Executives from public power utilities in North Carolina, Rhode Island and Minnesota recently detailed benefits and lessons learned from energy storage projects that their utilities have pursued.
The officials from Fayetteville Public Works Commission in North Carolina, Grand Rapids Public Utilities Commission in Minnesota and Rhode Island’s Pascoag Utility District, made their remarks during a session at the American Public Power Association’s (APPA) Public Power Forward Virtual Summit on Dec. 2.
Michael Kirkwood, General Manager at Pascoag Utility District, described a non-wires alternative project that “became a real money-saving option to avoid a large transmission expenditure that we were facing.” The project “fit in with some other reinforcements that we were doing on our system. The battery storage really made this possible and saved us a lot of money.”
Pascoag Utility District serves 4,900 customers in Pascoag and Harrisville, two villages in northwest Rhode Island. The PUD is connected to the outside world via two 5-mile 13.8 kV lines from investor-owned National Grid.
Peak load for the public power utility on the hottest summer days is about 13 megawatts. In 2018 and 2019, Pascoag Utility District started to reach the thermal limits of the main feeder line.
In 2019, Pascoag Utility District commissioned a system impact study that was completed by National Grid and offered several alternatives.
The public power utility determined that a non-wires alternative was the most cost-effective solution using a combination of substation enhancements and battery storage. The 3-megawatt/9-megawatt hour lithium-ion energy storage system is being built by Agilitas Energy.
The project has helped Pascoag Utility District avoid having to spend $6 million to $12 million “and if you look at that over 4,900 customers that’s a big nut to crack for a lot of years,” Kirkwood said.
The project will also increase reliability and reduce loading on the feeder lines, he noted.
Another panelist, Julie Kennedy, General Manager for Minnesota public power utility Grand Rapids Public Utilities, offered details on the utility’s solar plus battery storage project.
She noted that the project got its start in 2016 through a citizen initiative. A community solar project was initially considered, Kennedy said.
In late 2018, the public power utility presented a final report to its commission. “We said, you know what, it is a little bit difficult to make that subscription model work.” While the utility could have pursued that approach, “it really wasn’t meeting the hopes and desired outlook that we had had when we had our community outreach,” Kennedy said.
“What we did notice, though, was the parity in the pricing between solar only and the solar plus storage and so we started looking at those economics a little bit more closely and that is what caused us to add the energy storage.”
Along with US Solar and Grand Rapids Public Utilities, other parties involved in the project are Minnesota Power, a subsidiary of investor-owned Allete, the Itasca Clean Energy Team, and the City of Grand Rapids. US Solar is developing the two-megawatt solar array and one-megawatt/2.5-(megawatt?) hour energy storage battery on city-owned land near the Grand Rapids/Itasca County Airport.
Kennedy noted that installation of the solar panels at the site was completed in the fall. The storage battery “is, unfortunately, out at sea, still. We have been postponed with supply chain issues. Our next anticipated date is December 16. We are waiting to run our test energy. We are hopeful that it will be on site December 16,” with commissioning by the end of the year.
Meanwhile, Elaina Ball, CEO of Fayetteville Public Works Commission, detailed the utility’s community solar plus storage project.
“We were the first municipal community solar project in the state of North Carolina,” she noted. The project came online in 2019.
The 1-megawatt, 3,384 panel farm is located in northeast Cumberland County, adjacent to the utility’s Butler-Warner Generation Plant. In addition, the farm has 500-kilowatt battery storage. The battery is discharged 100% over two hours.
Ball said that the installed cost of the battery system itself “was a little over $900,000 and we expect about $5,500 in annual O&M costs just around the battery system and based on demand shaving that we’ve had, we expect our annual savings to be about $120,000. In a simple payback term, the battery is paying for itself in eight years.”
She said that “looking to the future, we want to add additional storage.” Ball noted that the utility’s wholesale contract allows for Fayetteville PWC to go up to 2 megawatts, “so we are in the process of adding another” one-and-a-half megawatts of storage.
“That’s really going to do two things. One, it’s going to be a four-hour discharge potential, which will give us much longer duration and give us an even better tool to hit that coincident peak window. But it’s also going to allow us to maximize our battery storage capacity. So we got our toe in the water, know how to operate this system” and the utility now wants to “push the capacity and we want to make sure that we’re getting as much value out of these resources as possible,” Ball said.
The utility is also studying additional community solar projects in its service territory. It is focused on looking at the economics of those projects, as well as “making sure that there’s customer demand to support additional resources in the community,” she said.
APPA Storage Tracker
APPA recently launched a Public Power Energy Storage Tracker, which is a resource for association members that summarizes energy storage projects undertaken by members that are currently online. The tracker is available here.