Release Date: December 4, 2012
Coal is the largest source of power globally and, given its wide availability and relatively low cost, it is likely to remain so for the foreseeable future. The High-Efficiency, Low-Emissions Coal-Fired Power Generation Roadmap describes the steps necessary to adopt and further develop technologies to improve the efficiency of the global fleet of coal. To generate the same amount of electricity, a more efficient coal-fired unit will burn less fuel, emit less carbon, release less local air pollutants, consume less water and have a smaller footprint.
High-efficiency, low emissions (HELE) technologies in operation already reach a thermal efficiency of 45%, and technologies in development promise even higher values. This compares with a global average efficiency for today’s fleet of coal-fired plants of 33%, where three-quarters of operating units use less efficient technologies and more than half is over 25 years old. A successful outcome to ongoing RD&D could see units with efficiencies approaching 50% or even higher demonstrated within the next decade. Generation from older, less efficient technology must gradually be phased out. Technologies exist to make coal-fired power generation much more effective and cleaner burning.
Of course, while increased efficiency has a major role to play in reducing emissions, particularly over the next 10 years, carbon capture and storage (CCS) will be essential in the longer term to make the deep cuts in carbon emissions required for a low-carbon future. Combined with CCS, HELE technologies can cut CO2 emissions from coal-fired power generation plants by as much as 90%, to less than 100 grams per kilowatt-hour. HELE technologies will be an influential factor in the deployment of CCS. For the same power output, a higher efficiency coal plant will require less CO2 to be captured; this means a smaller, less costly capture plant; lower operating costs; and less CO2 to be transported and stored.
- In 2011, roughly 50% of new coal-fired power plants used high-efficiency, low-emissions (HELE) technologies, predominantly supercritical (SC) and ultra-supercritical (USC) pulverised coal combustion units. Though the share of HELE technology has almost doubled in the last 10 years, far too many non-HELE, subcritical units are still being constructed. About three-quarters of operating units use non-HELE technology; more than half of current capacity is over 25 years old and comprises units of less than 300 MW.
- USC pulverised coal combustion is currently the most efficient HELE technology: some units reach efficiency of 45% (LHV, net), reducing global average emissions to 740 grams of carbon dioxide per kilowatt hour (gCO2/kWh). Efforts to develop advanced USC technology could lower emissions to 670 gCO2/kWh (a 30% improvement). Deployment of advanced USC is expected to begin within the next 10 to 15 years.
- To raise its efficiency, integrated gasification combined cycle (IGCC) needs to operate with gas turbines that allow higher turbine inlet temperatures. IGCC with 1 500°C-class gas turbines (currently under development) should be able to raise efficiency well above 45%, bringing CO2 emissions down towards 670 gCO2/kWh – and less for IGCC units with more advanced gas turbines.
- To achieve CO2 intensity factors that are consistent with halving CO2 emissions by 2050, deployment of carbon capture and storage (CCS) is essential. CCS offers the potential to reduce CO2 emissions to less than 100 g/kWh. Programmes to demonstrate large-scale, integrated CCS on coal-fired power units are under way in many countries. Some deployment of CCS is anticipated in the 2020s, with broader deployment projected from 2030-35 onwards.
- HELE technologies need to be further developed as:
- Inefficient power generation from low-cost, poor quality coal is currently being used by many countries.
- Though trials have demonstrated the potential to reduce emissions by co-firing biomass, the practice is not widespread.
- Operating coal-fired power plants consume copious quantities of water, a cause of major concern in arid regions and regions where water resources issues are gaining prominence.
- Non-greenhouse gas pollutants can cause severe health issues and often harm local infrastructure and, consequently, the local economy. Though technologies are available for reducing such emissions, not all countries yet deploy them effectively.