POWER Engineers designs renewable energy storage system for California utility

An Idaho company has received several awards for designing one of the nation’s largest energy storage systems.

The Pomona Energy Storage Facility, owned and operated by AltaGas with its natural-gas fired peaking power plant in the Los Angeles Basin, is a 20-megawatt lithium-ion battery storage facility — one of the largest in North America. It reduces the need to fire up natural gas generators at peak times while at the same time mitigating fluctuations from renewable energy sources such as wind and solar, said POWER Engineers Inc., the Hailey company that designed the system.

The American Council of Engineering Companies (ACEC) selected the facility to receive a National Recognition Award in the 2018 Engineering Excellence Awards competition. In addition, the project received a 2018 award from the Idaho branch of ACEC in the “Energy” category, POWER said.

Battery storage is important as electric utilities look to renewables, to provide electricity for times when the sun doesn’t shine or the wind doesn’t blow, said POWER CEO Bret Moffett.

“Battery storage is vital in order to realize the full benefits of renewable generation,” he said. “Utility-scale battery storage is large, complex and not easy to make work efficiently and effectively.”

Idaho Power isn’t considering such systems yet for two reasons, according to Brad Bowlin, communications specialist. First, as of the 2017 Integrated Resource Plan — a report the company generates every two years to examine energy demand for the next 20 years — the cost per megawatt hour for battery types was higher than that of other options. Second, the 2017 IRP indicated that Idaho Power didn’t need any new energy resources until 2026. “Because of our status as a regulated utility, we can’t develop new energy resources without first demonstrating a need,” he explained.

The utility will re-examine the issue for its 2019 report, Bowlin said. “We are continuing to monitor price trends and the scalability of the technology in the coming years,” he said. “We prepare the IRP every two years to capture those sorts of changes in the energy market.”

The facility has a discharge capacity of 80 megawatt hours, meaning it can store and discharge 20 MW  — the electrical needs of 15,000 homes — of instantaneous power and deliver it for four continuous hours, said Steve Harris, senior project manager, in Boise.

As far as technology, lithium-ion batteries were about the only game in town, Harris said. “Lithium-ion batteries were the only proven technology available in the required schedule,” he said. “The major design challenges at Pomona were determining where to place the batteries and how to interconnect them to the utility electrical grid.” The batteries use the same sort of lithium-ion technology as batteries people use every day, except the system used 12,240 of them, each weighing about 50 pounds, he said.

The technology is similar to that used by the Tesla energy storage system, but that system would not have fit in the available space, Harris said. Instead, POWER developed a custom layout of the batteries’ storage racks and enclosure to fit, he said.

Typically, batteries in such a system start to degrade within five to seven years, Harris said. “Additional batteries are added at this point, until the original batteries are ultimately replaced entirely.” Most major utility-grade lithium-ion battery suppliers have a “take back” provision, where they take back the batteries at the end of their useful life and recycle the materials into new batteries, he said.

The project was designed between August and November 2016, and was built between September and December 2017. Typically, such projects take at least a year, Harris said. The lithium-ion batteries, software control platform and power conversion technology were provided by Wärtsilä’s Greensmith Energy Management Systems. ARB was the contractor.