Guaranty, dated as of the 10th day of December, 1997
               that amends the Limited Guaranty made by NRG Energy for
               the benefit of Cogen, LLC dated September 19, 1997.



<PAGE>
                                                 Exhibit 10.27.18




               FIRST AMENDMENT TO LIMITED GUARANTY


       THIS   FIRST  AMENDMENT  to  the  Limited  Guaranty   (the
"Amendment")  is  made as of the 10th day of December,  1997  and
amends  the Limited Guaranty made by NRG Energy, Inc., a Delaware
corporation  (the "Guarantor") for the benefit  of  NRG  (Morris)
Cogen,   LLC,   a   Delaware  limited  liability   company   (the
"Principal")  dated September 19, 1997 (the "Limited  Guaranty").
Terms not defined herein shall have the meaning ascribed to  them
in the Limited Guaranty.

                      W I T N E S S E T H:

     WHEREAS, the Guarantor has made the Limited Guaranty for the
benefit of the Principal;

      WHEREAS, the Guarantor and Principal have agreed  to  amend
the Limited Guaranty as set forth below;

     NOW, THEREFORE, the parties hereto hereby agree as follows:

                           Section 1.
                     Amendment to Section 13

1.   Section 13 of the Limited Guaranty is hereby amended to read
as follows:

     "13.  Expiration  of Guaranty.  This Guaranty  shall  expire
upon the earliest of
          (a)  the payment by the Guarantor of the maximum amount
          of Guaranteed Obligations set forth in Section 1 above;
          (b)  expiration of the term of the O&M Agreement if  no
          claim  has  been  made by Principal  against  Guarantor
          prior  to  such  expiration;  provided,  however,  that
          Principal may make claims against Guarantor under  this
          Guaranty that arose prior to the expiration of the  O&M
          Agreement for a period of one hundred twenty (120) days
          after  the  expiration  of the O&M  Agreement;  or  (c)
          delivery by Operator to Principal of a letter of credit
          or  substitute  guaranty, in  each  case  in  form  and
          substance satisfactory to Principal, in an amount equal
          to the remaining obligation of Guarantor hereunder.  No
          extension  of  the  Guaranty shall be effective  unless
          evidenced   by   written  amendment   signed   by   the
          Guarantor."

                           Section 2.
                          Miscellaneous

2.   This  Amendment may be executed in one or more counterparts,
     each  of which shall be deemed an original, but all of which
     together shall constitute one and the same instrument.  This
     Amendment shall be governed by and construed in accordance with
     the laws of Minnesota, without giving effect to its provisions
     regarding conflict of laws.  Except as

<PAGE>

specifically  amended  hereby  the  provisions  of  the   Limited
Guaranty shall continue in full force and effect.  This Amendment
contains  the entire agreement between the parties hereto  as  to
amendment  of  the  Limited  Guaranty, and  any  representations,
endorsements, promises or arrangements, including those contained
in  any  prior drafts of this Amendment, if not embodied  herein,
shall not be of any force or effect.

3.   This Amendment is effective upon the later of (i) the date
on which written consent to this Amendment is given by The Chase
Manhattan Bank, as agent for Principal's Lenders, and (ii) the
date of this Amendment.

      IN  WITNESS  WHEREOF, the parties hereto have caused  their
duly  authorized representative to execute this Amendment  as  of
the day and year first written above.

NRG Energy, Inc.



By:/s/ Craig Mataczynski
Name:  Craig A. Mataczynski
Title:  Vice President