Pablo Vegas, the CEO of Texas grid operator ERCOT, said supply will be lowest compared to demand around 8 a.m. Thursday. However, about 10,000 megawatts of operating reserves will help keep the lights and heat on, even as demand spikes, according to the ERCOT grid and market conditions .

An arctic blast has enveloped Texas, plunging temperatures well below freezing in many regions of the state. Despite the extreme cold, the state’s electrical grid operator says it has met the higher demand for electricity.

The ongoing freeze will be the biggest test the grid has faced so far this winter as forecasted demand nears 84,000 megawatts.

Anytime the Texas power grid is the subject of a conservation advisory, or when the weather turns extreme in the Lone Star State, it's a good time to check on supply and demand. A statewide freeze has Texans cranking up the heat,