A number of automakers recently announced plans to produce vehicles powered by hydrogen fuel-cell technology as an environmentally friendly alternative to traditional fossil-fueled vehicles. Honda, Toyota and Hyundai have thrown their name into the hat with the latter automaker expected to launch a fuel-cell version of the Tucson SUV in the spring of 2014.

Honda, meanwhile, said they plan to roll out a commercial fuel-cell vehicle in Japan and the US in 2015 followed by a European launch at a later date. It'll be based on Honda's FCEV concept car unveiled in Los Angeles on Wednesday with a range of more than 300 miles per full tank.

Toyota on Wednesday also revealed the FVC concept car in Tokyo with a large grill and other openings to allow cooling air and oxygen inside. Hydrogen fuel-cell cards generate electricity used to power the vehicle by combining hydrogen with the oxygen in the atmosphere. The only byproduct of such vehicles is water which comes out of the tailpipe. Toyota said their fuel-cell automobile will also go on sale sometime around 2015.

It's still unclear at this point which environmentally friendly technology will ultimately stick with consumers. Companies like Tesla are betting the bank that pure electricity will power vehicles of the future while other automakers like those listed here seem to think hydrogen fuel-cell technology is the way to go. Others still are content with hybrid gas / electric vehicles that offer the best of both worlds.