Electricity storage options of the future

In order for households and industry to be reliably supplied with energy in the future, energy generation must be better planned and energy storage more effective. Due to the fact that solar and wind energy in particular are subject to strong fluctuations depending on weather and season, energy storage systems must be integrated into the systems. These store energy when energy demand is lower than energy production and release energy as soon as it is needed. This can happen on a small scale (household) as well as on a large scale in the power grid of an entire city or country.  

There are already many different ways of storing energy. These include, for example, the storage of thermal energy in heat accumulators or the storage of electrical energy in accumulators or capacitors. Energy storage is essentially divided into short-term and long-term storage. Short-term storage can be charged and discharged several times a day (example: electricity storage for PV systems). Long-term storage can store energy for days or even weeks (storage in the form of power-to-X technologies such as hydrogen).

The focus on electricity is important for the energy storage systems of the future, as this can be generated in a climate-neutral way with the help of solar and wind energy.

Opportunities for electricity storage

The focus on electricity storage is of great importance for the future, as it ensures better management of the electricity grid and can bridge the gap between peak load and peak generation. There are many different options for this, ranging from pumped storage, large-scale battery storage or photovoltaic battery storage.

Electricity storage in wind power plants

A part of a worldwide unique power plant concept of the water battery was designed by a company based in Sengenthal, the wind turbine storage, a combination of wind turbine and pumped storage. Here, the tower foundations of the wind turbine are used as a water reservoir (upper basin). In Gaildorf near Stuttgart, the world's largest wind turbine was erected in this respect, with a hub height of 178 metres and a total height of 246.5 metres. The wind turbine is part of a wind farm that includes a total of four other wind turbines. The water reservoirs have a storage capacity of 70 MWh and are connected by penstocks to a pumped storage power plant in the valley, which can deliver up to 16 MW of power, and the associated lower basin. In this way, surplus electricity can be absorbed by the water battery from the power grid and released. In this way, the power grid is to be kept stable in the future and an uninterrupted supply guaranteed.

Gravity as electricity storage

A Swiss company developed a solution whereby energy storage is done with the help of concrete blocks, the so-called concrete storage. The structure describes a huge metal tower (35 storeys high) on which concrete blocks are suspended from steel cables (up to 5,000 weights). Excess wind energy is used to raise the blocks into the air and then lower them again, generating fall energy (electricity). A metal tower already takes up the area of a football field and has six crane arms. A tower can have a storage capacity of up to 80 megawatt hours and is said to be able to deliver four to eight megawatts for eight to 16 hours, with an energy efficiency of 90%. 

Electricity storage through landscape adaptation

One notional way to store electricity is through the concept of a Ringwallspeicher hybrid power plant. The idea of a Ringwallspeicher is to allow areas without a naturally existing difference in altitude to store the to offer the possibility of storing electricity by means of a pumped storage power plant. The fictitious Ringwallspeicher hybrid power plant has a diameter of 11.4 kilometres, with the 215-metre-high Ringwalls enclosing the upper basin, which has a diameter of six kilometres. In cooperation with large wind energy and solar energy plants, the Ringwallspeicher is to provide two gigawatts of average power. The water areas are to enable recreational activities, such as mountain and winter sports. However, this large-scale design of a Ringwallspeicher will hardly exist. Due to the existence of natural differences in altitude, much smaller systems with comparable economic efficiency can be built using the same construction principle.

Conclusion: The topic of electricity storage in and for the future is becoming increasingly important. It is necessary to focus on the topic of energy storage in order to be able to ensure electricity generation and supply even in bad times. It is also a good way to counteract climate change.

EurA is always available for questions in the field of energy advice.

Author: Joke Brodersen