Exhibit 21(a) Subsidiaries of Illinova Corporation and Illinois Power Company State or Jurisdiction Name of Incorporation - ---- --------------------- Illinova Corporation Illinois Illinois Power Company Illinois IP Gas Supply Company Illinois Illinois Power Fuel Company (1) Illinois Illinois Power Capital, L.P. (2) Delaware Illinois Power Financing I Delaware Illinova Generating Company Illinois Electric Energy, Inc. (3) Illinois Illinova Resource Recovery, Inc. (formerly IPG Canfield Co.) Illinois IGC Krishnapatnam Company (formerly IPG Dominguez Co.) Illinois IPG Eastern, Inc. Illinois IPG Ferndale, Inc. Illinois IPG Frederickson, Inc. Illinois IGC Solutions, Inc. (formerly IPG LAP Cogen, Inc.) Illinois IGC Grimes Frontier, Inc. (formerly IPG Panorama Co.) Illinois IPG Paris, Inc. Illinois IPG Western, Inc. Illinois IGC Acquisition Co. (formerly IPG Aztec Co.) Illinois IGC Brazos, Inc. Illinois IGC Development Company Illinois IGC International, Inc. Cayman Islands IGC Grimes County, Inc. (formerly IGC Sub Co., Inc.) Illinois White Oak Energy Investors, Inc. Illinois ECI Energy, Ltd. (4) Delaware North American Energy Services Co. (5) Washington IGC ELCO Partnership, LLC (6) Cayman Islands IGC Jamaica Partnership, LLC (7) Cayman Islands IGC International II, Inc. Cayman Islands IGC Flores Partnership, LLC (8) Cayman Islands IGC Flores Partnership II, LLC (9) Cayman Islands FIG Leasing International, Inc. (10) Cayman Islands FIG Leasing International III, Inc. (11) Cayman Islands FIG Equipment, LLC (12) Cayman Islands IGC Aguaytia Partners, LLC (13) Cayman Islands IGC Mauritius Holding Company (formerly IGC-ABC Shanghai Co.)(14) Mauritius Illinova ZJ XC Company (15) Mauritius IGC Mauritius International Company (16) Mauritius IGC Uch, LLC (17) Cayman Islands Operaciones de Arequipa, LLC (18) Cayman Islands Tenaska-Illinova Generating Inter- national, LLC (19) Cayman Islands Fuerza Electrica de Latinoamerica,LLC (20) Cayman Islands IGC (Encoe), LLC Cayman Islands IGC Vietnam Development, Inc. Cayman Islands IGC STI Guna Company (21) Mauritius COE (UK) Corp. (22) Connecticut COE (Gencoe) Corp. (23) Connecticut Charter Oak (Paris), Inc. (24) Connecticut Illinova Energy Partners, Inc. Delaware Tenaska Marketing Ventures (25) Nebraska Illinova Insurance Company Vermont (1) Illinois Power Company owns 50% of the common stock of Illinois Power Fuel Company. (2) Illinois Power Company is the general partner in Illinois Power Capital, L.P., with a 3% equity ownership share. Illinois Power Capital is consolidated in the accounts of Illinois Power Company. (3) Illinova Generating Company owns 20% of the common stock of EEI. (4) Illinova Generating Company owns 47.5% of the voting common stock of ECI Energy, Ltd. (5) Illinova Generating Company owns 50% of the common stock of North American Energy Services Company. (6) IGC International, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 99% and IGC International II Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 1% of the common stock of IGC ELCO Partnership, LLC. (7) IGC International, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 99% and IGC International II, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 1% of the common stock of IGC Jamaica Partnership, LLC. (8) IGC International, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 99% and IGC International II, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 1% of the common stock of IGC Flores Partnership, LLC. (9) IGC International, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 99% and IGC International II, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 1% of the common stock of IGC Flores Partnership II, LLC. (10) IGC Flores Partnership, LLC (a subsidiary of IGC International, Inc. and IGC International II, Inc.) owns 51% of the common stock of FIG Leasing International, LLC. (11) IGC Flores Partnership, LLC (a subsidiary of IGC International, Inc. and IGC International II, Inc.) owns 51% of the common stock of FIG Leasing International III, Inc. (12) IGC Flores Partnership, LLC (a subsidiary of IGC International, Inc. and IGC International II, Inc.) owns 50% of the common stock of FIG Equipment, LLC. (13) IGC International, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 99% and IGC International II, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 1% of the common stock of IGC Aguaytia Partners, LLC. (14) IGC International II, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 100% of the equity of IGC Mauritius Holding Company Ltd. (15) IGC International II, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 100% of the equity of Illinova ZJ XC Company. (16) IGC International II, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 100% of the equity of IGC Mauritius International Company. (17) IGC International II, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 99% and IGC International, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 1% of the common stock of IGC Uch, LLC. (18) IGC International, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 99% and IGC International II, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 1% of the common stock of Operaciones de Arequipa, LLC. (19) IGC Uch, LLC (a subsidiary of IGC International, Inc. and IGC International II, Inc.)owns 50% of the voting common stock of Tenaska-Illinova Generating International, LLC. (20) IGC International, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 99% and IGC International II, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 1% of the common stock of Fuerza Electrica de Latinoamerica, LLC. (21) IGC International II, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 100% the equity IGC STI Guna Company. (22) IGC (Encoe), LLC (a wholly-owned subsidiary of Illinova Generating Company) owns 79.9% and COE (Gencoe) Corp. (owned 49% by IGC (Encoe), LLC) owns 20.1% of the common stock of COE (UK) Corp. (23) IGC (Encoe), LLC (a wholly-owned subsidiary of Illinova Generating Company) owns 49% of the common stock of COE (Gencoe) Corp. (24) IPG Paris, Inc. (a wholly-owned subsidiary of Illinova Generating Company) owns 100% of the common stock of Charter Oak (Paris), Inc. (25) Illinova Energy Partners, Inc. owns 50% of the equity of Tenaska Marketing Ventures.