In our latest webinar from our Exploring North Carolina’s Clean Energy Transition program (formerly Exploring NC Smart Grid), we heard about the status of utility-scale battery storage in North Carolina. The session featured Jason Handley, general manager of the Distributed Energy Group at Duke Energy; Erik Hall, director of energy services and technology at North Carolina’s Electric Cooperatives (NCEC); and our own David Farmer, senior engineering consultant at Advanced Energy. The presenters discussed how utility-scale battery installations are being applied in North Carolina and how they’re helping to meet sustainability goals and enhance grid reliability and affordability.
Webinar Recording: https://www.youtube.com/watch?v=9C3MEoqUSnI
Duke Energy’s Battery Storage Approach
For Duke Energy, energy storage — beyond battery storage, specifically — has a history that dates back nearly 50 years, with the introduction of a pumped storage hydro station at Lake Jocassee in 1973. The last decade, though, has seen a significant push for battery storage across the utility’s service territory. Duke installed its first commercial battery system in 2012, a microgrid and test facility in 2015, a grid-tied microgrid in 2016, North Carolina’s largest battery project in 2020 and 50 megawatts (MW) of battery storage in Florida, to be completed later this year. And there’s more to come.
Battery storage is an example of a “non-wires alternative,” a utility project or implementation that does not require — and can help defer the build-out of — traditional grid infrastructure, such as transmission and distribution investments. Additional examples of non-wires alternatives include other distributed energy resources and energy efficiency measures.
Battery storage, and energy storage more broadly, however, represents a new class of assets for utilities. Historically, utilities have had to match their supply of electricity with what consumers are demanding at any given moment. With storage, energy can be held and then dispatched at particular times, enhancing renewable energy integration, optimizing grid operations and driving down costs. Coupled with microgrids, energy storage can further support reliability and resiliency. The flexibility of battery storage is key to its success and its potential to add value across multiple avenues.
Throughout its service territory, Duke has about 35 MW of regulated energy storage in operation and 55 MW in service or under construction. In the Carolinas, Duke has two research and development projects — one at Mt. Holly and the other in McAlpine — as well as four distribution-side installations for a total of 19 MW. The main use cases include resiliency, reliability, transmission and distribution deferral, and bulk system services. Through three distribution projects in the Midwest (15 MW), battery storage is supporting resiliency and reliability while also providing frequency regulation. And the technology is being deployed similarly in Florida, where 50 MW will be online by the end of 2022.
Thanks to lithium-ion’s balance of storage duration and cost, Duke believes it will remain the dominant battery chemistry through at least the end of the decade. But the utility has its eyes on other storage technologies, too, some that have been around and others that are on the horizon. Particular technologies called out by Handley include flow batteries, flywheel energy storage and thermal storage.
Handley wrapped up his presentation by highlighting a few specific battery storage sites in Duke’s territory. A remote microgrid in Mt. Sterling, North Carolina, has a 10-kilowatt (kW) solar array and a 95-kilowatt-hour (kWh) battery working off-grid. Duke’s first commercial battery system in North Carolina, in Asheville’s Rock Hill community, is an 8.8-megawatt-hour (MWh) system that supports the utility’s Western North Carolina Modernization Plan and provides peak shifting and other bulk system benefits. And in Hot Springs, North Carolina, Duke collaborated with the town to implement a microgrid that is nearly ready for full implementation. The site will have 4.4 MWh of battery storage and 2 MW of solar capacity.
How exactly battery storage will progress will depend on regulatory and tax policies, interconnection costs and schedules, supply chain availability and more, but it is poised to play an increasing role in strengthening Duke’s grid and benefiting its customers.
Battery Storage Initiatives from North Carolina’s Electric Cooperatives
NCEC represents the generation and transmission co-op for 26 independent distribution co-ops across North Carolina. These co-ops serve about 2.5 million North Carolinians — about 24% of the state’s population — across 45% of its land mass in 93 counties. NCEC sees battery storage as being central to its goals of pursuing sustainable, affordable energy; leveraging innovation to improve reliability; and supporting the local community.
The co-ops’ broader demand response and distributed energy resource strategy is focused on visibility and coordination: Putting as many resources on the grid as possible can add to grid reliability and value. NCEC’s Hall reiterated the stacked services of battery storage and noted that the co-ops distinguish between financial impacts — which include market services, demand reduction and asset deferral — and service impacts — ancillary services such as voltage support and power quality, increasing site footprints to serve more homes and enhanced reliability.
Overall, North Carolina’s electric co-ops have four microgrids with a combined 3 MWh of battery storage, 14 solar-plus-storage sites with 45 MWh (to be completed by the first half of 2023) and 10 substation battery storage sites with 80 MWh, to be finalized later this year.
Digging deeper into specific projects, Hall highlighted the co-ops’ first microgrids, one on Ocracoke Island and the other in Lillington, North Carolina, at Butler Farms. Ocracoke has a 3-MW diesel generator, a 15-kW solar array, a 500-kW battery system providing 1 MWh, and connected thermostats and water heater controls. The Butler Farms microgrid, which consists of a 250-kW/735-kWh battery system, a 20-kW solar array, a 100-kW diesel generator and a 185-kW swine-waste generator, is jointly owned by NCEC and the farm. It can be islanded to power the farm and nearby homes in the event of an outage.
Heron’s Nest and Eagle Chase are residential microgrids. Each house in Heron’s Nest, a sustainable community, contains connected devices and has a solar array. There is additionally a larger array that serves the community as well as a 230-kW/255-kWh battery system. Eagle Chase, a resilient neighborhood, has a 558-kW/1-MWh battery system along with a propane generator. Overall, it has 36 hours of backup power.
Rose Acre Farms, a commercial poultry operation, is one of the co-ops’ solar-plus-storage sites. The goal of the project was to meet corporate sustainability goals. Phase 1 of the effort includes the solar-plus-storge component, while Phase 2 will implement a microgrid. This undertaking was the co-ops’ first to include a hazard mitigation analysis to highlight any risks and ways to address them.
The co-ops’ substation battery storage projects help to minimize siting, leasing and interconnection issues by utilizing existing substation property and infrastructure. These sites are also “black-start” capable, meaning they can operate independently of the grid and can restore power to parts of the co-op system if needed.
Next year, NCEC is hoping to explore how residential storage can be grouped and scaled up to create utility-scale effects and provide mutually beneficial grid services.
Hall concluded by offering considerations for battery storage implementation: 1) It’s not enough just to have the technology, it should be integrated into an aggregation platform for financial and operational benefits. 2) Inverter and site capabilities should be accounted for when evaluating battery storage use cases. 3) Additional assets — generation resources as well as connected devices — may add even more value to a battery system.
Thanks to its versatility, battery storage will continue to play a critical role in North Carolina’s transition to clean energy. Challenges and uncertainties remain — navigating increasing demand and supply chain constraints, finding and retaining people to progress the clean energy field, working through changing policy landscapes and identifying repurpose and recycling opportunities, for example — but it is an exciting time for the industry.
To learn more about battery storage and other aspects of North Carolina’s clean energy transition, visit www.ncenergytransition.org, and stay tuned for two more webinars this year.