The ruling revoked the federal energy ministry's 2007 congestion study, which had designated electricity transmission corridors of national interest in the Mid-Atlantic and Southwest.
In the appeals court decision, issued on February 1, the judges of the Ninth Circuit Court of Appeals ruled that the ministry had failed to consult enough with states for its congestion study and had failed to consider the corridors' environmental impacts adequately. The case had been brought by the California Wilderness Coalition, several states, state regulators and other environmental groups. The ruling is unlikely to be appealed in the Supreme Court.
It is the latest of three court and agency decisions that have limited or undermined the siting authority, established by the Energy Policy Act of 2005.
"The cumulative effect is a pretty useless law," says Rob Gramlich, senior vice-president for public policy at the American Wind Energy Association. "Other courts (had) weakened the policy, and its implementation was not as good as it could have been."
Marcus Wood of law firm Stoel Rives says the only way for the siting authority to ease the way for new transmission lines is if they were due to be built anyway. "If Congress wants to facilitate construction of such critical inter-regional facilities, it's probably going to have to pass a new law," he adds. Upgrading the country's transmission is fundamental to the deployment of wind power. States have lagged in approving the new lines needed to address unreliability and congestion.
The Energy Policy Act added section 216 to the Federal Power Act, authorising the energy ministry to designate the corridors and the Federal Energy Regulatory Commission to site transmission lines within those corridors. The wind industry has long questioned the initial choice of corridors in the Mid-Atlantic and Southwest on the grounds that they do not link enough windy areas with centres of population. It has also questioned the siting authority for not going far enough in its enforcement.