Alkaline fuel cells (AFCs) are the cheapest fuel cells to manufacture. These run in a similar way to batteries and have been used in Apollo Space programs as fuels and to make drinking water. The biggest drawback with AFCs is that it is extremely sensitive to CO2, the performance of the fuel cell rapidly decreases and the CO2 which may be present in the air poisons it. This makes this fuel cell very specialised to space and under-water usage.
Solid Oxide Fuel Cells (SOFCs) use methane and carbon monoxide in the fuel cell system and are mostly used in large scale power generating stations and industrial stations. These are however, currently being tested in the running of cars and we may see more from them in the future.
It may sound hard to believe but recent researchers have made it possible to produce pure, clean Hydrogen from sewage. Until recently this process would have used too much energy making it useless in the long run. But, the new biomass project researchers have just made it more efficient meaning that it could be powering our cars and homes in the future.