Convegni ATI - Accesso riservato soci CTI

Autore: R.L. Evans

Collana: BT - 34 - Mag 06 - Energy: production, distribution and conservation

Note:
For fuelling road transportation in the future, there has been much speculation about the use of hydrogen as an energy carrier, which according to many authors would usher in the “hydrogen economy”. However, hydrogen would just be an energy carrier, like gasoline or electricity is today, and would need to be “manufactured” from one of just three primary energy sources; fossil fuels, renewable energy, or nuclear power. If hydrogen is generated from a renewable primary resource, or from nuclear power, the first step in the energy conversion chain is the generation of electricity as an initial energy carrier. This carrier is then converted into hydrogen as a secondary carrier by electrolysis of water, which is then stored on-board the vehicle. The final step is conversion of the stored hydrogen back into electricity by the fuel-cell, and this is then used to power the electric propulsion motor. A parallel situation is a simple battery electric vehicle, in which a battery is used on-board the vehicle to store electricity. The “in-out” efficiency of these two different approaches has been compared, and shows that the hydrogen and fuel cell route would require three times the amount of primary energy as the battery storage route for a given vehicle power output. The successful development and introduction into the marketplace of the “plug-in hybrid vehicle” would mark the beginnings of a significant new transportation paradigm, eliminating the need for road vehicles to use petroleum fuels, at least for the majority of miles travelled. If electricity were to be generated primarily from sustainable primary energy sources, then road transportation would also become sustainable and would result in an “Electricity Economy”, rather than a “Hydrogen Economy”.