PUB00037

• Year: 1988
• Title: Colorado Joint Planning Study Economic Potential of Pumped Storage
• CWCB Section: Interstate & Federal
• Author: Colorado Water Resources and Power Development Authority
• Description: Assessment of whether pumped storage facilities are economically attractive to Colorado utilities
• Publications - Doc Type: Water Resource Studies

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operation and maintenance and fuel costs for all generation units including purchased
power) are referred to as system costs throughout this study. Initial expansion plans
(or "base case" plans) did not include potential pumped storage projects. A typical
pumped storage project was then inserted as a future generation resource option and
these associated costs were estimated again. The economic effects of pumped
storage were then measured by analyzing the difference in system costs in the base
case and the case with pumped storage. This approach was used for three scenarios
based on low, medium, and high load growth forecasts.

Base Case Results

For each of the utilities studied, a base case using the medium load forecast without
pumped storage was first developed. In order to estimate the extent of economy
energy interchanges between the utility systems, the analysis reflected existing
limitations on transmission interconnections between utilities. The base case analysis
modeled each utility system and identified future generation resources that could meet
load growth and reserve requirements at the least cost. Long-term purchases and
sales contracts between the utilities in the state were prespecified in the analysis.

Current interest rates, general price inflation rates, and future replacement of retired
thermal plants were incorporated in the modeling analysis. A 20-year study period
with a 30-year extension period was assumed. Resource additions were made only
during the first 20 years. The 30-year extension was included so that plant costs could
be included for the majority of the plants' service lives. Future prices of fuel reflected
utility estimates for the first ten years of the study and projections by Data Resources
Incorporated (DRI) for the later study years.

The summary of the base case expansion plan shows that under the medium load
forecast, new generation capacity may be needed in Colorado after 2000. In the high
load forecast however, new generation capacity may be required as early as 1997.
(The exact year depends on variables including transmission line capability, capacity
additions from Qualifying Facilities (QFs), utilization of demand-side alternatives, and
the ability of utilities to successfully sell or purchase power from other utilities in the
state.) An analysis of the base cases, without pumped storage capacity, showed that
Colorado may require about 1,382 megawatts (MW) of additional capacity during 1988
to 2007: 785 MW would be provided with the installation of two base-load coal-fired
units, 498 MW with the installation of eight combustion turbines (CTs), and 99 MW with

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