WMOD00379

• Title: Potential Opportunities for Precipitation Augmentation in the Eastern Tennessee Valley
• Date: 2/1/1988
• Weather Modification - Doc Type: Report

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These objectives would be accomplished through detailed physical observations.
The expected estimated cost of this 3-month program is approximately $810,000.

~.8 Summary of Cost-Benefit Analysis

An estimate of the potential benefits of cloud seeding to the Tennessee Valley
region was made by estimating the amount of additional water produced, deter-
mining its net value to the region, and estimating the cost of producing in an
operational environment. These results were combined to generate a benefit-cost
ratio that would be representatjve of a long-term operational cloud seeding
program.

Initial estimates of water production were made by applying the appropriate
results from past cloud seeding programs to the situation in the eastern TVA
region. A simple model was developed that augmented the historical inflow to
affected reservoirs. Augmentation amounts were consistent with current seeding
practices and historical results. Four augmentation scenarios were selected
which bracketed the range of expected results. These scenarios generated
streamflow increases of 3 to 9 percent over the period of interest (March 1 to
May 31).~ Actual increases varied according to week and reservoir. These
augmented hydrologies were used as input to TVA1s weekly scheduling model,
HYDROSIM, to determine the effect of this additional water. Results of
augmented model runs were compared with a base case that used the unaugmented
hydrology.

Model results for the four scenarios showed that average increases in energy
range from 140 GWH to 260 GWH. These results were calculated under the assump-
tion that the additional water would not be stored, but rather allowed to
flowthrough the system and not be stored immediately. It was estimated, that if
as much water as possible were stored, energy production could be increased by.
at least 10 percent over the values quoted above, although this scenario was not
run. Model results were provided to various TVA groups to make a determination
of the resulting benefits or disadvantages. It was the opinion of TVA personnel
that the only quantifiable benefit or disadvantage of cloud seeding would be -
power production.

The Division of Power Systems Operations determined that the additional power
produced would be worth from $1.2 million in the lowest augmentation scenario
and simulation year to $7.2 million in the highest. The average annual benefit
varied from $2.5 million to 4.6 million. The cost of an operational program was
estimated to be $0.7 million annually. Combining these two values results in
average annual benefit cost ratios from 3.6:1 to 6.5:1. Even in the years of
lowest annual energy gain operational seeding would have a benefit cost ratio of
1.7:1.

Based upon the results of this study and given its assumptions, it would be
concluded that cloud seeding to provide additional water and power in the TVA
region has the potential to be highly cost effective.

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