Evaluierung der Bohrungsintegritat von Wasserstoffspeicherkavernen Evaluation of the well integrity of hydrogen storage caverns

摘要

In order to fulfill the Paris climate change agreement,further expansion of the renewable energy sector is essential.The necessity is particularly evident in the growing public interest in the area of climate protection.Since the German renewable energies act(EEG)came into force in 2000,the share of renewable energies in the electricity sector has risen to 42% [1].This has been accompanied by a rise in surplus electricity production to a record high of 55 TWh in 2017,while expenditure by changing the power plant schedules(redispatch)measures and feed-in management has risen to over € 1.4 billion per year [2].The HYPOS(Hydrogen Power Storage & Solutions East Germany)project aims to make this surplus of renewable energy usable.Hydrogen is to be produced by electrolysis and stored in existing or newly constructed salt caverns.While extensive experience is available in the field of natural gas storage,there are only six hydrogen caverns worldwide.The challenge of hydrogen storage results from the different material properties compared to natural gas.Under typical storage conditions,hydrogen has twice the mobility.Furthermore,hydrogen is highly diffusive due to its small molecule diameter and can lead to hydrogen embrittlement in steels.In the sub-project H2 underground storage(H2-UGS),the TU Bergakademie Freiberg is concerned with the evaluation of the well integrity of salt caverns in relation to hydrogen.To this end,a series of permeability measurements are being carried out on various materials.Besides salt rock and cement,composite samples of casing and cement as well as sealing materials of subsurface equipment are planned.The measurement of the core samples(length=20 cm,diameter=10 cm)is carried out using a transient two-chamber system.Permeabilities up to a limit of 10 m~2 can be determined.The composite samples have the form of hollow cylinders(casing covered with cement)and simulate a section of a real borehole.With the help of these measurements,especially the permeability of the boundary surface between the two materials is to be examined.To carry out these measurements,a corresponding test facility will be set up in the research mine of the TU Bergakademie Freiberg.In addition to the project,a monitoring concept for hydrogen caverns is being developed.