National Grid has warned operators of large gas and nuclear power stations that they may be instructed to curtail output this summer to accommodate rising amounts of wind and solar generation. The UK electricity system operator forecast that demand on the national transmission network would fall close to record lows in the coming months because of the growing supply of power from small solar and wind farms which bypass the grid. In its annual Summer Outlook for energy supply and demand published on Tuesday, National Grid said growth of “distributed” renewables was making for a more volatile electricity system. The forecast highlights the rapid transformation under way in the UK energy system, and others around the world, as the rise of renewable power and the shift to local “distributed” generation erodes revenues for traditional fossil fuel and nuclear power stations, as well as for system operators such as National Grid. Increased supply and demand variability caused by periods of low demand and high levels of renewable generation can create operability challenges. We may need to take more actions to curtail generation and instruct inflexible generators to reduce output to balance the system. Almost 13GW of solar generating capacity is connected directly to local distribution networks, equivalent to four times the expected output of Hinkley Point C. Electricity demand is also being reduced by energy efficiency measures which are being promoted in the UK and elsewhere to reduce consumer costs and help cut carbon emissions. Another changing feature of the energy system is the shift in minimum demand on the transmission system from night to daytime on some summer days because so much electricity comes from solar farms during daylight hours. This happened for the first time on two occasions in April 2017 and National Grid said it expected more such occurrences this summer. A new scheme known as “enhanced frequency response” will be used for the first time this summer under which batteries and other forms of energy storage will be paid for to help balance supply and demand. Solar power accounted for almost a quarter of total UK electricity generation on the sunniest days of 2017. But it makes a minimal contribution during the darker winter months, when the UK still relies heavily on gas, coal and nuclear power.
FT 10th April 2018 read more »
Reuters 10th April 2018 read more »