Honda has rolled out a limited number of mid-sized sedans running on a hydrogen fuel-cell stack, an impressive bit of technology that misses being ready for prime time, partly because you can’t just ease into a 7-Eleven and get a fresh load of hydrogen, but also because there being no actual hydrogen lying around in usable form, the current practice is to subject water to electrolysis, a process requiring a pretty fair amount of electricity, which is not getting any cheaper.
Gerardine Botte of Ohio University may now have found the answer, using an electrolytic approach to produce hydrogen from urine the most abundant waste on Earth at a fraction of the cost of producing hydrogen from water.
How it works:
Urine’s major constituent is urea, which incorporates four hydrogen atoms per molecule importantly, less tightly bonded than the hydrogen atoms in water molecules. Botte used electrolysis to break the molecule apart, developing an inexpensive new nickel-based electrode to selectively and efficiently oxidize the urea. To break the molecule down, a voltage of 0.37V needs to be applied across the cell much less than the 1.23V needed to split water.
I had to look at the molecular structure to make sense of this. The hydrogen atoms in a molecule of urea are bonded to nitrogen atoms (in the two NH2 groups), and nitrogen has substantially less electronegativity than does the oxygen in good old H2O, making for a weaker bond.
And, let’s face it, we’re never going to run out of urine.