The need for flexibility in the German power grid and the contribution of large-scale battery storage systems
At a time when the energy transition plays a central role in German energy policy, the need for a flexible electricity grid is becoming increasingly clear. The integration of renewable energies such as wind and solar power poses new challenges for the existing grid, as these energy sources are inherently variable and unpredictable.
Germany wants to become climate-neutral quickly. At least 80% of electricity is to come from renewable energies by 2030. Once the coal phase-out has been completed, the electricity supply should be greenhouse gas neutral. This is the aim of the Renewable Energy Sources Act (EEG), which contributes to the implementation of the Paris Climate Protection Agreement. This is where the need for flexibility comes into play, which is crucial for the stability and reliability of the power grid.
Challenges of the German power grid
The traditional power grid was designed for continuous power generation from fossil fuels and nuclear power plants. These conventional power plants can keep their production relatively stable and do not always react quickly to changes in demand. In contrast, wind and solar power fluctuate greatly, depending on weather conditions and the time of day. This leads to periods of overproduction when there is plenty of wind and sun available, and times of underproduction when these sources do not provide sufficient energy. Variable renewable energies dominate the electricity mix – PV and wind will have a global share of 72% in 2050. The share of renewable energies in electricity consumption in Germany is growing steadily: from around six percent in 2000 to more than 50 percent in 2023. According to data from the Working Group on Renewable Energy Statistics (AGEE-Stat) at the Federal Environment Agency. At 51.8% in 2023, the share is 5.6 percentage points higher than the previous year's figure of 46.2%. This means that more than half of total electricity consumption was covered by renewable sources for the first time.
The role of flexibility
To compensate for these fluctuations and ensure a stable power supply, the power grid must be flexible. Flexibility means that the grid is able to respond to changes in electricity generation and demand at short notice. This can be achieved through various measures, such as flexible conventional gas power plants that can ramp up or down quickly, load management, in which electricity consumption is adjusted, and the use of energy storage systems. In the context of the European and German energy systems, this means that both electricity grid- and market must have the flexibility to compensate for fluctuations in the demand or supply of electricity to guarantee the stability and security of the electricity supply. The seven-fold increase in electricity generation from renewables that DNV forecast will lead to a corresponding 17-fold increase in global utility-scale energy storage capacity, which will rise from 1.75 TWh in 2023 to 30 TWh by mid-century.
Large-scale battery storage as a solution
A promising technology for increasing flexibility in the power grid is large-scale battery storage systems, which play an essential role in providing flexibility. These battery energy storage systems, or BESS for short, can store excess energy when production exceeds demand and feed this energy back into the grid when there is a deficit. This not only helps to stabilize the grid, but also the efficient use of renewable energies that could otherwise be lost. The existing flexibility of battery storage systems can also play a major role in reducing or avoiding grid bottlenecks in the bidding zones. Just like generation plants, storage systems such as large-scale battery storage systems must also be available for the redispatch measures of the transmission system operators. If these are strategically placed at grid nodes where grid bottlenecks often occur, they can even contribute particularly effectively to avoiding bottlenecks. In addition to normal redispatch measures, the storage systems can also optionally act as consumers. For example, large-scale battery storage systems can not only be throttled to zero before the occurrence of bottlenecks, as generation plants are, but also absorb surplus electricity produced. Once the bottleneck has been eliminated, the storage systems can feed this electricity back into the grid with a time delay.
Especially in light of the urgency with which flexibility options are currently needed in the power grid, storage systems therefore offer an enormously important addition to grid expansion, which can be implemented much quicker. This alternative is also relevant from an ecological and social point of view, because the German electricity grid is characterised by bottlenecks on the generation side. This means that in the event of excessive electricity production, renewables must be increasingly curtailed to ensure safe grid operation. At the same time, plannable (and thus almost always conventional fossil fuel) plants must be ramped up elsewhere to make up for the deficit. This process increases the CO2 emissions of electricity production and also causes costs due to the necessary redispatch of the plants, which in turn are borne by society through grid charges.
Advantages of large-scale battery storage systems
Large-scale battery storage systems offer several advantages:
- Grid stability: By providing energy quickly, battery storage systems can reduce voltage and frequency fluctuations caused by variable renewable energies. (dynamic controllability)
- Avoiding grid overloads: During periods of high production, battery storage systems can absorb excess energy and thus prevent the grid from being overloaded
- Efficient use of renewable energy: Instead of wasting or curtailing excess energy, it can be stored in battery storage systems and used at a later date
- Reducing dependence on fossil fuels: By storing and using renewable energies, the need for conventional power plants can be reduced.
The most widely used technology is Li-Ion technology. These storage systems are characterized by a high efficiency of over 90% and can provide full performance in fractions of a second.
In addition, we are seeing a significant decline in the investment costs of these large-scale battery storage systems with Li-Ion technology with an increasing energy density at the same time.
Examples and developments
In Germany, there are already several successful projects that demonstrate the effectiveness of large-scale battery storage systems. For example, a 5 MW battery storage system (at that time one of the largest BESS in Europe) was put into operation in Schwerin 10 years ago. WEMAG's battery storage system now has a capacity of 14 MW and a storage capacity of 15 MWh. From October 2024, a further augmentation of 2 MW of capacity and 5 MWh of storage capacity will be available after the current conversion. This will enable WEMAG to offer even more primary balancing power (FCR) and at the same time participate in short-term electricity wholesale, intraday electricity trading, on the stock exchange.
WEMAG's large-scale battery storage system is a pioneering achievement for the use of batteries for our energy system in Germany and Europe. This project shows that large-scale battery storage systems are not only technically feasible, but also economically viable. This has been the case for 10 years.
Three years ago, a battery system of superlatives was put into operation in Lower Lusatia (Niederlausitz) at the Schwarze Pumpe power plant. The electricity storage system consists of 26 containers and has a capacity of 50 MW and a capacity of 53 MWh. According to the operator LEAG, the battery storage system at the Schwarze Pumpe power plant was the largest in Europe at the time (2021). The "Big Battery Lausitz" is currently in continuous commercial operation and, among other things, performs primary control reserve (FCR) to compensate for short-term fluctuations in the power supply. This large-scale battery storage system thus contributes to a stable power grid. Electricity generation, consumption and storage are intelligently networked in this electricity storage system. With an innovative charging management system and the use of a new type of power plant control system, the plant makes an important contribution to the integration of renewable energies into the grid, according to the operator LEAG.
Whereas in recent years plants with a size of between 10 MW and 50 MW were planned, built and connected to the grid, we are now seeing a tenfold increase in output (projects in which DNV is involved). RTB projects with a connected load of 100 MW to 400 MW and pipeline projects up to 1000 MW are no longer exceptions but represent the current situation. DNV also sees this in more and more inquiries from our customers.
A lot of things are moving in terms of large-scale battery storage in Germany. In the next two years (until 2026), capacity is expected to increase fivefold from 1.5 - 2.0 gigawatt hours to 7.5 - 10 gigawatt hours, according to current studies. Even more "record-breaking" projects are to help with this. Germany is relying on the massive expansion of large-scale battery storage systems to drive the energy transition forward and ensure security of supply. (see electricity storage strategy of the BMWK). These storage systems are at the heart of stabilizing fluctuating electricity generation from renewable sources such as wind and solar.
Numerous large-scale projects, such as those in Alfeld with 137.5 MW (in Lower Saxony), Stendal 116.5 MW (Saxony-Anhalt) or Bollingstedt 103 MW (Schleswig-Holstein), are intended to help make the power grid more flexible and resilient.
In addition, manufacturers are continuously working on the further development of battery storage technologies. This includes both improving storage capacity and efficiency, as well as reducing costs. These advances are crucial to making large-scale battery storage a viable solution to the challenges of the modern power grid. A good investment, because in times of negative electricity prices, revenues are rising and the acquisition costs for BESS are currently falling. The expansion of Li-ion batteries in the market is reflected in our global projections of levelized cost of storage (LCOS). DNV expects the cost of utility-scale Li-ion battery systems to fall to below USD 200/MWh by 2030 and stabilize at this level globally, with even lower costs in markets such as North America and China.
Summary
The flexibility of the German electricity grid is essential to meet the challenges of the energy transition. Large-scale battery storage systems play a crucial role in stabilizing the grid and making efficient use of renewable energies. They store excess energy and release it when needed, stabilize the grid, prevent grid bottlenecks and increase the efficiency of renewable energies. Strategically placed, they can reduce bottlenecks and be implemented more quickly than grid expansion, which is also ecologically and economically advantageous.
Through the continuous development of these technologies, Germany and Europe can take an important step towards a sustainable and reliable energy supply.
Storage is essential for the inclusion of variable renewables in electricity and flexibility is key to manage this transition successfully.
11/7/2024 8:00:00 AM