Schwungrad Energie Ltd
The Role of Dynamic Energy Storage in Facilitating Further Renewable Generation onto the Grid.
Ireland is an island with limited interconnection and we already have high levels of renewable generation so EirGrid is experiencing issues now which other Grids will only face in a few years’ time. Significant further renewable generation on the grid will be required so that Ireland can meet its renewable energy targets in 2020. There is a limit to the amount of non-synchronous intermittent generation which EirGrid can accept onto the grid at any one time while still maintaining grid stability.
Most people are aware that renewable generation is intermittent and/or unpredictable in its output. Energy storage over several hours can be used to mitigate this problem i.e. store the output of wind or solar PV at times when it is particularly windy or sunny and then feed it back into the grid at times of low wind or sun and/or times of high demand. However, there is another problem of grid stability of which most people are not aware.
Up till now, conventional plant with heavy generators and heavy steam turbines, which were synchronised to the grid, had sufficient momentum to stabilise the grid – to ride through the bumps. The more wind and PV running, the less heavy conventional plant there is to provide stability. One solution for EirGrid is to bring on more conventional plants and run them at minimum output just so that they are there to provide stability to the grid by being ready to inject power rapidly onto the grid if that is required e.g. if another large generator trips. However these additional generators running at minimum output just to stabilise the grid, displace renewable generation. Curtailment of wind is already an issue and will increase at a faster rate as more and more (non-synchronous) renewable generation is connected.
The solution is to have plant which can inject power rapidly onto the grid when required without having to continuously produce energy. Dynamic energy storage such as flywheels and batteries will do this, providing synthetic inertia and other system services to provide grid stability. The flywheels use energy from the grid to speed up and store this energy ready to inject it back to the grid if it is required. Similarly the batteries use energy from the grid to charge them and hold this charge ready for use when required.
The vision for the future is a very high percentage of renewable generation so there will be very little conventional heavy plant on the grid to provide stability. Hence there will be a need for investment in new dynamic storage plant to provide the stability. This has been recognised by CER which accepts that annual payments for system services can increase from the current €60m to, potentially, €235m by 2020. It has also suggested that connections for such plant be facilitated. A new market for system services is being driven by EirGrid through its DS3 (Delivering a Safe Secure System) program. It is proposed to have an auction in H1 2018 for long term contracts (up to 15 years) for new plant. If the required plant is to be built, it is important that these auctions go ahead in 2018 and that the contracts include long term price certainty. Without that, funding will be extremely difficult, the plants will not be built and the grid will not be able to accommodate the level of renewables required to meet Ireland’s renewable energy targets in 2020, 2030, 2050.