How does the electric grid work?

Most Americans don’t have to think about where their energy comes from. If they’re lucky, they can just flip a switch or hit a button, and a hot meal or illuminated room is at their fingertips.

But as unprecedented climate events both put a premium on access to energy and disrupt critical infrastructure that delivers it, and as data centers double down on their consumption, the reliability of our energy supply has never been more important—or more tenuous.

As the first installment in Tech Brew’s series about the vulnerabilities (and opportunities) facing America’s power grids, we posed the most obvious questions to some experts.

So…just what is the grid, and how does it work?

Scott Harden, CTO at Schneider Electric, described the grid as “the most complex machine that mankind has ever created.” Despite its complexity, the concept is rather straightforward: “It’s essentially a system of wires that move electrons from sources of generation to points of use,” Harden told Tech Brew.

But “the grid” isn’t a single entity: Any given spot in the US is served by one of three regional grid systems—one of which serves only the state of Texas—though they do connect to each other on some level to distribute power to millions of customers.

Utilities that are part of the grid commonly generate their own electricity, transmitting it to customers directly. Some federal entities get involved in grid operations, too, like the government-owned Tennessee Valley Authority, which serves the titular state as well as portions of Alabama, Mississippi, Kentucky, Georgia, North Carolina, and Virginia.

Another distribution model came along in 1996, creating an alternative to the status quo “wholesale” electricity market. The government paved the way for independent system operators and regional transmission organizations to compete for the chance to buy and sell power services.

Since the early days of electrification, the grid has relied on the “funnel” model: Large, centralized power plants typically fueled by coal or natural gas generate a predetermined amount of electricity that the grid is expected to need. That energy is “delivered over a cascading series of wires that drop down in voltage from transmission to distribution down to local delivery, and then, ultimately, to the point of use, whether it’s a commercial facility or a home,” Harden said.

This model is unidirectional by nature: Power flows from the generation point down to the end user. But the grids of the future are moving toward a new model that more resembles a branching tree or a multi-lane highway.

“The grid is really being pushed outside of that to a new paradigm where power flows are not in any way directional,” Harden said. “They are changing continuously, and it’s becoming more and more dynamic.”

What are the benefits of a multi-directional grid?

As the grid moves to an ebb-and-flow model, it gains flexibility, allowing bulk renewable energy sources and consumer devices such as electric vehicles and rooftop solar panels to contribute back to the grid in times of high demand.

Incorporating renewable resources like solar and wind helps meet state, national, and global decarbonization goals, but they also “create more of a challenge for the grid operator to make sure there’s enough electricity at all times,” said Allan Schurr, chief commercial officer at microgrid company Enchanted Rock.

According to Nick Tumilowicz, director of product management at utility management company Itron, California and Hawaii both have high rates of battery attachment, meaning that homes outfitted with solar panels also have a way to store unused energy for later use.

That’s important for making renewable energy last longer than just the hours that the sun is shining or the wind is blowing, and it makes it possible to distribute that stored power across the grid to mitigate outages as energy demand fluctuates.

“They’re kind of like peanut butter and jelly because one is firm, and the other one is variable,” Tumilowicz said of pairing battery storage with solar energy. “Together, you can really do the grid a service.”

Electric vehicle charging is another, albeit more nascent, form of home energy generation that can give back to the grid. However, some automakers are wary about leaning too heavily on this option because it can take a toll on EV battery life.

More commonly, Tumilowicz said, homeowners with electric vehicles might pull from EV battery storage to power their own homes in case of an outage.

How is the grid impacted by new energy demands?

Advances in computing, manufacturing, and transportation are all placing strain on electric infrastructure designed to support needs of the past.

“What has changed most recently is the scale of data centers, and some other large loads,” Enchanted Rock’s Schurr said. “There’s a lot of reshoring of manufacturing that’s doing some of this too, and electric vehicle charging, especially for fleets. They’re adding load to the grid that the grid is not easily able to absorb.”

But these new sources of grid stress can also come with their own opportunities to introduce cleaner energy sources and more efficient management. For example, Schurr said, Enchanted Rock connects data centers to temporary “microgrid” systems powered by natural gas engines, replacing the status quo of diesel-fueled generators seen as heavier polluters.

Itron sees an opportunity to monitor electricity use from the “edge” of the grid, employing “smart” home meters that can direct a range of connected devices—from air conditioner units to EV chargers—to ramp up or down depending on demand.

“You’ve got this computer that now sits at the edge, that’s already on your house and my house,” Tumilowicz said. “It has the ability to measure the grid and to adjust the conditions of the grid based on its ability to talk to things where we live—customer energy resources.”

Schneider Electric’s Harden noted that electrification has upended the linear model of energy supply and demand that utilities relied on in the past. They must now approach the grid as a system that’s always in flux with variable loads and multiple energy sources, Harden said.

“Predictability when it comes to how much electricity that they generate is basically out the window now,” he said. “It’s [a] much more dynamic system.”