Thousands of households across Britain were ready as dusk fell on Monday evening: washing machines turned off, electric cars unplugged and, crucially, cups of tea delayed.
This thrift was not an effort to save money in the midst of an energy crisis – for the first time, families were being paid to use less electricity to help operators manage tight supplies.
National Grid decided to enlist households’ help on Sunday as the prospect of still, cold weather – dreadful for wind turbines – loomed on Monday evening.
It will need to do so again on Tuesday, with households due to be paid to avoid normal electricity usage between 4.30pm and 6pm.
These efforts mark the first real-world deployment of National Grid’s new “demand flexibility service”.
Under the scheme, households who voluntarily sign up are paid to shift their electricity usage outside of peak times when requested. Efforts to manage demand are intended to help cut the risk of blackouts.
“Stay warm, safe and comfortable during your Saving Session,” Octopus Energy, one of the UK’s largest suppliers, told its customers ahead of last night’s national turn down.
“Don't turn anything essential off. It can be good fun to light a few candles but don't feel you have to sit in total darkness to save.”
The “demand flexibility service” was introduced last year amid concern about power supplies this winter as Russia’s war on Ukraine caused turmoil in gas markets. Outages on France’s nuclear fleet, which typically exports power to Britain at times of heightened demand, increased pressure on Britain’s power system further still.
The first deployment of this response by the Grid outside of testing comes during a particularly vicious cold snap, which is forecast to lead to a spike in demand for electricity.
Yet while the scheme has been brought in at a time of emergency, demand flexibility services are set to endure.
Regulators and operators want consumers to become much more flexible about when they use electricity, as part of the shift to “net zero” carbon emissions. Ditching fossil fuels will mean supply of electricity becomes more intermittent, just as demand leaps.
“It’s something we strongly believe in,” Craig Dyke, head of national control at the National Grid’s electricity system operator, told BBC Radio 4’s Today programme of the “demand flexibility service”.
“It provides that additional flexibility not just for the system, but for all consumers themselves.”
Keeping the lights on is a tricky business – electricity supply and demand needs to be constantly balanced. Electrons cannot easily be stored at scale under current technology, meaning electricity must be generated when it is needed.
Historically, this has been relatively easy to manage – large coal and gas-fired-power plants that dominated the system can be relatively easily ramped up or down, depending on demand. Simply shovel more coal, or fire more gas.
Wind turbines and solar panels are far more capricious – output depends on the weather and the time of day. Turbines are no use if the wind is not blowing and, in fact, are currently switched off if the wind is blowing too hard. Solar panels are impotent at night.
Filling gaps in electricity supply during times of low wind currently means firing up coal, diesel or gas – a solution that officials see as unsustainable given the emissions.
At the same time, demand for electricity is only set to leap in the coming years as heat pumps, electric cars, and electric arc furnaces become the norm.
With supply less able to adapt to demand, it will fall to demand to be flexible. The Grid is laying the groundwork for electricity usage across the country to become variable according to fluctuating levels of supply throughout the day.
This will mean households being encouraged to, for example, run the washing machine or charge the car overnight, or install batteries to store power during windy periods.
The idea of using cheaper energy, typically overnight, is not new – the Economy 7 tariff has existed for decades. However, the Grid’s new ambitions are on a different scale and for different reasons.
Industry and regulators have been laying the groundwork for this sort of system for years. Smart metres, being rolled out across Britain, will enable households to buy electricity at lower prices when demand is low.
Ofgem chief executive Jonathan Brearley acknowledged this shift in a speech on Monday setting out his vision for the industry.
“Retailers will need to play a more fundamental role in decarbonisation and in the energy transition,” he said. “They will be on the front line of persuading customers to install the equipment needed to vary our energy usage where possible to match with times when demand is low and/or supply is high.”
Backers have been encouraged by the numbers who have signed up to the new “demand flexibility service”: more than one million so far. The money they made on Monday and Tuesday may well encourage others to follow.
Those in favour of the shift argue it will help consumers save money both on their electricity bills and on the overall costs of the system, as less generation and cables will need to be built. The Government has estimated greater flexibility could cut costs by £30bn-£70bn between 2020 and 2050.
However, the huge shift inevitably raises questions over fairness, viability, and availability of resources.
Tom Luff, senior advisor, policy and regulation, Energy Systems Catapult, says that people who cannot be flexible in their electricity usage must be protected.
“There's a huge opportunity for energy companies to think about how we allow people that really need to make those savings, the poorest in society, to be able to make the most of the flexibility.”
It is hoped consumers will be able to take a hands-off approach, using apps to programme appliances to charge or run when electricity is cheap and abundant, depending on the users’ needs.
“A change in price can get people to make a small change in behaviour which will benefit them as well as the system,” says Greg Jackson, chief executive of Octopus Energy.
“It’s much better to let people know that if they use it now it’s going to be cheaper, or you will be paid, and then let people make the decision.”
He adds: “There isn’t an infinite amount of anything. All resources are priced according to availability. It's far better that we make the most of what we've got.”