How the clock change impacts UK energy demand

The clocks are scheduled to go back one hour this Sunday 27th October. The change will cause an obvious shift in usage of the electricity system as evenings draw in earlier in the day.

It also accelerates the seasonal trend towards higher demand during the colder, darker winter months, placing increased pressure on power margins. This can lead to spikes in electricity prices, should supplies struggle to meet the higher demand.

 

Jump in demand decreases as overall downward trend continues

As forecasts currently stand, the average peak demand for the week following the clock change will be 4.4% higher than the week before. Consumption is expected to rise by almost 2GW as lighting usage increases during the traditionally higher post-work demand period.

 

Average Weekday Peak Demand Weekly average before Clock Change (GW) Weekly average after Clock Change (GW) Difference (GW) Increase (%)
October 2019 (Forecast) 38.9 40.6 1.7 4.4%
October 2018 40.0 43.6 3.6 9.0%
October 2017 40.7 43.7 3 7.4%
October 2016 42.2 44.8 2.6 6.2%
October 2015 43.9 45.2 1.3 3.0%
October 2014 43.0 44.0 1 2.3%

 

However, the forecasted rise in average peak demand in 2019 is lower than in recent years. Notably 2018 which saw the highest percentage change, as consumption rose by almost 4GW week-on-week.

Overall peak power demand has been dampened marginally this year, with consumption after the clock change peaking at 40.6GW on average, 3GW lower than last year. This reduction can be attributed partly to half-term school holidays, which fall on the week either side of the clock change depending on school catchments. Higher renewable levels have also contributed to reductions in demand.

The ongoing trend in reduced energy consumption year-on-year continues, meaning that demand is rising from a far lower base. Improvements in energy efficiency have been helping to reduce electricity use over the last ten years. A large part of the reduction in peak demand has been the use of new technology, resulting in smart and more efficient appliances, able to do more with less.

Expected demand before this month’s clock change is 5GW lower than the highest peak in 2015. Furthermore, the forecasted post-clock change peak is the lowest on record.

 

Graph displaying electricity demand during the clock change

The role of renewables

The increase in wind and solar capacity in recent years has contributed to the overall demand reductions. Higher volumes of on-site renewable capacity allow more generation to be provided off-grid as homes and businesses generate their own electricity supply during windy or sunny spells. This reduces demand on the national transmission system. The high levels of solar availability during the summer season were a particularly strong influence on demand levels this year as on-site solar panels increased embedded generation. This reduced demand requirements for the transmission network.

Wind power continues to deliver a growing percentage of the UK electricity mix. By the end of September 2019, the UK’s fleet consists of over 10,000 wind turbines with a total installed capacity of over 21.5GW. Overall wind generation in the UK has so far been 33% higher through 2019 than over the same time period last year.

 

Graph showing monthly wind generation

What happens when there’s no wind?

While high winds have the capability of cutting power demand, one of the biggest dangers to the National Grid electricity network is a high demand scenario, at a time when wind output is very low.

Lighting has a bigger impact on electricity demand than heating, as the majority of home heating is gas-fired. However, during severe cold snaps, electricity demand does spike as additional heating is needed to cope with the very low temperatures. This scenario occurred during the Beast from the East cold snap in February last year. However, robust winds provided high levels of low cost electricity to the grid.

A lack of wind would see supply margins placed under significantly more stress during a similar cold snap this winter. This would require additional supply being provided by gas and coal plant or imports to make up for the increased demand. Such a scenario is likely to require significant price rises in the Within-day and Day-ahead markets.

The National Grid’s Winter Outlook for 2019/20 expects that there will be a sufficient supply margin to accommodate a wide range of security of supply scenarios. However, the organisation’s statistical 1-in-20 peak demand forecast predicts a demand of 499mcm/d, greater than the highest recorded gas demand. This is an unlikely scenario, but demonstrates how a period of high demand and low renewable availability could coincide to increase short-term prices.

An end to the clock change?

There have been proposals dating back to 2015, from members of the European Parliament, to end summer time observance. In September 2018 the European Commission proposed an end to seasonal clock changes, asking that member countries decide by March 2019 which time they would observe year round. The proposal was approved in March 2019, by 23 votes to 11. However, the start date has been postponed until 2021 to allow a smooth transition.

The United Kingdom is due to leave the EU before the reform becomes effective, meaning that it would be left to the government to make their own decision on observing summer/winter time. If continued, Northern Ireland would have a one-hour time difference for half the year with either the Republic of Ireland or the rest of the UK. The House of Lords launched an inquiry in July 2019 to consider the implications of this, with a call for evidence ongoing.

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Britain running on sunshine as summer demand falls

The changes have come from an evolution in how energy is being used, and those who successfully manage these demand patterns, particularly if combined with Demand Side Response (DSR), could see significant cost savings.

Analysis from EIC has shown that maximum summer demand (seen between May and August) has fallen 17% in the last decade. From a peak of 44GW in 2012, maximum consumption for the current summer has fallen to just 35GW.

This near 10GW loss in demand is similar to the reduction seen during the winter. Furthermore, it’s not only peak consumption that’s been reduced but baseload generation. Minimum summer demand has fallen by 19% since 2009. How much of this is down to efficiency improvements or consumption moving behind the meter is unclear. However, the change does mean National Grid has nearly 10GW less electricity demand to manage on its transmission network.

 

maximum summer demand

 

The trend can be seen more clearly when broken down by month. Average peak demand during May 2012 was over 39GW. This year that figure was just 31.5GW, a reduction of over 7GW in only six years.

 

maximum demand per month

 

Improving energy efficiency

The cost of LED lighting halved between 2011 and 2013. During this time, consumers switching towards the more efficient bulbs helped facilitate a strong drop in demand. This could be helped further with news that the EU will ban the use of halogen lightbulbs from 1 September 2018.

Another major explanation for the demand drop, aside from efficiency improvements in appliances and lighting, is the significant growth in small-scale on-site solar capacity over the same period. Small-scale distribution connected solar has a capacity of under 4KW but the number of installations has grown from under 30,000 in 2010 to nearly 900,000 in 2018. An increase of almost 2,900%.

The total capacity of the small-scale solar now available is over 2.5GW, which is not far off the total capacity for the new Hinkley Point C nuclear power station.

As the use of small-scale solar (the type typically installed on housing or commercial property) has grown demand has fallen. More and more of within-day demand is being met by onsite generation. Consumers can take advantage of the bright and warm summer weather conditions to generate their own solar power, thus reducing the call for demand from the transmission network.

 

maximum demand vs solar

 

The solar impact

The introduction of high volumes of solar generation to the grid – total capacity across all PV sites is over 13GW – has also significantly altered the shape of demand. Consumption across a 24 hour period has flattened in recent years.

The traditional three demand peaks (morning, early afternoon, and evening) have shifted closer to the two peak morning and early evening winter pattern. The ability to generate high levels of embedded – behind the meter – generation during the day in the summer has flattened and at times inverted the typical middle peak. This has left the load shape peaking in early morning (as people wake up) and later in the evening, as people return home from work.

The absolute peak of the day has also shifted in time, moving from early afternoon to the typical early evening peak of 5-5:30pm, again similar to the winter season.

The below graph shows the change over time of the July load shape, which highlights both the reduction in demand and the change in shape, with consumption flattening during daylight hours as a result of behind the meter solar generation dampening network demand. With electricity costs – both wholesale and system – reflecting supply and demand, if consumption is being changed, then it also has an impact on these costs.

 

changing July load shape

 

Stay informed with EIC

Our in-house analysis highlights the impact of onsite generation on load patterns and the extent to which demand can be changed by taking action, and subsequently how behaviours can alter a business’ energy costs.

If you can shift demand away from historical high consumption periods, you can cut your energy costs and make significant savings. One such way to do this is by using smart building controls, such as our IoT-enabled Building Energy Management solution.

To find out more download our brochure, call 01527 511 757, or email info@eic.co.uk.