improvements. Some technologies could lead to sharp reductions in the amount of energy imported from unstable parts of the world, but not all could lead to such energy security improvements. And some technologies could reduce the cost of driving, but not all could lead to such economic benefits. Thus, the ultimate configuration of a hydrogen supply system will depend crucially not only on the technological successes but also on the trade-offs that individuals and societies are willing to make.
Chapter 8 contains a detailed examination of the various production technologies and of the possible technical advances that might give society and individuals the opportunity to make those choices. The discussion of production technologies in Chapter 8 makes use of the analyses presented in this chapter, together with those of Chapter 5, to make recommendations on the DOE hydrogen program.
The following findings are drawn from the analysis in this chapter:
Finding 6-1. In the committee’s optimistic vision of a transition to hydrogen for light-duty vehicles, 25 years from now the demand for hydrogen for these vehicles would be about equal to the current production of 9 million tons per year. This is only a small fraction of the 110 million tons required for full replacement of gasoline for light-duty vehicles.
Finding 6-2. A transition to a light-duty fleet of vehicles fueled entirely by hydrogen would dramatically reduce U.S. oil consumption and imports.
Finding 6-3. If coal, renewable energy, or nuclear energy is used to produce hydrogen, a transition to a light-duty fleet of vehicles fueled entirely by hydrogen would reduce total energy imports by the amount of oil consumption displaced. However, if natural gas is used to produce hydrogen, and if, on the margin, natural gas is imported, there would be little if any reduction in total energy imports, because natural gas for hydrogen would displace petroleum for gasoline.
Finding 6-4. The exclusive use of coal to produce hydrogen could significantly increase the scale of this domestic industry. This increase in coal production is unlikely to have any significant impact on coal imports, since all of the coal can reasonably be produced domestically. Oil imports could decrease greatly over time, resulting in a significant net decrease in energy imports.
Finding 6-5. Using current technologies, the land required for biomass to produce all of the hydrogen for fueling light-duty vehicles would be as large as the total amount of cropland in the United States. However, significant improvements in the yield of lands and the efficiency of biomass gasifiers could significantly reduce that figure. But because biomass does not appear to be economically viable even with technology advances, the committee does not expect much if any hydrogen to be produced by biomass gasification.
Finding 6-6. Using only natural gas for the production of the hydrogen for fueling light-duty vehicles would have a great impact on natural gas consumption and imports by the end of the 50-year time horizon in the committee’s analysis, but it would have only an insignificant impact during the next 25 years.
Finding 6-7. Carbon dioxide emissions from the total supply chain of hydrogen-fueled vehicles can be cut significantly only if the hydrogen that is produced is based entirely on renewables, or nuclear energy, or with sequestration of CO2 from fossil fuels. However, emissions of CO2 from all modes of transportation are projected to account for only 37 percent of total U.S. CO2 emissions; emissions from light-duty vehicles are only two-thirds of this 37 percent. Thus, sharply reducing overall CO2 releases would require carbon reductions in other parts of the economy, particularly in electricity production. Technology advances, other than those that make the use of nuclear energy or sequestration economic, would have very little additional impact on carbon releases.
Finding 6-8. Sequestration would involve a massive movement of carbon dioxide. While the United States probably has sufficient geological capacity to sequester these amounts, the sequestration of all the carbon dioxide possible could involve moving twice as much carbon dioxide as the amount of natural gas that the nation anticipates moving.
Finding 6-9. The penetration of hybrids into the marketplace, even absent hydrogen-fueled vehicles, could reduce fuel costs by tens of billions of dollars per year in the United States. Most current hydrogen production technologies would lead to a total driving cost higher than the total cost if hybrid electric vehicles ultimately dominated the fleet, but central station coal-based or natural-gas-based hydrogen production could keep total costs similar to those with hybrid electric vehicles.
Finding 6-10. With the possible future technology advances, all but biomass and grid-electric or photovoltaic-based electrolysis technologies could be operated at costs less than those that Americans have been willing to pay in fuel costs for driving gasoline-fueled conventional vehicles.
Finding 6-11. Although a transition to hydrogen could greatly transform the U.S. energy system in the long run, the impacts on oil imports and CO2 emissions are likely to be minor during the next 25 years. Thus, hydrogen—although it could transform the energy system in the long run—does not represent a short-run solution to any of the nation’s energy problems.