assisted active suspension; collision-avoidance systems; electric air-conditioning compressors; “drive-by-wire” steering; side and rear-view bumper cameras; electronic tire pressure control; and generally greater computer power for increasing control of the various vehicle systems. The need for these systems has already started a trend toward a new 42-volt (V) standard for vehicle auxiliaries in order to deliver more power. In principle, electric (fuel cell) vehicles and APUs provide an efficient way to meet these power demands.
Fuel cell vehicles are attractive potential replacements for ICE vehicles because they can offer performance similar to that of conventional vehicles, along with several additional advantages. These advantages include better environmental performance; quiet (but not silent) operation; rapid acceleration from a standstill, owing to the torque characteristics of electric motors; and potentially low maintenance requirements. Furthermore, FCVs have the potential to perform functions for which conventional vehicles are poorly suited, such as providing remote electrical power (for construction sites, recreational uses, and so on) and possibly even acting as distributed electricity generators when parked at homes and offices and connected to a supplemental fuel supply. FCVs also provide additional attractions to automakers: by eliminating most mechanical and hydraulic subsystems, they provide greater design flexibility and the potential for using fewer vehicle platforms and therefore more efficient manufacturing approaches.
For the FCV to be successful in the marketplace, it must satisfy customer desires and regulatory requirements (see Table 3-1). Fuel cell vehicles will easily meet a few of these desires and requirements. They will excel in fuel economy and emissions reduction. On the negative side, for the fore-seeable future they will likely be expensive, have less range, and be more difficult to refuel. Their ability to satisfy other demands and requirements is more ambiguous, depending on perceptions, design decisions, and near-term engineering improvements.
For early fuel cell systems to succeed in the marketplace, they must have special appeal in some market niches, even if these niches are relatively small. One niche might be created by the desire, especially in dense urban areas, to achieve zero tailpipe emissions. The only zero-emission vehicle type other than the direct-hydrogen FCV that is practical at the present time is the battery electric vehicle (EV), which is characterized by short driving ranges, long recharge times, and high costs. To the extent that zero-emission vehicles are encouraged or even mandated in certain areas, direct-hydrogen FCVs may have to compete only with battery EVs and not the entire suite of vehicle technology options. Such a situation could give them a much firmer foothold for breaking in to motor vehicle markets. Another niche might be made up of individuals and businesses that value the large amounts of electrical power carried on board, and that might find a suite of new uses that can only be imagined at this time. And still other niches could include those wanting APUs on trucks or off-road vehicles in areas where noise or pollution is a concern.
One important feature of FCVs that remains crucial for their development is the fact that PEM fuel cells run on either pure hydrogen or a dilute hydrogen gas “reformate” stream (though direct-methanol fuel cells, still in an early stage of development, operate on methanol). This hydrogen can either be stored on board the vehicle in one of several ways, or generated from another fuel with an on-board reformer.
To aid the transition to FCVs without major infrastructure changes, the energy and automotive companies have been working together to develop on-board reformers. On-board reformers convert a liquid (or other gaseous fuel) to hydrogen. Natural gas reforming is more difficult than liquid reforming, and thus the focus has been on liquids for on-board reformers. The most effort has been devoted to methanol and gasoline. DaimlerChrysler was a leader in developing an on-board methanol reformer, and the company unveiled prototype FCVs operating on methanol in the late 1990s. Other companies focused on gasoline reforming. But by 2003, all major automakers had suspended their development of on-board reformers and shifted their FCV efforts to direct hydrogen use. Several oil companies are known to be continuing their development of on-board reformers, which is an appropriate technology to be developed in an industrial R&D laboratory.
On-board reformers are attractive in that they obviate the need to build a hydrogen infrastructure. Methanol is easier to reform than gasoline is, but DaimlerChrysler and others suspended methanol reforming in part because of the challenge of developing a large-scale infrastructure for what was viewed as an interim fuel. More generally, gasoline (and methanol) reforming efforts were suspended by automakers because of several major disadvantages: on-board reformers impose substantial additional cost, add considerable complexity, reduce fuel efficiency, increase emissions, increase “engine” start-up times, and create additional safety concerns. Automakers and others considered these disadvantages to be too large to overcome the advantages of ready gasoline availability, especially when on-board reforming is considered an interim strategy until hydrogen is broadly available.
Most analysts agree that storing hydrogen on board FCVs is the best ultimate solution, but no hydrogen storage system has yet been developed that is simultaneously lightweight, compact, inexpensive, and safe. Further advances in hydrogen storage, so that FCVs can refuel quickly and have driving ranges comparable with those of conventional vehicles, thus constitute a key area for further development. Prototype FCVs have been built that store hydrogen as a cryogenic