Shaping Up The Duck Chart Independent Energy Producers Association Annual Meeting Mark Rothleder Vice President, Market Quality and Renewable Integration September 26, 2013

33% Renewable Portfolio Standard build-out through 2020 Slide 2

Flexible resources needed to balanced the net load demand curve Slide 3 Load & Net Load (MW) 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 14,000 16,000 18,000 20,000 22,000 24,000 26,000 28,000 30,000 32,000 34,000 Load, Wind & Solar Profiles---Base Scenario January 2020 Net_LoadLoadWindTotal Solar Wind & Solar (MW) 6,700 MW in 3-hours 7,000 MW in 3-hours 12,700 MW in 3-hours Net Load = Load - Wind - Solar

The “duck” illustrates the increased potential for over- generation condition and ramping needs. Potential Over-generation Slide 4 Ramping needs increase

Flexible resources would be dispatched to the net load demand curve Slide 5 CL – 6/ ,200 1,600 2,000 2,400 22,000 24,000 26,000 28,000 30,000 32,000 34,000 36,000 38,000 40,000 42,000 Load, Net Load, Wind & Solar---08/19/2013 LoadNetLoadWindSolar Load & Net Load (MW) Wind & Solar (MW)

Minimum net load began shifting from early mornings to the middle of the day Slide 6 Load & Net Load (MW) Wind & Solar (MW) ,000 1,200 1,400 18,000 19,000 20,000 21,000 22,000 23,000 24,000 25,000 26,000 27,000 28,000 29,000 Load, Net Load, Wind & Solar---1/1/2013 LoadNet LoadWindSolar

Actual wind and solar production can vary significantly from one day to the next ---- March 2013 Forecasting wind and solar production in the day-ahead timeframe is a challenge Slide 7

Ways to balance or reshape the “Duck” Generation Storage Demand Response Dispatchable Quick Start Wider Operating Range (lower Pmin) Load Shift Over Generation Mitigation Voltage Support Peak Load Reduction Dispatchable Wind/Solar Fast Ramping Regulation Frequency Response Slide 8