18-02-2013, 10:08 AM
Development of the Ultra High Efficiency Thermal Power Generation Facility
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Abstract
In order to combat global warming, attention has been increasingly shifting towards nuclear and renewable
energy such as wind and solar power generation as feasible power resource alternatives. The electric power
suppliers of Japan are aiming to increase the amount of nuclear and non-fossil fuel power generation by over
50% of total power generation by 2020. However, this does not translate into the complete eradication of the
traditional model as the remaining half will still be fossil fuel-based thermal power generation. Given these
circumstances, Japan has aggressively implemented of further measures to enhance the efficiency of thermal
power generation.
Introduction
Thermal Power Generation
The conviction that global warming prevention
and the generation of nuclear power and renewable
energies such as wind and solar power are
inextricably linked is an idea that has recently been
gathering force. Regardless, thermal power
generation still remains as the major source of
power supply and accounts for approximately 60%
of all power generated in Japan. Thus, enhancing
the efficiency of thermal power generation has been
deemed indispensible in order to achieve CO2
emissions reduction. Further, as Japan is a country
with few natural resources and is largely dependant
on imports for its energy resources, the impact of
the recent rise in fuel prices has been extreme. For
the effective utilization of fossil fuels, technology
for improving the efficiency of the thermal power
generation has become increasingly important from
both environmental and economical perspectives.
Improving Efficiency of Thermal Power
Generation
Figure 3 depicts the output trend of steam
conditions and the efficiency of TEPCO’s thermal
power generation. In the late 1950s, the main
source was steam power generation with its thermal
efficiency being around 39% (LHV). After the
Second World War, Japan’s thermal power
generation increased in efficiency and capacity.
This was achieved via repeated improvements of
the steam conditions (pressure and temperature) by
bringing in and absorbing the latest technologies
from Europe and the United States. In the 1970s,
the capacity and efficiency reached 1,000MW and
43%, respectively. Japanese technology for thermal
efficiency improvement has since then surpassed
that of its technological forefathers. At present, the
efficiency of the latest coal-fired Ultra Super
Critical (USC) thermal power plant has reached
45%.
Example of USC Power Plant in Japan -1
In order to enhance energy security and minimize
generation costs, TEPCO’s coal-fired Hitachinaka
Unit One (1,000MW) commenced commercial
operations in December 2003. For TEPCO, it had
been about 30 years since the last large scale
coal-firing power plant was constructed. In order to
increase the thermal efficiency and decrease CO2
emissions, the USC steam conditions of 24.5MPa,
600/600 deg-C was adopted. It achieved a thermal
efficiency of 45% (LHV) which is the highest class
in terms of coal-fired steam power generation levels.
Maximum efforts were put forth towards
environmental preservation. Highly efficient and
reliable denitrifying facility and electrostatic
precipitator and desulphurization facility had been
installed for the flue gas treatment. Further, woody
biomass fuel which is a kind of natural and
renewable energy is scheduled to be utilized as fuel
for Unit One from fiscal year 2012. When
implemented, it would reduce the annual CO2
emission by about 110 kilo tons.
Effective Use of Coal
From an energy security and economical
perspective, as coal is available in abundance and is
relatively inexpensive, it is considered to be a
promising fuel source for both now and in the
future. However, it is not possible to burn coal in
the combustor of the gas turbines. The use of coal
was limited to such activities as pulverized coalfired
steam power generation.
The technology to improve the thermal efficiency
of coal-fired power generation is called the
“Integrated Coal Gasification Combined Cycle”
(IGCC). Coal is gasified at the gasification furnace
which enables it to be used as fuel for an efficient
gas turbine combined cycle power generation.
Figure 17 is an outline of the IGCC.