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What Is the Truth About Hydrogen Generators?

Hydrogen power has often been touted as an alternative fuel for a post-fossil fuel future. While hydrogen has some advantages as a means to store energy, it also suffers from a variety of limitations as well.

  1. Significance

    • All water on Earth contains hydrogen; the molecular formula for water is H2O, meaning that each molecule of water has two atoms of hydrogen and one of oxygen. Consequently, hydrogen will never be in short supply. Splitting water to release hydrogen, however, requires energy input--there is no such thing as a free lunch in nature.

    Function

    • Hydrogen generators typically work by splitting water through electrolysis. The chemical reaction for electrolysis is the reverse of the combustion reaction for hydrogen. Burning hydrogen fuel combines hydrogen and oxygen to form water and releases energy. Splitting water, on the other hand, releases hydrogen and oxygen and consumes energy.

    Misconceptions

    • The laws of thermodynamics dictate that energy can neither be created nor destroyed, the disorder of a closed system must always increase, and no heat engine can operate at 100 percent efficiency. It follows from the laws of thermodynamics that there is no way to split water into hydrogen and oxygen, then recombine them and end up with more energy than you had in the beginning. A hydrogen generator will always take as much if not more energy to make hydrogen than will be released by burning the hydrogen it produces.

    Potential

    • Just because the energy input for a hydrogen generator is greater than the output doesn't necessarily mean that hydrogen is an impractical fuel. The key question is the source of energy used to power the hydrogen generator. If solar energy is used to power the hydrogen generator (e.g., through a photovoltaic cell), then the hydrogen generator becomes a way to store sunlight as fuel. The practicality of this kind of energy generation depends on the efficiency of production, the infrastructure for hydrogen storage and transportation, and the availability of cars that use hydrogen as fuel--all subjects of intense ongoing research as of 2010.

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