EXHIBIT 3.127

CERTIFICATE OF FORMATION

OF

      Peabody Natural Gas, LLC

         1. The name of the limited liability company is Peabody Natural Gas,
LLC

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

         IN WITNESS WHEREOF, the undersigned have executed this Certificate of
Formation of Peabody Natural Gas, LLC This 19th day of November, 1999

                                           /s/ James C. Sevem
                                           ------------------
                                              James C. Sevem

                                              Assistant
                                              Secretary/Authorized Person

                                                           STATE OF DELAWARE
                                                          SECRETARY OF STATE
                                                        DIVISION OF CORPORATIONS
                                                       FILED 11:30 AM 11/22/1999
                                                          991500333 - 3130473