Canada's largest battery, Oneida, comes online early and C$100 million under budget

HALDIMAND COUNTY, Ontario, May 2025 — The Oneida Energy Storage Project began commercial operation in May 2025 as the largest battery facility running in Canada, finished ahead of schedule for about C$700 million. Here's what happened, what it cost, and what went wrong.

Cost and outcome (as of May 8, 2025)

Outcome: commercial operation; now in Ontario's electricity markets. (IESO)
Cost: about C$700 million final, against an initial C$800 million estimate at financial close in 2023. (Northland Power) Savings: C$800M − C$700M = about C$100 million.
Public money: up to C$518 million from the Canada Infrastructure Bank, plus Natural Resources Canada funding. (Canada Infrastructure Bank; Oneida Energy Storage)
Contract: 20-year IESO capacity contract, entered under the Province's direction. (IESO)

What it is

Oneida stores 1,000 MWh and delivers up to 250 MW from 278 lithium-ion battery units that draw and store power from Ontario's grid, the partnership says. (Oneida Energy Storage) It is Northland's first operating storage project in Canada. (Northland Power)

The partnership says it doubles Ontario's energy storage from 225 MW to 475 MW. (Oneida Energy Storage) The CIB says it can meet the peak demand of a city the size of Oshawa. (CIB construction update)

"Battery storage projects, like Oneida, support system reliability as the grid powers broader electrification efforts," the IESO said. (IESO)

What it does for the grid

Ontario's grid is already more than 90% clean, the partnership says; Oneida adds capacity and reliability and is meant to help gas and nuclear plants run more efficiently while renewables grow. (Oneida Energy Storage)

It charges off-peak, when demand is low, and returns power at peak times, the CIB says, which reduces the need for gas-fired plants at peak demand. (CIB construction update; Canada Infrastructure Bank) Aecon handled the balance-of-plant engineering, procurement and construction. (CIB construction update)

Who owns it

The project was first developed as a 50/50 partnership between Six Nations of the Grand River Development Corporation and NRStor. (Oneida Energy Storage) Northland now owns about 70%, with SNGRDC, NRStor, Aecon Concessions and the Mississaugas of the Credit Business Corporation holding the rest. (Northland Power)

Six Nations said the project "aligns with our community's core values of protecting Mother Earth" and could model how private, public and Indigenous partners work together. (Canada Infrastructure Bank)

During construction, half of the 60-plus workers on site each day came from Aecon Six Nations, a joint venture of SNGRDC and Aecon, the CIB reported. (CIB construction update)

How it was paid for

The CIB's package was based on lithium prices at the time: a C$165 million short-term construction loan and a long-term loan of up to C$370 million to help partners carry the risks of a first-of-a-kind facility and fluctuating critical-mineral costs. (CIB construction update) The CIB says private capital alone was hard to attract because of the project's uncontracted revenue. (Canada Infrastructure Bank)

Oneida earns fixed capacity payments under the IESO contract plus revenue from energy sales and ancillary services. (Oneida Energy Storage)

"Delivering this project ahead of schedule and under budget is a clear demonstration of Northland's capability," said CEO Christine Healy. (Northland Power)

"This milestone reflects the strong collaboration among our project partners, including our First Nations partners, suppliers, and financiers," said Michelle Chislett, who runs Northland's onshore renewables business. (Northland Power)

What went wrong

Public risk-sharing was needed. The CIB stepped in because the project's uncontracted revenue made private-only financing hard. (Canada Infrastructure Bank)
Emissions estimates vary. The partnership estimates 1.2 to 4.1 million tonnes over the project's life; the CIB cites 1.2 million. (Oneida Energy Storage; Canada Infrastructure Bank)
"Ahead of schedule" isn't quantified. No source gives the original target date.
What we don't know yet: how Oneida has performed in Ontario's markets since May 2025, and why the build came in C$100 million under estimate.

Our follow-up question for Northland Power

What drove the C$100 million cost reduction, and how much of the long-term CIB loan was drawn?

Sources

Northland Power, “Northland Power Announces Commercial Operations at Oneida Energy Storage Project,” May 7, 2025. northlandpower.com
Oneida Energy Storage LP, “250 MW/1,000 MWh Oneida Energy Storage Project Commences Commercial Operations,” May 7, 2025, via GlobeNewswire (distributed by Northland Power). globenewswire.com
Independent Electricity System Operator, “Oneida Energy Storage Project Begins Commercial Operations,” May 8, 2025. ieso.ca
Canada Infrastructure Bank, “Oneida Energy Storage” project page. cib-bic.ca
Canada Infrastructure Bank, “Construction progresses at Oneida Energy Storage site” (undated). cib-bic.ca

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