Page 148 - Managing Global Warming

112 Managing Global Warming

(11.2%). The remaining 9.2% of the electrical energy is generated using oil (4.2%) and
renewable sources (biomass, wind, geothermal, and solar energy) (5%) in selected
countries.
3. Other energy sources such as renewable wind and solar power have a significant visible
impact in some countries, especially, where there are government incentives with electric-
ity prices guaranteed by legislation and power-purchase contracts. However, these appar-
ently attractive renewable-energy sources (wind, solar, tidal, etc.) are not reliable as full-
time energy sources for industrial power generation. To overcome this problem, a grid must
also include “fast-response” power plants such as gas- (coal-) fired and/or large hydro-
power plants.
4. In general, the major driving force for all advances in thermal and nuclear power plants is
thermal efficiency and generating costs. Ranges of gross thermal efficiencies of modern
power plants are as the following: (1) Combined-cycle thermal power plants—up to
62%; (2) Supercritical-pressure coal-fired thermal power plants—up to 55%; (3)
Carbon-dioxide-cooled reactor NPPs—up to 42%; (4) Sodium-cooled Fast Reactor
(SFR) NPP—up to 40%; (5) Subcritical-pressure coal-fired thermal power plants—up to
43%; and (6) Modern water-cooled-reactor NPPs—30%–36%.
5. In spite of advances in coal-fired thermal power plants design and operation worldwide,
they are still considered environmental “unfriendly” as a result of carbon dioxide emissions
and significant production of slag and ash wastes. Recently, legislated measures have been
proposed to limit such emissions, going beyond voluntary and regional emission credits and
allowable portfolios.
6. Combined-cycle thermal power plants with natural-gas fuel are considered as relatively
clean fossil-fuel-fired plants compared to coal and oil power plants, and are dominating
new capacity additions, because of their lower carbon dioxide production and lower costs
using natural gas derived from “fracking” processes.
7. Nuclear power is, in general, a nonrenewable source unless fuel recycling, thoria fuel, and/
or fast reactors are adopted, which means that nuclear resources can be used significantly
longer than some fossil fuels. Currently, this source of energy is considered as the most
viable one for baseload electrical generation for the next 50–100years.
8. However, all current Generations II and III and oncoming Generations III+ NPPs, espe-
cially, those equipped with water-cooled reactors, are not very competitive with modern
thermal power plants in terms of thermal efficiency (30%–36% for NPPs with water-cooled
reactors and 55%–62% for supercritical-pressure coal-fired and combined-cycle power
plants, respectively).
9. Enhancements are needed beyond the current building plans for NPPs; many of new
designs are coming from China. These new designs must compete in the world markets,
and if possible, without government subsidies or power price guarantees. New-generation
NPPs must have thermal efficiencies close to those of modern thermal power plants, i.e.,
within a range of at least 40%–50%, and incorporate improved safety measures and
designs.
10. The major advantages of nuclear power are well known, including cheap reliable baseload
power, high capacity factor, low carbon dioxide emissions, and minor environmental
impact. However, these factors are offset today by a competitive disadvantage with natural
gas and the occurrence of three significant nuclear accidents (Fukushima, Chernobyl, and
Three Mile Island)—the latter having caused significant social disruption together with
high capital costs.