238 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1958 
cities and towns. In fact, it is already here. The critical mass of 
uranium, the elaborate controls and shielding and the disposal of 
radioactive waste, all work against small atomic units. Emphasis 
is being placed on 100,000-kilowatt atomic power units and larger, 
with some consideration of 5,000-kilowatt units for special purposes. 
Undoubtedly, the successes of atomic power have had an influence on 
solar energy. ‘They have weaned us away from thinking only in 
terms of conventional combustion fuels. 
Unlike atomic energy, solar energy has no critical mass, no health 
hazards (except sunburn), and no waste products to dispose of. Any- 
one can go out in his yard and run a toy steam engine with free sun- 
shine. There is no power limit. Laboratory research and even pilot- 
plant operation for solar energy is comparatively inexpensive. 
Solar-energy utilization will probably start with small units costing 
not millions of dollars, but only thousands of dollars. They will find 
their first practical uses in rural, nonindustrialized areas. I do not 
mean to imply that the deserts of Arizona may not bloom with huge 
solar powerplants—but they won’t be important this year. 
Let me ask again why do we sense this upsurge of interest in the 
utilization of solar energy now, and why has the direct use of the sun’s 
energy been neglected so long? There are many reasons. Life has 
been too easy with concentrated energy in the form of coal, petroleum, 
natural gas, and waterpower. “Necessity is the mother of invention” 
and the scientists and engineers most capable of developing devices 
for making direct use of the sun have lived in industrialized countries 
where there has been no necessity for developing solar energy. These 
countries would not be industrialized unless they had plenty of fuel. 
Dollarwise, competition with cheap fossil fuels has been unattractive, 
and “social-conscious-wise” there has been no demand in the indus- 
trialized countries that could not be met with conventional sources of 
energy. 
But these conditions are changing and there are several factors which 
are contributing to our new interest in solar energy. We realize, as 
never before, that our fossil fuels—coal, oil, and gas—will not last 
forever. Several careful studies have been published in the last few 
years which point out that the depletion of our reserves will come 
sooner than we think. In the fuel-rich United States, the problem 
may be one for our grandchildren, but some countries already are feel- 
ing the pinch of a decrease in high-grade, easily minable coal. More- 
over, the population of the world is increasing rapidly and the demands 
for abundant energy are increasing still faster. Any estimates of the 
life of fuel reserves based on consumption at past rates are utterly 
unrealistic. 
