The evolution of a major power grid

Abstract

Seven years ago, the UK depended on coal-fired power to a large extent. Since then, the contribution of coal to the supply has been driven to a very low level. Some of the coal-fired stations have been converted to biomass, using imported wood pellets. Most have been replaced by combined-cycle gas turbine stations that are inherently more efficient and also, using natural gas as the fuel, less carbon intensive than coal. Nuclear makes a stable contribution, and hydropower and pumped storage make small contributions. Wind power has grown, and there were periods when it contributed over 8000MW to the grid - but also periods when it contributed less than 100MW. Latterly solar has entered the supply mix. These moves are tracked using the 5-minute data of Gridwatch, which also allows an assessment of the impact of non-dispatchable power on grid performance. Solar power appears to present particular challenges. The role of interconnections to Europe is also significant in the overall supply picture. These results are discussed in terms of plans to increase the nuclear contribution significantly in the near future, and the implications these findings might have for South Africa's desire to reduce its reliance on coal power for generation of electricity.