<SUBMISSION>
<ACCESSION-NUMBER>0001104659-21-066492
<TYPE>POS AM
<PUBLIC-DOCUMENT-COUNT>1
<FILING-DATE>20210514
<DATE-OF-FILING-DATE-CHANGE>20210514
<FILER>
<COMPANY-DATA>
<CONFORMED-NAME>ATLANTIC POWER CORP
<CIK>0001419242
<ASSIGNED-SIC>4900
<IRS-NUMBER>550886410
<STATE-OF-INCORPORATION>A1
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<FILING-VALUES>
<FORM-TYPE>POS AM
<ACT>33
<FILE-NUMBER>333-245462
<FILM-NUMBER>21922200
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>3 ALLIED DRIVE
<STREET2>SUITE 155
<CITY>DEDHAM
<STATE>MA
<ZIP>02026
<PHONE>617-977-2400
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>3 ALLIED DRIVE
<STREET2>SUITE 155
<CITY>DEDHAM
<STATE>MA
<ZIP>02026
</MAIL-ADDRESS>
</FILER>
<DOCUMENT>
<TYPE>POS AM
<SEQUENCE>1
<FILENAME>tm2116319d1_posam.htm
<DESCRIPTION>POS AM
<TEXT>
<HTML>
<HEAD>
     <TITLE></TITLE>
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<BODY STYLE="font: 10pt Times New Roman, Times, Serif">



<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>As filed with the Securities and Exchange Commission
on May&nbsp;14, 2021</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: right"><B>Registration No.&nbsp;333-245462</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 13pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>UNITED STATES</B></P>

<P STYLE="font: 13pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SECURITIES AND EXCHANGE COMMISSION</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>WASHINGTON, D.C. 20549</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 13pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Post-Effective<BR>
Amendment No.&nbsp;1<BR>
to</B></P>

<P STYLE="font: 13pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>FORM&nbsp;S-3</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>REGISTRATION STATEMENT <BR>
UNDER</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>THE SECURITIES ACT OF 1933</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 14pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>ATLANTIC POWER CORPORATION</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Exact Name of Registrant as Specified in Its
Charter)</P>



<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="border-collapse: collapse; width: 100%">
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center">British Columbia, Canada</TD>
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center">4900</TD>
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center">55-0886410</TD></TR>
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="font: 10pt Times New Roman, Times, Serif; text-align: center; width: 33%">(State or Other Jurisdiction of<BR>
Incorporation or
    Organization)</TD>
    <TD STYLE="font: 10pt Times New Roman, Times, Serif; text-align: center; width: 34%">(Primary Standard Industrial<BR>
Classification Code Number)</TD>
    <TD STYLE="font: 10pt Times New Roman, Times, Serif; text-align: center; width: 33%">(I.R.S. Employer<BR>
Identification Number)</TD></TR>
  </TABLE>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 1in"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>3 Allied Drive, Suite&nbsp;155</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Dedham, Massachusetts 02026</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>(617) 977-2400</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Address,&nbsp;Including Zip Code, and Telephone
Number,&nbsp;Including Area Code, of Registrant&rsquo;s Principal Executive Offices)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Terrence Ronan</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Chief Financial Officer</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Atlantic Power Corporation</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>3 Allied Drive, Suite&nbsp;155</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Dedham, Massachusetts 02026</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>(617) 977-2400</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Name, Address,&nbsp;Including Zip Code, and Telephone
Number,&nbsp;Including Area Code, of Agent For Service)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="text-align: center; font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><B>Copies to:</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="border-collapse: collapse; width: 100%">
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center; width: 50%">Craig B. Brod</TD>
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center; width: 50%">William Gorman</TD></TR>
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center">Benet J. O&rsquo;Reilly</TD>
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center"> Goodmans LLP</TD></TR>
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center">Cleary Gottlieb Steen&nbsp;&amp; Hamilton LLP</TD>
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center"><B>Bay Adelaide Centre-West Tower</B></TD></TR>
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center">One Liberty Plaza</TD>
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center">333 Bay Street, Suite&nbsp;3400</TD></TR>
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center">New York, New York 10006</TD>
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center">Toronto, Ontario M5H 2S7</TD></TR>
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center">(212) 225-2000</TD>
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center">(416) 979-2211</TD></TR>
  </TABLE>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 155.3pt"><B>Approximate date of commencement of proposed sale to
the<BR>
public: </B>Not applicable.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="text-align: left; font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-indent: 0.25in">If the only securities being registered
on this Form&nbsp;are being offered pursuant to dividend or interest reinvestment plans, please check the following box. <FONT STYLE="font-family: Times New Roman, Times, Serif"><FONT STYLE="font-family: Wingdings">&#168;</FONT></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-indent: 0.25in">If any of the securities being registered
on this Form&nbsp;are to be offered on a delayed or continuous basis pursuant to Rule&nbsp;415 under the Securities Act of 1933, other
than securities offered only in connection with dividend or interest reinvestment plans, check the following box. <FONT STYLE="font-family: Times New Roman, Times, Serif"><FONT STYLE="font-family: Wingdings">&#168;</FONT></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-indent: 0.25in">If this Form&nbsp;is filed to register
additional securities for an offering pursuant to Rule&nbsp;462(b)&nbsp;under the Securities Act, please check the following box and
list the Securities Act registration number of the earlier effective registration statement for the same offering. <FONT STYLE="font-family: Times New Roman, Times, Serif"><FONT STYLE="font-family: Wingdings">&#168;</FONT></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-indent: 0.25in">If this Form&nbsp;is a post-effective
amendment filed pursuant to Rule&nbsp;462(c)&nbsp;under the Securities Act, check the following box and list the Securities Act registration
statement number of the earlier effective statement for the same offering. <FONT STYLE="font-family: Times New Roman, Times, Serif"><FONT STYLE="font-family: Wingdings">&#168;</FONT></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-indent: 0.25in">If this Form&nbsp;is a registration
statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the
Commission pursuant to Rule&nbsp;462(e)&nbsp;under the Securities Act, check the following box. <FONT STYLE="font-family: Times New Roman, Times, Serif"><FONT STYLE="font-family: Wingdings">&#168;</FONT></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-indent: 0.25in">If this Form&nbsp;is a post-effective
amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional
classes of securities pursuant to Rule&nbsp;413(b)&nbsp;under the Securities Act, check the following box. <FONT STYLE="font-family: Times New Roman, Times, Serif"><FONT STYLE="font-family: Wingdings">&#168;</FONT></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-indent: 0.25in">Indicate by check mark whether the
registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth
company. See the definitions of &ldquo;large accelerated filer,&rdquo; &ldquo;accelerated filer,&rdquo; &ldquo;smaller reporting company,&rdquo;
and &ldquo;emerging growth company&rdquo; in Rule&nbsp;12b-2 of the Exchange Act. (Check one):</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in">Large accelerated filer <FONT STYLE="font-family: Wingdings">&#168;</FONT>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Accelerated
filer <FONT STYLE="font-family: Wingdings">&#120;</FONT>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Non-accelerated filer <FONT STYLE="font-family: Wingdings">&#168;</FONT>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Smaller
reporting company <FONT STYLE="font-family: Wingdings">&#120;</FONT><BR>
 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Emerging
growth company <FONT STYLE="font-family: Times New Roman, Times, Serif"><FONT STYLE="font-family: Wingdings">&#168;</FONT></FONT>&NegativeThickSpace;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-indent: 0.25in">If an emerging growth company, indicate
by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial
accounting standards provided pursuant to Section&nbsp;7(a)(2)(B)&nbsp;of Securities Act <FONT STYLE="font-family: Times New Roman, Times, Serif"><FONT STYLE="font-family: Wingdings">&#168;</FONT></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>DEREGISTRATION OF SECURITIES</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.25in">This Post-Effective Amendment No.&nbsp;1 relates
to the Registration Statement on Form&nbsp;S-3 (the &ldquo;Registration Statement&rdquo;) of Atlantic Power Corporation, a corporation
continued under the laws of British Columbia (the &ldquo;Registrant&rdquo;), filed with the Securities and Exchange Commission (the &ldquo;SEC&rdquo;)
and is being filed to deregister any and all securities that remain unsold or otherwise unissued under <A HREF="http://www.sec.gov/Archives/edgar/data/1419242/000110465920093988/tm2027239-1_s3.htm" STYLE="-sec-extract: exhibit">Registration No.&nbsp;333-245462, filed with the SEC on August&nbsp;12, 2020</A>, amended on <A HREF="http://www.sec.gov/Archives/edgar/data/1419242/000110465920098004/tm2027239-3_s3a.htm" STYLE="-sec-extract: exhibit">August&nbsp;24, 2020</A>, and declared effective by the SEC on August&nbsp;25, 2020,
pertaining to the registration of common shares (and associated rights to purchase common shares), debt securities, warrants, subscription
receipts and units comprised of any combination of these securities.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.25in">On May&nbsp;14, 2021, pursuant to an Arrangement
Agreement and Plan of Arrangement, dated as of January&nbsp;14, 2021, by and among the Registrant, Atlantic Power Preferred Equity Ltd.,
a corporation continued to the jurisdiction of British Columbia, Atlantic Power Limited Partnership, an Ontario limited partnership,
Tidal Power Holdings Limited, a United Kingdom private limited company (&ldquo;BidCo&rdquo;), and Tidal Power Aggregator, LP, a Cayman
Islands limited partnership (the &ldquo;Arrangement Agreement&rdquo;), BidCo acquired all outstanding common shares of the Registrant
(the &ldquo;Arrangement&rdquo;).</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.25in">As a result of the Arrangement, the Registrant
has terminated all offerings of the Registrant&rsquo;s securities pursuant to its existing registration statements under the Securities
Act of 1933, as amended, including the Registration Statement. In accordance with undertakings made by the Registrant in the Registration
Statement to remove from registration, by means of a post-effective amendment, any of the securities that had been registered for issuance
that remain unsold at the termination of the offering, the Registrant hereby removes from registration all of such securities of the
Registrant registered but not sold or otherwise issued under the Registration Statement, if any, as of the date hereof. The Registration
Statement is hereby amended, as appropriate, to reflect the deregistration of such securities, and the Registrant hereby terminates the
effectiveness of the Registration Statement.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SIGNATURES</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.25in">Pursuant to the requirements of the Securities
Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form&nbsp;S-3
and has duly caused this Post-Effective Amendment No.&nbsp;1 to the Registration Statement on Form&nbsp;S-3 to be signed on its behalf
by the undersigned, thereunto duly authorized, in the Town of Dedham, Commonwealth of Massachusetts, on May 14, 2021.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="font-size: 10pt"></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><B>ATLANTIC POWER CORPORATION</B></TD></TR>
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="width: 50%">&nbsp;</TD>
    <TD STYLE="width: 4%; font-size: 10pt; text-align: left">By:</TD>
    <TD STYLE="border-bottom: Black 1pt solid; width: 46%; font-size: 10pt; text-align: center">/s/ TERRENCE RONAN</TD></TR>
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt; text-align: center">&nbsp;</TD>
    <TD STYLE="font-size: 10pt; text-align: center">Terrence Ronan</TD></TR>
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><I>Executive Vice President and Chief Financial
    Officer</I></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><I>(Principal Financial and Accounting Officer)</I></P></TD></TR>
  </TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.25in">Pursuant to the requirements of the Securities
Act of 1933, as amended, this Post-Effective Amendment No.&nbsp;1 to this Registration Statement on Form&nbsp;S-3 has been signed by
the following persons in the capacities and on the dates indicated.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; text-align: center"><B>Signature</B></TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="border-bottom: Black 1pt solid; text-align: center"><B>Title</B></TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="border-bottom: Black 1pt solid; text-align: center"><B>Date</B></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid"><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">/s/ James J. Moore,&nbsp;Jr.*</P></TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">President, Chief Executive Officer and Director</P></TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>
    <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">May 14, 2021</P></TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="text-align: center">James J. Moore,&nbsp;Jr.</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>(principal executive officer)</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; text-align: center">/s/ Terrence
    Ronan</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>Executive Vice President and Chief Financial Officer</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">May&nbsp;14, 2021</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="text-align: center">Terrence Ronan</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>(principal financial and accounting officer)</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; text-align: center">/s/ Kevin T.
    Howell*</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>Chairman of the Board</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">May&nbsp;14, 2021</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="text-align: center">Kevin T. Howell</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; text-align: center">/s/ Richard
    Foster Duncan*</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>Director</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">May&nbsp;14, 2021</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="text-align: center">Richard Foster Duncan</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; text-align: center">/s/ Danielle
    S. Mottor*</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>Director</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">May&nbsp;14, 2021</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="text-align: center">Danielle S. Mottor</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; text-align: center">/s/ Gilbert
    S. Palter*</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>Director</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">May&nbsp;14, 2021</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="text-align: center">Gilbert S. Palter</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="2">* By:</TD>
    <TD STYLE="text-align: center">/s/ Terrence Ronan</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="border-top: Black 1pt solid; text-align: center">Terrence Ronan</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  <TR STYLE="vertical-align: top">
    <TD COLSPAN="3" STYLE="text-align: center">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Attorney-in-fact</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD>
    <TD STYLE="text-align: center">&nbsp;</TD></TR>
  </TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SIGNATURE OF AUTHORIZED U.S. REPRESENTATIVE
OF THE REGISTRANT</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.25in">Pursuant to the Securities Act, the undersigned,
the duly authorized representative in the U.S. of Atlantic Power Corporation, has signed this registration statement or amendment thereto
on May 14, 2021.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="border-collapse: collapse; width: 100%; font: 10pt Times New Roman, Times, Serif">
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="width: 50%; font-size: 10pt; text-align: right"></TD>
    <TD STYLE="width: 4%; font-size: 10pt; text-align: left">By:</TD>
    <TD STYLE="border-bottom: Black 1pt solid; width: 46%; font-size: 10pt; text-align: center">/s/ Terrence Ronan</TD></TR>
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="font-size: 10pt; text-align: right">&nbsp;</TD>
    <TD STYLE="font-size: 10pt; text-align: left">&nbsp;</TD>
    <TD STYLE="font-size: 10pt; text-align: center">Terrence Ronan</TD></TR>
  </TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.25in">&nbsp;</P>

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