Iqony large battery systems for greater supply security
In the wake of the energy transition, the share of renewable energies in the German electricity mix continues to rise – by 2030, 80 percent of gross electricity consumption in Germany is to be covered by renewable energy sources. This is encouraging, but it also leads to ever greater fluctuations in the electricity grid.
These fluctuations must be balanced out at short notice. Iqony broke new ground early on: by the beginning of 2017, we had invested around £85 million in six large battery systems – without making use of subsidies. In order to achieve a certain distribution across the grid, the large-scale battery systems were installed at several STEAG locations in Germany: Herne and Duisburg-Walsum in North Rhine-Westphalia, and Bexbach, Völklingen-Fenne and Weiher in Saarland. Find out here what these systems can do and why they will become increasingly important for security of supply in the future.
How fluctuations in the power grid arise
Fluctuations in the electricity grid occur when the total amount of electricity fed into the grid deviates from the total amount of electricity currently being consumed.
These fluctuations are increasing due to the growing share of renewable energies in the German electricity mix, as the production of solar and wind energy is uneven and cannot be predicted with any degree of accuracy. Sun and wind do not adhere to forecasts. Unexpectedly high or low consumption, errors in daily demand forecasts or power plant failures also lead to fluctuations in the electricity grid. Suddenly, there is more or less electricity in the grid than is needed, and the frequency deviates from the target value of 50 hertz.
Why these fluctuations must be compensated immediately
If the fluctuation in the power grid is ten millihertz or more, it must be compensated immediately so that the grid remains stable – "grid regulation" is the technical term for this.
An unstable grid could lead to malfunctions in electrical systems – for example, in industrial machinery or technical equipment in the power grid. This could ultimately result in a dreaded blackout, i.e. a total failure of the power grid.
To do this, they use what is known as control energy, which is advertised weekly and provided by suppliers accordingly. If the grid is undersupplied, the grid frequency falls below 50 hertz and energy must be fed into the grid (positive control power); if the grid is oversupplied, the grid frequency rises above 50 hertz and energy must be taken out of the grid (negative control power). A distinction is made between primary and secondary control power and minute reserve. Primary control power must be provided within 30 seconds, secondary control power within 5 minutes, and minute reserve within 15 minutes to the extent required.
Iqony will be breaking new ground in the future with regard to the provision of primary control power, which is put out to tender six times a day by transmission system operators.
With the German government's decision to phase out fossil fuel energy production, other technologies must take over the system tasks. For the first time, we have used large-scale battery systems for this purpose, and they are proving their worth day after day with a high degree of reliability. Within seconds, they compensate for frequency fluctuations in the power grid – by feeding energy into the grid when the frequency is too low or storing energy when the frequency is too high. The systems meet all currently applicable criteria for battery storage performance in primary control and beyond, as they have a minimum output of 15 minutes. This means they offer greater security than is currently required by the TSOs.
In developing the large-scale battery systems, we were able to draw on experience gained with the LESSY battery system as part of a research and development project in collaboration with Evonik and other partners. With the LESSY system installed at the Völklingen-Fenne power plant, we were one of the first providers to use a large battery (1 MW capacity) for primary control from February 2014 to the end of February 2016.
Backbone of grid balancing
Why primary control power must be available for 30 minutes
It must be available for at least 30 minutes so that the power grid can be supported and returned to safe and stable operation even in the event of major disruptions with prolonged fluctuations. Simulations by Iqony based on examples of major disruptions that have actually occurred, such as the faulty shutdown of two high-voltage lines during the disembarkation of a cruise ship on the Ems in 2006, have confirmed this.
We are familiar with this from portable electrical devices: when a lot of energy is required, several batteries are needed.
Our large battery systems work in a very similar way: basically, they are huge, rechargeable lithium-ion batteries that are connected to each other via a control centre. They are ideally suited for operation at medium charge levels, which is required for the provision of primary control power. Each large battery system consists of ten containers with a total output of 15 MW – none of the systems installed in Germany at the end of 2016 could match this output. By early 2017, we will have built a total of six systems with a capacity of more than 120 MWh – more than all other systems using the same technology combined. In 2023, battery storage will account for 630 MW of pre-qualified capacity, of which 90 MW will be attributable to Iqony alone. With this storage capacity, it would theoretically be possible to supply 300,000 households for one hour.
German-French-South Korean co-production
How our large battery systems are manufactured
The containers housing the technical equipment are built and preconfigured by industrial systems specialist Nidec in France, while the battery cells and modules are manufactured by LG in Ochang, South Korea. A special manufacturing process ensures that the JH3 lithium-ion battery cells take up little space and are extremely safe and stable.
A certain number of battery cells are assembled into a module. Each module has a protective circuit and a management system that monitors the status of the batteries. The battery modules are then transported by ship and lorry to the individual locations – strict attention must be paid to maintaining certain temperatures so that they are not damaged. On site, 17 battery modules are assembled in racks, which are installed in the containers and connected.
The environmental benefits of our large-scale battery systems
Until now, primary control power has mainly been provided by conventional power stations.
These power stations ramp up or ramp down electricity production depending on whether energy needs to be fed into or withdrawn from the grid. To do this, however, they must generate a certain minimum load at all times during the entire tender period of one week – and to do so, they burn coal, oil or gas. This is not necessary with our large batteries. In addition to providing the necessary storage capacity for integrating renewable energies, we are thus making a valuable contribution to climate and resource protection.
Why large battery systems will become increasingly important in the future
When conventional power stations are gradually taken off the grid in the near future, it is likely that the balancing of the grids will have to be carried out with virtually no conventional generation plants for an increasing number of hours each year.
By then at the latest, large batteries will be a very efficient and cost-effective alternative to today's conventional power plants for primary control power and security of supply, and in our view they will be indispensable.
In the context of the energy transition, large batteries will be able to take on even more tasks in the future, such as securing the power supply in decentralised grids, which are becoming increasingly important. Here, too, large batteries can compensate for fluctuations caused by fluctuating feed-in and consumption. This makes decentralised grids less dependent on the supra-regional high-voltage grid, reducing the need to expand this grid.
With the commissioning of the six large battery systems, Iqony took a big step towards the energy future as a pioneer.
In 2020, we broke new ground again and were the first to relocate a large battery system from Lünen to Bexbach. From 2023, we want to take another step into the future and highlight new opportunities for large battery systems.
