Public power utilities and their customers have played a key role in helping to maintain a reliable supply of power in the face of a historic heat wave that gripped the region in recent days and in turn placed power demand pressure on regional grids.
Several major cities in the Pacific Northwest have experienced temperatures over 100 degrees, shattering records for several days in a row.
Seattle City Light
One of those cities is Seattle, Washington, where public power utility Seattle City Light on June 28 noted that it was carefully monitoring external conditions and its systems to maintain reliable power to customers in Seattle and ther surrounding communities. “We have brought in extra crews to respond to unplanned outages and we have postponed planned outages at least through Tuesday, June 29 to minimize the impact on customers,” Seattle City Light said in a post on its website.
Julie Moore, Director of Seattle City Light’s Communications Division, broke out the peak demand that the utility saw during the heatwave as follows:
Friday: 1,293 MW
Saturday: 1,334 MW
Sunday: 1,381 MW
Monday: 1,533 MW
Tuesday: 1,412 MW
She noted that in an email to Public Power Current that on a typical June day with maximum temperatures around 70 degrees, “we would see a peak around 1,150 MW; when we’ve had the occasional hot spell with temperatures in the 90s, we have seen a peak load of around 1,300 MW.”
Leading up to the weekend and through June 29, the utility participated in daily calls with the Northwest Power Pool, which manages resource adequacy across the region. While Northwest utilities typically see their highest demand in the winter, not the summer, Seattle City Light and other utilities maintained adequate resources to meet the demands of this sustained heat wave. "The fact that we are a hydropower region, not overly dependent on intermittent resources like solar and wind, was very helpful in this situation," she said.
“We did see scattered outages throughout our service territory starting Friday evening and through yesterday [June 29], with the most on Monday, the hottest day. The bulk of City Light’s distribution system is overhead, although we do have parts of the system served via underground conduit and we also operate a network serving downtown and parts of the South Lake Union neighborhood. The heat is especially hard on underground infrastructure and the majority of outages over the past several days have been heat-related. Unfortunately, it takes more time to locate and repair underground equipment failures and our restoration speed is also impacted by excessive heat in the vaults that house that equipment – we worked hard to restore service quickly while keeping our employees safe.”
At the peak Sunday, "we had about 1,700 customer meters out of ~480,000 without power at one time. We continued to see scattered outages throughout the day on Monday. The number of customers impacted at any one time was mostly in the several hundreds, until around 9:30 p.m. when we saw two larger outages – 4,451 in north Seattle and 6,146 in southeast Seattle. At that peak, we had about 11,000 customers impacted. Fortunately, within about an hour, crews restored nearly all customers affected by those larger outages and as of 10:45 p.m., about 1,300 were still without power. Crews worked through Monday night to restore most of those customers.”
On June 29, the utility saw a handful of outages, “but it dramatically tapered off from what we saw on Monday,” Moore noted.
Snohomish County PUD
As with other public power utilities responding to the heat wave, Washington State’s Snohomish County PUD called on customers to do their part in helping to keep power demand down by making small changes to conserve energy like closing blinds and using small appliances in their kitchens.
In a June 25 tweet, Washington State’s Snohomish County PUD noted that “Some have asked if our power supply is at risk due to this heat. The short answer is no. We expect that energy demand on June 28 will be its highest ever in June. Fortunately, above-average water supply and snowpack this spring have us well-positioned going into summer. But when demand for power is high, we sometimes have to buy power on the market, & prices are high right now! Help us keep costs and rates low by conserving energy between noon and 10 p.m. Wash dishes, run laundry & take showers in the morning or late at night.”
As record-breaking heat bore down on the Pacific Northwest this past weekend, the Bonneville Power Administration (BPA) detailed several steps to position the federal power and transmission system to serve its customers during the weather event.
On the Power Services side of BPA, BPA said these factors were helping:
- The Columbia Generating Station, a nuclear plant owned by Energy Northwest that produces power marketed by BPA, recently returned online from a spring refueling outage, adding over 1,100 megawatts of generation in the Northwest and the West;
- Programmed fish spill on the lower Columbia and Snake rivers transitioned from spring to summer operations, increasing the federal hydropower generation from those facilities;
- The Bureau of Reclamation has the Grand Coulee reservoir well positioned to meet its refill target in early July, freeing up the remaining water flow to pass through the system for both power and non-power purposes.
BPA said that despite the lower-than-average water year, there is plenty of water behind Grand Coulee Dam and some snowpack left in the Canadian Rockies. Unlike 2015 and 2001, years with a similar volume of water, the shape of this year’s runoff has been slower with snow gradually melting above Grand Coulee, it noted.
On the transmission side, BPA said it was taking measures to ensure the safe and reliable flow of electricity over the weekend of June 26-27. BPA owns and operates more than 15,000 circuit miles of transmission lines across the Northwest and small amounts in Nevada, Utah and California.
Last Thursday, BPA restricted planned maintenance on its transmission grid from 6 a.m. Monday, June 28 through Tuesday, June 29 at 10 p.m., so the federal agency would be able to leverage the system to its greatest use when load was expected to increase with the start of the workweek.
“Having all of our lines available will help relieve congestion on the system,” said BPA Vice President of Transmission Operations Michelle Cathcart. “With these unprecedented temperatures, we want to ensure electricity can move freely and reliably meet customer demands.”
On June 29, BPA said in a tweet that it expected energy use in the Tri-Cities area of Washington State to peak between 5 and 7 p.m. “Please do what you can to reduce electricity use today. Thanks for helping us get through the heat of the day yesterday,” BPA said in the tweet.
City of Richland, Wash.
BPA transmits electricity to Richland Energy Services (RES) and other Tri-Cities utilities through a transmission system designed to meet peak and above-peak demand for power throughout the region.
BPA informed the City of Richland, Wash., that the week’s extreme heat was straining the regional electric energy transmission system. If total load approaches maximum system capacity, BPA will require RES to shift or shed load on its distribution system, the city noted on June 28.
RES “will do everything it can to manage load by shifting customer loads when possible. This is done behind the scenes and transfers electrical connections between distribution lines with little to no impact on citizens,” the city said in a news release.
Shedding load occurs when the demand for electricity approaches supply and BPA is forced to reduce power demand by temporarily removing some customers. This would require RES to disconnect power to some customers and result in short-term, rolling power outages, the city noted.
If shedding load is required by BPA, the city said it would focus on maintaining essential businesses and services. At that time customers will likely see some power outages from a half hour up to four hours. RES intends to minimize the duration of these outages by rotating them through the city, Richland said on June 28.
BPA’s notification to utilities to shed load can occur quickly, so it is unlikely that customers will be notified before an outage is implemented, the city noted.
Meanwhile, Benton PUD on June 29 said in a tweet that it had not been asked, nor was it planning, to shed load.
“We are asking customers to work together to conserve energy. Collectively as a community, we can make a difference. This will help in preparing in the event one of BPA’s major lines or critical equipment fails,” it said.
Benton PUD serves over 50,000 customers in Kennewick, Finley, Benton City, Prosser, and outlying areas in Washington State.
Heat wave extends to Canada, pressuring grid
In Canada, the province of Alberta’s power grid came under pressure in the wake of extreme heat.
In response to the ongoing heat wave across the province in Western Canada, the Alberta Electric System Operator (AESO) on June 29 asked Albertans to help conserve energy to ensure adequate supply and reduce the possibility of power outages.
“Yesterday we saw an unprecedented jump in energy use, reaching 11,512 MW, beating our previous summer peak demand record of 11,169 MW,” says Dennis Frehlich, Vice President, Grid Reliability, at AESO. “We’re on track to break that record for a second day in a row and so we’re asking Albertans to play their part to conserve energy.”