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                                                      Exhibit 3.1


                           AMENDED AND
              RESTATED CERTIFICATE OF INCORPORATION
                               OF
                   NRG GENERATING (U.S.) INC.

      NRG  Generating  (U.S.) Inc. (the "Corporation"),  formerly
known  as  O'Brien  Environmental  Energy,  Inc.,  a  corporation
organized  and existing under the laws of the State of  Delaware,
hereby   files   this   Amended  and  Restated   Certificate   of
Incorporation to amend Article Four from the Amended and Restated
Certificate  of  Incorporation filed on April  30,  1996  and  to
restate  in  its entirety its Certificate of Incorporation.   The
date  of filing of its original Certificate of Incorporation with
the Secretary of State, under its original name of O'Brien Energy
Systems,  Inc.,  was  December 5, 1983.  The  Corporation  hereby
certifies as follows:

      1.   This Amended and Restated Certificate of Incorporation
restates  the Certificate of Incorporation of the Corporation  to
read as set forth herein.

      2.    The  text  of  the  Certificate of  Incorporation  as
heretofore  amended  or  supplemented  is  hereby  corrected   to
properly  restate in Article Four the total number of  authorized
shares of stock of the Corporation and is hereby further restated
to read in full as follows:

           FIRST:    The name of the Corporation is:
                     NRG GENERATING (U.S.) INC.

           SECOND:   The address of the registered office of  the
Corporation in the State of Delaware is Corporation Trust Center,
1209  Orange  Street  in the City of Wilmington,  County  of  New
Castle,  and the name of its registered agent at that address  is
The Corporation Trust Company.

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           THIRD:    The purpose of the Corporation is to  engage
in  any  lawful  act  or activity for which corporations  may  be
organized under the General Corporation Law of Delaware.

          FOURTH:   (a) The total number of shares of stock which
the  Corporation  is  authorized  to  issue  is  seventy  million
(70,000,000), consisting of fifty million (50,000,000) shares  of
common  stock, having a par value of one cent ($0.01)  per  share
and twenty million (20,000,000) shares of Preferred Stock, having
a par value of one cent ($0.01) per share.

           (b)   The  Corporation shall not issue  any  nonvoting
equity securities provided that this provision, which is included
in  this  Certificate of Incorporation in compliance with Section
1123(a)(6)  of  the United States Bankruptcy  Code  of  1978,  as
amended,  shall have no force or effect beyond that  required  by
such  Section 1123(a)(6) and shall be effective only for so  long
as  such  Section 1123(a)(6) is in effect and applicable  to  the
Corporation.

           (c)  Shares of Preferred Stock may be issued from time
to  time in one or more series.  The Board of Directors is hereby
authorized  to  fix  the  voting  rights,  designations,  powers,
preferences  and the relative, participating, optional  or  other
rights,   if   any,  and  the  qualifications,   limitations   or
restrictions thereof, of any wholly unissued series of  Preferred
Stock;  and to fix the number of shares constituting such  series
(but not below the number of shares thereof then outstanding).

           FIFTH:    (a) Except as provided below, the bylaws  of
the  Corporation may only be made, repealed, altered, amended  or
rescinded by (i) the stockholders of the Corporation by the  vote
of  the holders of not less than sixty percent (60%) of the total
voting  power  of all outstanding shares of voting stock  of  the
Corporation or (ii) the directors of the Corporation by

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the  vote of a majority of the entire board of directors  present
at a meeting at which a quorum is present.

           (b)   Section  1.7(b)  (regarding  action  by  written
consent  of  stockholders);  Section 1.11  (regarding  notice  of
stockholder nominations and other stockholder business);  Section
2.1(b)   (regarding  the  number  of  directors);  Section   2.10
(regarding Independent Directors); and Section 3.2 (regarding the
Independent   Directors  committee),  of  the   bylaws   of   the
Corporation  may only be repealed, altered, amended or  rescinded
by  (i)  the  stockholders of the Corporation by a  vote  of  the
holders of not less than seventy-five percent (75%) of the  total
voting  power  of all outstanding shares of voting stock  of  the
Corporation  or  (ii)  the directors of the  Corporation  by  the
affirmative  vote  of  no fewer than the lesser  of  all  of  the
directors  then  in  office  or  six  (6)  of  the  Corporation's
directors;   provided  however,  that  Section  2.10   (regarding
Independent Directors) and Section 3.2 (regarding the Independent
Directors  Committee) may be altered or amended pursuant  to  the
provisions  of  subparagraph (a) of Article Fifth to  the  extent
necessary to comply with the provisions of the applicable listing
requirements  of  any exchange or market system  over  which  the
securities of the Corporation are to be traded.

           SIXTH:    A director of the Corporation shall  not  be
personally  liable  to  the Corporation or its  stockholders  for
monetary  damages  for breach of fiduciary duty  as  a  director,
except for liability (i) for any breach of the director's duty of
loyalty to the Corporation or its stockholders, (ii) for acts  or
omissions   not  in  good  faith  or  which  involve  intentional
misconduct or a knowing violation of law, (iii) under Section 174
of  the  Delaware  General  Corporation  Law,  or  (iv)  for  any
transaction from which the director derived an improper  personal
benefit.   If the Delaware General Corporation Law is amended  to
authorize  corporate action further eliminating or  limiting  the
personal liability of directors, then the liability of a director
of the Corporation

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shall be eliminated or limited to the fullest extent permitted by
the  Delaware General Corporation Law, as so amended.  Any repeal
or  modification of this provision shall not adversely affect any
right or protection of a director of the Corporation existing  at
the time of such repeal or modification.

           SEVENTH:   (a) Until April 30, 2002, (i) any attempted
sale,  transfer, assignment, conveyance, grant, pledge,  gift  or
other  disposition  of  any  share or  shares  of  stock  of  the
Corporation  (within the meaning of Section 382 of  the  Internal
Revenue  Code of 1986 (the "Code")), or any option  or  right  to
purchase such stock, as defined in the Treasury Regulations under
Section  382  of the Code, to any person or entity (or  group  of
persons  or  entities acting in concert) who either  directly  or
indirectly  owns or would be treated as owning, or  whose  shares
are  or  would be attributed to any person or entity who directly
or  indirectly owns or would be treated as owning, in either case
prior  to the purported transfer and after giving effect  to  the
applicable attribution rules of the Code and applicable  Treasury
Regulations,  5  percent or more of the value of the  outstanding
stock  of  the Corporation or otherwise treated as  a  5  percent
stockholder  (within the meaning of Section  382  of  the  Code),
regardless of the percent or the value of the stock owned,  shall
be void ab initio insofar as it purports to transfer ownership or
rights  in respect of such stock to the purported transferee  and
(ii) any attempted sale, transfer, assignment, conveyance, grant,
gift,  pledge or other disposition of any share of stock  of  the
Corporation  (within the meaning of Section 382 of the  Code)  or
any  option  or right to purchase such stock, as defined  in  the
Treasury Regulations under Section 382 of the Code, to any person
or entity (or group of persons or entities acting in concert) not
described in clause (i) who directly or indirectly would own,  or
whose  shares  would be attributed to any person  or  entity  who
directly or indirectly would own in each case as a result of  the
purported transfer and after giving

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effect  to  the  applicable attribution rules  of  the  Code  and
applicable Treasury Regulations, 5 percent or more of  the  value
of any of the stock of the Corporation (or otherwise treated as a
5-percent (5%) stockholder within the meaning of Section  382  of
the Code), shall, as to that number of shares causing such person
or  entity  to  be  a 5-percent stockholder, be  void  ab  initio
insofar as it purports to transfer ownership or rights in respect
of  such  stock  to the purported transferee; provided,  however,
that  neither of the foregoing clauses (i) and (ii) shall prevent
a  valid  transfer  if  (A) the transferor  obtains  the  written
approval  of  the  board  of directors of the  Corporation  which
approval  shall  not be unreasonably withheld  and  provides  the
Corporation with an opinion of counsel reasonably satisfactory to
the  Corporation .that (assuming, as of the date of such opinion,
the  full exercise of (i) all warrants issued under, and (ii) any
options  granted  pursuant  to  any  stock  option  plan  of  the
Corporation) the transfer shall not result in an ownership change
within  the meaning of Section 382 of the Code and any  successor
thereto  or  (B)  a  tender  offer, within  the  meaning  of  the
Securities Exchange Act of 1934, as amended, and pursuant to  the
rules and regulations thereof, is made by a bona fide third-party
purchaser  to purchase at least sixty-six and two-thirds  percent
(66-2/3%)  of  the  issued and outstanding common  stock  of  the
Corporation  and the offeror (i) agrees to effect, within  ninety
(90)  days  of the consummation of the tender offer, a  back  end
merger in which all non-tendering stockholders would receive  the
same  consideration  as paid in the tender offer,  and  (ii)  has
received  the tender of sufficient shares to effect such  merger.
Without  limiting or restricting in any manner the  effectiveness
of  the  foregoing provisions, the Corporation and any transferor
may  rely  and shall be protected in relying on the Corporation's
stockholder  lists and stock transfer records  for  all  purposes
relating to any opinion required hereunder.

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           (b)   In  the  absence of specific board  approval,  a
purported transfer of shares in excess of the shares that can  be
transferred  pursuant  to this Article SEVENTH  (the  "Prohibited
Shares") to the purported acquiror (the "Purported Acquiror")  is
not  effective  to transfer ownership of such Prohibited  Shares.
On  demand  by the Corporation, which demand must be made  within
thirty  (30)  days  of  the time the Corporation  learns  of  the
transfer  of  the  Prohibited Shares, a Purported  Acquiror  must
transfer  any certificate or other evidence of ownership  of  the
Prohibited  Shares within the Purported Acquiror's possession  or
control,  together  with  any dividends  or  other  distributions
("Distributions")  that were received by the  Purported  Acquiror
from the Corporation with respect to the Prohibited Shares, to an
agent  designated  by the Corporation (the "Agent").   The  Agent
will  sell  the Prohibited Shares in an arm's length  transaction
(over  a stock exchange, if possible), and the Purported Acquiror
will  receive  an amount of sales proceeds not in excess  of  the
price paid or consideration surrendered by the Purported Acquiror
for  the  Prohibited  Shares (or the fair  market  value  of  the
Prohibited  Shares at the time of an attempted  transfer  to  the
Purported  Acquiror by gift, inheritance, or a similar transfer).
If  the Purported Acquiror has resold the Prohibited Shares prior
to receiving the Corporation's demand to surrender the Prohibited
Shares  to  the Agent, the Purported Acquiror shall be deemed  to
have  sold  the  Prohibited Shares as an agent  for  the  initial
transferor,  and shall be required to transfer to the  Agent  any
proceeds of such sale and any Distributions.

           (c)  If the initial transferor can be identified,  the
Agent will pay to it any sales proceeds in excess of those due to
the  Purported Acquiror, together with any Distributions received
by  the  Agent.   If the initial transferor cannot be  identified
within ninety (90) days, the Agent may pay any such amounts to  a
charity of its choosing.  In no event shall amounts paid  to  the
Agent  inure to the benefit of the Corporation or the Agent,  but
such amounts may be used to

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cover expenses of the Agent in attempting to identify the initial
transferor.   If  the Purported Acquiror fails to  surrender  the
Prohibited Shares within the next thirty (30) business days  from
the   demand  by  the  Corporation,  then  the  Corporation  will
institute  legal  proceedings  to  compel  the  surrender.    The
Corporation  shall  be entitled to damages, including  reasonable
attorneys'  fees  and  costs,  from the  Purported  Acquiror,  on
account of such purported transfer.

           EIGHTH:    The  affirmative vote  of  the  holders  of
greater  than sixty-six and two thirds percent (66-2/3%)  of  the
total  voting power of all outstanding shares of voting stock  of
the  Corporation  shall  be required  for  the  approval  of  any
proposal  (1) that the Corporation merge or consolidate with  any
corporation,   person,  partnership,  trust   or   other   entity
("Entity"), or (2) that the Corporation sell or exchange  all  or
substantially  all of its assets or business,  or  (3)  that  the
Corporation issue or deliver any stock or other securities of its
issue in exchange or payment for any properties or assets of  any
Entity  or  securities issued by any Entity, and to  effect  such
transaction  the approval of stockholders of the  Corporation  is
required  by law or by any agreement between the Corporation  and
any national securities exchange.

          NINTH:    (a) Any attempted sale, transfer, assignment,
conveyance,  pledge  or other disposition of  any  share  of  the
Corporation's common stock to any Electric Utility  Interest  (as
defined below) shall be null and void ab initio.  No employee  or
agent,  including any independent transfer agent or registrar  of
this  Corporation, shall be permitted to record any attempted  or
purported  transfer made in violation of this provision,  and  no
intended transferee of shares of this Corporation's common  stock
attempted  to  be transferred in violation of this Article  NINTH
shall  be  recognized as a holder of such shares for any  purpose
whatsoever, including, but not limited to, the right to vote such
shares  of  common  stock  or  to  receive  dividends  or   other
distributions in respect thereof, if any.  The transferor and any
such intended transferee shall be

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deemed  to  have  appointed the corporation as  attorney-in-fact,
with full power of substitution and full power and authority,  in
the name and on behalf of the intended transferor and transferee,
to  sell, assign and transfer the shares of Common Stock  of  the
corporation  attempted to be transferred  in  violation  of  this
Article  NINTH,  and  to  do  all lawful  acts  and  execute  all
documents  deemed  necessary or advisable to  effect  such  sale,
assignment  and  transfer,  in  an arm's-length  transaction,  to
another entity or person; provided that the sale, assignment  and
transfer  to  such other entity of person does  not  violate  the
provisions  of this Article NINTH.  The Corporation  shall  apply
the  proceeds of any such sale first, to pay the expenses of  the
sale; second, to pay the intended transferee on whose behalf  the
shares  were sold, an amount equal to (i) the sum of the intended
transferee's cost of such shares (inclusive of brokerage fees and
expenses), plus interest on such cost at the then minimum rate of
interest  which would prevent interest on a non-interest  bearing
obligation  from  being imputed by the Internal Revenue  Service,
less   the   amount  of  any  dividends  or  other  distributions
inadvertently paid to said intended transferee in respect of such
shares, or (ii) the balance of such proceeds, whichever is  less;
and third, the balance of such proceeds, if any, shall be paid to
the corporation.   Notwithstanding the foregoing, the Corporation
shall  not  provide any proceeds to the intended  transferee,  if
such  intended  transferee has received  consideration  from  any
subsequent attempted transfer.

      (b)   This  Corporation  shall take all  appropriate  legal
action  to enforce the provisions of this Article NINTH in  every
case where there has been an attempted or purported transfer made
in  violation  thereof.   In taking any  action  hereunder,  this
Corporation,  and  its directors, officers and  agents,  will  be
fully  protected  in  relying upon any  notice,  paper  or  other
document  reasonably  believed by this Corporation  or  any  such
person to be genuine and sufficient, and, to the extent permitted
by  law,  in  no  event shall this Corporation,  or  any  of  its
directors, officers or

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agents,  be  liable  for  any  act performed  or  omitted  to  be
performed hereunder in the absence of gross negligence or willful
misconduct.  This Corporation and each of its directors, officers
and  agents  may  consult  with counsel in  connection  with  its
respective duties hereunder and, to the extent permitted by  law,
each  shall  be  fully protected by any act  taken,  suffered  or
permitted  in  good faith in accordance with the advice  of  such
counsel.

           (c)   For  purposes of this Article  NINTH,  the  term
"Electric  Utility  Interest" refers to an  electric  utility  or
utilities or an electric utility holding company or companies, or
any affiliate of either, in each case as those terms are utilized
by   the   Federal  Energy  Regulatory  commission  ("FERC")   in
regulations or orders implementing the Public Utility  Regulatory
Policies  Act of 1978, as amended, and its successors  ("PURPA"),
if  such entity's interest in this Corporation would be a utility
interest for the purposes of 10 C.F.R.  292.206.

          (d)  Whenever it is deemed by the board of directors to
be  prudent in protecting, preserving or obtaining for any of its
projects  (including  projects in which  this  Corporation  or  a
subsidiary  has  an  interest, whether  by  ownership,  lease  or
contract) the status of a "Qualifying Facility" (as defined under
PURPA), the board of directors of this Corporation may require to
be  filed with this Corporation as a condition to permitting  any
proposed  transfer, and/or the registration of any  transfer,  of
any  shares  of  this Corporation's common stock a  statement  of
affidavit  from any proposed transferee to the effect  that  such
transferee  is  not  an "Electric Utility Interest,"  as  defined
herein.

          (e)  The Corporation may, at any time that the Board of
Directors  of  the Corporation deems necessary  or  advisable  to
protect, preserve or obtain for any of its projects the status of
a  "Qualifying Facility", redeem any shares of its capital  stock
beneficially owned by any

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Electric  Utility  Interest at a redemption price  equal  to  the
"Fair Market Value" (as defined in subsection (h) below) of  such
shares of capital stock.

           (f)   In  the event the Corporation shall  redeem  any
shares  of  its capital stock pursuant to subsection  (e)  above,
notice  of  such redemption shall be given by first  class  mail,
postage  prepaid, mailed not less than thirty (30) days nor  more
than sixty (60) days prior to the redemption date, to each holder
of  record of the shares to be redeemed at such holder's  address
as  the  same appears on the books of the Corporation;  provided,
however,  that  no  failure to mail such notice  nor  any  defect
therein  shall  affect  the validity of the  proceeding  for  the
redemption  of any shares of capital stock to be redeemed  except
as  to the holder to whom the Corporation has failed to mail said
notice  or  except as to the holder whose notice  was  defective.
Each  such notice shall state: (i) the redemption date; (ii)  the
number  of  shares of capital stock to be redeemed and,  if  less
than  all the shares held by such holder are to be redeemed  from
such  holder,  the  number of shares to  be  redeemed  from  such
holder; and (iii) the place or places where certificates for such
shares are to be surrendered for payment of the redemption price.

           (g)  Notice having been mailed as aforesaid, from  and
after  the redemption date (unless the Corporation shall fail  to
provide  money  for the payment of the redemption  price  of  the
shares  called  for redemption) the shares of  capital  stock  so
called   for  redemption  shall  no  longer  be  deemed   to   be
outstanding,   and   all  rights  of  the  holders   thereof   as
stockholders of the Corporation (except the right to receive from
the   Corporation  the  redemption  price)  shall  cease.    Upon
surrender in accordance with said notice of the certificates  for
any  shares  so  redeemed  (properly  endorsed  or  assigned  for
transfer,  if  the board of directors shall so  require  and  the
notice  shall  so  state), such shares shall be redeemed  by  the
Corporation at the redemption price.

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In  case  fewer than all of the shares represented  by  any  such
certificate  are  redeemed,  a new certificate  shall  be  issued
representing  the unredeemed shares without cost  to  the  holder
thereof.

           (h)   For purposes of this Article NINTH, "Fair Market
Value"  shall mean the average of the closing sale prices  during
the 30-day period immediately preceding the redemption date of  a
share  of  capital stock of the Corporation as  reported  on  the
American Stock Exchange, Inc. (the "Amex"), or, if such stock  is
not  then  listed  on  the Amex, on the principal  United  States
securities exchange registered under the Securities Exchange  Act
of  1934, as amended, on which such stock is listed, or, if  such
stock is not then listed on any such exchange, the average of the
closing  sale  prices  or  closing bid quotations  (whichever  is
higher,  if  both are reported) with respect to a share  of  such
stock   during  the  30-day  period  immediately  preceding   the
redemption  date  of  a  share  of such  stock  on  the  National
Association of Securities Dealers, Inc. National Market System or
any  system  then in use, or if no such quotations are available,
the  fair market value on the redemption date of a share of  such
stock as determined by the board of directors in good faith.

           (i)   The board of directors of this Corporation shall
have  the  right to determine whether any transferee or purported
transferee  of shares of common stock of this corporation  is  an
"Electric  Utility  Interest"  and  to  determine  whether   this
Corporation's   projects  (including  projects  in   which   this
Corporation  or  a  subsidiary  has  an  interest,   whether   by
ownership,   lease   or  contract)  meet  the  requirements   for
"Qualifying Facility" status under PURPA.

           (j)   Nothing  contained in this Article  NINTH  shall
limit the authority of the board of directors of this Corporation
to  take such other action as it deems necessary or advisable  to
protect  this  Corporation and interests of its  stockholders  by
protecting, preserving or obtaining for any of this Corporation's
projects (including projects in which this Corporation or a

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subsidiary  has  an  interest, whether  by  ownership,  lease  or
contract) the status of a "Qualifying Facility" under PURPA.

           (k)   All  certificates representing  shares  of  this
Corporation's common stock shall bear the following legend:

                The  sale, transfer, assignment, conveyance,
          pledge  or other disposition of any of the  shares
          represented  by this certificate to any  "Electric
          Utility  Interest"  (as  hereinafter  defined)  is
          restricted  in  accordance with the provisions  of
          the    Certificate   of   Incorporation   of   the
          Corporation.    For  these  purposes,   the   term
          "Electric Utility Interest" refers to an  electric
          utility   or  utilities  or  an  electric  utility
          holding company or companies, or any affiliate  of
          either,  in each case as those terms are  utilized
          by   the   Federal  Energy  Regulatory  Commission
          ("FERC") in regulations or orders implementing the
          Public Utility Regulatory Policies Act of 1978, as
          attended,  and its successors ("PURPA"),  if  such
          entity's  interest  in  the Corporation  would  be
          utility   interest  for  purposes  of  10   C.F.R.
          292.206.

           TENTH:     The  provisions set forth in  this  Article
TENTH  and  subparagraph  (a)  of Article  FIFTH  (regarding  the
alteration  of  bylaws) may not be repealed  or  amended  in  any
respect  unless  such  repeal or amendment  is  approved  by  the
affirmative  vote of the holders of not less than  sixty  percent
(60%)  of  the  total voting power of all outstanding  shares  of
voting stock of the Corporation.

           ELEVENTH:  The  provisions set forth in  this  Article
Eleventh,  in  subparagraph (b) of Article FIFTH  (regarding  the
alteration  of  certain bylaws) and in Article EIGHTH  (regarding
the  greater than sixty-six and two thirds percent (66-2/3%) vote
of stockholders

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<PAGE>

required  for  certain mergers or other corporate  combinations),
may  not be repealed or amended in any respect unless such repeal
or  amendment is approved by the affirmative vote of  holders  of
not  less  than  seventy-five percent (75%) of the  total  voting
power   of  all  outstanding  shares  of  voting  stock  of   the
Corporation.

           TWELFTH:  The Corporation reserves the right to amend,
alter,   change  or  repeal  any  provision  contained  in   this
Certificate  of  Incorporation, in the manner  now  or  hereafter
prescribed by statute and in accordance with Articles  TENTH  and
ELEVENTH hereof.



      IN  WITNESS  WHEREOF, this Certificate  of  Correction  and
Restated  Certificate  of Incorporation  which  restates  in  its
entirety  the  provisions  of  the Corporation's  Certificate  of
Incorporation, having been duly adopted by the Board of Directors
of  the  Corporation in accordance with the provisions of Section
242  of the General Corporation Law of the State of Delaware, has
been executed on the 8th day of January, 1997.




                         /s/ Timothy P. Hunstad
                         Timothy P. Hunstad
                         Treasurer and Chief Financial Officer


ATTEST:

/s/  Karen A. Brennan
By:  Karen Brennan
Its: Secretary