The Bonneville Power Administration pulled the trigger on its controversial wind curtailment plan Tuesday night, temporarily limiting the output of wind farms connected to its transmission system in order to accommodate surging hydroelectric generation due to high spring water flows.
BPA, which markets the power from the federal hydroelectric system in the Columbia Basin and operates much of the region’s electrical grid, said high water and hydroelectric output combined with low nighttime energy demand led it to limit other generation between midnight and 5 a.m. The agency said it first sought to limit coal, natural gas and other thermal generation to minimum levels required for grid stability, then it pulled the plug on about one tenth of the wind generation in its control area. The wind curtailment involved 200 to 350 megawatts of generation for five hours, totaling approximately 1,400 megawatt hours of power.
BPA says rising runoff has pushed dissolved gas levels at most of the eight federal dams on the Lower Snake and Columbia Rivers above Washington and Oregon water quality standards, which threatens protected salmon and steelhead. Under those circumstances, it says it can’t reduce hydro generation because that means sending more water over the spillways, which increases gas levels.
The agency says the situation could persist for the foreseeable future during periods of low electricity demand.
“There’s still a lot of snowpack and a lot of water to come down,” said BPA spokesman Doug Johnson.
Wind developers and investor owned utilities who have built their own wind farms contend BPA has no right to unilaterally cancel their transmission contracts, particularly when it provides no compensation. BPA does substitute free hydropower for the lost power deliveries, but it does not make up the lost tax and renewable energy credits that are only generated when wind farms are operating.
Renewables advocates believe BPA’s tactics are discriminatory and are designed to protect its surplus power revenues, which go to reduce electricity rates for the publicly owned utilities that buy power from the agency.
Wind developers and their customers are widely expected to sue the federal agency over the curtailment actions.
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