The ‘Mousetrap’: Challenges of the Fluctuating Demand on the Electricity Grid in the UK

Abstract

Currently, in the UK the power demand fluctuates throughout the day, especially during wintertime. The shape of the demand curve resembles the profile of a ‘mouse’. Around the tail area the energy consumption increases gradually, and that represents the demand during early morning hours which eventually flattens until the early evening. The head of the ‘mouse’ represents the early evening hours and the load on the grid peaks sharply. These sudden surges in power demand could potentially damage the grid leading to possible blackouts. In addition, this makes it difficult to depend on renewable energy such as wind turbines and solar panels without the use of energy storage. To examine the link between people’s behaviour and the grid, Covid-19 lockdown patterns were explored as it was a time of change in behaviour. Even during COVID-19 restrictions, which had an impact on people’s lives, the shape of the power demand curve did not significantly change; it followed the same shape of a ‘mouse’ compared to pre and post Covid periods, but during the pandemic the energy demand levels were slightly lower. The results suggests that in order to improve the stability of the demand, and hence remove this ‘mousetrap’, alternatives such as using renewable energy combined with electric and thermal energy storage systems can be integrated into the grid, which eventually can lead to flatten the demand curve.

14.1 Introduction

It is important for power stations to maintain capacity security, so the provided electricity is sufficient to satisfy the demand. In addition, a balance between the supply and the demand of electrical energy must be in place, as it affects the frequency of the grid. According to the GB Security and Supply Standard, the frequency fluctuations must be limited to ± 0.2 Hz for normal power station operation [1]. In wintertime, the load pattern of the grid fluctuates as seen in Fig. 14.1.

Fig. 14.1

Hourly power demand in the UK in wintertime which resembles a mouse profile (based on data from [2])

Figure 14.1 show cases the hourly power demand in the UK in cold seasons. The shape of the curve resembles a mouse. In particular, the back torso and the ears areas show when peaks on the grid appear. At around 5 a.m. the power demand gradually reaches approximately 42 GW over a period of 4 h. It remains relatively flat until around 4 p.m. where the load on the grid increases sharply by roughly 3 GW. With the demand curve’s shape of a mouse, it would be challenging to use more renewable energy and provide stable electrical energy.

Currently, the UK is on the path to reduce fossil fuels from the energy generation mix. It is expected the country to reach net zero carbon emissions by 2050 [3]. Some of the strategies the government is planning to adopt in order to become carbon neutral is to increase the capacity of wind and solar sources of electricity, electrify the transportation by banning fossil fuel vehicles by 2050, and decrease dependence on fossil fuels for the heating sector by implementing heat pumps as part of the Heat and Building Strategy for meeting the net-zero 2050 targets [3]. In addition, lockdown restrictions led to 13% drop in carbon emissions in 2020 compared to 2019 [4]. On top of that the electricity price has increased sharply, approximately 43% as of 2022 compared to 2020 [5].

Figure 14.2 presents the current electricity generation mix in the UK. From the graph it is evident that the majority of the current electricity is generated by gas at around 47% [2]. The capacity of wind and solar have increased slightly in 2021 compared to 2020 [6]. Although, the wind and solar capacities have increased, the environmental conditions are still not favourable for these sources to provide and maintain steady electricity throughout the day [2]. This suggests that UK still have to rely on fossil fuels to provide electricity during peak hours or when wind and solar are not enough and therefore contribute to more carbon emissions [2].

Fig. 14.2

UK electricity generation mix 2022 (based on data from [2])

The Covid-19 pandemic is considered as one of the most impactful global health emergencies in the century. It has not only affected the health of people, but also indirectly through lockdowns the economy of almost every country around the world as well as the energy demand and consumption.

With the confinement measures many people throughout the world were forced to work from home, which is expected to have some effect on the electricity consumption. For most countries the start of lockdown measures were implemented between February and March 2020. After that each country individually assessed the right time to open the businesses and the borders depending on the infection rates [7]. For Germany and most of the US, there was a considerable reduction in electricity demand [7]. In addition, Poland is a country that similar to the UK implemented more than one lockdown for 2020 [8]. Research investigating the impact on the energy demand in Poland due to Covid-19 concluded that the restrictions caused a drop of approximately 23% in energy consumption during the first lockdown in March–May period 2020 and around 11% during the second lockdown in October–November period of the same year [8]. A similar situation can be noticed in Turkey (Türkiye) where the first incident of Covid-19 was detected in March 2020 and restrictions followed soon after [9]. In April and May of the same year, the electricity production dropped by around 15% and 16.5% respectively compared to the same months in 2019 [9]. According to the same research, the electricity consumption of the industry and residential sectors increased slightly in 2020 compared to 2019, but there was a considerable reduction for the business sector in 2020, suggesting that the businesses have great influence on the energy consumption in Turkey [9].

In the UK the first lockdown measures were introduced on 26th March 2020. During this time people were advised to stay at home and work from home [10]. In June of the same year the restrictions were slowly removed until 5th November 2020, when a second lockdown came into force, which continued until 2nd December [10]. Particularly, in the UK the only increase that was noticed during 2020 was of gas consumption as the majority of people were forced to work from home [11]. Industry and business buildings tend to be more energy efficient when it comes to heating [11]. Overall, it was estimated that there was a drop in electricity consumption in the commercial and industrial sectors between March and June of 2020, which resulted in a significant reduction of carbon emissions. However, households with houses that were not properly insulated were affected by increased energy bills during the winter lockdown period [11].

14.2 Methodology

As shown in Fig. 14.1, the electricity demand in the UK resembles a mouse profile. What is the cause in the change in demand? To address this, the authors have investigated the grid patterns in the UK in winter before and during Covid-19 pandemic lockdown. Firstly, a graph using data from Gridwatch [2] has been developed to showcase the daily demand in wintertime along with each source of electricity in the UK. The reason for that was to see how the demand fluctuates throughout the day and when load peaks occur. After that we compared the annual electricity consumption in the UK from 2012 to 2021. This allowed us to monitor whether the overall consumption is increasing or decreasing. The Covid-19 restrictions took place in 2020 and 2021 in the UK. In particular, the strictest and longest measures happened between March 2020 and June 2020, as well as November 2020. That is why we looked into the daily electrical energy consumption on a November weekday and on a weekend for 2019, 2020, and 2021 as the ambient temperatures can drop as low as 1 °C during that month as shown in Fig. 14.3 [12]. This analysis allowed to determine not only how lockdown measures affected the energy consumption, but also if the demand curve followed the same fluctuations curve as pre and post pandemic period.

Fig. 14.3

Ambient temperature in Nottingham, UK in November 2020 (based on data from [12])

14.3 Results

Figure 14.4a and b represent the daily power demand in winter and the annual electricity consumption in the UK respectively.

Fig. 14.4

The daily power demand in the UK (a) and annual electricity consumption in the UK (b) (based on data from [2])

From Fig. 14.4a it is evident that the majority of the demand is satisfied by gas. There are very sharp peaks on the grid at around 5 a.m. and again at 4 p.m. From Fig. 14.4b, it can be noticed that in 2020 the annual consumption was lower than the rest of the years. In 2020 there were 2 lockdowns that took place, one in spring and one in winter [10].

Figures 14.5a and b represent the hourly demand on weekdays and on weekends respectively in November. November was chosen specifically as the 2nd lockdown in the UK took place for the whole duration of that month in 2020. In both figures, the power demand followed a similar pattern, in the shape of a ‘mouse’. The main noticeable change is during the weekdays in 2020, the increased demand in the morning starts at around 7 a.m., and the evening one at around 5 p.m., compared to approximately 4 a.m. and 4 p.m. for 2018, 2019, and 2021. One of the reasons for the shift of the demand peaks is the daily habits and activities of people across the UK. Many were forced to work from home due to the Covid-19 restrictions [10]. In regard to Fig. 14.5b, there is no considerable change in the demand pattern during the weekends for all the analysed years.

Fig. 14.5

Hourly demand comparison on a weekday (a) and hourly demand comparison on a weekend (b)

Figures 14.6a and b present the shape of the power demand curves compared to previous years and with 2020 lockdown period. The shape of the 2020 curve resembles a mouse following the same trend as previous years. This shows that Covid-19 affected only the amount of consumed electricity, but it did not impact the shape of the demand curve.

Fig. 14.6

The shape of the hourly weekday demand (a) and the shape of the hourly weekend demand comparison (b)

14.4 Discussion and Conclusion

This paper has focused on the electricity consumption in the UK, and the electricity consumption patterns. It seems we are in the UK ‘trapped’ in user patterns by the ‘mouse’ shape, even during Covid-19 pandemic lockdown. This paper has considered the winter season before and after lockdown. We have examined in more details the month of November because the ambient temperature can drop below 2 °C and it was during the second lockdown in the UK. This suggests that households would use more heating, thus increasing the energy demand during that month. Whereas during the first lockdown between March and June, the weather is warmer. In our hourly demand comparison for the weekdays and weekends in November we analysed the data between 2018 and 2021. However, the pandemic did not affect the fluctuating power demand, as show in Fig. 14.6a and b as it followed similar trend as previous years. This current shape of a mouse creates a challenge ‘a trap’ in promoting more stable electricity. Especially when the UK electrifies the transport and heating sectors via electric vehicles and heat pumps. The strain on the grid could be severe if the same power demand is followed. For that reason, more battery storage systems combined with solar panels or wind turbines should be implemented along with thermal storage to reduce the peak load on the national grid and flatten the curve. More analysis will be performed in the future to analysis the reasons for such patterns and how to avoid them.