krash wrote:If we're hypothesizing that hydrogen stations are going to be widely available, why aren't we looking into hydrogen combustion engines?
Currently, the primary source of hydrogen is through reforming natural gas. That is, you strip methane of its carbon and you are left with hydrogen. The problem with burning hydrogen is that some of the exhaust byproducts that form from burning hydrocarbons still exist. Primarily NOx emissions. From a storage standpoint, it is similar to methane so you either keep it under high pressure or at low temps so it offers only one practical advantage. Burning hydrogen does not emit CO2. However, in a well to wheel analysis, in order for it to have zero CO2, the carbon atoms stripped from the methane in the reforming process needs to be sequestered by attaching it to something other than oxygen that is stable enough not to ultimately end up as CO2 later either or sequestering the CO2 altogether. Ultimately, for all the trouble, its probably just easier to burn methane directly. Its already a low carbon fuel as it yields the least amount of carbon for each unit of energy.
Fuel cells would eliminate exhaust byproducts but share the same problems otherwise.
Ultimately, the ideal scenario for hydrogen as a fuel would be if we could use it as an energy storage medium by getting it from water. The original energy source would have to be a renewable source for it to make it of any long term practical value though (as an alternative fuel).