This is a critical time for UK renewable energy and opportunity abounds as decarbonisation, decentralisation and digitalisation are driving significant change across the electricity network. The Committee on Climate Change envisages that the UK can decarbonise up to 95% of power generation through the continued rollout of low-carbon generation, using the policy instruments and principles set up under the UK’s Electricity Market Reform programme. However, a big open question as we progress towards net-zero, is how much energy storage will be required to ensure that we have a secure, stable, flexible and decarbonised energy sector?
The Net-Zero Report produced by the Committee on Climate Change suggests getting to over 80% wind and solar power is likely to require a ten-fold expansion, from 3GW of storage today to over 30GW in the coming decades. National Grid’s Future Energy Scenarios predicts the UK will install up to 13GW of new storage capacity over the next fifteen years, assuming a significant move towards more renewable energy.
To facilitate this, National Grid will have to achieve its stated ambition of transforming the operation of the UK’s electricity system by putting in place innovative systems, products and services to ensure that the network is ready to handle zero-carbon energy.
The role of storage
There are various ways to introduce the flexibility needed to integrate low carbon power sources – interconnectors to neighbouring countries, demand-side response and energy storage systems all play a part.
In order to balance the supply and demand of electricity in real time, National Grid has contracts in place with generators and large energy users to provide temporary extra power, or a reduction in demand. These reserve services are needed if a power station fails, for example, or if forecast demand differs from actual demand, and the requirement for storage.
The system frequency of 50Hz changes when there is a mismatch in the energy added to the system by generators and the energy taken off the system by demand consumers. This mismatch acts to either speed up or slow down the frequency of the grid, and frequency response is the balancing service used to counteract this change. It is a significant market; in fact, keeping the power system stable makes up a tenth of the total cost of generating electricity.
Decarbonisation has produced high levels of renewable generation which has different operating characteristics, plant dynamics, data quality, flexibility and inertia contribution to the electrical network. This has increased National Grid’s reserve and response requirements.
Numbers show that renewables supplied more electricity than fossil fuels in the third quarter of 2019 and this trend is increasing. Furthermore, the requirement for storage grows more quickly at higher levels of wind and solar penetration. It is an exciting shift, but the nature of intermittent renewable generation means that the requirements are more volatile and less predictable. System inertia will further decrease as we move towards our zero-carbon ambition.
Additionally, demand reduction, particularly at minimum demand times, when the proportion of renewables and nuclear generation is increasing, means there is little flexibility in output from the market position. In these scenarios National Grid is required to take action to meet its frequency control requirements, which means it needs more and more faster-acting frequency response services to support operational needs.
Frequency response and reserve are essential balancing services which National Grid procures from industry providers to support the secure operation of the national electricity transmission system. Frequency response services ensure that deviations in system frequency are mitigated within seconds, while reserve services provide additional sources of power over longer timescales, in the form of either increased generation or reduced demand.
As the drive for decarbonising the power sector continues, the UK could source 70-80% of its power from wind and solar power by 2050, so storage will be critical to balancing the peaks and troughs created by low carbon generation.
I’ve worked in the energy storage market for a number of years, and I am genuinely excited by the challenges and the opportunities for all stakeholders.
There are now various commercialised energy storage technologies, including pumped hydro storage, flywheel, compressed air and batteries. Part of the excitement around storage comes from the rapidly falling costs that many storage technologies are seeing, but it is battery energy storage which continues to be deployed at the fastest rate.
Lithium-ion battery packs now cost around 85% less than they did at the start of the decade. Crucially, they do not require any mechanical movement and allow extremely short control times and start times in the range of a few 10s of milliseconds at full load, which makes them the perfect match for the response and reserve services that discussed above.
With this in mind, I would suggest that the one thing that would help facilitate the continued rollout of energy storage most is the rapid progression of SNAPS.
National Grid’s System Needs and Product Strategy (SNAPS) was launched in 2017. It provides an overview of System Needs over the next five years and serves as consultation on Product Strategy in order to simplify and evolve balancing services and the products that we use to address these system needs. To its credit, the consultation achieved its purpose in understanding the views of the balancing services market, but there is still work to be done. In particular, if we are to effectively apply the tool of flexibility to meet the challenges of net zero.
Things are moving in the right direction as seen by the BEIS consultation on revamping energy storage planning rules – allowing energy storage projects larger than 50 MW to be assessed by the local planning authorities rather than via the national (NSIP) regime which is costly and lengthy. It is important that the Government and Ofgem work together to deliver the Smart Systems and Flexibility Plan which provides a route map for energy storage in the UK, and for new flexibility, markets to emerge from the distribution networks.
With all this happening, as a nation, we should be able to use energy storage to unlock the true potential of renewable energy offering decarbonised, flexible, stable and yet economical power supply to the end-users.
Vijay Shinde is Chief Technical Officer at Harmony Energy, currently chairs the REA’s UK Energy Storage and Large Scale Power & Markets groups and is a member of its Distributed Energy Resources Group. He is also a founder member of the Power Responsive Storage Working Group.
This article appeared in the February 2020 issue of Network magazine.