INGENIEUR
INGENIEUR
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Increased generation turndown capabilities when loads are low( e. g. due to a spike in VRE generation);
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Faster generation start-ups with less damage to plant equipment when loads are high( e. g. due to a decrease in VRE generation);
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Faster load changes to allow for flexible load-following due to the variable output of VRE; and
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Reserve shutdown at minimal cost. Cold, and to a lesser extent warm, starts can significantly add to coal-fired generation costs, including variable O & M costs, when compared with consistent generation.
Coal-fired Power Generation
Coal-fired electricity generation will remain a substantial part of the Asia-Pacific region, as well as global, energy mix for decades to come. Coal remains the most abundant fossil fuel on earth, with proven global reserves of nearly one trillion metric tons. At current consumption rates, this would allow for another 150 years of generation. Reserves of coal are much greater than those of natural gas and oil in terms of energy content as well. Recoverable reserves of coal are present in over 75 countries and mining and combustion have remained relatively inexpensive, which has led to coal being an important component of the global energy mix for many decades.
As of 2012, coal-fired generation accounted for approximately 55 % of electricity production in the Asia-Pacific region, up from 32 % in 1990. More than 92 % of this electricity is generated using hard coal – bituminous, some anthracite and a small portion of coking coal. In absolute terms, coal-fired generation increased from 1,207 TWh in 1990 to 5,888 TWh in 2012, a compound annual growth rate( CAGR) of 7.47 %. Over this period however, generation from VRE sources increased from 38 GWh of electricity production in 1990 to nearly 164,000 GWh( 164 TWh) in 2012, a CAGR of 46.3 %. Total electricity production from all sources nearly tripled from 3,743 TWh in 1990 to 10,739 TWh in 2012.
The majority of power plants using coal in the region use pulverised coal( PC) combustion technology, which encompasses subcritical, supercritical, USC and A-USC. A number of countries in the Asia-Pacific region, including China, India, Indonesia, Japan, Republic of Korea and Thailand, are using fluidised bed combustion( FBC) technology. Integrated gasification combined cycle( IGCC) technology can be found in select countries in the region including China, Japan and the Republic of Korea.
With respect to PC combustion technology, the main parameters to consider when profiling the global stock of CFPPs are size( nameplate power generation capacity in MW), age( based on when the power plant was built) and performance level( combustion technology differentiated by temperature). The typical maximum efficiency can vary significantly depending on site-specific factors such as weather conditions, extent of maintenance and type of operating regimes.
High-efficiency, low-emissions coal-fired Power Generation
Average global coal-fired plant efficiency rests at around 33 %, as of 2012( IEA, 2013b). In order to increase these efficiencies, a transition towards more efficient HELE coal-fired generation should take place. HELE coal-fired generation includes supercritical, USC and A-USC PC technologies, typically in the range of up to 42 % for supercritical, 45 % for USC and up to 50 % for A-USC( IEA, 2013b). The aim of deploying HELE technologies is twofold: to increase conversion efficiencies and to reduce CO 2 emissions. Both supercritical and USC technologies are available now, with even higher efficiencies possible when A-USC becomes more readily available.
Poorer quality or low-grade coals( such as lignite) are candidates for more efficient generation, notably by employing pre-combustion drying. Global shares of supercritical and USC coal-fired generation rest at approximately 28 % as of 2012. With coal-fired generation comprising 55 % of electricity production in the Asia-Pacific region as of 2012, addressing more efficient coalfired generation is a necessity.
66 VOL 67 JULY-SEPTEMBER 2016