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important, it contributes a fairly small fraction to the
present demands of the world, and estimates do not sug-
gest that it could ever expand so as to supply the whole
of the demands. During the long run of a million years,
a great deal more energy will be needed.
It is worth giving consideration in a little detail to the
shortage of energy, both because of its tremendous im-
portance to human life, and because it is possible to speak
about it with some confidence. There are going to be
many shortages of all sorts of things in the future; for
example, metal mines will be exhausted, and many of
the metals we now use will run short some day some
of them in the very near future but it can reasonably be
expected that fairly good substitutes will be found for
them. But energy is different; there is no substitute for
energy, and no way of creating it. It is no use adopting
the Micawber attitude that "something will turn up",
an attitude which may be admissible over the shortages
of metals; but not for energy, because for that nothings
can turn up. The utmost that can be done is to discover
the key to unlock some known but at present unavail-
able source of energy. This is true even of what many
will regard as a newly discovered source, atomic energy;
for the existence of this energy has been long known,
and the novelty is that the key has only recendy been
found. In the light of these considerations, I shall devote
a little space to considering what are the future prospects
64
MATERIAL CONDITIONS
of energy for the use of humanity, and from what
sources it may be derived.
Atomic energy has been much discussed in recent
years as a source of power which may ultimately replace
coal. It is certainly too early to estimate this with con-
fidence, but the prospects are really not very bright. The
only method of getting atomic power, which is at pre-
sent in sight, is from uranium. Now uranium is a fairly
common element, commoner than silver but not as
common as lead, but present estimates suggest that the
total energy that could be derived from the earth's
uranium is very roughly as much as has come and will
come from coal; it is unlikely to be ten times as much,
and it is certainly not a thousand times as much, so that
it would not help in the long ages to come. Moreover
there are very few mines where it is strongly concen-
trated, and for the rest it would be a costly and destruc-
tive business, to work over vast bodies of poor ore in
order to win relatively tiny quantities of uranium.
The matter is made only a little better by the existence
of the rather commoner element thorium, which has
not yet been tamed into giving up atomic energy,
though this will probably happen some day. The pro-
duction of energy from uranium or thorium, as far
as we can judge, will always have to be done in "piles",
which have to be very large units if they are to work
at all, so that the distribution of the power to the
users is itself quite a problem. Furthermore there are
really formidable secondary difficulties associated with
making energy from uranium. There is the familiar
political danger that it is impossible to get the power
B 65
THE NEXT MILLION YEARS
without at the same time making large amounts of ex-
plosive material suitable for atom bombs. Then also
there are made large quantities of intensely radio-active
fission products, the cinders of the furnace, and even at
the present time, when developments are still almost
rudimentary, the disposal of these cinders is a formidable
problem. On the whole then the prospects of power
from uranium are not very good; it may be a useful
palliative in the energy shortage, but it almost certainly
will not provide a long-term solution.
It is well known that there may be a possibility of
making atomic explosives from hydrogen, and, since
this is a source of energy, it might some day be made
into a fuel to yield power. It is the isotope, heavy hydro-
gen, that would be used, and though its proportion in
hydrogen, or in water, is very small, still there are
broadly speaking unlimited stocks of it. In practice it
takes a good deal of energy to separate it out from the
ordinary hydrogen, but the amount is trivial compared
to the energy it would yield after the separation. There
seems little doubt that the heavy hydrogen will some
day be made to explode with the help of a suitable
detonator, but this would be useless as a source of power;
for that purpose it is necessary that it should be made to
"burn" slowly, and this may be an insoluble problem.
If, however, it could be done, it might yield a permanent
solution of the fuel problem.
To complete the picture of atomic energy, there is
ordinary hydrogen, which potentially contains most
energy of all. It is ordinary hydrogen atoms that yield
the energy which keeps the sun and stars hot; this they
66
MATERIAL CONDITIONS
do through a series of rather complicated reactions at
enormous temperatures which gradually unite them
into helium through the agency of atoms such as carbon
and nitrogen. As far as we can judge this energy is per-
manently locked up in the case of the hydrogen on
earth, and perhaps it is a good thing; for if it were not
so, there would be quite a probability some day of an
explosion which would wreck the whole earth, and
indeed the solar system. The "burning" of heavy [ Pobierz całość w formacie PDF ]