capacity, and to concentrate such plants in clusters (power parks). Power 
plants having capacities of 2000 megawatts exist today, and 20,000 mega- 
watt power parks are being planned. For facilities of this size, it is essential 
that the frequency and impact of significant man-induced changes in 
weather and climate downwind be determined and planned for. Con- 
siderable data already exist with which we can develop preliminary assess- 
ments. The problem is not a trivial one. We have already seen lines of 
manmade clouds downstream from 2000 megawatt plants.* 
Decisions on power plant siting are an increasingly important re- 
sponsibility of State and local regulatory commissions'and such Federal 
agencies as the Atomic Energy Commission and the Environmental Pro- 
tection Agency. With the trend toward planning power facilities offshore 
and along the coast, maritime and coastal zone management agencies too 
will become involved. 
It is important that when decisions are made, climatic impact be taken 
into account. NACOA therefore recommends that power plant siting 
environmental impact statements be required to include an evaluation 
of the effect on local climate resulting from the heat discharge. Since the 
capability of assessing the cumulative long-term effects of such decisions, 
despite its importance, is rudimentary, NACOA also recommends that a 
climatic effect research program be funded as an integral part of the 
R&D effort to develop new energy techniques and concepts. 
* Facilities of this size release approximately 3 x 109 watts of heat to the environ- 
ment, more than the total kinetic energy production in a tornado and only slightly 
less than that in a thunderstorm. A shower producing 1 cm of rain in 30 minutes 
over an area of 36 square kilometers releases 5 X 1011 watts of latent heat. As 
power parks continue to increase in size, there is an increasing likelihood that 
showers and even severe local weather will take place in their vicinity. Th energy 
release from a 20,000 megawatt power park is great enough to trigger natural 
showers and thunderstorms, and recent studies in St. Louis have already shown 
such effects. 
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