H2 storage needs to exceed existing gas storage: GIE

Hydrogen storage capacity needed in Europe would fall "far short" of demand by 2050, even if all available gas storage facilities were repurposed, gas infrastructure body GIE said in a report based on a proposed European Hydrogen Backbone (EHB) project.

The report focuses on 19 EU member states, as well as the UK and Switzerland, the same framework used by EHB. Maximum possible hydrogen storage capacity in these 21 countries using existing gas storage sites could reach 264.7TWh by 2050, according to GIE, but this would be well below storage needs of 466.4TWh, based on the ratio of gas storage capacity to estimated demand (see table).

The group identifies about 1.1PWh of working gas capacity in these countries with demand of about 4.62 PWh/yr, but the much lower volumetric energy density of hydrogen compared with natural gas would greatly reduce the energy that can be stored in existing storage site.

Repurposing all salt caverns — the most suitable sites for large-scale hydrogen storage — could provide about 50TWh of hydrogen storage space by 2030. But this would also be insufficient to meet hydrogen storage needs of 72.2TWh. And the majority of this space would be concentrated in Germany, which would account for 39.5TWh of Europe's salt cavern storage.

Other storage facilities far behind

Salt caverns are the only kind of storage facility whose suitability for hydrogen is already proven, according to GIE's report.

Hydrogen is already being stored in salt caverns in Teesside in the UK, as well as in Texas.

First hydrogen storage is expected at a lined rock cavern site in Sweden in 2022, and studies on hydrogen storage in depleted gas fields and aquifers are continuing.

Still, porous structures such as depleted gas fields and aquifers are "showing fair potential to cover further storage needs for pure and blended hydrogen", GIE said.

The group expects that the levelised cost of hydrogen storage will be cheapest in salt caverns, followed by depleted gas fields, aquifers and hard rock caverns.

Total potential hydrogen storage capacity of salt caverns in Europe is about 85PWh, of which 23PWh is located onshore, according to a 2020 study cited by GIE. Offshore capacity is concentrated in salt domes under the North Sea, but the economic and ecological viability of such caverns is still unclear.

While this would be more than enough capacity to meet Europe's needs, exploiting it would require "a tremendous number" of sites to be developed, GIE said. And the high concentration of caverns in northwest Europe and a few clusters in the continent would make balancing a hydrogen network difficult because many countries would not have access to them. There are considerable barriers to development and major practical limitations to relying on salt caverns alone, GIE said.

Repurposing existing storage sites could take 1-7 years, depending on existing infrastructure, while the development of new sites would take 3-10 years, it said.

Salt caverns typically take 3-7 years to develop, with much of that period taken up by permitting, and depleted gas fields and aquifers — which would account for 215TWh of hydrogen after repurposing — take 3-10 years to be developed.

But it is difficult to generalise findings for underground storage because of the varying geological characteristics of each site, GIE said.

By Auguste Breteau