ABSTRACT
Electricity generation using coal started towards the end of the 19th century. The earliest power stations had an efficiency of around 1%, and needed 12.3 kg of coal for the generation of 1 kWh. This amounted to 37 kg CO2 emissions per kWh. With research and development and increasing experience, these low efficiency levels improved rapidly. In addition, technical advancements with coal processing and combustion technology which enabled a steady increase in the steam parameters ‘pressure’ and ‘temperature’, resulted in a further rise in efficiency. By 1910, efficiency had increased to 5%, reaching 20% by 1920. In the 1950s, power plants achieved 30% efficiency, but the average efficiency of all operating power plants was still a modest 17%. In the next stage, the use of cooling towers for the removal of heat that could not be converted to electricity became a necessity, in addition to the removal of pollutants, SOx and NOx, from exhaust gases; this resulted in a reduction of efficiency because these technologies consume energy. However, continuous development resulted, around the mid 1980s, in an average efficiency of 38% for all power plants, and best values of 43%. In the second half of the 1990s, a Danish power plant set a world record at 47%. Today, the average efficiency of coal-fired power plants in the world is around 33% on LHV basis.
