WEDNESDAY, MAY 18 AT 12:00PM - PACIFIC. Hydrogen has the highest chemical activity of any fuel, is 75% of known mass in the universe, and reacts with oxygen from our atmosphere to form water. As such, hydrogen has always been the fuel of choice for both high performance and clean energy applications. So why are we still using inferior fuels? Logistics. Although hydrogen is the best of fuels by many measures, it is also the worst of fuels when it comes to storage and transport.