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In order to manage the UK’s electricity system to the highest standards possible, the National Grid publishes the expected demands of the system ahead of the summer and winter periods. As the energy network in the UK is currently at the start of an energy transition1, this year’s summer outlook is particularly interesting and Powerstar has summarised it below, including notable elements such as:

  • The key characteristics of the summer period
  • How the energy transition has magnified the trends of the summer period
  • Over-generation and energy storage


The key characteristics of the summer period

As the UK climate warms up, and the nation receives more hours of daylight throughout the summer, there is lower demand for electricity and higher variability of the day-to-day demand due to the fluctuations in weather2.

These characteristics are exemplified by the expected demands on the system for the summer period of 2018. The peak transmission system demand is anticipated to be 33.7GW between the high summer months of June-August with the minimum transmission system demand expected to be 17GW, both of which are lower than the 2017 weather corrected outturn.


How the energy transition has magnified the trends of the summer period

These traditional characteristics of the summer period are becoming magnified as the energy transition gathers pace due to the amount of distributed energy on the network. Distributed energy is defined as generation that is connected to the local distribution network, rather than the transmission network, therefore is not directly visible to the National Grid and reduces demand on the transmission system. One key area in which the use of renewable energy, perhaps the most common form of distributed energy, has transformed the system is that the traditional summer minimum demand occurred at night but can now occur during the day. This is due to the increased amount of energy generated by solar in the summer that can be utilised to meet a large portion of electricity demand throughout the country, leading to less reliance and therefore strain on the National Grid as it does not need to match the demand with supply.

This is a trend that is likely to increase as the amount of renewable energy grows further and the decarbonisation effort, outlined in the Clean Growth Strategy, progresses further. As the Government has plans to make the UK a worldwide leader in clean growth, the energy needs of the nation are set to be met by cleaner sources of energy which will further reduce the strain on the grid and flatten out historic fluctuations.

When this is combined with decentralisation connected microgrids can use energy from local generation and storage independently of the grid. It is clear this has led to a decline in reliance and demand required from the National Grid. Further efforts towards decentralisation would benefit the National Grid as it would lessen the strain and therefore serve to make it a much more reliable system which would also improve the UK’s security of supply, giving it a better chance of becoming the international leader for clean growth than if it continued with an antiquated, centralised system in which it is possible to place too much strain on a small number of power plants.


Over-generation and storage

Despite the positive outcomes that can be seen as a result of the increased uptake of renewables, there is an underlying issue that needs to be addressed, the possibility of over-generation and wasted energy. Ensuring renewable energy does not go to waste

In the summer outlook the National Grid acknowledged that action may need to be taken this summer to curtail generation and possibly instruct inflexible generators to reduce their output in order to balance the system.

As a result of this, there is likely to be wasted energy in the UK this summer which is something that energy storage technologies can solve. Energy storage solutions, such as the market leading Powerstar VIRTUE, can harness energy from renewables by storing excess energy which can then be timeshifted for use at a later date when the amount of renewable generation is not as high which has multiple benefits.

The first of these benefits is that the energy is not wasted and therefore the need for curtailment is lessened as any excess generation is simply stored for later use. Secondly, this would again lead to the UK becoming cleaner as the energy used at a later date, perhaps when little other renewable generation is available, would still be classed as renewable energy and would therefore increase the renewable share of the energy mix, additionally the more effective utilisation of renewable energy would reduce the requirement of backup generation such as peaking plants and diesel generators which would positively impact on the environment. Lastly, there is a significant cost saving that can be achieved from this, with figures showing that as much as 55% of electricity costs come from non-commodity charges3, the ability to use previously stored energy to reduce the peak tariffs that are charged for distribution could potentially be a significant saving to a company.

This year’s summer outlook from the National Grid is certainly a positive one which highlights the positive impact that the energy transition is already having as it takes strain away from the grid due to the increased share of renewables in the energy mix. However, the outlook shows that as the energy transition continues to gather pace, new problems such as renewable over-generation and volatility will emerge and energy storage is set to play a key role as the reliance on renewables, which by their nature are variable, increases.

The adoption of the decentralised energy network which utilises energy storage, distributed generation, energy efficiency, and demand response is likely to deliver a greener but also a more secure and reliable network. This is because the energy storage and demand response elements of decentralisation will work in tandem to smooth the imbalance of demand that could be caused by renewable volatility and is currently caused by the inefficiencies of a centralised model.


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