- Milestone reached for conversion of existing caverns for hydrogen use

- Tightness of cavern with hydrogen proven

- "This is the kick-off for practical application research at the Etzel cavern storage facility," says project manager Carsten Reekers, STORAG ETZEL: "We have gained positive insights into the use of bore hole equipment with high-pressure hydrogen and the handling of hydrogen in the cavern field for future large-volume storage!"

As part of the H2CAST research project, STORAG ETZEL, together with project partners, has successfully completed the first gas tightness test with hydrogen at a cavern borehole in Etzel.

Extensive material tests were carried out in preparation for the test and during the test phase. In total, the team injected several thousand standard cubic metres of gaseous hydrogen from sustainable, "green" production into the well.

At over two months, the test period was significantly longer than is the case with comparable tightness tests under nitrogen. "We wanted to make sure that the result was reproducible and to continue to gain experience in dealing with hydrogen as a medium," says project manager Carsten Reekers, explaining the long period.

Among other things, the test, which was approved by the mining authority LBEG provided insights into how the current measurement results under hydrogen can be compared with the standardised procedures under nitrogen as the test medium.

In another test set-up, the team tested the draining of part of the hydrogen. The hydrogen was burnt in a controlled manner in order to test the ignition behaviour, to test safety devices and to measure the sound emissions.

This additional operational test in the Etzel cavern field also answers questions for the practical handling of hydrogen in comparison to natural gas. In order to pass on first-hand knowledge, representatives of the local fire brigades and the LBEG accompanied this test. This also included an initial, practical training session. In the course of the preparations, experts on site also trained the participating employees of the H2CAST Etzel research project in theory and practice. The test procedures with hydrogen were analysed and optimised in terms of safety.

"Hydrogen was introduced into a cavern for the first time at the Etzel site. The results of the test run were consistently positive - the processes were controlled at all times and proceeded as planned. However, we still have major tasks and questions to deal with within the framework of the H2CAST project, but we see ourselves on a very positive path," says Reekers.

The next step will be to complete the planning for the further expansion of the hydrogen caverns. Before the end of this year, two cavern boreholes are to be equipped so that the storage of larger quantities of hydrogen can begin as part of the H2CAST demonstration project. Detailed tests will be carried out again at a later date, then using the maximum permissible rock mechanical pressure of the caverns. After that, the filling with hydrogen can begin.

Further information on the hydrogen pilot project and project partners can be found here at www.h2cast.com.