How can energy be stored? This question has occupied the energy industry for a long time and will become increasingly important in the future. This is also how our managing director Jan-Oliver Heidrich sees it: “The next big topic will be the mandatory expansion of energy storage technology.”
The field of storage technology is currently facing many challenges. How can we store energy in a more climate-friendly, space-saving and cheaper way in the future in order to use renewable energies even in bad weather and thus take another big step towards the energy transition?
Storage for the energy transition: why is this topic so important?
Due to the weather, 2021 was a below-average year for wind energy and solar power, which means that the share of renewable energies in the electricity mix fell below the 50 percent mark again. The generation of electricity from photovoltaic and wind systems is not always reliably stable. In order to be able to ensure the generation and thus the use of electricity from renewable energies even in bad times, while we continue to build on these energy sources, we cannot avoid the topic of energy storage.
First we had the obligation to set up e-charging stations, now the topic of photovoltaics follows and then I see the topic of storage inevitably coming up. This will certainly be an issue for trade and Co.
Jan-Oliver Heidrich, Managing Director of Areva Energie-Handels-Gesellschaft
What is energy storage
An energy storage system is a system that absorbs energy and releases it again at a later point in time – exactly when it is needed. As a rule, the energy is released as it is absorbed. The energy can only be partially converted during storage. There are different forms of energy for which an energy storage device is required. A distinction is made between two types of storage for electrical energy:
- short-term storage
- or long-term storage
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To the short-term storage include pumped storage power plants, compressed air storage and battery storage. The special thing about short-term storage is that they can absorb and release energy several times a day. This is particularly interesting for companies and retailers.
Used by a long-term storage speaking, this applies to hydrogen or methane and large storage hydroelectric power plants, which store electrical energy not only for a short time, but for days and weeks.
How is energy stored
Pumped storage power plants are currently the primary form of energy storage, accounting for over 90 percent. If electricity is left over during periods of low usage, it is used to pump water into a basin in the pumped storage power plants.
And if the power is needed again? The basin is then emptied and the water that runs off is fed into turbines, which generate electricity and ultimately feed it into the grid.
Already knew? With this type of energy storage, about 20-25 percent of the stored energy is lost. This means that the efficiency of pumped storage power plants is around 75 to 80 percent. How much energy can ultimately be stored depends on various factors and circumstances.
Energy storage of the future: Energy storage systems for the energy transition
The use of renewable energies should also increase in the future. For this purpose, the current technologies for energy storage must be expanded, because those currently available will no longer be able to handle this in the future.
Many of the new solutions are still being planned or developed. Hydrogen seems to be one of the most attractive energy stores of the future. Because the Federal Ministry for Economic Affairs and Energy has already developed a hydrogen strategy and thus created a “framework for action for the future generation, transport, use and further use of hydrogen and thus for corresponding innovations and investments”.
Energy storage systems: Power-to-X
Ever heard of sector coupling? In the course of the energy transition, applications from the areas of electricity, heat and mobility are being reconnected on the basis of renewable energies. There are various solutions that are summarized under the term “Power-to-X”. Surplus electricity and various forms of energy or purposes are brought together here.
- power to gas describes the generation of gas from electricity.
- Power to heat describes the generation of heat from electricity.
- Power to Liquid describes the generation of liquid fuel from electricity.
power to gas
Power.to-Gas uses excess green electricity to split water into hydrogen and oxygen using electrolysis. From this point on, there are two options for feeding the regeneratively obtained hydrogen into the natural gas network:
- If the hydrogen is fed directly into the natural gas network, the admixture can currently be up to 10 percent.
- If, on the other hand, the hydrogen is further processed into synthetic gas, there is no admixture limit to be observed.
The clear benefit here is storage capacity. Over 40 gas storage facilities have a capacity of 230 TWh, while pumped storage plants in Germany have a capacity of 0.04 TWh.
The production of hydrogen can be used in many ways for a more climate-friendly environment, but is currently very expensive and hydrogen is therefore often referred to as the “champagne of the energy transition”.
Battery storage is becoming more and more important, especially in view of the decentralized energy transition through photovoltaic systems on the roof or tenant electricity.
The lithium-ion battery is the most common form of energy storage and is currently installed in almost all mobile phones and laptops. But it is also used for e-bikes and e-cars, as well as to store solar power.
Local battery storage is flexible. This also accounts for their advantage over other energy storage devices. Another advantage is that the electricity can be stored and used directly on site. This means that the networks are not burdened and fewer power lines are needed. At present, however, battery storage systems are still very expensive and only store small amounts of excess electricity. In addition, storage capacity is constantly lost due to frequent loading and unloading.
In order to use the advantages of battery storage in the future and to compensate for the disadvantages, capacitors could be used in their place. These are already widely used today and are characterized by the lightning-fast storage and delivery of large amounts of electrical energy. They last longer than batteries and complement solar and wind power generation.
Energy storage in practice using the example of electromobility
Energy storage systems offer new opportunities, especially in the field of electromobility. The focus is on the battery capacities and performance. An increase in battery energy has already been clearly recorded in recent years. In the next step, an expansion of this as a publicly accessible energy network is conceivable. In this way, electromobility in Germany could be significantly expanded. If the number of electric cars increases and a corresponding infrastructure is created, the energy can be fed into the public grid according to need, availability and possibility and is therefore also available for use at a later point in time.