Terrorists could black out large segments of the United States for weeks or months by attacking the power grid and damaging hard-to-replace components that are crucial to making it work, the National Academy of Sciences said Wednesday, according to the New York Times. By blowing up substations or transmission lines with explosives or by firing projectiles at them from a distance, the report said, terrorists could cause cascading failures and damage parts that would take months to repair or replace. In the meantime, it warned, people could die from the cold or the excessive heat, and the economy could suffer hundreds of billions of dollars in damage.
While the report is the most authoritative yet on the subject, the grid's vulnerability has long been obvious to independent engineers and to the electric industry itself, which has intermittently tried to rehearse responses. Changes in the electric industry have made the grid more vulnerable in recent years, experts say. The grid was mostly built to serve the needs of individual utilities, but regulators have cut the generation companies loose from the companies that transport and distribute power to foster a competitive market. That has resulted in far more electricity being shipped much greater distances and in difficulty winning consensus to build new lines.