With the expansion of renewable energies, the topic of energy storage is becoming increasingly important. The fluctuating supply of wind and solar power into the grid poses a challenge for energy suppliers and consumers who wish to intelligently balance supply and demand and ensure the security of supply. Modern storage technologies are a central element in this process, enabling grid stability, flexibility and integration between electricity, heating and mobility sectors.
“Storage technologies are currently one of the most exciting areas in electronics,” says Jan-Christoph Pakusa, Product Manager for Power Supply and Measurement Technology at reichelt elektronik. “A variety of innovative technologies not only opens up new opportunities for storing energy more efficiently across industries, but is also a decisive factor in the success of the energy transition. All in all, this affects not only the economy, but also our society as a whole.”
Energy storage – a key technology for a successful energy transition
The importance of storage technologies for the energy system of tomorrow is particularly evident in three areas:
- On the one hand, renewable energies such as wind and solar energy depend on the respective weather conditions and are characterised by their volatile electricity generation. Generation often does not coincide with electricity demand, for example when a great deal of solar power is fed into the grid at lunchtime, while the peak usage period occurs in the evening. Energy storage systems play an important role in this context by absorbing excess generation and providing it again later as required. In this way, they help to smooth production fluctuations, increase the predictability and system integration of renewable energies and reduce the need for regulations that would otherwise be necessary in the event of grid overload, for instance.
- On the other hand, storage plays a central role in security of supply and network stability. To maintain a stable power grid, a constant frequency of 50 hertz is required, which can be endangered by fluctuating power inputs and varying consumption loads. Storage technologies can respond in timespans from milliseconds to minutes, compensating for frequency deviations within the scope of primary control. Load peaks can also be dampened by using accumulators, which lead to a reduced need for cost-intensive peak-load power stations. Decentralised storage in households or businesses also increases the resilience of the overall system. The advantages are tangible — a reliable supply, the reduction of blackout risks and cost savings in network expansion.
- In addition, storage technologies are indispensable for the transformation of the energy system toward climate neutrality. The use of renewable energies alone is not enough to entirely replace fossil fuels. In the short-term, battery storage will allow flexible adaptation to daily fluctuations and a balance between day and night hours. In the medium to long run, long-term storage facilities such as hydrogen, power-to-gas processes or pumped storage power plants are required to bridge longer phases of reduced production, for example during seasonal dark spells. As a result, storage facilities provide the basis for a fully renewable and fossil-free energy supply, increase independence from fossil fuels and make a decisive contribution to the decarbonisation of other sectors such as heating, cooling, mobility and industry.
Central technologies
If you take a look at the technological developments themselves, it becomes clear that while different storage solutions will become increasingly important in parallel, they vary depending on the area of application and also offer different advantages and potential for the energy system of the future:
Battery storage
Battery storage is currently a key issue when it comes to flexible and quickly available energy storage. Lithium-ion batteries in particular have become established in numerous applications in recent years, thanks to high efficiency levels of up to 95%, short response times and a notable increase in affordability. They are used both in private home storage—often in conjunction with photovoltaic systems—as well as in larger commercial and industrial systems, where they reduce load peaks and optimise internal consumption. In addition, they make important contributions to maintaining grid frequency and providing short-term energy availability in order to keep the power grid stable.
However, there are still challenges with regard to raw material dependencies on lithium, nickel or cobalt, as well as issues relating to the circular economy. In research, the focus is therefore increasingly on new generations of batteries. Sodium-ion batteries are considered a promising alternative, because they use fewer critical raw materials despite having a lower energy density. Solid-state batteries in turn promise greater safety and energy density, but are currently still the subject of intensive development work and are only planned for market entry in the medium-term.
Power-to-gas solutions
Power-to-gas and hydrogen storage systems are growing in importance alongside battery storage systems. Electrolysis can convert renewable electricity into hydrogen, which can be stored and used in a variety of sectors — from industry to mobility to electricity reconversion.
While the degree of efficiency in the reconversion is currently still limited, the following factors are driving forward its development: falling electrolysis costs, the planned expansion of pipelines and storage capacities in salt caverns. Hydrogen is a key option, especially for industrial processes in the chemical or steel industry and for long-term storage over seasonal periods.
Thermal storage
Thermal storage is another central technology, especially in the context of the heating transition and energy integration. Water and salt storage facilities can store heat over longer periods of time, converting renewable electricity surpluses into usable heat. In solar-thermal power plants, molten salts are already used for intermediate storage. In addition, the use of power-to-heat is gaining relevance, for example, to stabilise the power grid or to supply district and local heating systems.
Pumped storage power
Pumped storage power plants are a proven large-scale storage solution that have played a key role in the energy mix for decades thanks to their high efficiency and large capacities. They are particularly suitable for grid stabilisation, peak load coverage and black start capability, so that a pumped storage power plant can be put back into operation without an external power supply following a large-scale power failure. While the potential for expansion in Germany is limited by geographical and social factors, the technology remains of central importance in countries and regions with suitable sites, for example in Scandinavia or the Alps.
Other storage technologies
In addition to established large storage systems, niche solutions are becoming increasingly important, which represent interesting alternatives depending on the location or type of application.
Compressed-air energy storage (CAES) uses excess electricity to compress air in underground caverns and, when required, release this air to drive turbines and generate electricity. Modern adiabatic concepts increase efficiency by also storing the heat generated during compression and re-using it to heat the compressed air upstream of the turbine. Classic systems, on the other hand, rely on the use of natural gas to replace the heat lost during the storage process in power generation. They use the gas to bring the compressed air to the required temperature before it is released, thereby ensuring turbine efficiency. For this reason, they are not yet completely climate-neutral.
Redox flow batteries store energy in liquid electrolytes and allow flexible dimensioning of power and capacity. They excel in terms of operational reliability, long lifespan and good scalability, but their low energy density and high investment costs have therefore limited them to stationary large-scale storage systems.
Gravity energy storage, in turn, relies on mechanical principles by using excess energy to lift large masses that generate current when lowered again. Initial pilot projects in Europe show potential through robust technology and low-cost raw materials, although efficiency and space requirements are still limiting factors.
These approaches demonstrate that innovative solutions are also being developed beyond the most prevalent storage systems, which, depending on the geographical framework conditions and economic perspectives, can make a complementary contribution to the energy infrastructure of the future.
Trends and perspectives in the evolution of storage technologies
Over the next ten years, energy storage will continue to evolve as a result of increasing technological diversity and close interaction with other sectors, such as heating, mobility and industry. “Energy integration” ensures that renewable energy can be used not only for electricity, but also for heating systems, electric vehicles or industrial processes, and that storage technologies are pivotal in offering a balance between these aspects.
Lithium-ion batteries remain the leading technology for the time being. They already dominate home storage, electromobility and large network storage systems, benefit from massively increased production capacities and sharply reduced costs, and will continue to be of importance in an optimised form, for example as lithium-iron-phosphate variants or further developed NMC variants. NMC stands for lithium-nickel-manganese-cobalt oxides: These batteries are characterised by a high energy density and are used in particular in electric vehicles and stationary large storage facilities, while lithium-iron-phosphate batteries are valued above all for their high level of safety and long service life.
At the same time, new battery types are of increasing importance. Due to the use of cheaper and more readily available raw materials, sodium-ion batteries enable more cost-effective stationary storage despite their lower energy density. Solid-state batteries could unlock new potential in five years’ time, particularly in electromobility, through higher energy densities, greater safety and a longer service life. Redox flow systems will also be used as a made-to-last and scalable solution, especially in large stationary storage systems. As a result, an increasingly heterogeneous technology mix is developing, in which different systems in different fields of application complement each other.
New opportunities through smart integration and networking
Parallel to this technological breadth, the increasing integration of multiple energy sectors is coming into focus. Power-to-heat applications convert excess power directly into heat, thereby helping to stabilise the grids and supply heating networks. Power-to-gas solutions, in particular green hydrogen, open up a new scope for industrial processes in the steel and chemical industry or for seasonal balancing between summer and winter.
The establishment of hydrogen networks and cavern storage facilities will lay the foundations for a hydrogen economy in the coming years. In addition, synthetic fuels (“e-fuels” such as methanol or synthetic kerosene) are produced from renewable electricity, first via hydrogen using electrolysis and then by forming compounds with CO₂, resulting in liquid or gaseous fuels. These are of particular importance for areas such as shipping and aviation, as these sectors cannot be fully electrified for technical reasons. The closer integration of electricity, heating, mobility and industry results in efficiency gains and a noticeable reduction in CO₂ emissions.
Digitalisation and the use of smart energy management systems are also becoming increasingly important. While the first home storage systems are already optimising the self-consumption of photovoltaic systems, private and commercial storage systems are developing from isolated individual solutions to systemically networked units in the electricity grid. Virtual power plants bundle thousands of small and large energy stores to provide grid-stabilising services. Intelligent control solutions also enable automatic peak shaving in plants and enterprises, which reduces network charges while alleviating the load on the energy system. Using artificial intelligence to accurately predict weather, consumption and price data, storage is controlled dynamically and in a market-oriented manner.
Establishment on the market brings economies of scale
In addition, economic and ecological framework conditions are changing noticeably. Battery storage, which was limited by high costs just a few years ago, is becoming increasingly profitable due to economies of scale and technological progress. Forecasts predict that costs could fall by more than half by the mid-2030s, while improved design will lead to significantly longer lifespans.
At the same time, a separate recycling industry for lithium, nickel and cobalt is being established, which would reduce dependence on critical raw materials. Second-life concepts for used vehicle batteries further extend the service life of the systems. In addition to economic effects, sustainability is also gaining importance, further fuelling the market ramp-up. As a result, storage systems are evolving from a technology primarily propped up by funding instruments to an independently viable business model that provides key system services while also opening up market opportunities.
Looking to the future: challenges and opportunities
The further development of sustainable storage technologies is regarded as the key to a reliable and climate-compatible energy supply. However, several hurdles have to be overcome in order for energy storage to reach its full potential. In terms of technology, the focus is on dependence on critical raw materials such as lithium, cobalt and nickel, the limited service life of many battery systems and the previously low efficiency of long-term storage. In particular, seasonal storage solutions such as hydrogen or synthetic energy sources are still in the early stages of development.
In economic terms, high investment costs, uncertain amortisation periods and continuing insufficient access to energy markets are the inhibiting factors. Regulatory barriers exist due to complex framework conditions, such as double grid fees or a lack of standardisation in the integration of decentralised storage systems into the electricity grid. Social acceptance issues, for example in large-scale projects such as pumped storage power plants or hydrogen infrastructures, also play a role.
On the other hand, storage technologies offer significant opportunities. New developments such as sodium-ion and solid-state batteries promise greater sustainability, greater safety and lower dependence on raw materials, while power-to-gas and thermal storage will become more relevant for cross-sector applications in the long-term. Reducing system costs, increasing service life and more efficient materials make storage more and more economically attractive.
At the same time, digitalisation and smart energy management are creating innovative business models, ranging from grid-friendly control to peak load management and energy communities. This means that storage is developing not only into technical buffers, but also into a strategic component of a decentralised, resilient and climate-neutral energy system.
Images: Adobe Stock
