to generate electric power, representing about 50 percent of the total power produced (EIA, 2003). The remaining 8 percent of consumption occurs in coke plants, other industrial plants (including combined heat and power applications), and residential and commercial uses.
On a worldwide basis, approximately 34 percent of all power is generated with coal, which is expected to fall to 31 percent by 2025. Outside the United States and Europe, the most common use of coal is in the steel industry and for steam and direct heating in industrial applications (e.g., chemical, cement, and pulp and paper industries). China, India, and Russia are other large users of coal.
About 20 percent of the nation’s electricity is produced by nuclear power plants, which consume uranium. Low-cost uranium for nuclear reactors is currently very plentiful in the United States and elsewhere in the world. Very few nuclear reactors are being built these days, so little exploration for uranium has occurred in recent decades. However, a nuclear revival, whether for electricity or hydrogen, would spur uranium prospecting and might cause uranium prices to escalate in the long term.
Current known, recoverable world resources of uranium are approximately 3.1 million tons, estimated to be sufficient for about 50 years at current levels of consumption. A doubling of price from present levels is projected to create a 10-fold increase in these resources. Moving from current nuclear power technology to breeder reactors is estimated to increase uranium utilization another 60-fold (World Nuclear Association, 2002). Breeder reactors, however, would aggravate some of the issues now associated with the nuclear industry, including those surrounding safety and nuclear proliferation, while possibly reducing the waste disposal problem.
It is clear that there is an enormous supply of available fuel for use in nuclear power plants. However, the future of nuclear power in the United States is by no means clear. Current problems with the further use of nuclear power in the United States include economics—costs for new nuclear power plants are above current market acceptability—and public acceptance, which may have moderated in recent years but remains to be tested.
Electric power is produced from a variety of fuels and energy sources. In 2001, coal was responsible for over 50 percent of U.S. electric power, nuclear for roughly 20 percent, natural gas for 17 percent, hydroelectric for 8 percent, and others for the remaining 5 percent (EIA, 2003). The electric power system includes approximately 10,400 generating stations, with a total installed capacity of 786 gigawatts (EIA, 2001). In addition, there is a significant distributed electric power generation capacity of about 70 GW from about 10 million generators, which operate for widely varying periods of time each year (see Chapter 3 in this report).
Nearly 160,000 miles of high-voltage electrical transmission lines in the United States carry power from power stations to load centers (Edison Electric Institute, 2002). In addition, distribution lines carry the power from substations to end users. The electrical power system is fundamentally different from the liquid or gaseous fuel supply systems, which involve fluid flows that are relatively easy to direct and control. Electric power flow, which is dictated by complex physics principles, can often be difficult to control.
New transmission lines are increasingly difficult to build, largely because of public opposition. This appears to have been a contributing factor behind the widespread blackout in August 2003. The transmission system is being used for purposes for which it was not originally designed, and upgrades are not keeping pace with the increasing loads on it. Unless this situation is corrected, it may hamper the use of electrolyzers in distributed hydrogen generation facilities. Building pipelines to carry hydrogen may encounter some of the same siting problems. Distributed power systems, using small generating plants (probably burning natural gas) close to hydrogen load centers may help to overcome transmission constraints but may also increase vulnerability to natural gas disruptions.
Electricity is very expensive to store, so it is generated as needed. Hydrogen is somewhat easier to store and, as discussed elsewhere in this report, hydrogen could be used in conjunction with the electric system as backup storage, so that hydrogen would be generated at times of ample power in a reversible fuel cell and reconverted as needed (see Chapter 8 and Appendix G in this report).