UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Item 1.

Security and Issuer

This statement on Schedule 13D (this “Statement”) relates to the shares of common stock, $0.0001 par value per share (the “Common Stock”), of FuelCell Energy, Inc., a Delaware corporation (the “Company”).  The Company’s principal executive offices are located at 3 Great Pasture Road, Danbury, Connecticut 06813.

Item 2.

Identity and Background

(a) - (c) and (f).  This Schedule 13D is being filed by NRG Energy, Inc. (“NRG Energy” or the “Reporting Person”), a Delaware corporation.  NRG Energy is principally engaged in the business of the ownership and operation of power generation facilities and the supply of energy and related services.  The address of its principal place of business and of its principal executive office is 211 Carnegie Center, Princeton, New Jersey 08540.

Certain information with respect to the directors and executive officers of the Reporting Persons is set forth in Annex A which is attached hereto and incorporated by reference, including each director’s and executive officer’s business address, present principal occupation or employment, citizenship and other information.

(d) - (e).  During the last five years, neither NRG Energy, nor, to the best of its knowledge, any person listed in Annex A hereto, have (i) been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (ii) been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

Item 3.

Source and Amount of Funds or Other Consideration

The shares of Common Stock were acquired by NRG Energy using its working capital.  The aggregate purchase price of the 14,644,352 shares of Common Stock acquired by NRG Energy was $35,000,000.

Item 4.

Purpose of Transaction

On July 30, 2014, NRG Energy entered into that certain Securities Purchase Agreement (the “Purchase Agreement”) with the Company.  Pursuant to the Purchase Agreement, on July 30, 2014, NRG Energy purchased from the Company 14,644,352 shares of Common Stock, at a price per share of $2.39, the closing price for the Common Stock on July 29, 2014.  In addition, for no additional consideration, the Company issued NRG Energy a warrant (the “Warrant”) to purchase 2,000,000 shares of Common Stock at an exercise price of $3.35 per share.  The Warrant is exercisable at any time, in whole or in part, until the earlier of (a) July 30, 2017 and (b) the date of a change of control (as defined in the Warrant) of the Company.  In addition, under the Purchase Agreement, the Company granted NRG Energy the right to appoint a person to the Board of Directors of the Company.

In connection with the Purchase Agreement, NRG Energy entered into a Loan Agreement (the “Loan Agreement”) with the Company’s wholly owned subsidiary, FuelCell Energy Finance, LLC, providing for a $40 million revolving construction and term financing facility for the purpose of accelerating project development by the Company and its subsidiaries. The Financing Agreement provides that certain of the Company’s subsidiaries may borrow amounts under such agreement to finance the construction of projects.  The interest rate is 8.5% per annum for construction-period financing and 8.0% thereafter.

Prior to July 30, 2014, NRG Energy (i) had acquired 2,400,000 shares of Common Stock from the Company in a private placement transaction and (ii) was issued warrants to purchase up to 5,000,000 shares of Common Stock in connection with a joint teaming and co-marketing agreement between the Company and NRG Energy, of which warrants to purchase 1,250,000 shares of Common Stock have expired and warrants to purchase 3,750,000 shares of Common Stock are not presently exercisable and will not become exercisable within 60 days of the date of this filing.

NRG Energy acquired the shares of Common Stock and the Warrant for investment purposes.  Except as otherwise described in this Schedule 13D, neither the Reporting Person nor, to the best knowledge of the Reporting Person, any of the persons listed on Annex A to this Schedule 13D, currently has any plans or proposals that would result in or relate to any of the transactions or changes listed in Items 4(a) through 4(j) of Schedule 13D.

Item 5.

Interest in Securities of the Issuer

(a)  NRG Energy beneficially owns 19,044,352 shares of Common Stock of the Company, which includes 2,000,000 shares of Common Stock underlying the Warrant.  Such shares of Common Stock represent approximately 6.66% of the outstanding Common Stock (based upon 269,313,119 shares of Common Stock issued and outstanding immediately prior to the closing on July 30, 2014 as reported by the Company to NRG Energy in the Purchase Agreement).  As of the date of this filing, no executive officer or director of NRG Energy beneficially owns any shares of Common Stock of the Company.

(b)  NRG Energy has sole dispositive and voting power with respect to the 17,044,352 shares of Common Stock and, upon exercise of the Warrant, NRG Energy shall have sole dispositive and voting power with respect to the 2,000,000 shares of Common Stock issued thereby.  To the best of NRG Energy’s knowledge, this Item 5(b) does not apply to any person named in Annex A hereto.

(c)  Except as described in this Schedule 13D, neither NRG Energy nor any of the persons listed in Annex A hereto has effected any transactions in the securities of the Company during the past sixty days.

(d)  Not applicable.

(e)  Not applicable.

Item 6.

Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer

Other than as described in Items 3, 4 and 5 and the agreements incorporated by reference and set forth as exhibits hereto, neither NRG Energy nor, to the best of NRG Energy’s knowledge, any of the persons named in Annex A hereto, is a party to any contract, arrangement, understanding or relationship with respect to any securities of the Company.

Item 7.

Material to be Filed as Exhibits

1.     Securities Purchase Agreement, dated July 30, 2014, between NRG Energy, Inc. and FuelCell Energy, Inc.

2.     Warrant, dated July 30, 2014, issued by FuelCell Energy, Inc. on behalf of NRG Energy, Inc.

NRG ENERGY, INC.

By:

/s/ Christopher Sotos

Name:

Christopher Sotos

Title:

Senior Vice President

Name

Principal Occupation or Employment

David Crane

Chief Executive Officer and Director

Kirkland Andrews

Executive Vice President and Chief Financial Officer

Mauricio Gutierrez

Executive Vice President and Chief Operating Officer

David R. Hill

Executive Vice President and General Counsel

John W. Ragan

Executive Vice President and Regional President, Gulf Coast

Ronald B. Stark

Vice President and Chief Accounting Officer

Denise M. Wilson

Executive Vice President and President, New Businesses

Name

Principal Occupation or Employment

E. Spencer Abraham

Director; Chairman and Chief Executive Officer of The Abraham Group

Kirbyjon H. Caldwell

Director; Senior Pastor at the Windsor Village United Methodist Church

Lawrence S. Coben

Director; Chairman and Chief Executive Officer of Tremisis Energy Corporation LLC; Executive Director of the Sustainable Prevention Initiative; Consulting Scholar at the University of Pennsylvania Museum of Archaeology and Anthropology

Howard E. Cosgrove

Director and Chairman; member of Board of Trustees of the University of Delaware

David Crane

Chief Executive Officer and Director

Terry G. Dallas

Director

William E. Hantke

Director

Paul W. Hobby

Director; Managing Partner of Genesis Park, L.P.; director of Stewart Information Services Corporation (Stewart Title)

Edward R. Muller

Director and Vice Chairman

Anne C. Schaumburg

Director; director of Brookfield Infrastructure Partners L.P.

Evan J. Silverstein

Director

Thomas H. Weidemeyer

Director; director of The Goodyear Tire & Rubber Co., director of Waste Management, Inc.; director of Amsted Industries Incorporated

Walter R. Young

Director