WSP04440

• File Number: 8220.111.A
• Description: Central Utah Participating Project
• State: UT
• Basin: Colorado Mainstem
• Date: 5/1/1984
• Author: USDOI-BOR
• Title: Diamond Fork Power System
• Water Supply Pro - Doc Type: Report/Study

HOW WILL DIAMOND FORK OPERATE?

Water releases through the Diamond Fork Power System will be made according
to downstream agricultural, municipal, and industri al demands. These
downstream water uses will have priority over power generation. However,
operation of the Fifth Water Pumped Storaoe Powerpl ant is not constrained.
by downstream water demands. The averaoe annual flow-throuoh eneroy of 403
GWH produced by the project was determined by usino operation studies based
on the 1921-1973 hydrologic period.

Table 2 summarizes the monthly energy produced at the powerplants based on
average hydrologic conditions. The pumped storage energy production figures
shown in the table are based on an assumed annual pl ant capacity factor of
16 percent. This average annual plant capaclty factor was used in
p 1 ann in9 reports and represents Rec 1 amati on I s es timate of the long-term
average operating conditions throughout the life of the project. However,
the Fifth Water Pumoed Storaoe Powerplant has a theoretical capability of
operating on a weekly cycle at a 34~rce'l~~!n_Lcapacity factor. The
actual operation of the pl ant wi 11 be according to the needs of the power
users. The pumpback energy requirements shown in Table 2 are based on a
turnaround efficiency of 75 percent.

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The Fifth Water Pumped Storage Powerplant has been designed to operate
on a weekly cycle. The plant will have the capability of generating at
capacity for 12 hours each weekday, with pumpback energy being suppl ied
on weeknights and weekends. Fifth Water Reservoir contains enough capacity
to store the equivalent of approximately 31,500 MWH of energy. During an
emergency, this capacity could be used to operate Fifth Water Pumped
Storage at maximum output for up to 29 hours.

Three operating cases have been analyzed in order to illustrate the rela-
tionship of energy generated by Fifth Water Pumped Storage Powerplant and
the amounts of pumpback energy required. Each operating case was evaluated
using typical summer and winter releases from Strawberry Reservoir. The
July operations shown assume an average flow through component of 690 cfs.
The January operation was based on an average flow through component of 128
cfs. Capacities and energy shown for each case are for the Fifth Water
Pumped Storage Powerpl ant only and do not include the capacity and energy
generated at Syar, Monks Hollow and Diamond Fork Powerpl ants.

Under Case 1, the pl ant would be operated to meet 850 MW peaks of 4-hour
duration each weekday. The remaining plant capacity was assumed to be set
aside for reserves. Figures 5 and 6 show the assumed operation patterns
for a week in July and January, respectively. The amount of energy
generated during the summer and winter weeks was 17,000 MWH. The primary
difference between the summer and winter operation was the iITIount of pump-
back energy required. The winter operation required approximately 19,600
MWH of pumpback energy, whereas the summer operation required only slightly
more than 6,000 MWH of pumpback energy. Thi s difference is due to the
larger releases from Strawberry Reservoir flowing through the system during
the summer months to meet downstream water needs. Figure 7 shows how the
static head would fluctuate during January operation in Case 1.

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