When Ozarks Electric Cooperative officials joined leaders of Fayetteville, Arkansas, in October 2020 for the dedication of solar and battery storage projects to power the city’s wastewater treatment plants, much of the talk focused on clean energy.

“The wastewater treatment plants are in our service territory, so the project offered an opportunity to reduce our load and help the city save on its energy costs,” says Ashley Harris, vice president of marketing and communications for the Fayetteville-based co-op. “We worked with the city and with the developer throughout the design and construction, and excess power generated by the sites is used by our members.”

Less than five months after the dedication ceremony, those facilities would prove to be an essential source of reliable power during a historic regional demand crisis.

“We needed to use some of that stored energy at a very critical time,” Harris says. The co-op does not serve most of the city, but the plants and some surrounding areas developed in recent years are on co-op lines.

When a mid-February cold snap last year drove record low temperatures from North Dakota to Texas and triggered unprecedented demand for electricity and natural gas, regional grid operators ordered widespread power curtailments. Utility systems encouraged conservation among their residential users and called on their commercial and industrial users to suspend nonessential electricity use.

“We reached out to our key accounts to help us with our curtailment effort,” says Troy Scarbrough, Ozarks EC’s vice president of engineering and operations.

When the co-op contacted Fayetteville officials, they quickly agreed to go even further, offering up the 10 megawatts of solar power and 24 megawatt-hours of battery storage at wastewater treatment plants east and west of the city and on-site backup generation that was maintained and available.

“We were glad to do what we could to help area residents keep their lights and heat working,” says Peter Nierengarten, Fayetteville’s environmental director.

While electricity from the renewable assets at the treatment plants was diverted for co-op use, the city secured a steady supply of diesel fuel to keep the generators and sewage systems running normally.

As the solar arrays helped meet real-time demand, power from the energy storage systems was charged and discharged at strategic times. Some residents served by a local investor-owned utility did experience limited rolling blackouts, but the co-op reported no supply-related outages during that cold February week.

“Every megawatt of resources or curtailment was critical to avoid the need for rolling blackouts,” Scarbrough says. “Every megawatt-hour generated during certain hours was extremely expensive, so Ozarks reacted to optimize the solar generation and dispatchability of the energy storage.”

Following the incident, co-op officials reviewed their response and determined that the combination of solar generation and storage, coupled with the on-site generation from other key accounts, amounted to 50 MW of curtailment during the unprecedented seven-day high-demand period.

They specifically called out the work of their key accounts team, who have built strong relationships with their industrial and institutional accountholders.

“We take the need to be ‘trusted energy advisers’ very seriously. It’s one of our core principles,” Scarbrough says. “The relationships we’ve built with the city and our C&I members made all the difference here. Without those close contacts, things might not have gone so well.”