The Technology

Discover how air produces energy

A large battery

driven by compressed air?

How is it possible that are creates energy? That is a question we hear quite often. Therefore we will explain the technique step by step. When the wind blows and the sun shines a lot of sustainable energy is generated. However, there is a major problem; the energy network is out of balance during sunny and windy days as there is a limit to the amount of energy it can transport. To solve this problem the wind mills and solar panels are turned off. Therefore a lot of sustainable energy is not being used.  That is what we would like to change by saving sustainable energy for the days the wind doesn’t blow and the sun doesn’t shine. By turning the sustainable energy into compressed air, save it in a cavern and let the air out through a turbine which turns it into energy again we prevent us from using fossil fuel.

All in all, this technique is called compressed air energy storage (CAES).

The Design

It all starts with the design of the installation and the two salt caverns in which compressed air is stored. Our colleague Hedzer is responsible for this. The permits are then applied for and the design is worked out down to the smallest detail. Once the necessary permits have been granted, the actual construction begins.

The Construction

The construction can roughly be divided into two parts: the underground salt caverns and the installation. Subterranean salt caverns are large, solid cavities in the salt layers in the soil that are made by dissolving salt. This can be done by pouring water into the salt layer, which makes salt liquid, this is called brine. The brine is transported via pipes to the industry. After that, the cavern needs rest before it is put into use. Parts are then placed at the top of the cavern to make the connection with the above-ground installation.

The installation that will be built on the surface consists of compressors to compress air and pump it into the cavern. During the compression of air, a lot of heat is released. To cool that air before it enters the cavern, we use hybrid cooling towers. As a result, the temperature in the cavern is around 50 degrees Celsius. This is an ideal temperature to ensure the stability of the cavern. During the operation of the CAES facility, in the storage phase, electricity is used to force air into the cavern. In the generation phase, the compressed air is released and heated to drive turbines, which produces electricity when needed. When feeding power back into the electricity grid, we use two Turbine Expanders with a total capacity of 320 MW. During the expansion of the air, it cools down.

Facts and Figures

In the Netherlands, we use 58% natural gas, 26% coal and 13% other forms of energy to generate electricity. Only 8% of our energy comes from renewable energy sources.

Our technology makes it possible to store 4 gigawatts of energy. This can be compared to the electricity needs of approximately all households in the province of Groningen.