Got A/C? Keeping the power on during extraordinary heat

MOSES LAKE — It was a hot summer in the West. Hot enough in late June and early July to strain power grids and prompt rolling blackouts in places like Spokane. Just as the heat was at its worst.

But the power kept flowing in Grant County, in large part because of the constant work of engineers and power managers at Grant County Public Utility District.

“Extreme weather events we train and prepare for,” said Dale Campbell, a senior manager of power production engineering for Grant PUD. “They are an opportunity for us to show what we’re made of.”

Campbell oversees more than 2,000 megawatts of electricity generation: 1,221 at Wanapum Dam; 950 at Priest Rapids Dam; and roughly 28 megawatts in Quincy, Potholes and a wind project south of the Tri-Cities. He says that as long as there is water behind the Grand Coulee Dam, there are “not equipment limits” on what the PUD can generate.

“We are well-equipped for extreme cold and extreme hot, and none of our equipment was ‘opted out’ of normal range,” he said.

Campbell said the PUD, like any utility, plans at least 18 months in advance for major maintenance outages, and then keeps updating those plans, working with the Northwest Power Pool (NWPP) to coordinate the generation and delivery of electricity across the region.

Based in Portland, Oregon, the NWPP covers British Columbia, Washington, Oregon, Idaho, Nevada, Utah and parts of Wyoming, Montana, California, Colorado and the Canadian province of Alberta, coordinating power supplies between local and regional utilities and power generators.

According to Jesus Lopez, the senior manager for power delivery at Grant PUD, generation isn’t the problem in hot weather — transmission is. Electricity generated at very high voltages can travel farther, but must be converted, or “stepped down,” to lower voltages by transformers. They can get hot, pushing transformers to their limits.

The PUD has 10,000 ground transformers and 24,600 overhead transformers.

Lopez said most of the PUD’s big oil-cooled transformers also have some amount of air cooling to draw off even a degree or two in very hot weather.

“It’s better than nothing, and every degree makes a difference,” he said.

It’s also important to ensure the power delivery system is secure enough so that small local power outages, such as when a tree falls on a power line, don’t cause a cascade of failures across the grid.

“We have the highest level of reliability in the event of unexpected faults,” Lopez said.

According to Heather Rosentrater, a senior vice president of energy delivery for Spokane-based Avista, the company’s power grid is designed for a high of 104 degrees but saw temperatures reach as much as 120 degrees during the heat wave in late June and early July.

Heat causes greater demand as customers switch on air conditioners, Rosentrater said, and that puts more stress on the company’s delivery system, which can stress transformers and force them to go down in the heat.

Avista did have some rolling power outages this summer, done purposefully to protect the equipment from major failure, she said.

“We did it on a neighborhood level,” she said. “It was a perfect storm.”

Grant County PUD Senior Manager of Wholesale Power Marketing and Supply Rich Flannigan said the PUD also keeps a close eye on the spot electricity market in case there are opportunities to sell surplus power or a need arises locally for additional juice.

June and July were very tight power markets, he said, with very little surplus to spare.

“We saw prices spike here and there,” he said. “But we got pretty lucky, and we were able to import a little bit. But we do have enough capacity to meet these extreme events.”