Hydrogen is a clean-burning fuel, and when combined with oxygen in a fuel cell, it produces heat and electricity with only water vapor as a by-product. But hydrogen does not exist freely in nature: it is only produced from other sources of energy, so it is often referred to as an energy carrier, that is, an efficient way to store and transport energy.
Hydrogen can be made directly from fossil fuels or biomass, or it can be produced by passing electricity through water, breaking the water into its constituent components of hydrogen and oxygen. Some envision a future "hydrogen economy," where hydrogen is produced from a variety of energy sources, stored for later use, piped to where it is needed, and then converted cleanly into heat and electricity.
Most hydrogen production today is by steam reforming natural gas. But natural gas is already a good fuel and one that is rapidly becoming scarcer and more expensive. It is also a fossil fuel, so the carbon dioxide released in the reformation process adds to the greenhouse effect. Hydrogen has very high energy for its weight, but very low energy for its volume, so new technology is needed to store and transport it. And fuel cell technology is still in early development, needing improvements in efficiency and durability. The challenges NREL researchers are working on to help make a hydrogen economy a reality include:
- Fuel Cells — Improving fuel cell technology and materials needed for fuel cells.
- Production — Developing technology to efficiently and cost-effectively make hydrogen from renewable energy sources.
- Storage — Developing technology to efficiently and cost-effectively store and transport hydrogen.
For more basic information on fuel cells, see the U.S. Department of Energy's fuel cells fact sheet.
Also see the U.S. Department of Energy's Fuel Cell Technologies Office.