BPA Curtails Wind Farm Electricity Generation
by Ted Sickinger
The Oregonian, May 18, 2011
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.
Overgeneration Announcement related to graphic.
To safeguard salmon and steelhead and assure reliable energy delivery during these unusually high seasonal river flows, BPA has taken the following measures, which it took as a last resort and had been working to avoid. BPA will update this site at 9 a.m. and 3 p.m., Monday through Friday.
[May 24, 9 a.m.] On May 23 and 24, BPA temporarily limited the energy output of regional generators, including wind generation, from 11 p.m. May 23 through 5 a.m. May 24. The output limited ranged from approximately 17 to 175 megawatts per hour, totaling about 550 megawatt hours.
[May 20, 9 a.m.] BPA temporarily limited the energy output of regional generators, including wind generators, from 11 p.m. May 19 until 5 a.m. May 20. During that six hour period, approximately 600 to 1,200 megawatts per hour of wind generation, totaling about 5,300 megawatt hours, were impacted.
[May 19, 3 p.m.] No current limits on generation
[May 19, 9 a.m.] BPA temporarily limited the energy output of regional generators, including wind generators, from 11 p.m. May 18 until 5 a.m. May 19. During that six hour period, slightly less than 1,000 megawatts per hour of wind generation, totaling about 5,700 megawatt hours, were impacted.
[May 18, 3 p.m.] No current limits on generation
[May 18, 9 a.m.] BPA temporarily limited the energy output of regional generators, including wind generators, from midnight until 5 a.m. May 18. Approximately 200-350 megawatts of wind generation per hour, totaling about 1,400 megawatt hours, were impacted.
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