For a fourth consecutive day, the Bonneville Power Administration (BPA) curtailed generation during the low-demand pre-dawn hours because abundant hydro generation left too little room on the agency’s transmission system.
The agency curtailed 1,000 MWh of generation between 1 a.m. and 5 a.m. on May 2, a BPA spokesperson told TransmissionHub. Details about the amount and type of generation curtailed were not available as of press time.
Wednesday morning’s cutback came on the heels of curtailments in the early morning hours of April 29 and 30, and May 1. So far this season, BPA has curtailed more than 20,000 MWh of generation from thermal and wind generators.
Wind operators in the Pacific Northwest are upset about the curtailments, with some charging that BPA is taking the actions to serve its economic self-interest.
“Bonneville has not provided a clear explanation of why the curtailments were ordered,” a spokesperson for Iberdrola Renewables told TransmissionHub on May 1.
However, BPA officials confirm the agency does not receive revenue when replacing renewable energy with federal hydropower and estimate their financial exposure for reimbursing wind producers for the spring season shutdowns could be as high as $50m.
BPA officials say the curtailments were based on the capacity of the transmission system, the generation limits of other resources, and limits on the amounts of total dissolved gases in the water below its dams set by Washington law.
Prior to ordering curtailments, BPA ordered the area’s thermal generators to reduce their output to minimum generation levels. When a thermal generation unit is shut down completely, a specified period of time must elapse before that unit can be restarted. Depending on demand, a lack of availability of thermal generation could have an adverse effect on reliability.
BPA filed a protocol with FERC on March 6 that is intended to help reimburse wind generators for those lost credits, but that protocol has been widely criticized by area wind producers as not going far enough. A FERC spokesperson told TransmissionHub on May 2 that it was not possible to predict when the agency would rule on the protocol.