Power Plant Engineering

Resources and Reserves. Geological resources include all coal that may become economic at
some time in the future. Reserves include all coal that is known to be technically and economically
recoverable under today’s conditions. These estimates are old (1978) and not updated recently. The
world total estimates for coals resources are (in billion tonnes) : Hard coal : 7725 and Brown coal :
2399. The proven reserves are 493 and 144 resp. World possesses vast resources of coal, far more than
any of those of any other fossil fuel. However, almost 90% of the coal resources are concentrated in
four countries: USSR (45%), US (24%), China (13%) and Australia (6%). US, USSR and China pro-
duce about 60% of coal output and the other major producers are (25% share): Poland, Germany, UK,
Australia, South Africa and India. Today, most of the world’s coal production is still consumed in the
countries where it is mined. Only about 10% is traded internationally. The major portion of coal is used
for electricity generation.
2.8.5 NUCLEAR ENERGY
Nuclear power production is based on the energy released when an atomic nucleus such as
uranium undergoes fission following the absorption of a neutron to form a compound nucleus. This
compound nucleus is unstable and may break into two or three smaller atomic nuclei with the simulta-
neous emission of several neutrons together with the release of considerable amount of energy. These
neutrons may themselves be absorbed by other nuclei, and if enough of these are uranium nuclei, it is
possible for a chain reaction to develop. Chain reactions form the basis of the operation of a nuclear
reactor. Fission of a single atom of uranium yields 200 MeV (= 3.2e
–11
J), whereas the oxidation of one
carbon atom releases only 4 eV. Natural uranium consists of 99.3% 
238
U and only 0.7% of lighter
isotope 
235
U, but it is the latter that provides the most readily available fission energy in nuclear reactor.
The maintenance of chain reaction, with exactly one neutron (on average) eventually causing another
fission, is the design objective of any nuclear reactor.