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 Hydrogen, a colorless, odorless chemical substance, is the most abundant element in the universe, and it has properties that make it an ideal medium for storing energy. Unfortunately it is not found free, it is always bonded to something. In order to use it, we need to separate it from the molecule to which it is attached. There are two ways that hydrogen is easily split from a larger molecule. Hydrogen can be separated from the oxygen atoms in water by a process called electrolysis. This means adding electricity to the water to split the molecule into its parts. The hydrogen is then captured and stored. If the electricity used for electrolysis comes from a renewable source, like photovoltaics, or wind power, then the hydrogen is also a renewable fuel.
The other way to get hydrogen is to split it off an organic molecule. Fossil fuels are organic molecules called hydrocarbons. Biomass is made up of organic molecules called carbohydrates. Either source can be put through a process called reformation that “cracks” the hydrogen atom free from the larger molecule. Presently, fossil fuels such as coal, oil or natural gas are the most common source for hydrogen. Using fossil fuels as a hydrogen source creates carbon dioxide emissions just like burning fossil fuels. Hydrogen derived from fossil fuel sources is not a renewable fuel. When hydrogen is made from renewable energy sources, such as photovoltaics, wind power or hydropower, it is an excellent example of a renewable fuel.
Hydrogen derived from either electrolysis or reformation can be stored in tanks until needed. The hydrogen is like a battery, storing energy for later use. Fuel cells can convert stored hydrogen into electricity. Fuel cells work by splitting apart the hydrogen atom into its electron and proton parts. The electrons will flow as electricity that can be used to power vehicles, homes or go into the power grid. When the electrons get back to the fuel cell they combine with the protons again and with oxygen from the atmosphere to make water and heat both of which can be captured and used. This process avoids the emissions and harmful byproducts associated with fossil fuels.
Hydrogen is a way to store energy in a useful form. The appeal of hydrogen is that it can be used much the same way we currently use fossil fuels. For example, it can be moved around in trucks, ships and pipelines, and stored like we currently store natural gas and gasoline. |
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