With 5,000 hydrogen-powered cars on the road today, providers are still trying to fill in some technical potholes.
But the hope of clean, direct energy for personal transportation still thrives.
Sandia National Laboratories has teamed up with First Element, the largest American hydrogen retailer, to work on software models that will help refueling stations switch to liquid hydrogen.
Hydrogen would be a good way to fuel cars since its only emission is water vapor. It's also abundant.
But in the gaseous state, hydrogen isn't very dense and not much can be kept on site.
Liquid nitrogen could be pumped just like gasoline and even transported in a similar way. It would fit current gasoline models and could make more pumping stations feasible.
Software models will address storage concerns for liquid hydrogen, which must be kept at -423 degrees F. This makes leaks an issue since liquid hydrogen freezes the air when it escapes.