Gerardine Botte, an Ohio University professor, sees the liquid as a solution thanks to the particular composition of its major component, urea. Its make-up, a 2-to-1 ratio of hydrogen and nitrogen, is convenient because hydrogen can be extracted from nitrogen using much less electricity than that needed to, say, pull apart hydrogen and oxygen. (It's a matter of 0.037 Volts versus 1.23 Volts, if you really need to know.)