Federal energy regulators approved rules on Thursday to keep secret certain information about U.S. power plants, large transmission lines and oil and natural gas pipelines, citing post-Sept. 11 security concerns. In keeping the information away from extremist groups, the rules would also restrict the general public’s access. The information to be kept secret includes pipeline maps and electric grid flow diagrams that could reveal congested areas when moving energy supplies, the Federal Energy Regulatory Commission (FERC) said. Other off-limits information includes pipeline inspection reports, detailed blueprints and emergency action plans that energy plants must file with regulators. Immediately after the Sept. 11, 2001, attacks on U.S. cities, FERC and other agencies, like the Nuclear Regulatory Commission and Environmental Protection Agency, quickly withdrew public information on critical energy facilities. Full Story