National Grid: depressed demand in summer due to Covid-19 a ‘challenge’ to system stability

Low electricity demand in the summer could present a challenge to managing the electricity system, system operator NGESO said in its weekly Covid-19 briefing.

The balance of supply and demand in the summer has been a growing problem over recent years, as demand is much lower and may be served by onsite capacity such as rooftop PV, while generation from solar PV and other ‘must run’ renewables has increased.

It means that ‘dispatchable’ plant that would otherwise be asked to flex up and down to help manage inertia, voltage, etc, are not in use. The problem is made more acute because voltage has to be managed locally, so NGESO needs access to a variety of plant across the country.

That issue is likely to be exacerbated if Cover-19 measures continue to reduce electricity demand.

As far back as 2017 National Grid predicted that it would have, at times during the summer, 3-5GW of excess ‘inflexible’ demand on the system.It responded by offering contracts for a product that had already been in use the previous summer, known as ‘Demand Turn-Up’, in which certain customers were paid to use more power. That has been replaced by so-called ‘foot room’ reserve. 

The system operator pointed out that it had already experienced periods of operation with demand as low as 17GW (compared to 30-40GW in the winter). But if it has to respond to low demand by paying renewables to shed their load and allow more expensive – but flexible – generation to start up, it will raise customer costs.

NGESO asked generating companies to provide information if they thought their plant could offer services to help provide footroom or other services it requires, as well as passing on up to date information about outages.

It also asked supply companies to provide information about their customer demand predictions, split by customer type, so it could benchmark and refine its models.


Further reading

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National Grid prepares to manage 3-5GW of excess inflexible power in the summer of 2017

Flexitricity to provide ‘Demand turn-up’ to National Grid