Community Solar Farm And Batteries Test Power Of Austin's Electric Grid

Apr 11, 2018

In East Austin – just east of Airport Boulevard and a short drive from downtown – you’d rightly expect to find a new crop of houses going up. Instead, you'll find La Loma Community Solar Farm.

“There’s a lot of reasons why this parcel really couldn't have been used for something like housing or other redevelopment,” Danielle Murray, manager of solar energy services at Austin Energy, says.

Danielle Murray, manager of solar energy services at Austin Energy, says the utility will respond if customers believe renewable energy is important.
Credit Gabriel C. Pérez / KUT

“There’s a railroad to our south that has freight traffic on it, a water channel down the middle of the site, flood plain issues, protected trees," she says. "We’re in the flightpath, as you can hear from some of the overhead noise.”

Instead, these 16 acres hold enough solar panels to power 440 households. It’s a part of Austin Energy’s longstanding effort to promote solar. But, it’s also part of a unique experiment that could help utilities store more electricity.

For years, Austin Energy has subsidized residential rooftop panels. But those programs give rebates to homeowners, who tend to be wealthier, not renters or people who don’t make much money.

The utility is pitching La Loma as a kind of democratization of solar. A share of the electricity produced here is sold at a discount to consumers who normally couldn't afford it.

“We’re a municipal utility, we’re here to serve our constituents,” Murray says. “If they believe that renewable energy is important and that we should be doing more of it, we’re going to try and do that with and for our customers.”

Projects like this might also serve the utility’s interests.

“Utilities are worried about a death spiral,” says Dan Cohan, a professor of civil and environmental engineering at Rice University.

When people put solar panels on their houses, they generate their own power instead of buying it from the utility. 

“The concern to them is that as they start to lose some customers, then their fixed costs get divided over fewer and fewer customers. That drives up the cost and then, in turn, that makes it even more attractive for more people to defect from the grid.”

Big projects like La Loma might be a way for utilities to keep selling power to customers, while also going solar. In Austin, which wants 55 percent of energy used to be renewable by 2025, these projects become even more important. 

Solar Plus Storage

But there’s even more happening here than community solar. It's behind a big walled-off section of the lot that buzzes with electricity as you approach.  

Austin Energy's Lisa Martin leads the way into the Kingsbury Substation, which houses a giant rechargeable battery.
Credit Gabriel C. Pérez / KUT

This is the Kingsbury Substation. Austin Energy has built a giant rechargeable battery with financial help from the state and the Department of Energy.

It's in a 46-foot-long white container “essentially the size of the back of an 18-wheeler,” says Lisa Martin, manager of advanced technologies for Austin Energy.

The battery at the Kingsbury Substation stores enough electricity to power about 300 homes for two hours.
Credit Gabriel C. Pérez / KUT

The battery is charged by the solar power generated here, storing enough electricity to power around 300 homes for up to two hours. It’s one of a few batteries the city has put around the East Side to test what energy storage might mean for the future of the electric grid.

As Martin puts it, the utility wants to figure out “the best way to pair solar with storage and maximize the value.”

She says one way batteries help is by smoothing out the intermittency of renewable energy, a source that is usually only available when the wind blows or the sun shines. With batteries, you can use power from the sun at night.

There are also financial benefits.  

“We might charge the battery when prices are low and [use its energy] when prices are high,” Martin says.

Maintaining Grid Reliability

Because of its ability to capture renewable energy and deploy it later, battery storage is often seen as the key to a grid free of energy created by fossil fuels. But Martin thinks that's a long time coming.

“If we only relied on intermittent renewable energy and battery storage pairings, we also have to make sure that the rest of the reliability of the grid is maintained,” she says.

To understand the challenge of maintaining grid reliability it might help to think of electricity as water. 

“It’s a little like building a dam,” says Michael Webber, deputy director of the Energy Institute at UT Austin. “You kind of want to keep the dam empty, so that when it rains you can catch the water. Except you kind of want the dam to be full, so that when it doesn’t rain you have water available. Same thing with the battery.”

In the short term, Cohan says he doesn’t think large-scale battery storage will be a necessary part of including more wind and solar on the grid. 

“Right now [energy produced in Texas] is 18 percent wind and just 1 percent solar, so we’re doing just fine without a lot of battery storage,” he says.

But, he says, as renewable energy grows and energy prices rise in the summer, the need for energy storage will increase.