In 1950, the English mathematician Alan Turing devised what he called “the imitation game.” Later dubbed the Turing test, the experiment asks a human participant to conduct a conversation with an unknown partner and try to determine if it’s a computer or a person on the other end of the line. If the person can’t figure it out, the machine passes the Turing test.
Power grid operators are now preparing for their own version of the game. Virtual power plants, which concatenate small, distributed energy resources, are increasingly being tapped to balance electricity supply and demand. The question is: Can they do their job as well as conventional power plants?
Grid operators can now find out by running these power plants through a Turing-like test called the Huels. To pass the Huels test, the performance of a virtual power plant must be indistinguishable from that of a conventional power plant. A human grid operator serves as the judge.
Virtual power plant developer EnergyHub, based in Brooklyn, N.Y., developed the test and outlined it in a white paper released today. “What we’re really trying to do is fool the operators into feeling that these virtual power plants can act and feel and smell like conventional power plants,” says Paul Hines, chief scientist at EnergyHub. “This is a kind of first litmus test.”
What Are Virtual Power Plants (VPPs)?
The virtual-versus-conventional power plant question is a timely one. Virtual power plants, or VPPs, are networks of devices such as rooftop solar panels, home batteries, and smart thermostats that come together through software to collectively supply or conserve electricity**.**
Unlike conventional power generation systems, which might crank up one big gas plant when electricity demand peaks, VPPs tap into small, widely disbursed equipment. For example, a VPP might harness electricity from hundreds of plugged-in electric vehicles or rooftop solar panels. Or it might direct smart thermostats in homes or businesses to turn down heat or cooling systems to reduce demand.
The technology is emerging at a time when concerns over data centers’ electricity demand is hitting a fever pitch. The consultancy BloombergNEF estimates data-center energy demand in the United States will reach 106 gigawatts by 2035–a 36 percent jump from what it had projected just seven months ago.
How utilities and grid operators will meet the growing demand is unclear and faces challenges on many fronts. Turbines for natural gas plants are backordered and new nuclear reactors are still years away. Wind and solar, while cheap and fast to build, don’t produce the 24/7 electricity that data centers demand, and face an uphill political battle under the Trump administration.
All of this together has created an opening for VPPs, which could add gigawatts to the grid without significantly jacking up electricity rates. “It’s a political issue. If you said you’re going to get electricity costs under control, this is literally the only way to do it in 12 months,” says Jigar Shah, a clean energy investor at Multiplier in Washington, D.C., who led the U.S. Department of Energy’s Loan Programs Office under the Biden administration.
VPPs could also reduce utilities’ need to invest in distribution equipment, avoiding supply chain shortages and inflated costs, Shah says. “There is no other idea that you could possibly deploy in 12 months that would have that big of an impact,” he says.
According to a 2024 U.S. Department of Energy report, VPPs could provide between 80 and 160 gigawatts of capacity across the U.S. by 2030—enough to meet between 10 and 20 percent of peak grid demand.
How Can VPPs Gain Grid Operator Trust?
But first, VPP developers have to win over grid developers. Benchmarks like the Huels test are crucial to building that trust. “In order for us to build our reliance on VPPs, they do need to pass the Huels test and operators need to be able to count on” the VPPs delivering power when called upon, said Lauren Shwisberg, a principal in the nonprofit research group Rocky Mountain Institute who co-authored a recent report on VPPs and was not involved in the development of the test.
Matthias Huels, an engineer who spent more than four years at EnergyHub, first came up with the idea for the test in 2024. After workshopping the idea with colleagues and, somewhat ironically, ChatGPT, Huels presented the concept to the company.
Huels designed the test subjectively. Currently, in its earliest iteration, it appears to follow a guideline akin to the Supreme Court’s “I know it when I see it” test for what distinguishes pornography from erotic art. That is to say: passing the test depends on who’s judging. If a grid operator finds the power from a VPP as dependable as electricity from an actual power plant burning gas to produce electrons, then the VPP has passed.
There are four levels to the Huels test. To reach level 1, a VPP must be able to shave off demand from the grid by, for example, successfully scheduling smart thermostats to dial down when the grid faces maximum demand. To reach level 2, a VPP must be able to respond to market and grid data and dial down demand when prices hit a certain level or tap into solar panels or batteries when power is needed. Human decision makers are involved at these levels.
Passing the Huels test comes at level 3. That’s when a VPP can function automatically because it’s proven reliable enough to be indistinguishable from a gas peaker plant–the type of power station that comes online as backup only when the grid is under stress. Passing level 4 involves VPPs acting fully autonomously to adjust output based on a number of actively-changing variables throughout the day.
“The imitation game that Alan Turing came up with was: Can a computer fool an interrogator to think it’s actually human even though it’s a computer,” Hines says. “We propose this idea of a test that would allow us to say: Can we fool a grid operator into thinking that the thing that’s actually solving their problems is this aggregation of many devices instead of a big gas plant?”
Can VPPs Mimic Gas Peaker Plants?
Peaker plants only generate power about 5 percent of the time over their lifespans. That makes them easier for VPPs to mimic because, like peaker plants, the limited amount of power that can be made available by demand response or harvested from batteries only provides bursts of power that last a few hours at a time.
Far more difficult is stacking up to a full-scale gas plant, which operates 65 percent of the time or more, or a nuclear plant, which usually operates at least 95 percent of the time. Getting there would involve equipping a VPP network with long-duration storage that could be powered up during the day when solar panels are at peak output and discharged all night long. “You start talking about VPPs with large amounts of batteries that can run 365 days per year,” Hines says. “That’s a road we can go down.”
EnergyHub has been putting its VPP systems through the Huels test. Last year, EnergyHub successfully ran trials with Arizona Public Service, Duke Energy in North Carolina, and National Grid in Massachusetts. In Arizona, EnergyHub’s software dialed into homes with solar panels and smart thermostats and ran air conditioners to “pre-cool” houses during the day when the sun was generating lots of electricity. This allowed the state’s biggest utility to reduce demand during peak hours when residents would typically return home from work to turn on televisions and crank up their air conditioners.
“You have too much power in the middle of the day because of solar, then the early evening comes and you get people ramping up their evening loads right as the solar is ramping down,” Hines says. “You need something that can feather through that schedule. We created something that can do this.”
That lands the company somewhere between a 2 and 3 on the Huels testing scale. Passing level 3 “is going to take a few years,” Hines says.
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