EXHIBIT  21.1     SUBSIDIARIES  OF  THE  REGISTRANT.


U.S.  SUBSIDIARIES



Name of Subsidiaries     State of Organization  Trade Names
- -----------------------  ---------------------  -----------
                                          
Penn Wilson CNG, Inc. .  Delaware               None
Penn CNG Holdings, Inc.  Delaware               None



FOREIGN  SUBSIDIARIES



Name of Subsidiaries                      Country of Organization  Trade Names
- ----------------------------------------  -----------------------  -----------
                                                             
PennWill, S.A. de C.V. . . . . . . . . .  Mexico                   None
Camiones Ecologicos, S.A. de C.V.. . . .  Mexico                   None
Grupo Ecologico Industrial, S.A. de C.V.  Mexico                   None
Estacion Ambiental, S.A. de C.V. . . . .  Mexico                   None
Estacion Ambiental II, S.A. de C.V.. . .  Mexico                   None
Serinc, S.A. de C.V. . . . . . . . . . .  Mexico                   None