1. California Independent System Operator ISO Department of Market Analysis1 ISO Department of Market Analysis Analysis of Day Ahead Congestion Costs, Curtailments, and Unscheduled ETC Transmission Capacity By Keith Casey ISO Department of Market Analysis February 8, 2000

2. California Independent System Operator ISO Department of Market Analysis2

3. California Independent System Operator ISO Department of Market Analysis3 = Cost Savings to SP15 Load = Cost Increase to NP15 Load Market Results: Congestion (Path 15 Rating = 0) Market Results: No Congestion on Path 15 SP15 NP15 PUPU Gen. Cost Gen. Cost Q SP15 Q NP15 Demand SP15 Demand NP15 P SP15 P NP15 S SP15 S NP15 SP15 NP15SP15+NP15 PUPU Gen. Cost Gen. Cost Q SP15 Q NP15 Q TOTAL Demand SP15 Demand NP15 Demand NP15+SP15 Supply NP15+SP15 Export to NP15 S SP15 S NP15

4. California Independent System Operator ISO Department of Market Analysis4 Day-ahead Import Curtailments of COI (Apr 98 - Mar 99)

5. California Independent System Operator ISO Department of Market Analysis5 Day-ahead Import Curtailments of COI (Apr 99 - Nov 99)

6. California Independent System Operator ISO Department of Market Analysis6 Day-ahead South to North Curtailments of Path 15 (Dec 98 - Nov 99)

7. California Independent System Operator ISO Department of Market Analysis7 Day-ahead North to South Curtailments of Path 15 (Dec 98 - Nov 99)

8. California Independent System Operator ISO Department of Market Analysis8 Day-ahead Import Curtailments of NOB (Feb 99 - Nov 99)

9. California Independent System Operator ISO Department of Market Analysis9 Day-ahead Import Curtailments of Palo Verde (Feb 99 - Nov 99)

10. California Independent System Operator ISO Department of Market Analysis10 Day-ahead Import Curtailments of Eldorado (Feb 99 - Nov 99)

11. California Independent System Operator ISO Department of Market Analysis11 Methodology for Calculating Curtailments For hours having day ahead congestion on COI: –Actual Curtailments = Initial New Firm Use (NFU) Schedule - Final NFU Schedule –Unscheduled ETC Capacity = Hour ahead TTC - Total Real-Time Schedules* –Estimated curtailments if unscheduled ETC was available to the day ahead market = Max (0, Actual Curtailments - unscheduled ETC capacity) * Real-time Schedules refers to final tie-point schedules at the end of the ETC scheduling deadline of 20 minutes prior to the operating hour.

12. California Independent System Operator ISO Department of Market Analysis12 Potential Annual Cost Savings to Load from Making ETC Capacity Available to the Day Ahead Market (Dec 98 - Nov 99)