By the Numbers: Energy Crunch; August 2003; Scientific American Magazine; by Rodger Doyle; 1 Page(s)

Summer now often means rolling blackouts and brownouts-on top of rising utility bills and higher prices at the pumps. Unpredictable circumstances can lead to energy headaches-hot weather partly caused California's infamous shortages of 2001-but the main culprit is inadequate investment and lack of an integrated power grid to transmit electricity from one area to another during emergencies.

The chart shows an increasing gap between consumption and domestic production, one that historically has been filled by importing fuels, mostly oil and natural gas. The growing dependence on imports puts the U.S. at risk, not only because 53 percent of the world's proven oil reserves are in the volatile Persian Gulf region but because pipelines and international sea lanes must be protected. Additionally, the growing need for imports contributes to the economic vulnerability of the U.S. by increasing the foreign trade debt [see By the Numbers, February 2000]. And of course, fossil-fuel consumption produces carbon dioxide and other heat-trapping gases, thereby contributing to global warming.