What they're really working on is developing vehicles that run on hydrogen. Used by NASA in the Apollo landings, hydrogen vehicles have been around since the 60s and 70s. The complex nature of obtaining and storing hydrogen leads to high costs, complicated technology, and high inputs of electricity and (already scarce) fresh water. Scientists are working on different ways to tap this power in safe, affordable, and sustainable ways.
Do you know what is not exactly scarce? Wastewater. 5 million tons of ammonia enter in the wastewater stream each year. Dr. Gerardine Botte of Ohio University has been working to develop ways to exact hydrogen from wastewater, specifically urine. Because of the high amounts of ammonia (made of one atom nitrogen and thee atoms hydrogen), it's a good candidate for hydrogen harvesting. Even better, Dr. Botte has found that ammonia in urine actually releases hydrogen more easily than clean water, because not as much energy/electricity has to be used to break apart the bonds.
Only five percent as much energy is needed to break the ammonia molecules apart, and because each molecule contains three hydrogen atoms, not two as in H20, more hydrogen is freed each time a molecule is split up. Less energy spent and more atoms freed makes extracting hydrogen from urine much cheaper than extracting it from fresh water -90cents for the energy equivalent of a gallon of gas vs. $7.10 for hydrogen electrolyzed from water, Botte says. And best of all, fuel cells provide clean energy, because when hydrogen and oxygen are combined to generate electricity, the only "exhaust" created by the process is water (which could be drunk to aid in the production of more urine). No greenhouse gasses are released at all.