being intensely researched for the longer term. Considerable progress has been made in both areas, and there are indications that hybrid electric vehicles will be marketed by the Big Three auto companies by 2004. The fuel cell R&D also shows considerable promise, although serious problems remain.
Some of the manufacturing and materials R&D from PNGV has already produced realized benefits. The 21st Century Truck Partnership, just getting under way, is attacking another important segment of motor fuel consumption and promises additional gains.
To date, DOE’s transportation technology R&D has had very little effect on the energy consumption or environmental impact of the U.S. transportation sector. Many programs prior to 1993 were generally unsuccessful in meeting their goals, as indicated above. The PNGV program, while so far falling well short of its principal goal of developing a marketable 80-mpg car, has had some successes in developing useful manufacturing technologies that are just being introduced in production. Also, there is promise that, as a result of PNGV, motor vehicles with significantly improved fuel economy will be introduced into the market in the near future. Whether they will make up a significant fraction of the U.S. fleet and thus mitigate the relentless increase in transportation fuel consumption remains uncertain.
DOE transportation R&D is split among several offices and is conducted by a variety of entities. PNGV, the USABC, and the 21st Century Truck Initiative are major activities, all directed at similar goals and with overlapping technologies. They need to be well coordinated and in good communication with each other. It would appear to be up to DOE to ensure this coordination and communication on preproprietary R&D, because industry participants are usually somewhat reluctant sharers.
The light truck and sport utility vehicle segments of the transportation system were largely ignored until recently, when they came to represent about 46 percent of the light-duty market (EPA, 2000). Heavy-duty trucks and buses, which consume about 25 percent of the motor fuel in the United States (EIA, 1998), also received inadequate attention until recently. Fortunately, much of the PNGV technol-
BOX 3–7 Proton Exchange Membrane Fuel Cell: Insurance from a High-Risk Technology
It may be that the world must further constrain its emissions of regulated pollutants and of greenhouse gases, like CO2, as well. But how can that be done while still retaining the personal automobile as a principal form of transportation?
The proton exchange membrane (PEM) fuel cell vehicle, picked by PNGV as the long-term alternative to the internal combustion engine (ICE) hybrid vehicle for achieving the 3X fuel economy goal, may provide one practical answer. There are other possibilities, of course, such as electric vehicles with electricity from renewable or nuclear sources and biomass-fueled ICE hybrids. But the fuel cell vehicle is high on the list because of the potential for ultralow emissions, high efficiency, fuel flexibility, and high performance. Enormous progress has been made as a result of DOE and private investment since 1990. This investment has stimulated interest, so that now the private sector invests more than DOE.
It is a risky business, however, because of the remaining technical and economic problems, including the especially formidable one of getting the cost of PEM fuel cells down to a competitive level. But Ford, DaimlerChrysler, and General Motors are spending significant amounts of money in the expectation that if circumstances demand it, they can do it.
But it’s not just the fuel cell that must work. A whole new fuel infrastructure is required if the personal vehicle is to be decarbonized. If the energy efficiency of fuel supply and preparation is low, then the high efficiency of the fuel cell itself will be attenuated, and if the ultimate source of the fuel is a hydrocarbon, then CO2 from the fuel preparation must be dealt with somehow.
Williams (1998) explains one possible approach. Hydrogen is manufactured centrally from fossil fuels (natural gas and coal) with capture of the resulting CO2. The CO2 by-product would be sequestered in coal seams, in depleted oil and gas reservoirs, in deep saline aquifers, or perhaps in the deep ocean. The hydrogen product would be pressurized and piped to filling stations, where fuel cell vehicles are refueled. The vehicle itself emits nothing in use except water vapor.
These fuel infrastructure changes would be daunting and expensive. Ogden (1999) points out that the transition might be accomplished gradually, with hydrogen produced first from natural gas at distributed filling stations. Central plants would replace these as the need for sequestration became compelling. Alternatively, hydrogen might be supplied without carbon emissions from the hydrolysis of water using off-peak nuclear power or renewable electricity.
The fuel cell vehicle may be considered as technological insurance to reduce the cost of avoiding adverse climate change. In the bargain, cleaner cities could result. This is the sort of R&D the government should support. The potential public good benefits are worth the high investment risk. The private sector is unlikely to take this risk alone.