Storage: The tanks of the future

Solar power and wind energy account for a growing share of the total energy supply. How can green electricity continue to be constantly and reliably integrated into the grid? Electric vehicles could play an important role in the future. This requires a clear policy commitment to supporting low-carbon technologies.

Lithium-ion batteries are the power supplier for electric vehicles. But they can do much more. After their time on the road, they therefore make one more stopover before they are professionally recycled and the resulting raw materials are fed back into the battery cycle. When used in large storage tanks, they compensate for fluctuations in the electricity grid with a total capacity of 40 megawatts. This adds value for both sides: For Daimler, the economic benefit of the batteries is increasing, and batteries are also making an important contribution to the energy turnaround in the energy sector. According to industry projections, the share of renewable energies in electricity consumption will rise from the current level of just under 43 percent to 65 percent in the year 2030. The experts from Mercedes-Benz Energy know exactly how this works.

smart battery modules of the third generation in the spare parts store of Mercedes-Benz Energy in Kamenz.

For energy suppliers, this increase is associated with challenges. They have to supply consumers with electricity even when the sun is not shining and the wind is not blowing. However, hydropower plants and pumped-storage power plants are still frequently used for this energy compensation for economic considerations. The technology uses a natural gradient to channel water from a higher reservoir into the valley – the energy released in the process can be used to drive turbines. Electricity is generated. The reverse process, in which water is pumped back into the reservoir via turbines, consumes excess energy. The disadvantage: Pumped-storage power plants can only be operated in mountainous regions.

Prospects for "rolling storage"

Looking to the future, electric vehicle batteries can also contribute to covering short-term power needs in the energy network during their use phase in the car. This is known as bidirectional charging. The idea is that electric vehicles located at a charging station can both absorb and deliver electricity - depending on the needs of the current power situation in the grid.

Electric vehicles like the Mercedes Benz EQC (EQC 400: Electricity consumption in kWh/100 km (combined): 21.3-20.2; CO2 emissions in g/km (combined): 0**) can contribute to covering short-term electrical power needs as "rolling storage tanks".

Green harvest at risk

However, a number of fundamental questions still have to be answered before this. For example: What exactly should the future electricity mix look like? Do we need more wind turbines? Opponents of wind energy reject this, which is why the German Federal government has enacted a distance rule for wind turbines near residential areas in its climate protection package, which has attracted widespread criticism.

Biomass? This energy source has the advantage that its conversion to electricity can be controlled according to demand, but the cultivation of plants that can be used for energy production is viewed very critically, especially when it stands in direct competition with food production. So, should there be more photovoltaic installations? At least the German government has refrained from the planned ban on subsidies for photovoltaic systems in May 2020 in order to accelerate the energy turnaround in Germany.

Solar power as an imported good

Although global radiation has increased strongly in recent years, compared to other countries, Germany does not offer the best climatic conditions for a rich harvest of solar power compared to other countries. Against this background, another storage technology is also gaining in importance in the context of the energy turnaround: Power-to-X. This refers to the conversion of electrical power (from green sources) into material storage, i.e. into hydrogen or synthetic fuels. The advantage: Solar energy could be generated and converted in southern countries and imported via pipelines or tankers. With its national hydrogen strategy, the German Federal Government has already been promoting approaches to the production, transport and use of the gas for years. The goal is to make Germany becomean international pioneer in the area of green hydrogen and to gain the global market leadership for hydrogen technologies in the long term. Jens Kanacher, who led until mid-March 2020 the Competence Center for Energy Systems and Storage at the energy provider Innogy, speaks of an "import turnaround" in this context.

Jens Kanacher, until mid-March 2020 head of the Competence Center for Energy Systems and Storage, deals with issues concerning the transition to a CO2-neutral, digitalized and decentralized energy industry.

New hope in liquid salt

Furthermore, researchers are also testing other methods for physical storage of green electricity in various projects. Installations for liquid salt storage could also be interesting for economic reasons: During the processing, large quantities of liquid salt are heated by excess wind or solar power. The hot salt can in turn generate enough steam to operate a power plant turbine.

The development of new storage technologies requires a reliable policy framework. Experts are convinced that this would also lead to further technological innovations, which, like the energy storage systems from Mercedes-Benz Energy, would make a valuable contribution to the energy revolution.

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