An excerpt:There are three major areas of fuel availability-related (asopposed to utilization related) research areas to move towards hydrogen-based transportation.
1) Hydrogen production. Currently, essentially all hydrogen is produced from steam-reforming of natural gas. Further, this is an endothermic process resulting in the heating value of hydrogen obtained being less than that of the feedstock natural gas. Additional energy is required for compression or liquification as well as for transportation. For large scale hydrogen production, a large new supply of national gas or other primary feedstock would be needed if production techniques are used. The dissociation of water to produce hydrogen utilizes an almost unlimited supply of feedstock, but the electrical energy required to produce a unit of hydrogen is at least double that of the electrical energy which would be produced by consuming that unit of hydrogen in a fuel cell. Consequently, innovative and inexpensive primary energy sources, such as renewables or perhaps nuclear will have to be exploited to produce the hydrogen. Even with acceptable primary energy sources, the total power requirements and production facilities to replace even a fraction of current petroleum energy are staggering.
2) Infrastructure. For hydrogen-powered vehicles to be commercially viable, fuel must be readily available to the consumer, nationwide. There are currently perhaps around 200,000 refueling stations for gasoline. These refueling stations accommodate vehicles which have ranges in excess of 300 miles and can be refueled in minutes by persons with no expertise or training. Thus, it is likely that at least tens of thousands (perhaps many more) refueling sites for hydrogen, distributed all around the united States will be needed to support large-scale production and sale of hydrogen-powered vehicles. Since there is currently virtually no infrastructure to provide this capability, clearly some innovative infrastructure approaches are necessary.
3) Vehicle refueling and on-board storage of hydrogen. The energy density of hydrogen (energy stored-per unit of storage volume) is much less than that for gasoline or other alternative fuels. For example, to store on-board the same energy available from the typical 16-gallon gasoline tank would require abour a 200 gallon volume for compressed (5000psi) hydrogen gas or about 60 gallons for liquid hydrogen (at --424F). Even if the on-board energy efficiency is assumed to be double (for a non-hybrid system) or tripled (for a hybrid system), the resulting volume of about 70 gallons for compressed hydrogen would likely present a sever challenge to the vehicle designers. The use of liquid hydrogen would ease the storage volume problem, but producing liquid hydrogen is very energy intensive, and handling it at -423F presents obvious safety problems. >>Full Report ...