A sunny outlook for 2018 summer generation?

In its Summer Outlook Report 2018 the National Grid is predicting peak transmission system demand of around 33.7GW, with a weather corrected minimum of 17GW between 1st June and 31st August this year. Daytime demand is predicted to be 20.1GW, with all these figures slightly lower than 2017.

The System Operator expects generators and interconnector imports to be able to comfortably satisfy demand, however, it also notes that managing input from renewable sources may create challenges for balancing the system with ‘traditionally’ generated power.

The forecast highlights a downward trend in summer system demand over the past four years – the 2015 minimum was 18.4GW – with the report also noting that historical lowest demand usually occurred overnight.  However, with renewable generation now playing a significant role, demand low points may now occur during the day – a phenomenon first experienced in April last year.

Given that National Grid may require “inflexible generators to reduce their output in order to balance the system” as a result of renewable energy input, there is a greater-than-ever need to be able to accurately predict daily output from renewable generators. 

The report provides some insight into National Grid’s efforts to forecast more accurately, citing its project with Network Innovation Allowance (NIA) partner, Sheffield Solar, which has developed a system to provide near-real time estimates of solar power outturn across the UK’s 327 Grid Supply Points. Further work with the Met Office is also allowing significant improvements in forecasting for solar generation.

Even with low demand periods in the summer being used as maintenance time for power stations – particularly coal-fired – the Report predicts a comfortable cushion between peak demand (33.7GW) and minimum available generation (42.1GW).

The Report also covers Europe and the Interconnected market, with National Grid concluding that positive price spreads during summer 2018 will work in the GB market’s favour, with exports to Ireland, France and the Netherlands in particular.

One consequence of the downward trend in demand is the potential for high voltage occurrences, something that requires management by National Grid – known as System Operator Actions.  The report highlights three key actions:

  1. Longer advance contracts with generators
  2. Within-day trading actions
  3. Bid Offer Acceptances in the Balancing Mechanism

The Report states that National Grid is expecting to increase the number of actions in future.