Environmental Concerns
One of the benefits of hydrogen fuel is the reduction of greenhouse emissions. Greenhouse gases trap heat waves that are reflected by the earth and contribute to global warming. Greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxides, ozone and CFC’s. Hydrogen as a fuel produces virtually no emissions. When pure hydrogen is fed into a fuel cell vehicle, the only by-product is water vapor. In a combustion engine, small amounts of nitrogen oxides can be produced as well due to the high temperature of the reaction.
Comparing the performance of hydrogen and gasoline can be problematic because hydrogen is a gas at room temperature. For this reason, comparisons are often made based on energy equivalence. A gallon of gasoline and a kilogram of hydrogen both contain about 120 megajoules of energy. When used in a fuel cell, hydrogen is 2.4 times more efficient than gasoline used in an internal combustion engine. The average internal combustion engine car gets about 27 miles to the gallon. A hydrogen fuel cell vehicle gets about 65 miles per kilogram.
While carbon dioxide is not directly produced by hydrogen vehicles, some carbon dioxide is emitted in the production of the hydrogen.
| Production Method | Kg CO2/Kg H2 |
|---|---|
| Coal Gasification | 19 |
| Gas Reformation | 17.6 |
| Electrolysis-Grid | 12 |
| Electrolysis-Renewable | 0 |
Table 1 – Carbon Dioxide emissions
National Research Council (U.S.), Committee On. The Hydrogen Economy : Opportunities, Barriers, and R&D Needs. New York: National Academies P, 2004.
The ideal production method would be electrolysis using renewable energy sources because it would completely eliminate carbon dioxide emissions.
