As can be seen in all current media, the conflict with Russia is severely testing the European electricity and energy network. If the conflict escalates further, it is conceivable that not only will the heat supply be affected by a possible gas shortage in winter, but that the electricity supply reliant on Russian gas and Russian coal will also face a major challenge.
Even if it is not obvious at first glance, the extreme fluctuations in electricity prices and price peaks currently observed are a sign that security of supply is not — yet — threatened. This is because these show, albeit painfully, that the electricity market can ensure that demand is met even in times of fuel scarcity through appropriate price signals. The signals not only have an effect on the supply side, where the available generation capacity is strongly stimulated to produce electricity from all remaining sources. The demand side is also responding, and electricity consumption is being saved in view of high prices in industry and commerce, and increasingly also in households. The price signals therefore make it possible to ensure security of supply, i.e. meeting electricity demand regardless of price. In such a situation, experts say that there is “adequate resources”.
But what happens when an already tense situation, as we are currently observing, is accompanied by further challenges and unforeseen incidents?
An example from 2006 shows how sensitively the power grid can react to this, in which, as a result of a normally routine shutdown of just a single high-voltage line across the Ems in northern Germany, the entire European electricity grid briefly unbalanced and disintegrated into three separate networks (West, North-East and South-East Europe). As a result of the passage of a large ship, this high-voltage line was switched off as planned, but several errors in calculating the consequences of the shutdown led to a system crash, in which up to 10 million households had no electricity available for 30-60 minutes and also massively affected rail traffic.
If such difficulties coincide with the current tense fuel situation, the power grid faces a real challenge. Particularly with the further important expansion of renewable energies for the energy transition, which are significantly more volatile and less controllable than conventional large power plants, ensuring security of supply in the German power grid is more important than ever before, so that there cannot be the worst case of a blackout, i.e. the complete, large-scale collapse of the power supply.
To ensure security of supply, there are various instances and escalation levels available in the power grid in order to avoid the disaster of a blackout. Thanks to the high flexibility of energy storage systems, they can actively contribute to avoiding these worst cases in every instance.
As already described above, the electricity market is the first instance to balance out any differences in supply and demand. By using energy storage systems on the market, they can make a contribution to security of supply right from the start.
If, for example, there is a surplus of renewable energy in the grid, the price falls as a result of the excess supply. As a result of this price signal, the energy storage devices can then absorb the excess power. The opposite case is also true. With increased consumption and low supply, the price on the electricity market rises, which allows energy storage devices to feed in the previously stored electricity and thus be able to compensate for the difference between supply and demand. This also counteracts a potentially dangerous situation in which a scarcity ultimately leads to a drop in grid frequency and even a collapse of the power supply. More information on energy storage trading on the electricity market is available in our glossary entry”Intraday trading“described.
In this way, energy storage systems can help alleviate critical situations on the electricity market, such as the current one, where there are extreme price fluctuations. The dampening of price peaks increases security of supply, as the electricity market has more security reserves to be able to meet existing demand at any time.
If the market's ability to react is insufficient or if unforeseen, short-term incidents such as the failure of a large power plant or instabilities in grid operation occur, for example as a result of the incorrect calculations of line utilization via the Ems described above, control energy is retrieved from the transmission system operator. Control energy represents an energy reserve to compensate for short-term, unplanned fluctuations between power generation and electricity consumption.
Due to the rapid responsiveness of some energy storage devices (such as battery storage devices) and because they can both absorb and feed in electricity, they are particularly suitable for providing control energy. If power must be made available to increase the grid frequency, energy storage devices can feed in the stored electricity. If the grid frequency has to be reduced, the storage system can absorb and store electricity within a very short period of time.
In the second instance, energy storage systems can therefore actively increase supply security by providing transmission system operators with high-quality control energy for dynamic grid support.
If it is not possible to compensate for fluctuations in the grid frequency even through the use of balancing energy and other emergency instruments, the power grid will disintegrate into so-called “islands” in the worst case. As with the incident in 2006, smaller, separate sub-networks are created in the power grid. In the best case scenario, it will then be possible to stabilize the network frequency in at least some of these “islands”. Potential damage caused by network fluctuations to transformers, lines and consumers can thus be contained and the problem area causing the problem isolated.
However, since some regions typically produce a surplus of electricity, which is then transported to regions with lower electricity production, balancing grid frequencies during island operation is a real challenge. In the example from 2006, the island network of North-West Europe produced a surplus of electricity and had to drop power plants in the short term, i.e. stop their production in order to reduce the grid frequency and ensure security of supply. However, South-Eastern Europe had an electricity deficit, which is why consumers had to be dropped here, resulting in a number of power outages in households and industrial plants.
Energy storage systems can also support security of supply in this instance. Through the high flexibility In island companies, they can stabilize the island's network frequency and thus prevent shedding of plants and, in particular, from consumers.
Should the worst case occur despite all security measures and the network frequency of the islands cannot be maintained, a blackout will ultimately occur. A total power outage in the affected regions. All generation plants are shut down and no consumer is supplied with electricity anymore. It is now time to rebuild small islands of the power grid, restore the grid frequency locally and slowly synchronize these small islands back to a power grid.
Some energy storage devices, in particular large battery storage systems, have a rare ability here. The black start ability. This means that the large battery storage systems can set up a network with a 50 Hz frequency and supply consumers with electricity without an initial external power supply. Many conventional power plants, such as coal or gas power plants, can only be restarted with an external power supply. The energy storage systems can therefore provide these power plants with the initial power supply, which is critical when they start up, so that the network can be rebuilt piece by piece.
Although there are still a number of legal hurdles before the black start capacity of energy storage systems can be fully exploited, these should be removed in the next few years.
In all instances of supply security, energy storage systems can make a major contribution to making the German power grid safer and more independent. Through market use, they can balance supply and demand, can react to short-term and unforeseen incidents by providing balancing energy, and they can effectively stabilize the grid frequency when operating on an island and thus prevent power outages. Even in the event of a blackout, some energy storage systems — in particular large battery storage systems — are able to make a decisive contribution to security of supply due to their black start capacity by helping to quickly rebuild the grid.
Energy storage systems therefore not only offer an effective way to make the power grid more flexible and prepare it for the target of 80% renewable electricity generation in 2030, as stated in our article”Large-scale battery storage as a key technology in the energy revolution“described in more detail, but can also stabilize the power grid and thus actively support the development of a secure and, above all, independent power supply.
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