Last September, in the final days of what was then the hottest summer in human history, scorching temperatures threatened to knock out the Texas power grid.
As air conditioners around the state strained to keep homes and businesses cool in 100-plus-degree heat, the state’s grid operator declared an energy emergency, asking all Texans to save electricity between 6 and 9 p.m.
Ada Garcia, a Houston homeowner, didn’t have to touch her thermostat to pitch in. Her utility company remotely shut off her air conditioner nine times that day as part of a power-saving strategy that is already propping up grids around the country as they deal with booming demand and a growing share of unpredictable wind and solar power.
On a typical September day, the Texas grid has plenty of reserves to protect against high demand or a drop in power generation. But one evening last September, blistering heat, the setting sun and a drop in wind shrank reserves to unusually low levels.
At 7:25 p.m., grid operators declared an emergency and called on demand reductions. One such reduction came from Garcia’s home, where energy providers remotely shut off the AC throughout the day to ease the pressure on the grid.
Without this intervention, reserves might have approached critical levels, ultimately requiring rolling blackouts for hundreds of thousands.
Garcia, who was working in her home office, had no idea that Texas was teetering on the edge of an energy crisis that evening or that Octopus Energy, her power company, was waging a battle in her living room to save the grid.
But these small adjustments to her thermostat saved about 10 kilowatt-hours of electricity, which is enough to wash about 20 loads of laundry.
“I never really notice when they change the thermostat,” said Garcia, who signed up for the energy-saving program in exchange for a discount on her monthly power bill.
Around the state of Texas, Octopus and other power companies raised thermostats, paused electric car chargers and tapped into home batteries in thousands more of their customers’ homes. They also paid stores, data centers and office towers to shut off lights and air conditioners and slow down their computers.
All told, Texas utilities made 2.6 gigawatts of electricity demand disappear in the critical moments when the grid was in crisis — the equivalent of a large nuclear power plant.
That’s why programs like this one are called “virtual power plants.”
Experts say they will be crucial for helping the United States clean up the electric grid without facing blackouts — and without waiting years for new power plants and transmission lines to go through permitting and construction.
“They can be deployed very quickly using [devices] that are already in people’s garages or on people’s rooftops or in people’s basements,” said Mark Dyson, a managing director in the electricity program at the clean energy think tank RMI.
