Sometimes quoted as the main component of a new and good hydrogen storage material, ammonia (NH3) could this time rival hydrogen in the race to fuel our vehicles – it could just be The solution to the fuel crisis. Since hydrogen is hard to transport and store, ammonia fills in that niche and makes up for a perfect fuel.
Although it’s highly toxic if swollen or inhaled, when burned, ammonia produces only nitrogen and water vapor, so it’s not harmful for the environment in any way (most of the air we breathe is nitrogen).
Two researchers from the Texas Tech University, Fleming and Tim Maxwell, have started building a system that could produce ammonia in gas stations and that’s no bigger than the size of a truck.
They used the Haber-Bosch process as their basis (through which ammonia is produced industrially), and slightly adapted it for being suited to mobile applications.
In their system, a piston rapidly compresses hydrogen and nitrogen, heating the gases to 400 °C. The mixture is fed into a chamber containing an iron oxide catalyst, which sparks a reaction that further heats the gases and generates ammonia. In a third chamber, the mixture decompresses and cools down to room temperature. As it does so, it pushes against another piston, from which mechanical energy is recovered and fed back to the compressor, significantly cutting the process’s power consumption.
Finally, a heat pump cools the mixture down to around -75 °C, liquefying the ammonia for collection.
Cars that already run on a gasoline-ethanol blend (the so-called “flex-fuel” vehicles) could be easily retrofitted to run on a blend of gasoline and ammonia. The researchers are already studying an engine called “the free piston engine” (we wrote an article on it back in 2008 – see the link) that could be made to run exclusively on ammonia, with no gasoline involved whatsoever.
The scientists say their method of making the ammonia fuel could bring the cost of production down to 20 cents/liter.