Large-Scale Hydrogen Underground Storage for Securing Future Energy Supplies

by Fritz Crotogino & Sabine Donadei, KBB UT, Hanover / Germany & Ulrich Bünger & Hubert Landinger, LBST, Ottobrunn / Germany

Introduction
In recent years the role of hydrogen in future energy scenarios has moved somewhat into the background. Now its significance is being highlighted even more as it may play an important role during and after the transition from fossil fuels to renewable energy sources concerning two areas in particular.

ENERGY INDUSTRYNERGY INDUSTRY
The energy industry is facing the need to store extremely large quantities of energy for long-term to seasonal periods in order to adapt the fluctuating and non-dispatchable energy production from wind and solar resources to the actual demand, which is no longer feasible using conventional technologies. In today’s fossil-based energy industry, seasonal fluctuations, strategic reserves, and compensation of shortages and shut-downs are largely balanced out by the storage of fossil fuels (e.g. Germany and France both have reserves covering around 2 months of demand). With a reach of only around 1 hour (Germany), today the storage of electrical energy plays a very subordinate role. The possibility to outsource the storage capacity to fossil fuels will decrease more and more in a future electricity-based energy industry, i.e. the long-term storage capacities for electrical energy will have to be much longer than 1 hour.

In recent years pumped hydro and compressed air energy storage (CAES) systems were almost exclusively seen as suitable methods for balancing out fluctuating wind and PV feed-in into the transmission grids. In contrast, the latest investigations - and particularly the comprehensive study published by VDE /1/ have identified the limitations of these storage technologies, particularly with respect to total storage capacities. Hydrogen alone can facilitate the storage of large quantities of energy to balance out long periods of poor wind power supply and seasonal fluctuations. Hydrogen large scale storage will be the only means in the long term to provide electrical energy in quantities and at a quality level consumers are accustomed to, in parallel to the downscaling of major capacities from fossil power plants and nuclear power stations. Furthermore, the relevant large volumes which need to be stored can most likely only be accommodated underground in geological formations – primarily in man-made salt caverns.

SUPPLYING FUEL CELL VEHICLES WITH HYDROGENUPPLYING FUEL CELL VEHICLES WITH HYDROGEN
The limited range and low storage capacity of battery electric vehicles as well as the limited availability of biofuels limiting its long term use to heavy duty transport such as trucks, rail and aircraft, require the use of hydrogen powered fuel cell vehicles for a wide range of vehicle segments. After a transition phase, hydrogen needs to be mainly produced from renewable electricity such as wind and solar power. Also for the transport sector it will be necessary to balance out seasonal fluctuations and to build up reserves to prepare for shortfalls, etc.

Most of today’s infrastructure investigations on future hydrogen supply have either addressed the development of hydrogen demand or the build-up of hydrogen refuelling stations including onsite hydrogen storage capacities as well as onboard hydrogen storage.

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