So you have converted your old Ford Taurus into a clean, hydrogen-powered vehicle, and now you are looking for a convenient way to generate your own hydrogen? According to a team of scientists in France, help may be on the way.
Okay, so you probably didn't alter a car to run on hydrogen-and if you did, why would you choose a Ford Taurus? Nevertheless, a more efficient means of hydrogen production could open up a series of other advancements in energy technology.
Production of hydrogen for rocket propellant or fuel cells has some significant drawbacks at the commercial scale. Conversion of methane is the typical method, which is a bit of an environmental tradeoff-hydrogen for fuel cells is produced, but the methane conversion process produces significant carbon dioxide. An alternative method is to split water into its hydrogen and oxygen components, but this process requires very high temperature and thus uses large amounts of energy.
The French team is looking for a way to expedite methods that naturally produce hydrogen. One such method involves the mineral olivine, a form of magnesium iron silicate with a typical greenish-yellow color. Under high pressure in the presence of water, olivine will react with the oxygen present in the water molecules, releasing hydrogen as a result. However, under natural deep-water conditions the conversion process can take weeks.
The research team reasoned that aluminum would act as a catalyst and allow efficient hydrogen production at a much lower temperature. Using a diamond anvil cell (a small high-pressure vessel), the team reacted olivine with water for 24 hours from between 200 to 300°C at two kilobars of pressure in the presence of aluminum oxide. The resulting production of hydrogen was anywhere from seven to fifty times quicker than the typical process.
What happens to the olivine? The resulting mineral is known as serpentine-named for its greenish-brown, scaly surface that resembles snakeskin. As reaction byproducts go, this is relatively benign.
The French team's work was published this summer in American Mineralogist, and they also presented their results at the 2013 Fall Meeting of the AGU (American Geophysical Union) in San Francisco.
While olivine and aluminum (and, of course, water) are readily available, scaling a process like this will take further advancements. It's still an improvement over the natural process, and the overall process should be more efficient than methane conversion, but a means of applying the required temperature and pressure in a low-carbon or carbon-free process on a commercial scale remains many years away.
Granted, you won't be reacting olivine in a diamond anvil cell to power your Ford Taurus anytime soon. But the principle of accelerating natural methods of hydrogen production is attracting continued research, and this research focuses on the desired path of overall cleaner energy-not only in devices, but also in the cleaner generation of fuel for the devices. Higher demand for fuel cells over time should drive the economics of a cleaner, scalable hydrogen production process in the right direction.