Coal is the principal fuel for the global generation of electrical power. It is the leading source of power generation in OECD countries and the dominant fuel source behind economic growth in non-OECD countries. However, while coal provides over 40% of the world’s electricity, it is responsible for more than 70% of the CO2 arising from electricity generation. Local air pollution arising from coal-fired electricity generation has also come under close public scrutiny in the communities and urban areas where plants are located. Carbon capture and storage is not yet cost-effective for large-scale application. In the meantime, while new plants deploy high-efficiency, low-emissions technologies, ensuring that the existing fleet of coal-fired plants operate at the highest possible efficiency can lead to reduced CO2 emissions, lower fuel consumption, improved air quality and decreased water demand. This report examines the potential for improvement in the performance of existing coal-fired plants. Two operating units were selected to identify measures that would improve their net efficiency. Each unit was investigated to explore the means to improve the efficiencies of its boiler and its turbine as well as to reduce the auxiliary energy consumption of the unit as a whole. The results demonstrate the enormous potential to increase efficiency, with each percentage point increase capable of reducing CO2 emissions by many millions of tonnes over a unit’s operational lifetime.