LOS ANGELES --- Proponents of two emerging green technologies --- hydrogen fuel cells and plug-in electric hybrids --- are squaring off in an increasingly tense battle, according to a report in the Los Angeles Times. They are competing for publicity, manufacturer acceptance, favorable regulation and funding for research and investment. This competition is growing more fierce as the technologies move closer to commercial readiness. The stakes are so much higher now, and both sides are arguing that their technology is the most commercially viable. At stake is more than $2 billion in federal funding over the next five years. Fuel-cell vehicles use hydrogen to generate electricity to power the car. Fuel-cell vehicles emit only water. But some plug-in hybrid proponents argue that producing hydrogen requires three to four times more energy than the hydrogen later generates in the fuel cell, the Times reported. These critics also contend that fuel-cell vehicles are too expensive and that hydrogen molecules can't be easily contained without the use of energy-using compressors or maintaining them in liquid form at very low temperatures. On the other hand, some fuel-cell technology backers argue that plug-in battery technology isn't advanced enough for long-range driving and that a national fleet of plug-in vehicles would overload the electric infrastructure. Meanwhile, automakers are taking steps to invest in both technologies. The Bush administration has favored fuel cells. In the president's 2003 State of the Union address, he called for a national commitment to fuel cells and pledged $1.2 billion for the first five years of a 10-year development program. For 2007, the Energy Department budgeted $195.8 million for hydrogen fuel cell technology research and development, compared to just $50.8 million for hybrid and electric propulsion, the Times reported.