BOISE, Idaho (AP) — The Federal Energy Regulatory Commission says Idaho Power's long-term purchase agreement with wind farms means that it must buy electricity from the farms even when demand for power is low. The commission's decision, reached Thursday, is good news for Idaho wind farms but a loss for the state's largest utility. Idaho Power officials have contended that they should be allowed to stop contractually required electricity purchases during periods of light load. The company says the requirement forces them to back down other energy generators like coal-fired plants to balance the power system, increasing costs in the long run. The federal regulatory commission found the rules don't allow for unilateral curtailment, and that any associated costs were taken into consideration when the long-term agreements were created.