts for most of the commercially produced hydrogen in the United States. This method is used in industries to separate hydrogen atoms from carbon atoms in methane (CH4). The steam reforming process results in carbon dioxide emissions.
Electrolysis uses electricity
Electrolysis is a process that splits hydrogen from water using an electric current. The process can be used on a small scale or on a large scale. Electrolysis does not produce any emissions other than hydrogen and oxygen. However, if the electricity used in the process is produced from fossil fuels, then there are pollution and carbon dioxide emissions indirectly associated with electrolysis. However, the electricity used in electrolysis can also come from renewable sources like wind and solar.
Other methods of producing hydrogen
Research is underway to develop other methods used to produce hydrogen. These methods include using microbes that use light to make hydrogen, converting biomass into liquids and separating the hydrogen, and using solar energy technologies to split hydrogen from water molecules.
Use of hydrogen
Nearly all of the hydrogen consumed in the United States is used by industry for refining petroleum, for treating metals, for producing fertilizer, and for processing foods.
Rocket fuel is the main use of hydrogen for energy
The National Aeronautics and Space Administration (NASA) is the largest user of hydrogen as a fuel. NASA began using liquid hydrogen in the 1950s as a rocket fuel, and NASA was one of the first to use fuel cells to power the electrical systems on space craft.
Hydrogen fuel cells produce electricity
Hydrogen fuel cells produce electricity by combining hydrogen and oxygen atoms. This combination results in an electrical current. Hydrogen fuel cells are efficient, but expensive to build.
There are many different types of fuel cells that can be used for a wide range of applications. Small fuel cells have been developed to power laptop computers, cell phones, and military applications. Large fuel cells can provide electricity for emergency power in buildings and in remote areas that do not have power lines. Hydrogen use in vehicles is a major focus of fuel cell research and development.
Hydrogen use in vehicles
The interest in hydrogen as an alternative transportation fuel is based on hydrogen's ability to power fuel cells in zero-emission electric vehicles, its potential for domestic production, and the fuel cell vehicle's potential for high efficiency.
There are about 500 hydrogen-fueled vehicles in use in the United States. Most hydrogen-fueled vehicles are buses and automobiles with an electric motor powered by a fuel cell. A few of these vehicles burn hydrogen directly. The high cost of fuel cells and the limited availability of hydrogen have limited the number of hydrogen-fueled vehicles.
The refueling challenge
There are about 40 hydrogen refueling stations for vehicles in the United States. About 12 are available for public use, nearly all of which are located in California. Production of hydrogen cars is limited because people won't buy hydrogen cars if there are no refueling stations, and companies won't build refueling stations if there are no cars and no customers. In May 2014, the California Energy Commission started a $46.6 million program to help fund the development of 28 publicly accessible hydrogen refueling stations in California to promote a consumer market for zero-emission fuel cell vehicles.