The three problems standing in the way of a full blown hydrogen economy are:
- Hydrogen creation
- Hydrogen storage
- Hydrogen usage (fuel cells)
I recently stumbled upon two interesting articles that address the former two.
Borrowing from two different research areas that he’s pursued over his career, Sandia researcher Rich Diver (6218) has invented a whole new way to make hydrogen to power automobiles and homes.
His invention, the Counter Rotating Ring Receiver Reactor Recuperator (CR5, for short), splits water into hydrogen and oxygen, using a simple, two-step thermochemical process.
The CR5 is a stack of rings made of a reactive ferrite material, consisting of iron oxide mixed with a metal oxide such as cobalt, magnesium, or nickel oxide. Every other ring rotates in opposite directions. Concentrated solar heat is reflected through a small hole onto one side of the stack of rings. The side of the rings in the sunlit area is hot, while the other side is relatively cold. As the rotating rings pass each other in between these regions, the hot rings heat up the cooler rings, and the colder rings cool down the hot rings. This arrangement results in a conservation of heat entering the system, limiting the energy input required from the sunlight.
Steam runs by the rings on the cooler side causing a chemical reaction to take place, allowing the ferrite material to grab oxygen out of the water, leaving the hydrogen. The hydrogen is then pumped out and compressed for use.
Rich envisions fields of large mirror dish collector systems making hydrogen, which would be stored and sent to stations where hydrogen-electric hybrid vehicles could “fill up.”
Imagine this: your fuel gauge is hovering near empty. You stop by the nearest store, turn in your empty hydrogen cartridge, buy a full one and pop it into your car. Presto, you’re on your hydrogen-powered way again, emitting just the faintest traces of water out the tailpipe.
Single-walled carbon nanotubes are essentially a one-atom-thick layer of carbon rolled into a tube. All the carbon atoms are on the surface, allowing easy access for bonding. The carbon atoms have double bonds with each other. The incoming hydrogens break the double bonds, allowing a hydrogen to attach to a carbon while the carbon atoms renew their grip on each other with single bonds. The carbon nanotubes offer safe storage because the hydrogen atoms are bonded to other atoms, rather than freely floating as a potentially explosive gas.
The researchers estimated that five percent of the total weight of the hydrogenated nanotubes came from the hydrogen atoms, and they are already working to boost that number. For its FreedomCAR program, the Department of Energy has set the goal of developing a material that can hold six percent of the total weight in hydrogen by the year 2010. Because hydrogen is the lightest element, the storage material also needs to be light—as is carbon—to hold a high percentage of hydrogen by weight.