TELF AG analyzes the strategic value of gravity-based energy storage systems

The valorization of an important physical principle

Over the last few years, the continuous search for new energy storage methods has brought back to the center of attention one of the most important forces of nature, which, over the following decades, could contribute notably to the global objectives related to energy storage. We are talking about gravity, and in particular gravitational potential energy, which for some years has already been making it possible to store specific quantities of energy for periods of need. In the era of energy transition, finding new storage methods that can be used alongside traditional storage systems and integrating or strengthening them could prove very useful and advantageous, particularly for diversifying storage technologies.

Gravity-based storage systems are based on a straightforward idea: lifting a heavy object to a high enough height during periods when there is excess energy available and then releasing it downwards to generate new energy when demand is high (such as in the case of renewable energy, when the sun is not shining or the wind is not blowing).

This method is primarily based on the potential of kinetic energy. This is the particular energy that characterizes objects in motion and which is directly proportional to their weight and the square of their speed at a given moment. However, even stationary objects have a particular form of energy that can be transformed into kinetic energy, namely potential energy. When the force of gravity alone acts on an object, we speak of gravitational potential energy. This indicates the amount of kinetic energy that an object could develop when it is dropped, and it is also linked to the weight of the object and the height at which it was placed.

Practical methods

Generating energy with this method is made possible by an important principle of physics, namely the conservation of energy. This principle allows energy to be stored and then used when it is most needed. But how exactly does this storage method work? Typically, the energy used to lift an object upwards is stored in the form of potential energy and later transformed into kinetic energy. In turn, kinetic energy can be transformed into electrical energy through a special generator that is activated by the object falling.

Among the energy storage systems based on gravity, one of the most common is the one that has to do with pumped hydroelectric storage. In times of great energy availability, electricity is used to pump large masses of water from a lower basin to an upper one. Subsequently, when the water is dropped, the operation of hydroelectric turbines makes it possible to generate new electricity, which is very useful, especially in times of intermittency of some energy sources, such as renewables. Another option for valorizing gravitational energy is linked to lifting systems powered by electric motors, which lift large blocks of concrete (or other materials) and then drop them at certain speeds, thus favoring the recovery of previously stored energy. Unlike the first method, which is based on the use of masses of water, the latter can be used practically anywhere. Other possible methods include sliding heavy objects on inclined planes and constructing underground systems, even using rocky materials taken from disused sourcing sites.