Lead from the front Texas Nodal 1 Texas Nodal Market Implementation Program Implementation Scenarios September 6, 2006

Lead from the front Texas Nodal 2 Scenario #1 – single release (baseline) (Nodal Market live & Zonal Market Shutdown July 2009) EMS Early Delivery Systems MMS CRR MIS NMMS Commercial Systems ERCOT & MP Readiness Q2 2008Q3 2009Q4 2008Q3 2008Q2 2007Q1 2007Q4 2006Q4 2007Q3 2007Q1 2008Q3 2006Q Outage Scheduler EDW “UI in production” Q Qualification Freeze EDS 3 (TXMACS 0.3) SCED; MP SCED Offers EDS 4 TXMACS 0.4) with selected MPs EDS 5 (TXMACS 0.5) MMS FATMMS SAT CRR Design, Build, Pre-FATCRR FATCRR SAT Final MP Interface Specs 3/31 MP Registration complete MIS FATMIS SAT 168 hour market trial FATSAT Naming Convention DB NMMS Build Common model update process NODAL GO LIVE MIS (EMS/MMS/CRR) Design, Build, Pre-FAT EDW FATEDW SAT Statements Layout Script test Credit Monitoring End of Trials MP Nodal RegistrationMP Financial & Operational Qualification EMS SATEMSEMS FAT EMS Requirements, Conceptual Design MIS SAT MIS (SCED) Design, Build, Pre- FAT MIS FAT MMS Design, Build, Pre-FAT MMS Requirements, Conceptual Design OS SATOS BuildOS FAT OS Requirements, Conceptual Design CRR Requirements, Conceptual Design Commercial Systems Design, Build, Pre-FATCS FATCS SAT EDW Requirements, Conceptual Design SCED SATSCED BuildSCED FAT SCED Requirements, Conceptual Design Registration ready MPSCED Offers Business Requirements complete 10/30 Preliminary MP Interface Specs 12/31 CS FATCS SAT EDW FATEDW SATEDW FATEDW SAT CS Requirements, Conceptual Design EDW Design, Build, Pre-FAT MIS FATMIS SAT Begin MP trial participation “Non-binding settlements” Financial Transfer CS FATCS SAT EDS 4 MP SAT TXMACS 1.0 Live operations MIS FATMIS SAT “CRR Auction for Go Live” OTS SAT OTS FAT EDS 3 Data Validation NMMS Conceptual Design Naming Convention information collection Model Data Certification Model Data Remediation Reconciliation Assumptions affecting the critical path The current State Estimator will meet the necessary criteria Current NMMS product will be capable of providing Real Time Models for any Nodal System Vendors selection will be done by Mid-June Vendors will share detailed design documents with other vendors for interface definitions TDSPs will be trained on new NMMS and there will dual entry of models – into the new NMMS and into GENESYS. ERCOT will have enough staff to handle this work To allow for interface definitions, detailed design documents of individual projects can be completed 80 hours after one another. The order of completion will be NMMS – MMS/EMS/SE – CRR/Outage Schedule – Commercial Systems – MIS/EDW To satisfy section 17.3 of the Nodal protocols, ERCOT will deploy COGNOS and SAS to provide PUCT with the ability to generate reports ERCOT would need 6 months of integration testing on applications such as MMS, CRR and NMMS Areva’s EMS will handle CIM models All systems have to conform with the integrated Data Dictionary TPTF will hold review meetings as required for approval of requirements and conceptual design documents

Lead from the front Texas Nodal 3 Scenario #2 – 3 incremental releases & slack removed (Release 2 & Zonal Shutdown July ’08, Release 3 January ’09) EMS Trials & Implementation MMS CRR MIS NMMS Commercial Systems ERCOT & MP Readiness Q2 2008Q3 2009Q4 2008Q3 2008Q2 2007Q1 2007Q4 2006Q4 2007Q1 2008Q3 2006Q Integration EDW Q Qualification Freeze EDS 3 EDS 4 MMS FATITEST CRR Design, Build, Pre-FATCRR FATITEST Final MP Interface Specs 3/31 MP Registration complete 168 hour market trial Real Time Operations GO/NO GO Zonal Shutdown GO/NO GO MIS (EMS/MMS/CRR) Design, Build, Pre-FAT EDW FATITEST Statements Layout Script test End of Trials MP Nodal Registration MP Financial & Operational Qualification ITESTEMSEMS FAT EMS Requirements, Conceptual Design ITEST MIS (SCED) Design, Build, Pre- FAT MIS FAT MMS Design, Build, Pre-FAT MMS Requirements, Conceptual Design ITEST OS Build FAT OS Requirements, Conceptual Design CRR Requirements, Conceptual Design Commercial Systems Design, Build, Pre-FATCS FATITEST EDW Requirements, Conceptual Design ITESTSCED BuildSCED FAT SCED Requirements, Conceptual Design Registration ready MPSCED Offers Business Requirements complete 10/30 Preliminary MP Interface Specs 12/31 CS Requirements, Conceptual Design EDW Design, Build, Pre-FAT MIS FATITEST Begin MP trial participation EDS 4 MP SAT OTS ITEST OTS FAT EDS 3 Data Validation Planning UI FAT ITEST Naming Convention DB Common model update process NMMS Conceptual Design Naming Convention information collection Model Data Certification Model Data Remediation Reconciliation NMMS Build Outage Scheduler EDS 1/2 BuildFATITEST Requirements, Conceptual Design ITESTOS FAT Forward Markets GO/NO GO Single Entry Model GO LIVE Q Operations UI

Lead from the front Texas Nodal 4 Scenario #3 – Release 2 & 3 combined & slack removed (Nodal Market live & Zonal Market Shutdown January 2009) EMS Early Delivery Systems MMS CRR MIS NMMS Commercial Systems ERCOT & MP Readiness Q2 2008Q3 2009Q4 2008Q3 2008Q2 2007Q1 2007Q4 2006Q4 2007Q3 2007Q1 2008Q3 2006Q Outage Scheduler EDW Q EDS 3 (TXMACS 0.3) SCED; MP SCED Offers EDS 4 TXMACS 0.4) with selected MPs MMS FATMMS SAT CRR Design, Build, Pre-FATCRR FATCRR SAT Final MP Interface Specs 3/31 NODAL GO LIVE MIS (EMS/MMS/CRR) Design, Build, Pre-FAT EDW FATEDW SAT Statements Layout Script test EMS SATEMSEMS FAT EMS Requirements, Conceptual Design MIS SAT MIS (SCED) Design, Build, Pre- FAT MIS FAT MMS Design, Build, Pre-FAT MMS Requirements, Conceptual Design OS SATOS BuildOS FAT OS Requirements, Conceptual Design CRR Requirements, Conceptual Design Commercial Systems Design, Build, Pre-FATCS FATCS SAT EDW Requirements, Conceptual Design SCED SATSCED BuildSCED FAT SCED Requirements, Conceptual Design Registration ready Business Requirements complete 10/30 Preliminary MP Interface Specs 12/31 CS Requirements, Conceptual Design EDW Design, Build, Pre-FAT MIS FATMIS SAT EDS 4 MP SAT TXMACS 1.0 Live operations OTS SAT OTS FAT EDS 3 Data Validation Qualification Freeze MP Registration complete 168 hour market trial End of Trials MP Nodal Registration MP Financial & Operational Qualification MPSCED Offers Begin MP trial participation Planning UI FAT ITEST Naming Convention DB Common model update process NMMS Conceptual Design Naming Convention information collection Model Data Certification Model Data Remediation Reconciliation NMMS Build Operations UI EDS 1/2 Single Entry Model GO LIVE

Lead from the front Texas Nodal 5 Scenario #4a – 3 incremental releases, timed for seasonality (Release 2 & Zonal Shutdown October ’08, Release 3 February ’09) EMS Trials & Implementation MMS CRR MIS NMMS Commercial Systems ERCOT & MP Readiness Q2 2008Q3 2009Q4 2008Q3 2008Q2 2007Q1 2007Q4 2006Q4 2007Q1 2008Q3 2006Q Integration EDW Q EDS 3 MMS FATITEST CRR Design, Build, Pre-FATCRR FATITEST Final MP Interface Specs 3/31 MP Registration complete 168 hour market trial Real Time Operations GO/NO GO Zonal Shutdown GO/NO GO MIS (EMS/MMS/CRR) Design, Build, Pre-FAT EDW FATITEST Statements Layout Script test End of Trials MP Nodal Registration & Qualification sequence ITESTEMSEMS FAT EMS Requirements, Conceptual Design ITEST MIS (SCED) Design, Build, Pre- FAT MIS FAT MMS Design, Build, Pre-FAT MMS Requirements, Conceptual Design ITEST OS Build FAT OS Requirements, Conceptual Design CRR Requirements, Conceptual Design Commercial Systems Design, Build, Pre-FATCS FATITEST EDW Requirements, Conceptual Design ITESTSCED BuildSCED FAT SCED Requirements, Conceptual Design Registration ready MPSCED Offers Business Requirements complete 10/30 Preliminary MP Interface Specs 12/31 CS Requirements, Conceptual Design EDW Design, Build, Pre-FAT MIS FATITEST Begin MP trial participation EDS 4 EDS 4 MP SAT OTS ITEST OTS FAT EDS 3 Data Validation Planning UI FAT ITEST Naming Convention DB Common model update process NMMS Conceptual Design Naming Convention information collection Model Data Certification Model Data Remediation Reconciliation NMMS Build Outage Scheduler EDS 1/2 BuildFATITEST Requirements, Conceptual Design ITESTOS FAT Forward Markets GO/NO GO Single Entry Model GO LIVE Q Operations UI

Lead from the front Texas Nodal /01/08 Scenario #4b – 3 incremental releases, timed after seasonal 2008 peak (Release 2 & Zonal Shutdown October ’08, Release 3 December 1, 2008) EMS Trials & Implementation MMS CRR MIS NMMS Commercial Systems ERCOT & MP Readiness Q2 2008Q3 2009Q4 2008Q3 2008Q2 2007Q1 2007Q4 2006Q4 2007Q1 2008Q3 2006Q Integration EDW Q EDS 3 MMS FATITEST CRR Design, Build, Pre-FATCRR FATITEST Final MP Interface Specs 3/31 MP Registration complete 168 hour market trial Real Time Operations GO/NO GO Zonal Shutdown GO/NO GO MIS (EMS/MMS/CRR) Design, Build, Pre-FAT EDW FATITEST Statements Layout Script test End of Trials MP Nodal Registration & Qualification sequence ITESTEMSEMS FAT EMS Requirements, Conceptual Design ITEST MIS (SCED) Design, Build, Pre- FAT MIS FAT MMS Design, Build, Pre-FAT MMS Requirements, Conceptual Design ITEST OS Build FAT OS Requirements, Conceptual Design CRR Requirements, Conceptual Design Commercial Systems Design, Build, Pre-FATCS FATITEST EDW Requirements, Conceptual Design ITESTSCED BuildSCED FAT SCED Requirements, Conceptual Design Registration ready MPSCED Offers Business Requirements complete 10/30 Preliminary MP Interface Specs 12/31 CS Requirements, Conceptual Design EDW Design, Build, Pre-FAT MIS FATITEST Begin MP trial participation EDS 4 EDS 4 MP SAT OTS ITEST OTS FAT EDS 3 Data Validation Planning UI FAT ITEST Naming Convention DB Common model update process NMMS Conceptual Design Naming Convention information collection Model Data Certification Model Data Remediation Reconciliation NMMS Build Outage Scheduler EDS 1/2 BuildFATITEST Requirements, Conceptual Design ITESTOS FAT Forward Markets GO/NO GO Single Entry Model GO LIVE Q Operations UI

Lead from the front Texas Nodal 7 Scenario Summary DAM/REAL-TIME/RUC IMPLEMENTATION & ZONAL SHUTDOWN JULY 1, 2009 –Scenario #1 – single release (baseline) (Nodal Market live & Zonal Market Shutdown July 2009) REAL-TIME/RUC IMPLEMENTATION & ZONAL SHUTDOWN JULY 1, 2008 FOLLOWED BY DAM IMPLEMENTATION JANUARY 1, 2009 –Scenario #2 – 3 incremental releases & slack removed (Release 2 & Zonal Shutdown July ’08, Release 3 January ’09) DAM/REAL-TIME/RUC IMPLEMENTATION & ZONAL SHUTDOWN JAN 1, 2009 –Scenario #3 – Release 2 & 3 combined & slack removed (Nodal Market live & Zonal Market Shutdown January 2009) REAL-TIME/RUC IMPLEMENTATION & ZONAL SHUTDOWN OCTOBER 1, 2008 FOLLOWED BY DAM IMPLEMENTATION FEB 1, 2009 –Scenario #4a – 3 incremental releases, timed for seasonality (Release 2 & Zonal Shutdown October ’08, Release 3 February ’09) REAL-TIME/RUC IMPLEMENTATION & ZONAL SHUTDOWN OCTOBER 1, 2008 FOLLOWED BY DAM IMPLEMENTATION DEC 1, 2008 –Scenario #4b – 3 incremental releases, timed after seasonal 2008 peak (Release 2 & Zonal Shutdown October ’08, Release 3 December 1, 2008)