4.3- FUEL CELL VEHICLE

4.3.1- PERFORMANCE ASPECTS

Despite of the greater complexity of the FCV fuel-cell engine, which allocates sophisticate temperature and moisture regulation devices, its tank-to-wheel efficiency, of 35%, is more than the double of its counterpart's one, the ICV. That's because of the much more efficient oxidation carried inside PEMFC, which transforms the released energy directly into electricity, unlike the internal combustion vehicle, which uses the kinetic power of the explosion.

The autonomy of the current FCV prototypes is widely variable depending on the hydrogen storage system and the size of the tank or device; however, its average achievable range is equal or barely superior to the BEV's and much lower than the ICV's.

By the other side, its fast energy reload, carried in hydrogen stations, which would be similar to refilling gasoline or gasoil, is an important advantage over the BEV, which generally requires several hours to be recharged and might appear less reliable to the consumers.

4.3.2- ENVIRONMENTAL ASPECTS

The propriety that makes FCVs attractive as an alternative for internal combustion automobiles is that they don't emit any tailpipe compound derived of their operation but water vapor, a fact that would reduce urban pollution and, by the way, all the related environmental and health problems. It uses no petrol to run, but hydrogen, which can be produced from various energetic sources, an interesting fact as a way to reduce the oil consumption.

In the same way as the electricity in the BEV, the use of hydrogen displaces the in-city pollution caused by the traffic to the place where it is produced. The real environmental concern about the hydrogen economy is, consequently, the way in which this gas is obtained. Most of the current proponents of this system argue that, since hydrogen can be obtained through electrolysis, electricity from small-scale renewable sources (such as photovoltaic and wind power) could be widely used in order to produce it.

However, from an objective point of view it is hard to believe that, given the current low relevance of the renewable energy sources in the global electric network, such an economy would be based on those technologies. Oppositely, and given the current modus operandi of most of the energetic companies and governments, it is predictable that they would tend to produce hydrogen cheaply in massive, centralized hydrocarbon-based plants (that is what currently happens in the electric system).

To put it briefly, a massive FCV implantation would not imply a net reduction of GHG emissions from to transportation, but it would eliminate toxic releases in habited areas. In any case, it is still impossible to consider the hydrogen economy in a more empirical way, since it is still a hypothesis of a possible energy system for transportation without real analyzable facts.

4.3.3- ECONOMIC ASPECTS

The principal drawback of a massive hydrogen-powered traffic system, a scheme also known as "hydrogen economy", is, actually, the fuel generation, as well as the complexity of its handling and storage. Current predictions show that the entire process would be extremely energy intensive, since producing, compressing/liquefying and delivering hydrogen to pump stations consumes between three and four times its LHV, given that the overall efficiency of the cycle is of about 25%.

In brief, the problem of this hypothetic "hydrogen economy" is that producing this fuel consists, essentially, in spending power converting an energy source (such as fossil fuels, biomass or electricity from renewable sources) into a more expensive one (hydrogen) that often offers worse physic proprieties than the prime product, as in the case of natural gas and liquid hydrocarbons. So, on balance, it results more efficient to consume those energy sources directly. As a result, hydrogen will hardly ever be cheaper than common fuels.

Besides, there's the problem of the astronomic price of a FCV. Due to the great expenses of producing the PEMFC, which is a really complex device that contains platinum (a precious metal), along with the inexistence of a dedicated industry, the average current prototypes cost more than a million dollar, and the sole fuel cell stack over $3,000/kW and has a shorter lifespan than an ICE. It must be added to this fact that the global cost of a hydrogen infrastructure can reach between $1 and $5 trillion dollars, and that the price of hydrogen will hardly ever be more economic than any energetic counterpart.

In conclusion, the implantation of a hydrogen economy faces two foremost problems: on the one hand, the bad physic proprieties of this fuel and the energy waste of its production; on the other hand, the conflict between the inexistence of a hydrogen system and the lack of a sufficient demand.