Routine Tree Trimming Does Help Reduce Power Outages, Study Finds

As we get into the winter months, there are concerns about the power grid. A new study found one of the best ways to decrease the number of outages during storms is tree cutting.

Connecticut has some of the highest urban tree cover in the nation, and those trees and their limbs come down pretty easily in storms.

A UConn Ph.D. student looked at just how effective it is to cut these limbs as a preventative measure. The study, which was funded by the Eversource Energy Center, found it is in fact pretty effective.

"We found out that trimming was very good at reducing the extreme effects when we had storms and such. So a little bit like vaccines, they protect you against the most serious effects of a disease," explained Marcello Graziano, a research fellow for the Connecticut Center of Economic Analysis at UConn and the Eversource Energy Center.

The study, which looked at data from 2009 to 2015, found that Eversource's tree-cutting program led to 900 fewer tree-caused power outages each year. That means 18,000 fewer customers were affected.

And for those who did end up in the dark, the length of the outage dropped by 54%.

"We found out that at least up to four years out this trimming was effective at reducing the negative effects of fading vegetation throughout the grid," Graziano said.

"Also we've identified that picking certain areas, picking the right spot, will have just as good as a benefit as just sort of doing routine, oh, we trimmed here four years ago, we'll trim here again, and in four years, you know, having that spatial component in this study really brought to light this idea of optimizing the effectiveness of their tree trimming, and picking out areas of high vulnerability to employ that method," said Adam Gallaher, UConn Department of Geography Ph.D. candidate.

Eversource has received a lot of criticism for its tree-trimming program. But this study shows that their work does in fact make a difference.

"One of the most shocking things for me from growing up in the Midwest and moving out to New England was the price of electricity. I mean, it's about 11 cents on average throughout the United States. And Connecticut on average is about 19 cents a kilowatt-hour. And so you're really paying a premium for that electricity. And if you're not getting a reliable grid, it's you're gonna get some backlash from consumers," Gallaher explained.

But Gallaher says Eversource could do a little better. He said tree cutting is timely, costly and labor-intensive, but the company would be better served by increasing those efforts and focusing on certain areas where the grid is most vulnerable.

Eversource did announce a $72 million investment in the program earlier this year.

The study did not include data from Tropical Storm Isaias last year, which left hundreds of thousands of people without power for days, so it's unclear what effect tree trimming would have had on that.