nature or results of terrorist attacks on electric power systems in this country. Furthermore, NERC’s intention to consider costs as well as benefits may work against protection against extreme but unlikely risks that cannot be quantified, including terrorist attacks. Overall, however, establishment of an ERO with real authority is a significant step forward. In addition, EPAct includes measures that should encourage the construction of new transmission lines and the development of new technologies to improve the efficiency and reliability of the power grid, steps that should also provide increased resistance to terrorist attacks. DOE’s report On the Road to Energy Security describes how it is carrying out its responsibilities under EPAct (DOE, 2006).

DHS’s National Infrastructure Protection Plan (NIPP) provides an overall approach to protecting critical infrastructure, including electric power systems (DHS, 2006a). DHS’s analysis of terrorist capabilities and motivations suggests that infrastructure could be a prime target, especially as protection is enhanced at other targets. The plan calls for (1) strong public-private partnerships to foster relationships and facilitate coordination within and across critical infrastructure and key resource sectors; (2) robust multidirectional information sharing that will enhance the ability to assess risks, make prudent security investments, and take protective action; and (3) a risk management framework establishing processes for combining consequence, vulnerability, and threat information to produce a comprehensive, systematic, and rational assessment of national or sector risk. Not addressed in the NIPP, however, is the issue of how private entities can be expected to assume the large costs required to make the system more robust against low-probability events.

DHS revised National Response Plan, a broad, comprehensive plan for preparing for a wide range of emergencies, also addresses critical infrastructure, including electric power systems (DHS, 2006b).


•  By their very nature, electric power transmission and distribution systems are not perfectly reliable. Keeping power flowing to customers is a continuous process of control, recovery, and repair. Most outages involve only the distribution system. However, occasionally storms, accidents, or other events cause disruption of the high-voltage transmission system. Power systems are designed and operated to cope with such disturbances and to restore service as rapidly as possible.

•  Well-planned attacks on the power system, undertaken by informed terrorists, could result in power outages with extents and durations that are much larger than those produced by all but the largest natural events. Damage to critical, difficult-to-replace system components could be extensive, making restoration of power slow and extremely difficult.

•  Although major terrorist organizations have not attacked the U.S. power delivery system, such terrorist attacks have occurred elsewhere in the world. Simply turning off the power typically does not terrorize people. However, the United States should not ignore the possibility of an attack that turns off the power before staging a large conventional terrorist event, thus amplifying the latter’s consequences. Nor should the possibility of a series of attacks designed to do major damage to the economy and to the public’s sense of security and well-being be ignored.

•  Economic costs from a carefully designed terrorist attack on the U.S. power delivery system could be as high as hundreds of billions of dollars (i.e., perhaps as much as a few percent of U.S. gross domestic product).

•  Both industry and government have begun to address the risks of terrorism to the power delivery system, but there is much more that can and should be done.


BBC. 2003. “Italy Launches Blackout Inquiry.” BBC news online. September 30, 2003. Available at Accessed August 2007.

Chang, S.E., T.L. McDaniels, and D. Reed. 2005. “Mitigation of Extreme Event Risks: Electric Power Outage and Infrastructure Failure Interactions.” Pp. 70–90 in The Economic Impacts of Terrorist Attacks, H.W. Richardson, P. Gordon, and J.E. Morre II, eds. Northampton, Mass.: Edward Elgar Publishing.

CNN. 2003. “Italy Recovering from Big Blackout.” CNN. Sept. 28, 2003. Available at Accessed August 2007.

DeMarco, C.L. 1998. “Design of Predatory Generation Control in Electric Power Systems.” Pp. 32–38 in Thirty-First Annual Hawaii International Conference on System Sciences, Vol. 3. New York: IEEE.

DHS (Department of Homeland Security). 2006a. National Infrastructure Protection Plan. Available at Accessed September 2006.

DHS. 2006b. National Response Plan. Available at Accessed October 2006.

DOE (U.S. Department of Energy). 2006. On the Road to Energy Security: Implementing a Comprehensive Energy Strategy: A Status Report. Available at Accessed September 2006.

DOE/EIA (Energy Information Administration). 2007. Revenue from Retail Sales of Electricity to Ultimate Customers by Sector, by Provider. Available at Accessed October 2007.

DOE/FERC (Federal Energy Regulatory Commission). 1978. The Con Edison Power Failure of July 13 and 14, 1977. Washington, D.C.: U.S. Government Printing Office.

EPRI (Electric Power Research Institute). 2003. Distribution Reliability Indices Tracking Within the United States. Report No. 1008459. Palo Alto, Calif.: EPRI.

FERC. 2006. Order Certifying North American Electric Reliability Corporation as the Electric Reliability Organization and Ordering Compliance Filing. Available at Accessed September 2006.

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