Hydrogen economy in need of substantial storage capacity

Hydrogen is a great white hope of the energy transition, as it is considered to be a key to decarbonising industry, for instance in steel production and the chemical sector. It is the envisaged fuel for trains, lorries, ships and – farther down the road – even airplanes. Moreover, it could help heat our homes in the winter. The European Commission expects green hydrogen, which is produced using renewable energy sources, will account for up to 14 percent of energy supply by 2050. This compares to some two percent at present.

Plans foresee hydrogen being produced above all in windy areas, namely in offshore wind farms or coastal regions. However, this means that it will have to be transported and stored in huge amounts and over long distances. Transportation and distribution are expected to be handled by a large pan-European network of pipelines, referred to as the European Hydrogen Backbone (EHB), acting as the main connector of 19 EU member states as well as Switzerland and the United Kingdom.

This vision has been taken onboard by Gas Infrastructure Europe (GIE), which has calculated the need for hydrogen storage capacity in 2030 and 2050 in a study co-authored with business consultancy Guidehouse. Also included in the paper is an outlook on storage capacity in Europe, highlighting its significant role in building a hydrogen network. In addition, the report addresses conversion and retrofit options for existing storage facilities as well as geographical availability and restrictions.

Initial need assessments aim high

GIE bases its computation of required storage capacity on the current ratio of gas storage capacity to annual gas consumption, from which it derives the future need for hydrogen. Distributed across the 21 countries forming the hydrogen backbone, the study finds that gas storage capacity totals approximately 1,096 terawatt hours (TWh). Germany’s roughly 228 TWh in storage capacity rank the country among the frontrunners in Europe, followed by Italy and the Netherlands. However, the aggregate need for gas amounts to 4,624 TWh. Accordingly, Europe’s storage capacity currently accounts for about 24 percent of annual demand.

Applying this ratio to hydrogen, based on anticipated demand for hydrogen, the study’s authors arrive at a storage need throughout Europe of approximately 70 TWh in 2030 and 450 TWh in 2050. For the time being, these figures are rough estimates, as prognoses regarding future hydrogen demand in Europe vary strongly. “This first assessment is not based on a deep dive. Furthermore, anticipated hydrogen demand is much higher than currently envisaged for example by politicians in Germany. Therefore, these figures are more ballpark than anything else and will become more accurate in the coming months,” says Jörg Albers, Senior Manager Sales & Regulation at RWE Gas Storage West GmbH.

At first glance, storage needs do not appear to be particularly substantial compared to existing capacity. However, hydrogen has a much lower energy density and different compression profile than gas. This means that the storage volume required for hydrogen is roughly five times higher than for the same amount of gas. In other words, 70 TWh in hydrogen storage capacity translates into approximately 350 TWh in gas storage capacity. Another hurdle that needs to be taken is that some gas storage facilities cannot accommodate hydrogen. Potentially usable storage systems must thus be converted.

Extensive underground storage: salt caverns especially well suited

According to the study, subterranean storage systems are generally the most effective solution when it comes to storing large quantities of hydrogen over long periods. Salt caverns are the underground storage sites especially well-suited to fulfil this purpose. These systems are large artificial cavities in rock salt formations, situated at a depth of some 1,000 metres. Prevailing air pressure and the properties of the salt deposits make these stores extremely tight and gas impermeable. Worldwide, salt caverns house three hydrogen storage facilities, one of which is located in Europe. Salt caverns have been used for this purpose for over 50 years in Teesside, Great Britain.

So far, only pure hydrogen can be stored successfully in salt caverns. However, the study finds that other underground storage options also harbour potential: depleted porous rock reservoirs, aquifers and rock caverns. The study’s authors believe it is important to explore these storage options as well given the geographic limitations to creating salt caverns. Salt caverns in the 21 EHB countries have a (theoretical) hydrogen storage capacity of a mere 50 billion kWh. This would not even suffice to meet demand in 2030 calculated by GIE.

GIE predicts that the lion’s share of hydrogen demand until 2030 will be concentrated in certain regions, referred to as hydrogen valleys, which will largely manage their hydrogen supply locally. Subterranean storage systems will form a central part of these hubs. From 2030 to 2050, supply and demand will continue to rise, and a densely spun pan-European hydrogen network will emerge beyond the valleys. Building and converting gas storage facilities will take some time. Gas Infrastructure Europe thus calls for the earliest possible creation of storage options in order to support the construction of a Europe-wide hydrogen network.