Storing power key to expanding use of renewable energy

Buncombe County and the city of Asheville have big plans for increasing the area’s use of renewable energy while moving away from fossil fuels. By 2042, a majority of Buncombe County commissioners declared in December, the entire community will run on renewable fuel sources. And the city has been working toward its goal of reducing its carbon emissions by 80 percent by 2039, announcing last year that a 31 percent reduction from 2001 levels has been achieved so far.

The will to embrace renewable energy sources like solar and wind power is clearly there, but how about the way? The success of the county’s and city’s energy goals, say local experts, hinges on the availability of battery storage — and lots of it.

“Battery storage is a critical part of having a 100 percent renewable energy grid,” says Phelps Clarke, a co-founder of Fairview-based Sugar Hollow Solar, which has completed over 150 solar installations collectively generating over a megawatt of solar capacity since its launch in 2010. “That’s because renewable energy sources are intermittent. The sun doesn’t always shine, and the wind doesn’t always blow. We have to have a way to store energy to use when we need it.”

Local energy activist and Energy Innovation Task Force committee member Ned Ryan Doyle agrees. “Investments in energy storage are a key component to a more reliable and resilient grid,” says Doyle. “It provides a foundation for the expansion of true clean energy sources.”

Changing to batteries

Duke Energy, which provides the majority of Western North Carolina’s electricity, says it’s making progress in ramping up its battery storage capacity. But despite the utility’s breathless press releases, only one installation is operational as this article goes to print — and there’s no way to describe its size as anything other than tiny.

“Our first project was to install a microgrid at the top of Mount Sterling,” notes Robert Sipes, a Duke Energy vice president who heads the company’s Western Carolinas Modernization project.

Located in the Cataloochee area near the Tennessee border, the peak is home to a National Park Service radio transmitter. Keeping the station supplied with electricity has long been a challenge, Sipes says, since the line that powered it “ran 6 miles through some of the most rugged terrain we have in our system. When we had storms, we would have a bunch of outages. It would take a long time to get them back on because you can’t drive to get to that line; you have to hike in.”

A microgrid, Sipes explains, is a way to segment the electrical system into smaller parts and isolate one part from the rest of the system to provide more reliable service. The compartmentalized system on Mount Sterling includes a small battery charged by a 10-kilowatt solar array.

Sipes says the Mount Sterling project taught Duke Energy two things: “We demonstrated that a microgrid could be more economical than traditional methods of providing service to our customers. By serving that tower the way we are it is lowering cost. We also demonstrated that we can provide more reliable service.”

Hot Springs and beyond

With the Mount Sterling project under its belt, Duke Energy set its sights on a facility in Hot Springs that will be “the largest microgrid that we have ever installed by the time we have it in service [in 2019],” Sipes says. Featuring a 3-megawatt solar array and a 4-megawatt battery, the new station will provide backup power for Hot Springs, which Sipes points out shares many characteristics with Mount Sterling. “It’s served by a line that runs 10 miles through very rugged terrain and it’s the only line that we have that provides service into Hot Springs,” he explains. “When something happens to that line, those customers are out for a long time.”

The battery backup could sustain the town’s peak energy load of 1 megawatt for four hours, according to Jason Walls, Duke’s Asheville-area community and government relations manager. But in real-life conditions, he continues, “the battery should last much longer because the load will likely be much lower.” In such a situation, Duke Energy would notify customers of the need to conserve energy until permanent service could be restored and the solar system could also contribute generating capacity, he explains.

Asheville will get its own utility-scale battery installation in 2019 when Duke Energy adds a 9-megawatt lithium-ion battery system at an existing substation in the Rock Hill community near Sweeten Creek Road. That setup will help the electric system operate more efficiently by providing “frequency regulation and other grid support services,” according to a press release.

Sipes says it’s not only the cost savings associated with improvements in battery technology that make these projects more viable than in the past. Increasing sophistication in the control systems and related technologies required to operate batteries also plays a role. “As batteries have become more viable options to use on the power system, the systems to operate them have had to evolve as well,” Sipes says.

It’s likely that the company will continue to do more of these projects in the future, Sipes tells Xpress. “We are actively looking at other opportunities to use battery technology as part of the solution in Western North Carolina,” he says.

Duke Energy previously announced plans to install a solar farm as part of upgrades at its Lake Julian power station, and Walls says the company is evaluating the possibility of including a battery storage component on the site. The solar array will be located where a 41-acre coal ash storage pond is being excavated and removed. Adjacent to the coal ash pond, two 280-megawatt natural-gas-fired generating units are now under construction, with completion scheduled for 2020.

On the home front

While utility-scale battery storage may be the wave of the future, some local power consultants point out that batteries have been used since the early days of the solar industry in this area. Weaverville’s Sundance Power Systems, for example, was founded in 1995 and today serves over 1,000 customers in the region.

Battery backup has always been an important part of Sundance’s capabilities, says Dave Hollister, the company’s CEO. From the beginning, batteries “provided a place to put the energy that the solar panels produced during sunny daylight hours,” he explains. “The batteries would provide the energy during nighttimes and cloudy periods.”

In 2005, the N.C. Utilities Commission established net metering rules that allow an individual homeowner or business to use the power grid as temporary storage for any excess energy that isn’t needed right away.

Even with net metering as an option, plenty of people still want to have a battery system, says Hollister. For many, the appeal is having a sustained backup power source. “You can run a generator for a few days, but if you run a generator for a week or two, you will run out of propane,” he says. “If people are trying to organize some level of autonomy in their home, they can sustain their home through significant power outages with a battery.”

Some people may invest in batteries because they are worried about the possibility of changes in the regulatory environment. House Bill 589, signed into law by Gov. Roy Cooper in July, initiated a review of net metering laws in North Carolina. With net metering under the microscope, “Batteries could make a lot more sense in a few years,” says Sugar Hollow Solar’s Clarke.

Finally, people invest in batteries because they want or need to live off-grid. “If someone is building a house and the utility provider can’t get power to it, or it costs a lot of money to run power to it, or if they can’t get right of way, they’ll install batteries,” Hollister says.

Piece of the puzzle

Despite the promise of batteries to make wider use of renewable sources of energy feasible, they’re not a silver bullet for all of Western North Carolina’s energy needs. “Batteries aren’t the solution,” says Sipes. “They are part of the solution. There is not a model out there that shows how batteries alone can address our electrical needs today. There are other pieces that need to fall into place.”

Because the availability of solar energy varies with the time of day and cloud cover, Sipes continues, the amount of battery capacity required to ensure a continuous supply of power would be “hugely expensive.”

Cost isn’t just a factor at the utility scale; it’s a factor in residential battery storage as well. “There is not a huge economic case for individuals investing in battery storage in their homes right now,” says Clarke. He points out, however, that those who are investing in battery storage are playing an important role in driving the industry. “Solar is great, and you are doing your part,” says Clarke, “but if you want to be a pioneer, you should try out batteries. These are the investments the industry needs to push things forward,” says Clarke.

Hollister is certain that a future with adequate battery storage is possible. “There are several ways batteries can be used,” he explains. “You don’t necessarily need solar panels. You can use a battery system, and if the economics are right based on the utility, you charge the battery during off-peak times and use the battery during on-peak times and you’re just another peaking power plant.”

But Hollister, who has used a solar and battery storage system at his home for 23 years, points out that the real freedom comes when battery technology is coupled with renewable energy. “When the power goes out, I don’t even know it,” he says.

“It feels terrible to have your power go out and realize, ‘I have no water. I don’t have any heat’,” says Hollister. “Batteries are critically important to be able to store the power when you have production and use it when you don’t. It all comes back to that basic equation,” he says.

“Energy is what makes everything happen,” says Hollister. “The energy storage revolution is upon us.”