Western’s Use of the GT-MAX
Model
Sam Loftin - General Engineer
Western Area Power Administration -
CRSP CSC
Discussion Topics
Overview of Western Area Power
Administration
Overview of the CRSP CSC
Overview of Glen Canyon Environmental
Process
Overview of Western’s customers and
contract arrangements
How we use the GT-MAX model
Long-term Replacement Power
Background
Western is an agency of the U.S.
Government, Department of Energy
Established in 1977 during energy crisis
to increase emphasis on energy
One of four Power Marketing
Administrations covering most of U.S
Multipurpose Water
Development Projects
Irrigation water storage and distribution
Hydroelectric Power Generation and
Transmission - revenue source
Flood Control
Recreation
Wildlife
Multipurpose Water
Development Projects
(Continued) Hydroelectric Power Generation and
Transmission - revenue source
What Western does
Market Hydroelectric Generation - over
10,000 MW at 55 power plants
45,800 GWH energy sales and
$740,000,000 revenue last year
Deliver power over 27,123 km high
voltage transmission system
638 wholesale customers in 3.38 million
square km service area
Background of CRSP CSC
1,855 MW installed capacity
8,698 GWH energy and $176,000,000
revenue last year
3,843 km of high voltage transmission
line
125 wholesale customers
Other Generation Resources
Upper Molina - 9 MW, 32 GWh
Lower Molina - 5 MW, 15 GWh
Elephant Butte - 28 MW, 109 GWH
Towaoc - 11 MW, 9 GWh
McPhee - 1 MW, 1 GWh
Deer Creek - 5 MW, 37 GWh
Changes in operations at
Glen Canyon Dam
Operational
Constraint
Historic Flows
(Pre-1991)
ROD Flows
(Post 1997)
Minimum release
(cfs)
3,000 summer
1,000 rest of year
8,000 - 7 am - 7 pm
5,000 at night
Maximum release
(cfs)
31,500 25,000
Daily fluctuations
(cfs/24 hrs)
28,500 summer
30,500 rest of year
5,000; 6,000; or 8,000
depending on release
volume
Ramp rate (cfs/hr) Unrestricted 4,000 up
1,500 down
Overview of Power Contracts
CRSP CSC share of customer load
averages about 25%
Cost of hydro power is generally much
less than other customer resources
CRSP CSC delivers whatever
hydropower is available based on
hydrological forecasts
Overview of Power Contracts
(continued)
Hydro capacity is two-thirds of that
previously available
Available Hydro Power varies monthly
Power delivered at significantly higher
load factor
Total price paid by customers varies
Overview of Power Contracts
(continued)
Customers have choice of replacing
remainder up to contracted amount
– Replace it themselves (purchase or self
generation)
– CRSP CSC replaces it on short term (6
months)
– CRSP CSC replaces it on long term (30+
months)
Available Hydro Power
Determination
Estimate available hydro power for upcoming
6 months from water forecasts using GT-MAX
Apportion power to each customer, notify
them, and find out their purchase needs
Determine purchases by CRSP CSC
Merchant Function
Water forecasts are updated monthly, so
hydropower forecasts updated monthly
Graph of one week output from
model July
Load vs. Generation
Case 18b (Load Sensitivity)
0
100
200
300
400
500
600
700
800
900
1,000
1,100
1,200
1,300
1,400
Sun Mon Tue Wed Thu Fri Sat
Day of Week
MW
Load
Generation
50% AHP
100% AHP
Non-Reimbursable
Expense Determination
Law allows power customers to not
repay costs for Glen Canyon test flows
Model “normal” operations without test
flows in GT-MAX
Compare revenue from “normal”
operations to actual operations
Difference in revenue is non-
reimbursable
Non-Reimbursable Expense
Determination (continued)
CRSP CSC modeled operation for
1993-1997
Determined difference between
“normal” and actual operations
Saved power customers $43 Million
between 1993 and 1997
CRSP CSC will also model any future
test flows
Upcoming Flaming Gorge and
Aspinall EIS
CRSP CSC will study changing operations at
Flaming Gorge and Aspinall
Compare cost of operational changes and
impact to power customers using GT-MAX
Use information from GT-MAX in negotiations
on preferred alternative
Preserve maximum generation/operational
flexibility possible
Long Term Replacement Power
Replace hydropower “lost” to
operational constraints on long term
Customers have choice of short-term,
long-term, or self replacement
Customers have choice of amount and
timing of replacement power
Long Term Replacement Power
(continued)
RFP for supply and/or demand-side
resources
Evaluate costs quantitatively on a
uniform $/MWh basis
Evaluate non-cost factors qualitatively
Long Term Replacement Power
(continued)
Use GT-MAX to model vendor
proposals integrated into CRSP CSC
power system
Determine optimum proposal(s) to
minimize purchase costs
Customers declined to participate in
long term replacement because of cost
CRSP CSC Merchant Function
Merchant Function schedules hydro
power resources to meet loads
Purchases from regional spot market
Sells surplus hydro power to spot
market
Looks for opportunities to buy and sell
at profit
CRSP CSC Merchant Function
(continued)
Use GT-MAX to optimize hydro power
operations (amount, location, timing)
Increase revenue, decrease purchase
costs, optimize limited hydro resource