Fuel Cells and the Hydrogen Economy
(The Bigger Picture)
In addition to the advantages of fuel cells vs. batteries and ICE's the use of hydrogen as a fuel opens up a number of exciting possibilites for the broader energy system of society. Most of the time when we use energy to light and heat our homes or run our computers to allow us to communicate we use it in the form of electricity. However we don't mine or harvest electricity directly, it's only a carrier of energy generated by other means (e.g. coal, hydro, nuclear). The source-agnostic characteristic of electricity allows a great deal of flexibility, however it has one problem in that it is exceedingly difficult to store on large scales.
The only service society requires that can’t tap into this flexibility is transportation. If you want to get from point A to point B (and you can’t propel yourself) you have to use fossil-fuels as the energy carrier. Since transportation (personal and commercial) accounts for approximately 20% of all energy use in industrialized economies this represents a substantial demand that is locked in for fossil fuels. Much of the talk about North American energy security is a direct result of this inflexibility and the fact that most remaining easily accessible oil reserves are located in the middle east.
The Case for the Hydrogen Economy
Hydrogen has been touted as a solution to this problem due to it’s relatively simple creation from electricity and water through electrolysis. We’ve already established the commonality of electricity no matter what source was used to generate it, if we could easily create a transportation fuel from that electricity we could in turn decouple our transportation network from fossil fuels. The other advantage of hydrogen is given its convertibility from electricity it can act as a storage medium for electricity. Medium scale electricity storage will also allow more flexibility in adding intermittent electricity sources to the grid such as wind and solar power.
However, in order for hydrogen to be a viable energy carrier we also need to have a device that can convert it back to electricity, such as a fuel cell. Although internal combustion engines can be used to burn hydrogen, the higher efficiency of fuel cells makes the round-trip efficiency of storing and releasing energy more economical.