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in tackling climate change. A one percentage point improvement in the efficiency of aconventional pulverized coal combustion plant results in 2-3 per cent reduction inCO 2emissions. Highly efficient modern coal plants emit almost 40 per cent lessCO 2than the average coal plant currently installed.Efficiency improvements include the most cost-effective and shortest lead time actionsfor reducing emissions from coal-fired electricity. This is particularly the case indeveloping and transition economies where existing plant efficiencies are generallylow while coal usage in electricity generation is increasing.The average global efficiency of coal-fired power plants is currently 28 per cent, comparedwith 45 per cent for the most efficient plants (see Figure 2-1). A programme of repoweringexisting coal-fired plants to improve their efficiency, coupled with the installationof newer and more efficient plants, will reduce CO 2emissions significantly. Althoughthe deployment of new, highly efficient plants is subject to local constraints, such asambient environmental conditions and coal quality, deploying the most efficient plantpossible is critical to enable these plants to be retrofitted with CCS in the future.Efficient plants are a prerequisite for retrofitting with CCS because capturing, transportingand storing the plant’s CO 2will consume significant quantities of energy. Inefficientplants will undermine the capacity to deploy CCS technologies.Figure 2-1: Efficiencies of coal-fired power plants2000Sub-criticalSupercriticalUltra supercritical (IGCC)Emissions (gCO /kWh)215001000500Global average efficiencyof power plantsEfficiency of stateof-the-artpower plants025 35 45 55Efficiency (%, HHV)Note: 1% increase in efficiency = 2-3% decrease in emissionsSource: IEA "Focus on Clean Coal" (2006)Improving the efficiency of old and inefficient coal-fired plants would reduce CO 2emissionfrom coal use by almost 25 per cent, representing 6 per cent reduction in globalCO 2emission. These significant emission reductions can be achieved by replacing49