As of 2010, hydrogen is growing in popularity as a promising sustainable alternative fuel source. Research continues toward determining whether hydrogen fuel can reverse the effects of decades of continued fossil fuel use. The global auto industry is designing and manufacturing hybrid vehicles since hydrogen is a burnable fuel for internal combustion engines. Hydrogen fuel cells combine with oxygen drawn from the air, producing energy to run the engine and emitting only water from the tailpipe. Ultimately, what the long-term impact of the use of hydrogen as a global fuel has on plants, animals, soil, water and humans remains speculation. Known consequences of hydrogen affecting the planet’s atmosphere come from research completed by California Institute of Technology, or Caltech, in 2006. According to the study, the results of anticipated leakage of hydrogen from vehicles, hydrogen manufacturing and transport of the elemental gas is not all good news for the planet. The Caltech scientists view the study as a means to identify potential environmental issues before they happen.
Atmosphere - Research estimates emissions into the atmosphere growing from 60 to 120 trillion grams a year by replacing fossil fuel with hydrogen globally. The Caltech research approximates this is four to eight times the hydrogen human actions normally release into the air. Further study results determine continued use of hydrogen as the replacement for fossil fuel will double or triple the normal impact on the atmosphere. These figures remain uncertain until scientists gain more understanding of the effects of using hydrogen as an energy source.
Ozone - Estimates from the Caltech study of potential hydrogen fuel effects on the planet's atmosphere show a 10 percent decrease in the ozone from the inevitable leaks. With moisture buildup from hydrogen combining with oxygen, the upper atmosphere cools, causing indirect destruction of the ozone. Increased hydrogen fuel emissions adding moisture to the stratosphere may raise the rate and size of polar stratospheric clouds and aerosols. These both lead to ozone reduction.
Greenhouse Effect - A 2006 British science study names hydrogen an indirect greenhouse gas. According to the European Commission DG Environment News Alert Service, the research concludes emissions from a global change to hydrogen energy produce an increase in methane and ozone global warming gases. This research is another example of the diversity of the potential effects hydrogen energy brings to the environment and adds to the growing support among scientists of the need for further studies.