Prospectus Filed Pursuant to Rule 424(b)(3) (424b3)

PROSPECTUS SUPPLEMENT NO. 9	Filed pursuant to Rule 424(b)(3)
(To prospectus dated October 21, 2021)	Registration No. 333-260094

ARCHAEA ENERGY INC.

110,334,394 SHARES OF CLASS A COMMON STOCK

7,021,000 WARRANTS TO PURCHASE SHARES OF CLASS A COMMON STOCK

This prospectus supplement is being filed to update and supplement the information contained in the prospectus dated October 21, 2021 (the “Prospectus”), with the information contained in our Current Report on Form 8-K filed with the Securities and Exchange Commission (the “SEC”) on March 28, 2022 (the “8-K”). Accordingly, we have attached the 8-K to this prospectus supplement.

The Prospectus and this prospectus supplement relate to the issuance by us of up to 18,883,492 shares of our Class A common stock, par value $0.0001 per share (the “Class A Common Stock”), which consist of (i) 11,862,492 shares that may be issued upon the exercise of the 11,862,492 warrants (the “Public Warrants”) originally sold as part of the units issued in the initial public offering (the “IPO”) of Rice Acquisition Corp. (“RAC”), (ii) 6,771,000 shares of Class A Common Stock that may be issued upon the exercise of the 6,771,000 warrants originally issued to Rice Acquisition Sponsor LLC (the “Sponsor”) and Atlas Point Energy Infrastructure Fund, LLC (“Atlas”) in a private placement that closed simultaneously with the consummation of the IPO (the “Private Placement Warrants”) and (iii) 250,000 shares of Class A Common Stock that may be issued upon the exercise of the 250,000 warrants issued to Atlas in a private placement that closed simultaneously with the consummation of the Business Combinations (as defined in the Prospectus) (the “Forward Purchase Warrants” and, together with the Public Warrants and the Private Placement Warrants, the “Warrants”). Each Warrant is exercisable to purchase for $11.50 one share of Class A Common Stock, subject to adjustment.

In addition, the Prospectus and this prospectus supplement relate to the resale from time to time of 6,771,000 Private Placement Warrants, 250,000 Forward Purchase Warrants and 110,334,394 shares of Class A Common Stock by the selling security holders named in the Prospectus or their permitted transferees (each a “Selling Securityholder” and, collectively, the “Selling Securityholders”). The 110,334,394 shares of Class A Common Stock consist of (i) 29,166,667 shares of Class A Common Stock issued in a private placement that closed concurrently with the consummation of the Business Combinations, (ii) 2,500 shares of Class A Common Stock issued to the Sponsor in a private placement prior to the consummation of the IPO, (iii) 18,883,492 shares of Class A Common Stock issuable upon exercise of the Warrants, (iv) 5,931,350 shares of Class A Common Stock issuable upon redemption of the 5,931,350 Class A units of LFG Acquisition Holdings LLC (f/k/a Rice Acquisition Holdings LLC) (“Opco”) held by the initial stockholders of RAC, all of which were issued prior to the consummation of the IPO, (v) 23,000,000 shares of Class A Common Stock issuable upon redemption of the 23,000,000 Opco Class A units issued as partial consideration upon consummation of the Aria Merger (as defined in the Prospectus) and (vi) 33,350,385 shares of Class A Common Stock issuable upon redemption of the 33,350,385 Opco Class A units issued as consideration upon consummation of the Archaea Merger (as defined in the Prospectus).

This prospectus supplement updates and supplements the information in the Prospectus and is not complete without, and may not be delivered or utilized except in combination with, the Prospectus, including any other amendments or supplements thereto. This prospectus supplement should be read in conjunction with the Prospectus, and if there is any inconsistency between the information in the Prospectus and this prospectus supplement, you should rely on the information in this prospectus supplement. The information in this prospectus supplement modifies and supersedes, in part, the information in the Prospectus. Any information in the Prospectus that is modified or superseded shall not be deemed to constitute a part of the Prospectus except as modified or superseded by this prospectus supplement.

You should not assume that the information provided in this prospectus supplement or the Prospectus is accurate as of any date other than their respective dates. Neither the delivery of this prospectus supplement and Prospectus, nor any sale made hereunder, shall under any circumstances create any implication that there has been no change in our affairs since the date of this prospectus supplement, or that the information contained in this prospectus supplement or the Prospectus is correct as of any time after the date of that information.

The Class A Common Stock is listed on the New York Stock Exchange (“NYSE”) under the symbol “LFG.” On March 25, 2022, the last sale price of the Class A Common Stock as reported on the NYSE was $21.00 per share.

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Investing in our securities involves certain risks, including those that are described in the “Risk Factors” section beginning on page 7 of the Prospectus dated October 21, 2021, as updated and supplemented by the section entitled “Risk Factors” included in our Annual Report on Form 10-K for the year ended December 31, 2021 (which was attached to Prospectus Supplement No. 7, dated March 18, 2022).

Neither the SEC nor any state securities commission has approved or disapproved of the securities to be issued under the Prospectus or determined if the Prospectus or this prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense.

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The date of this prospectus supplement is March 28, 2022.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

Current Report

Pursuant to Section 13 or 15(d) of the securities exchange act of 1934

Date of Report (Date of earliest event reported): March 22, 2022

ARCHAEA ENERGY INC.

(Exact name of registrant as specified in its charter)

Delaware		001-39644		85-2867266
(State or other jurisdiction of incorporation)		(Commission File Number)		(I.R.S. Employer Identification No.)

4444 Westheimer Road, Suite G450 Houston, Texas		77027
(Address of principal executive offices)		(Zip Code)

(346) 708-8272

(Registrant’s telephone number, including area code)

Not applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐	Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class		Trading Symbol(s)		Name of each exchange on which registered
Class A common stock, par value $0.0001 per share		LFG		The New York Stock Exchange

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☒

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 13(a) of the Exchange Act. ☐

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

On March 25, 2022, upon completion of the Offering (as defined and described below in Item 8.01) and pursuant to the Stockholders’ Agreement, dated September 15, 2021 (the “Stockholders Agreement”), by and among Archaea Energy Inc. (the “Company”), the Company’s stockholders listed on Schedule I thereto, and certain other parties listed therein, Scott Parkes was automatically removed as a member of the Company’s board of directors (the “Board”).

As previously disclosed, pursuant to the terms of the Stockholders Agreement, among other things, the Ares Investor (as defined in the Stockholders Agreement) has the right to designate one director for appointment or election to the Board (the “Ares Director”) for so long as the Ares Investor holds at least 50% of the Registrable Securities (as defined in the Stockholders Agreement) held by it on September 15, 2021, and on the first date after September 15, 2021 that the Ares Investor fails to hold such amount, the Ares Investor’s director designation right shall cease and the term of the then-current Ares Director shall thereupon automatically end. Mr. Parkes served as a member of the Board as the Ares Director, and as a result of the Offering, the Ares Investor ceased to hold any Registrable Securities.

The Board expects to re-appoint Mr. Parkes as a Class I director in the second quarter of 2022.

Item 8.01 Other Events.

On March 22, 2022, the Company entered into an Underwriting Agreement (the “Underwriting Agreement”) with Aria Renewable Energy Systems LLC (the “Selling Stockholder”) and Barclays Capital Inc. and Jefferies LLC, as representatives of the underwriters named in Schedule I thereto (the “Underwriters”), relating to the offer and sale (the “Offering”) of 12,993,603 shares of the Company’s Class A common stock, par value $0.0001 per share (the “Class A Common Stock”), by the Selling Stockholder at a price to the public of $17.75 per share. Pursuant to the Underwriting Agreement, the Selling Stockholder granted the Underwriters a 30-day option to purchase up to an additional 1,949,040 shares of Class A Common Stock (the “Option”). The Underwriters exercised the Option in full on March 23, 2022, and the Option closed concurrently with the Offering on March 25, 2022.

The Company did not sell any securities in the Offering and did not receive any proceeds from the sale of the shares offered by the Selling Stockholder.

The Underwriting Agreement contains customary representations and warranties, agreements and obligations, closing conditions and termination provisions. It also provides for customary indemnification by each of the Company, the Selling Stockholder and the Underwriter against certain liabilities and customary contribution provisions in respect of those liabilities.

The foregoing description of the Underwriting Agreement is not complete and is qualified in its entirety by reference to the copy of the Underwriting Agreement, which is filed herewith as Exhibit 1.1 and incorporated into this Item 8.01 by reference.

The Underwriting Agreement and the above descriptions have been included to provide investors and security holders with information regarding the terms of the Underwriting Agreement. They are not intended to provide any other factual information about the Company or its subsidiaries or affiliates or equity holders. The representations, warranties and covenants contained in the Underwriting Agreement were made only for purposes of that agreement and as of specific dates; were solely for the benefit of the parties to the Underwriting Agreement; and may be subject to limitations agreed upon by the parties, including being qualified by confidential disclosures made by each contracting party to the other as a way of allocating contractual risk between them that differ from those applicable to investors. Moreover, the subject matter of the representations and warranties is subject to more recent developments. Accordingly, investors should be aware that these representations, warranties and covenants or any description thereof alone may not describe the actual state of affairs of the Company or its subsidiaries, affiliates, businesses or equity holders as of the date they were made or at any other time.

Item 9.01. Financial Statements and Exhibits.

Exhibit Number		Description
1.1		Underwriting Agreement, dated as of March 22, 2022, by and among Archaea Energy Inc., Aria Renewable Energy Systems LLC and Barclays Capital Inc. and Jefferies LLC, as representatives of the underwriters named in Schedule I thereto.

104		Cover Page Interactive Data File (embedded within the Inline XBRL document).

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date: March 28, 2022