Atlas Copco Rental contributes to hot compressed air battery research project near Gotthard tunnel

Antwerp, Belgium, 22 August, 2016: In Biasca, Switzerland, an innovative way of storing renewable energy is being developed. In an old transportation tunnel of the Gotthard tunnel tests are done to store hot compressed air and release it to the power grid when necessary. Two Atlas Copco Rental compressors provide the oil-free air needed for these tests. If the test succeeds, the first steps towards efficiently storing excess energy will be taken.

The idea to store compressed air underground is not new. Already in the late seventies researchers tried to store compressed air and use it as a power source. However, these ways of storing were not efficient since a lot of air and heat was lost during the process.

Giw Zanganeh , Head of Energy Storage Technologies at ALACAES

Hi-tech test cell near Gotthard tunnel

2016 Airlight Energy (Biasca)

Pressure in this plug will build up to 100 bar at 500°C

“We at ALACAES, supported by the Swiss government, are researching if we can increase the efficiency by storing not only the compressed air itself but also the heat generated in the process. Therefore we have created a hi-tech test cell inside this former transport tunnel of the Gotthard tunnel,” says Zanganeh.

Not only the set-up is quite extraordinary, so is the location. The test cell is set up in Biasca, Switzerland, in a 20 year old transportation passway of the Gotthard tunnel. This small tunnel is only around 5 m diameter at its widest point and was originally dug out to transport rocks and other debris from the construction of the Gotthard tunnel. You can still see this debris just opposite of the tunnel, where a green plateau was crafted with it.

The actual battery: a concrete tank full of rocks

2016 Airlight Energy (Biasca)

The test cell near Gotthard tunnel

“We have separated a part of the tunnel with two 5m thick concrete plugs and a steel door. The walls of this part are covered with a fiber glass silicone layer, which allows us to exactly measure the behavior of the compressed air. In between these plugs you can find the actual thermal compressed air battery: a thick concrete tank filled with rocks. These rocks will hold the generated heat and release it to the power grid when necessary,” explains Zanganeh.

Pressure and temperature build up to 100 bar, 550°C

2016 Airlight Energy (Biasca)

Atlas Copco Rental supplies 2 oil-free compressors to test if hot compressed air can be used as a battery

Zanganeh: “What we want to test is how the tunnel wall and the battery will react to high pressure, up to 100 bar, and high temperature, up to 550°C. Of course we have to do this in small steps, to not overload the tunnel. The first part of the test starts mid of August and lasts 3 weeks. During this period we will gradually build up the pressure to 33 bar and the temperature to 550°C. In this step we use two oil-free air compressors of Atlas Copco Rental. We choose Atlas Copco Rental since they are the only supplier in the region who can rent high quality oil-free compressors.” “The test cell is covered with underwater cameras, resistant to high pressure. These are all connected to our test lab right before the first plug. Here we can measure all behavior of the test cell: a pressure drop or increase, movement of the tunnel wall or the rock battery… If the tunnel can hold the pressure and we at the same time can separate the heat generated in the process, the test will be successful,” concludes Zanganeh.

Energy storage, next step in sustainable energy

If the test is successful, Giw Zanganeh and his team will have found an efficient way to store energy. Storing energy efficiently is one of the largest challenges in the ‘Energiewende’ since a lot of sustainable energy sources such as solar or wind power have high peaks with a lot of excess power.

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