In May this year the Irish grid dropped below normal operating range (49.9Hz- 50.1Hz) for about 14 minutes. According to our data, it was the longest under-frequency event seen in years. Statkraft’s Kilathmoy and Kelwin-2 battery storage projects immediately stepped up to support the electricity grid, with data showing they provided an initial response to the event in just 180 milliseconds.
Most of the time batteries such as these sit in standby watching the frequency. But, as soon as it sees the frequency drop below the trigger level, it responds automatically. In the blink of an eye, it injects active power to support the grid and stabilise the system. Over the full period of the under-frequency event, the batteries did just what they were designed to do from the initial drop below the 49.8Hz trigger, to the eventual recovery above that level about 12 minutes later.
Solar and wind power plants provide clean renewable energy, but the electricity grid has historically relied on fossil fuel generators to provide stability in the grid. As renewables grow, displacing fossil fuels, we need to find new ways of providing the stability the grid requires. As this under-frequency event shows, battery storage facilities can provide a vital support to the Irish grid and help us to facilitate more and more renewable energy on the system.
Keeping the power grid stable has become more challenging as we get more and more of our energy from wind and solar power. The major challenge is to ensure we maintain a stable frequency and voltage on the grid.
Here in Ireland, we are not using all of the renewable energy that we are producing. The system operators rely on running gas or coal power plants not for energy purposes, but to provide support services to the grid and in doing so they shut down wind power plants that could have supplied electricity, in order to make room for these fossil fuel plants. We aim to increase the share of renewable electricity from the current 40% to 70% by 2030. If we are to achieve that goal, we must support and progress stability solutions for the grid that do not emit CO2.
Battery technology is a very efficient method of delivering zero-carbon frequency support services such as this. In an emergency, batteries can both absorb and deliver power to the grid in milliseconds. However, batteries are not yet deployed to store large amounts of energy in the Irish market. The battery projects deployed in the Irish market to date have reserves for half an hour of operation, but in the future batteries will deliver longer-duration storage, which will be crucial to enabling our 2030 targets
There are a number of challenges we face when it comes to grid services, not least the increasing demand on the electricity grid system, but the potential is there to transform our grid system. Battery projects like Kelwin-2 and Kilathmoy will provide reliable, ultra-fast active power reserves to stabilise the grid when needed. That is why they are a key part of the puzzle in allowing high levels of renewable energy to operate on our electricity grid as we drive towards a 70% renewable electricity target for 2030.