"power grids" in the below refers to the power grids supplying electricity to the region from Texas to California, so I think "THE power grids" is right. Similarly, "demand" refers to the demand for electricity in the same region, so "THE demand" seems right. I was wondering whether I get it right.
It comes at 56:00 in the news clip, https://archive.org/download/KNTV_20220611_013000_NBC_Nightly_News_With_Lester_Holt/KNTV_20220611_013000_NBC_Nightly_News_With_Lester_Holt.mp4?t=660/720&ignore=x.mp4
-- Dangerous heat wave --
Here in the West tens of millions are suffering through a dangerously early heat wave gripping the region from Texas to here in California. The triple-digit temperatures causing concern over whether power grids can meet demand. Here’s Miguel Almaguer.
Tonight the brutal broil across much of the West, a heat wave so oppressive, forecasters say it could be dangerous or even deadly for some of the 51 million Americans now trapped under a heat dome. “I try not to go out because of the heat as well”