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Electricity generation in the world of nuclear power industry 95

usually not considered during estimation of variable power sources costs: (1) costs of
fast-response power plants with service crews on site 24/7 as a back-up power; and (2)
faster amortization/wear of equipment of fast-response plants. Furthermore, consid-
ering the fast changes in climate, possible catastrophic events such as powerful hur-
ricanes, melting ice caps in mountains, and changes in solar activity, countries should
not rely on unreliable renewable sources such as hydro, wind, and solar, unless there is
a significant backup energy source.

3.3 Modern thermal power plants

In general, the vast majority of thermal power plants [1,2,25] are based on the follow-
ing thermodynamic cycles:
(1) Rankine steam-turbine cycle (the mostly widely used in various power plants; usually, for
solid, gaseous and liquid fuels, but other energy sources can be also used, for example, geo-
thermal, solar, etc.) (Fig. 3.27) with regeneration and steam superheat. Rankine cycle can be
at subcritical pressures—older coal- and gas-fired power plants, also, geothermal and solar-
thermal plants, and at supercritical pressures (for more details on supercritical pressures, see
the following publications: [26–29])—at modern advanced coal- (gas-) fired power plants.
(2) Brayton gas-turbine cycle (the second one after the Rankine cycle in terms of application in
power industry; only for clean gaseous fuels) (Fig. 3.28A and B, upper schemes);
(3) Combined cycle, i.e., combination of Brayton and Rankine cycles in one plant (only for
gaseous fuels) (Fig. 3.28). Subcritical-pressure Rankine cycle is used at combined-cycle
power plants.
(4) Diesel internal-combustion-engine cycle (for Diesel fuel used in Diesel generators). (The
largest diesel generators in the world are 50-MW el ( 68,000hp) Hyundai diesel engines
installed at the 200-MW el (50MW el 4 engines) Vasavi Basin Bridge Diesel-Generator
Plant (Chennai (formerly Madras) India) (www.worldmaritimenews.com and www.
hyundaicorp.com);
(5) Otto internal-combustion-engine cycle (usually, for natural or liquefied gas, but also, gas-
oline can be used for power generation; however, it is more expensive fuel compared to
gaseous fuels), also used in internal-combustion-engine generators (Fig. 3.29).
It should be noted that internal combustion engines electrical generators are very
important for emergency/backup power at nuclear and other power plants, and various
installations.
The major driving force for all advances in thermal power plants is directed toward
increasing thermal efficiency in order to reduce operating fuel costs and minimize spe-
cific emissions. Typical ranges of thermal efficiencies of modern thermal power
plants are listed in Table 3.8 for reference purposes.
Despite all advances in thermal power plants design and operation worldwide, they
are still considered as environmentally “unfriendly” due to significant carbon dioxide
emissions (for example, the largest in the world 5780MW el Taichung coal-fired power
plant (Taiwan) (Fig. 3.4) is the world’s largest emitter of carbon dioxide with over
40 million tonnes per year [1,2]) and air pollution as a result of the combustion
process. In addition, coal-fired power plants produce significant amounts of slag
and ash, and other greenhouse gases such as SO 2 , which contributes to acid rains.