1. Assumptions for 2005/2006 Objective Capability Determination NEPOOL PSPC Dec. 20, 2004

2. 12.20.2004Power Supply Planning Committee2 Assumptions List AssumptionMore than 20 MW Effect on Objective Capability CapacityNo OP4 Actions 9 and 10No Minimum Operating ReserveYes Load ForecastYes Unit AvailabilityYes Demand Response ProgramsYes 5% Voltage ReductionYes Tie BenefitsYes Needs PSPC DiscussionCovered in Presentation

3. 12.20.2004Power Supply Planning Committee3 Objective Capability Assumptions Capacity –Existing capacity will be equal to those assets and ratings noted in 2005 CELT Report –Capacity additions based on ISO-NE recommended units and PSPC discussions Ridgewood Generation (8.4 MW) Berkshire Wind (15 MW) – For PSPC discussion Kendall ST 3 and CT Reactivation – For PSPC discussion –Capacity attrition to include those with RC approved 18.4 applications for deactivation or retirement

4. 12.20.2004Power Supply Planning Committee4 Objective Capability Assumptions OP-4 Actions 9 and 10 –Total of 45 MW –Verified with Operations that capacity is not enrolled in ISO-NE Demand Response Program

5. 12.20.2004Power Supply Planning Committee5 Objective Capability Assumptions Minimum Operating Reserve –OP-4 Action 12 –Modeled in Westinghouse as –200 MW –Verified with Operations (???)

6. 12.20.2004Power Supply Planning Committee6 Objective Capability Assumptions Load Forecast –2005/2006 load forecast input into the Reliability Model will be consistent with the 2005 CELT Forecast

7. 12.20.2004Power Supply Planning Committee7 Objective Capability Assumptions Unit Availability Options –5-year Average Using EFOR –Using EFORd values Adjusted EFOR values for months with missing data NERC Class Average EFORd values for months with missing data

8. 12.20.2004Power Supply Planning Committee8 Objective Capability Assumptions Preliminary Data (Jan-00 through Oct-04) Unit CategorySummer MW 04/05 OC Assumed EFOR Weighted EFOR Weighted EFORd Fossil10,133.55.765.316.73 CC2,765.41.312.444.88 New Unit CC8,072.8New Unit CC Maturity6.32 Diesel63.72.231.615.02 Jet1,869.73.263.357.08 Nuclear4,387.12.661.453.74 Hydro3,195.50.930.913.81 Total System30,487.73.803.405.52 –Pre-SMD EFORd data assumes NERC class average –Summer MW per Dec-04 SCC Report

9. 12.20.2004Power Supply Planning Committee9 Objective Capability Assumptions ISO-NE Demand Response Program - Recommended Assumptions –Only reliability programs used in determination Real-Time 30-Minute Demand Response Real-Time 2-Hour Demand Response Real-Time Profiled Response –Assets enrolled and ready to respond as of Jan. 1, 2005 will be included

10. 12.20.2004Power Supply Planning Committee10 Objective Capability Assumptions ISO-NE Demand Response Program EFOR modeling of assets based on results of August 20, 2004 performance audit –EFOR = 1 – (Interruption MW / Total Enrolled MW) ProgramLoad ZoneAssumed EFOR RT 2-hour Demand ResponseCT65% ME12% NEMA88% WCMA84%

11. 12.20.2004Power Supply Planning Committee11 Objective Capability Assumptions ProgramLoad ZoneAssumed EFOR RT 30 Minute Demand ResponseCT0% NEMA40% NH32.5% SEMEA38% VT43% WCMA100% Profiled ResponseME85.5% NEMA100% VT100% RT Price ResponseNo RT Price Response MW assumed for 2005/2006 OC Calculation ISO-NE Demand Response Program

12. 12.20.2004Power Supply Planning Committee12 Demand Response (as of November 30, 2004) * SWCT assets are included in CT values and are not included in Total

13. 12.20.2004Power Supply Planning Committee13 Objective Capability Assumptions 5% Voltage Reduction amount to be used in OC determination –For further PSPC discussion

14. 12.20.2004Power Supply Planning Committee14 Objective Capability Assumptions Tie Benefits –For further PSPC discussion