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2009 State of the Market Report

Load and Resources

We calculate the reserve margin as follows:

E ast Internal Load Internal Demand3

36,987 34,090

- -

43,200 43,200

16.8% 26.7%

42,100 42,100

13.8% 23.5%

39,688 39,688

7.3% 16.4%

Central Internal Load Internal Demand

37,615 35,576

2,032 2,032

46,866 46,866

30.0% 37.4%

44,230 44,230

23.0% 30.0%

41,030 41,030

14.5% 21.0%

W est Internal Load Internal Demand

25,568 24,101

2,234 2,234

34,812 34,812

44.9% 53.7%

26,941 26,941

14.1% 21.1%

24,716 24,716

5.4% 11.8%

W UMS Internal Load Internal Demand

12,532 11,552

712 712

17,114 17,114

42.3% 54.3%

15,988 15,988

33.3% 44.6%

15,118 15,118

26.3% 37.0%

M IS O Internal Load Internal Demand

112,701 105,318

5,549 5,549

141,993 141,993

30.9% 40.1%

129,259 129,259

19.6% 28.0%

120,552 120,552

11.9% 19.7%

Reserve margin = [(Capacity + Firm Imports) ÷ Internal Demand or Load] – 1.

Table 1: Capacity, Load, and Reserve Margins for each Midwest ISO Region 2009-2010 Planning Year

1

2

M idwest IS O S um mer-Rated Capacity fr om its 2010 S um mer Assessm ent, including full rating for Run of River. High T em perature capacity is based upon tem pearture derates that occurred in the Day-A head m arket of A ugust 1, 2006.

m argins), b) we include all physical capacity, not only those designated as capacity (increases our margins), c) w e calculate our m argins based on internal load and internal demand w hile the M idw est IS O's is generally based on internal demand, d) w e exclude estimated forced outage rates (increases our m argins).

Region

3

4

Net Inter nal D emand estim ate excludes interruptible load and behind the meter generation. Our planning reserve m argins differ from the Midw est IS O ’s because: a) w e include tem perature-related deratings (reduces our

Load

Net

Capacity

Reserve

Capacity

Reserve

Capacity

Reserve

Imports

M arg in

Margin

Margin4

Firm

Nameplate

Available Capacity1

High Temp. Capacity2

Reserve margins are highly sensitive to the assumed maximum-capacity levels and whether interruptible demand is included. Using nameplate capacity levels and the projected capacity changes for 2010, we find the reserve margin for the Midwest ISO region is 31 percent based upon internal load and 41 percent based upon internal demand. These reserve margins vary within the Midwest ISO subregions from 17 percent to 45 percent based upon internal load and from almost 27 percent to more than 54 percent based upon internal demand. Nameplate capacity-based reserve margins are considerably higher in the western half of the Midwest ISO footprint.

These reserve margins are similar to 2009 levels and notably higher than in prior years due to lower peak load levels over the past two years, and indicate that the Midwest ISO currently has a substantial capacity surplus. However, when the typical deratings and the temperature-sensitive

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