New technological breakthrough allows a smaller tank to be used for methane powered vehicles. Current use is usually confined to large mass transit vehicles that have sufficent space for a large fuel tank. Growing up, a friend of mine's Dad had a large methane powered cargo van. The tank on it took up an area equivalent to a row of seats. Methane molecules don't compress well, so methane storage tanks are usually under pretty high pressure. The new technology utilizes an interesting resource to allow a storage method under lower pressures.
"The goal of Pfeiffer’s research was to develop a way to hold the natural gas at lower pressures, which would shrink tank sizes. To do this, Pfeiffer developed a way to transform corncob waste into carbon briquettes that act like a sponge to suck up and store natural gas at higher densities.
Tiny pores in the corncobs store the natural gas “in a way which makes the methane molecules very happy to be close to each other,” said Pfeifer. To transform the corncobs into briquettes, they are heated in the absence of air, essentially turning them into charcoal. Meanwhile, a chemical process “drills” extremely tiny holes and tunnels in the briquettes that can exert strong forces to hold the methane in place."
Obviously, corncobs are a pretty common resource, particularly in the Midewestern US. Other attempts to create such briquettes have focused on other agricultural products like coconuts and olive pits, but none have created the storage capacity that the corncobs have. The new tank stores methane at one-seventh the pressure and it is far smaller than a conventional natural gas tank, one which could easily fit inside a passenger vehicle. It should be noted that while methane burns more cleanly that gasoline, it has a far larger greenhouse effect when released into the atmosphere.