Reducing fuel use also diminishes all the environmental impacts associated with the extraction, processing and transport of that fuel, eg less noise, less traffic and less ash for disposal after combustion. There may, however, be a trade-off at times between emission control and efficiency. For example, the installation of low NO x burners at power stations may result in lower fuel combustion efficiency and increase fuel use by around one percent. On the other hand, some methods of improving efficiency, such as higher oxygen intake, can potentially increase NO x emissions and such upgrades have to be evaluated very carefully to determine the overall cost and environmental benefits. Future Developments Research and development is steadily improving the thermal efficiency of existing plant, through reductions in energy use by both major and ancillary components.
Thermal efficiency is also a prime consideration in the development of new generation systems.
New coal combustion techniques, such as gasification and fluidised beds are being developed, including the utilisation of combined cycles. The laws of thermodynamics set a limit on the maximum efficiency with which useful energv can be extracted from any given energy conversion system. Other physical constraints prevent the achievement of the maximum thermodynamic efficiency, but the electricity industry is gradually reducing the gap between this limit and the actual efficiency achieved in its generating plant. The recent introduction of gas and steam combined cycles in CCGTs has brought significant improvements in the efficiency of UK electricity generation by fossil-fired plant. Efficiency in electricity generation is an important aspect of both the commercial and environmental performance of the industry.