Atlantic Power Preferred Equity Ltd. — Capital/Financing Update 2021

May 11, 2021

ATLANTIC POWER LIMITED PARTNERSHIP 5.95% MEDIUM TERM NOTES DUE JUNE 23, 2036 CUSIP No. 04878TAA5 / ISIN No. CA04878TAA57

REDEMPTION NOTICE

• TO: Holders of 5.95% Medium Term Notes due June 23, 2036 (the “ Notes ”) of Atlantic Power Limited Partnership (the “ Issuer ”)

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Reference is made to the trust indenture dated as of June 15, 2006 between the Issuer (as successor to EPCOR Power L.P.) and BNY Trust Company of Canada, as trustee (as successor to CIBC Mellon Trust Company) (the “ Trustee ”), as amended by the first supplemental indenture dated as of May 10, 2021 between the Issuer and the Trustee (as amended, the “ Indenture ”).

Notice is hereby given pursuant to Sections 4.3 and 4.8 of the Indenture that, conditional on closing of the Transaction (as defined below), C$210,000,000.00 principal amount of Notes outstanding will be redeemed (the “ Redemption ”) as of May 14, 2021 (or such later date as the closing of the Transaction occurs) (the “ Redemption Date ”), upon payment of a redemption amount equal to the aggregate of (i) C$1,060.71 for each C$1,000 principal amount of Notes outstanding, and (ii) all accrued and unpaid interest thereon up to, but excluding, the Redemption Date (collectively, the “ Redemption Amount ”).

The Redemption is subject to and conditional upon the closing of the transaction among Atlantic Power Corporation, Atlantic Power Preferred Equity Ltd., the Issuer and certain affiliates of infrastructure funds managed by I Squared Capital Advisors (US) LLC, as contemplated by an arrangement agreement dated as of January 14, 2021, as amended on April 1, 2021 and April 29, 2021, and as may be further amended from time to time (the “ Transaction ”).

The Redemption Amount will be payable upon presentation and surrender of the Notes called for redemption at the following corporate trust office or through such other delivery arrangements as may be established between the registered holders of Notes and the Trustee and consented to by the Issuer:

The Bank of New York Mellon

BNY Trust Company of Canada 1 York Street, 6th Floor Toronto, ON M5J 0B6

Attention: Sameer Khan

The interest upon the principal amount of Notes called for redemption shall cease to be payable from and after the Redemption Date, unless payment of the Redemption Amount by the Issuer to the Trustee shall not be made on the Redemption Date as contemplated upon closing of the Transaction.

[Signature Page to Follow.]

DATED: May 11, 2021

ATLANTIC POWER LIMITED PARTNERSHIP , by its general partner, ATLANTIC POWER GP INC.

Per: “Terrence Ronan” Name: Terrence Ronan Title: Authorized Signing Officer

[ Signature Page – Notice of Redemption ]