BPA curtailed nearly 30,000 MWh of generation in July

High wind, abundant water, and low summer demand combined to force the Bonneville Power Administration (BPA) to curtail nearly 30,000 MWh of generation during portions of seven days in July, representing 59.6% of the 49,614 MWh curtailed so far this year.

Record rains in June in Canada combined with mild temperatures contributed to the oversupply, a BPA spokesperson told TransmissionHub July 30.

“They did have record precipitation in June in Canada, and that’s still what we’re looking at,” the spokesperson said, indicating that more curtailments could lie ahead.

“We’ve still got a lot of water to the north,” the spokesperson continued. “We’re going to have a lot of water for the next 45 days or so, which is somewhat rare.”

The agency is expecting demand to increase as the summer wears on, but that does not mean it will be time to relax.

“From a power production standpoint, it does tend to get hot in August [in the Northwest] and to our south, but we’ve still got to work with the [U.S. Army] Corps of Engineers and others to manage that water effectively,” the spokesperson added.

Before July, the agency curtailed 20,345 MWh of generation over five days: April 29 through May 2, and again on June 30.

When generation must be curtailed, the agency works with thermal generators to displace that source of power first. Typically, thermal plants shut down first because they can save on fuel costs, the spokesperson said. However, wind producers have production tax credits and renewable energy credits that depend on continued wind generation, so they are curtailed after thermal generation.

Last spring, BPA curtailed wind turbines during a period of high water flows in the Columbia River. The agency was forced to route the water through power-generating turbines because spilling the large quantity of water over spillways would have increased total dissolved gasses to a level that would endanger salmon.

The curtailment prompted wind producers to file a complaint with FERC, accusing the BPA of violating contracts for firm transmission rights and of treating them in a discriminatory manner. FERC responded with an order finding that BPA’s curtailment policy represented noncomparable transmission service and requiring BPA to file a revised tariff to provide transmission service on conditions comparable to those it gives itself.

The agency 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. (Docket No. EL11-44-000). FERC has not yet ruled on the protocol.

During 2011, BPA curtailed 97,500 MWh of generation.

The agency spokesperson said, “We’re estimating it will cost us about $12m to reimburse wind producers for the production curtailed during the 2012 season, but our total exposure could be as high as $50m.”