Figure 1 Electricity production by resource in the Asia-Pacific region in 1990 , 2012 ( TWh )
for higher-efficiency supercritical , USC or advanced ultra-supercritical ( A-USC ) CFPPs .
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Variable operations and maintenance ( O & M ) costs are also generally lower for subcritical plants than for supercritical , USC , or A-USC CFPPs due to the lower pressures and temperatures required for combustion .
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LCOEs , however , are generally lower for supercritical , USC and A-USC CFPPs when compared with subcritical CFPPs because they require less fuel in order to generate the same amount of electricity . Thus , when a long-term view is taken , high-efficiency , low emission ( HELE ) generation is more cost-effective over the lifetime of a CFPP than less-efficient subcritical generation , due to lower fuel requirements .
Adverse externalities of coal-fired generation should be considered when deciding which type of generation technology to employ . The costs associated with negative externalities are not included in LCOE calculations ; meaning HELE generation would be even more attractive if they were considered .
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Globally , coal-fired power generation is a leading source of sulphur oxides ( SOx ), nitrous oxides ( NOx ), particulate matter
( PM ) and mercury , along with other toxic pollutant emissions .
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According to the International Energy Agency ( IEA ), in 2011 , electricity and heat generation accounted for 42 % of global
CO 2 emissions , of which 72 % was derived from one source – CFPPs ( IEA , 2013a ).
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The share of coal in Asia-Pacific ’ s energy mix has drastically increased over the past decade , accounting for approximately 55 % of electricity generation as of 2012 ( see Figure 1 ) ( ESCAP , 2015 ).
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Per kWh , coal has nearly 20 % more greenhouse gas ( GHG ) emissions than oil , more than twice as much GHG emissions as gas , and almost 22 times more GHG emissions than solar photovoltaics ( PV ).
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Consumption of energy is directly tied to water consumption , with 15 % of the world ’ s total water withdrawals used for energy production in 2010 . Within the energy sector , thermal power plants ( burning fossil fuels and nuclear ) are the most intensive users of water .
To allow for the integration of increasing shares of variable renewable energy ( VRE ), coal assets must increase operating flexibility by improving performance in the following areas :
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