Impacts of Intermittent Generation - Large Energy Storage Systems - page 33

TABLE 2.1
Ramp Rates for PSCO's Coal-Fired Plants

10-Minute Ramp Rate

Ownedor
IRPResource

Capacity
(MW) Plant Fuel (MW) %Cap

Arapahoe 3 Coal Owned 45 6 13

Arapahoe 4 Coal Owned 111 5 5

Cabin Creek A HE Owned 162 95 59

Cabin Creek B HE Owned 162 150 93

Cherokee 1 Coal Owned 107 6 6

Cherokee 2 Coal Owned 106 6 6

Cherokee 3 Coal Owned 152 22 14

Cherokee 4 Coal Owned 352 20 6

Comanche 1 Coal Owned 325 22 7

Comanche 2 Coal Owned 335 22 7

Fort. St. Vrain NG Owned 690 75 11

Pawnee Coal Owned 505 16 3

Valmont 5 Coal Owned 186 14 8

Valmont 6 Coal Owned 43 43 100

Arapahoe 5, 6, and 7 NG IRP 122 20 16

Blue Spruce NG IRP 271 81 30

Brush 1 and 3 NG IRP 76 18 24

Brush 2 NG IRP 68 19 28

Brush 4 NG IRP 135 44 33

Fountain Valley NG IRP 238 34 14

Manchief NG IRP 261 97 37

Rocky Mountain Energy NG IRP 587 103 18

Spindle Hill NG IRP 269 119 44

Thermo Fort Lupton NG IRP 279 147 53

Tristate Brighton NG IRP 132 55 42

Tristate Limon NG IRP 63 27 43

Valmont 7 and 8 NG IRP 79 38 48

HE = hydroelectric. NG = natural gas.

generation curve with the event (July 2), then compare the results over the
duration of the event (Method A). Table 2.2 summarizes the calculations. The
measured emission rates for July 29 are presented in the first row. The second
row indicates total emissions for the no-wind scenario; the third row shows
total emissions associated with July 2 generation. Analyzing the emission
impacts in this manner results in the estimate that the wind event reduced
SO 2 by 730 lb, NO X by 1,386 lb, and CO 2 by 392 tons (bottom row). The limita-
tion of Method A is that it replaces the actual emissions that occurred on July
2 with estimated emissions from a stable day; they are lower because of the
inefficiency of the boiler by cycling as described above.