KANSAS CITY, Mo. — Reliance on wind power is under the microscope this week, as rolling power outages have impacted the metro.
Sub-zero temperatures knocked some wind turbines offline, according to Evergy.
Icy blades and frozen hydraulic fluid are two of the factors impacting the machinery itself. Plus, the wind just hasn't been blowing very hard.
It matters because wind is one of the major energy sources for the regional power grid run by Southwest Power Pool (SPP).
"They have one of the largest portfolios of wind generation in the United States," Chuck Caisley, of Evergy, said. "And that wind generation continues to be under some duress and continues to have issues."
The amount of energy coming from wind fluctuates, just like the weather.
SPP data from 2020 shows just how much it can vary. For instance, on one day in April, there was enough wind energy to power 73% of the power grid's load. However, on another day in July, there was only enough wind to cover about 1%.
The average for 2020 was 31%, marking the first time wind was the No. 1 fuel source for the year. Coal and natural gas are the other top sources.
Considering the impact the weather has had on turbines, some have wondered if there's too much reliance on wind energy.
Lanny Nickell, SPP executive vice president and chief operating officer, acknowledged that question will come up as the events of the past few days are reviewed. But he cautioned against drawing conclusions about energy sources based on their performances during unusual conditions.
"We have to understand that these events are very, very, very rare," Nickell said, "and we have to be reasonable in terms of our expectations."
A spokesperson for SPP said the lack of wind energy generation this week did not surprise the organization, which develops forecasts to predict wind performance.
"Speaking of this specific cold-weather event, there's not been enough wind to serve more than about 10% of systemwide load at most," SPP's Derek Wingfield wrote in an email. "Though wind has come in a little higher than we had forecast beforehand. Our operators are used to working around forecast variance like this, and in those cases we rely on other fuel sources to make up the difference."
On its website, SPP posts a pie chart showing the mix of energy sources being used at a given time to power the regional grid. At 5 p.m. on Wednesday, coal and natural gas were the top fuel types in use. Wind clocked in at just 2.4%.
On an average day, wind power typically accounts for 30% to 35% of electricity, according to Evergy, but as of Tuesday morning, that number was down to 18%.
However, the utility company has repeatedly pointed out it's not just about wind.
"It's all types of generations that have significant issues when you're talking about the kinds of temperatures we've been having over an extended period of time," Caisley said.
For example, there's stress on the supply of natural gas as homes, businesses and power plants compete for the same resources.
Coal isn't immune either, since piles are stored outside and become wet when it rains or snows.
"One, it becomes very high in moisture content, and the second thing is it becomes almost like concrete," Caisley said. "So it's very difficult to get into the power plant to burn and make electricity."
All of those factors created the perfect storm for the problems seen over the past week.