Summertime, and the living is easy as the old song goes. And you might be forgiven for thinking that was the case for those managing the UK’s electricity and gas system. But as Roisin Quinn, Head of Energy Strategy and Policy at National Grid explains, you’d be some way off the mark.
The challenges posed by tightening electricity margins and potential threats to gas supplies over the winter are probably the aspects of National Grid’s work which generate the most column inches.
So you might be forgiven for thinking that the summer is a quiet time for those of us at the company who operate the electricity and gas transmission systems.
The nature of the challenge
The summer time, however, can be just as challenging – it’s just the nature of the challenge that changes.
Our electricity control room expects to see the summer minimum demand level continue to fall. This is the moment during the year at which demand for electricity is at its absolute lowest. This year we expect a minimum demand of 18.6GW between 5am and 6am on a Sunday in late July. To put this into context, winter peak demand in 2014-15 was almost three times that level.
Demand is low at this time of the year because of the warmer and brighter weather, the number of people taking holidays and away from factories and offices – and also because we could have large amounts of wind and solar power available.
The unique conditions of summer minimum demand can mean our engineers have to take actions to ensure voltage on the network doesn’t exceed acceptable levels.
A major television event might mean we have to prepare for any surge that occurs when viewers take a break from their screens to make a cup of tea or switch on lights in other rooms around the house.
Although we don’t have a World Cup or a Royal Wedding this summer, another Andy Murray final at Wimbledon or a big soap storyline might mean we’re put on standby to dispatch power to meet any pick-up in demand.
We also may need to manage wind generation in Scotland when wind speeds are high and overall system demand is low. This is sometimes done through ‘constraint payments’, where generators are paid to come off the grid for a short period of time – the most cost-effective approach while we work to strengthen the network.
On the gas system, we can be pretty confident there will be plenty of available supply during the summer. Supplies of LNG (liquefied natural gas) to Europe are expected to be more plentiful this summer than in previous years. The restart of nuclear reactors in Japan is an important factor, as it’s likely to mean Japan has a reduced need for imported LNG.
Maintenance in the North Sea can mean it’s far more difficult to predict whether the gas that comes in will come from interconnectors, LNG or storage. Over a typical summer day, LNG could make up anywhere between 5% and 50% of gas on the system. This makes it more challenging to know where the gas will enter the UK system and to make sure the system is ready in advance.
Injections and withdrawals
The fact that, during the summer, mid-range storage sites see injections and withdrawals also increases unpredictability when it comes to operating the gas system during the summer.
Ultimately, summer is a time when our electricity and gas control rooms still have to make sure forecasting and planning is spot on. That’s why each year we work with industry to pull together an outlook reports for summer. There’s also one for winter.
There is a huge amount of useful information for the energy industry in our full Summer Outlook document. It’s a really good read, so if you’re interested in learning more about energy, I’d encourage you to take a look.