Hydrogen Underground Storage in Porous Reservoirs
European potential for hydrogen storage in depleted gas fields and aquifers
UHS potential
This story map provides information about the potential for underground hydrogen storage (UHS) in existing European gas storage sites - the depleted gas fields and aquifers collectively termed "porous reservoirs". It is one of the deliverables of the HyUSPRe project , a consortium of organizations across research and industry working together to establish the feasibility and potential of implementing hydrogen energy storage in porous reservoirs across Europe.
The potential for hydrogen storage in porous reservoirs consists primarily of depleted gas fields, and to a much lesser degree, aquifers. The known reserve of operational and planned natural gas storage sites in Europe - 86% depleted gas fields and 14% aquifers – if converted, provides up to 415 TWh of hydrogen storage capacity. Most hydrogen storage sites will have a capacity of 1-5 TWh, and will mostly be developed in relatively small, depleted gas fields hosted in sandstone reservoirs at a depth of 500-2,500 m. Additionally, a small number of large sites, 10-20 TWh, will probably be developed, which are typically deeper and have lower working gas-to-cushion gas ratios, reflecting the higher operational reservoir pressure conditions. Aquifers and carbonate reservoirs will most likely make a fractional contribution to storage.
The 415 TWh of hydrogen storage capacity represents a 17% storage share for a mid-range scenario of 2,500 TWh of annual hydrogen demand. Factoring in a possible contribution of 50 TWh from salt cavern storage conversion - not addressed in this project - the total capacity through conversion of existing and planned sites approaches 20% of annual demand. The current European average for natural gas storage is 30%. The HyUSPRe longlist indicates that, even for scenarios with a high displacement of natural gas storage by hydrogen, the reserve will need to be augmented with additional storage capacity.
The interactive map above shows the location and potential hydrogen capacity of depleted gas fields (green circles) and aquifers (blue circles) currently used for storing natural gas. It also shows the 2040 pipeline network for hydrogen transport (orange lines) as envisioned by the European Hydrogen Backbone initiative ( www.ehb.eu) . The circle size indicates the high-end estimate of storage capacity for hydrogen in 140 existing and planned natural gas storage sites. Closed and planned sites are ringed in red and yellow respectively. Additional data is displayed in a pop-up window when a site is selected on the map.
The European portfolio is divided into four regions: Northwestern, Central, Eastern, and Southern; and reviewed by countries within those regions. The figure below shows the regional and country-level potential for hydrogen storage in porous reservoirs that are currently used for storing natural gas. The potential hydrogen storage capacity of existing sites lies between 375 (low-end) and 450 TWh (high-end). Further scrutiny of the longlist also excluded a number of sites (mainly in Ukraine), which reduced the high estimate to 415 TWh. The reported range reflects the two methodologies used for capacity conversion: the low-end is based on energy density; the high-end is based on withdrawal rate and the ratio of working gas to cushion gas – see the deliverable D1.5 ( link ) of the HyUSPRe project for more detail. More than half of the capacity is located in Italy, the Netherlands, and France – the top-three countries with highest potential.
*Ukraine, 9 sites excluded: BVU as an extreme outlier; 8 sites as not on EHB network
The information for the atlas is stored in the HyUSPRe database. This database, which is largely resourced with public data from Gas Infrastructure Europe (GIE) and the International Gas Union (IGU), includes site-specific data for 140 existing and planned underground gas storage sites in porous reservoirs. The site-specific data include the storage capacities and performance of storage sites for natural gas, as reported by the operators, and hydrogen, as estimated in this project, which are further detailed in the linked report , D1.5, cited above.
Northwest Europe
Introduction to region
The Northwest region includes storage sites in the Netherlands, Germany, Denmark, Belgium, Ireland, and the UK. The total capacity for hydrogen storage lies between 86 and 127 TWh. The regional sites consist of 8 aquifers and 21 depleted gas fields. The region is notable for a small number of large storage sites with some of the highest performance metrics in Europe.
Belgium
Belgium has one entry in the HyUSPRe longlist, Loenhout, an aquifer located in the northwest of the country close to the trunkline from the Netherlands to France. The site is owned and operated by Fluxys. Gas is stored is in a tight carbonate reservoir of Dinantian age at a depth of 1080 m. The potential capacity for hydrogen storage is 2-3 TWh. Both the depth and the size of this site are close to the average for European storage.
Denmark
Denmark has one porous reservoir storage site at Stenlille, west of Copenhagen and close to the Baltic Pipe interconnector between Poland and the North Sea. Gas is stored in a sandstone aquifer, the Gassum formation, at a depth of 1600 m. Stenlille is operated by Gas Storage Denmark. Conversion of Stenlille would provide 1.5-2 TWh of hydrogen storage capacity.
Germany
Germany has the second largest and most diverse portfolio of gas storage sites in Europe with a combined storage capacity for natural gas of 258 TWh, of which 96 TWh is in porous reservoirs (37%) and 162 TWh in salt caverns (63%). The largest storage site, Rehden, is a depleted gas field, 45 TWh. Most of the salt caverns are located in the northwest of the country.
Germany has eleven sites in depleted gas fields: 10 operational, 1 closed. Germany also has 6 small aquifer sites located in the middle of the country between Frankfurt and Nuremberg. These account for about 5 TWh or 2% of the country’s natural gas storage capacity. The potential for hydrogen storage in re-purposed porous reservoirs lies between 24 and 28 TWh.
Germany lies at the centre of a network of trunklines that connect the northwestern storage cluster and Netherlands and North Sea supply into eastern and central Europe and France to the south. German gas storage plays a pivotal role in balancing regional demand, helping to secure European supply in the event of disruptions.
Ireland
Ireland has one planned site, a depleted gas field at Kinsale Head with a capacity of 1.5 to 2 TWh for hydrogen storage. Kinsale Head is one of three sites being considered. The other two are Poolbeg salt caverns in Dublin Bay and a depleted gas field in the Shannon estuary.
The Netherlands
The Netherlands has the third largest porous reservoir inventory in Europe: four storage sites in depleted gas fields, operated by NAM and TAQA, with a total natural gas storage capacity of 140 TWh. These are Alkmaar, 5 TWh, Grijpskerk, 28 TWh, Bergermeer, 48 TWh, and Norg, 59 TWh. Norg and Bergermeer are among the largest sites in Europe - the European average is 9 TWh. The reservoirs are also deep, at a depth of 2000 to 3500 m below the surface and are sealed by Zechstein salt. The unusually large sites reflect their supporting role for Groningen, the ageing supergiant gas field.
The Netherlands has the potential to store large amounts of hydrogen, with a vast portfolio of onshore and offshore depleted gas fields, a strategic location, proximity to the emerging wind farm industry of the North Sea, and a historic role in trans-national network balancing. The existing gas storage sites, when re-purposed, have a potential hydrogen storage capacity that lies between 35 and 60 TWh.
United Kingdom
The United Kingdom has a surprisingly small provision for natural gas storage. The current capacity is 15 TWh: 11 TWh from six onshore salt caverns and 4 TWh from two depleted gas fields. This represents less than 2% of the UK's total natural gas demand in 2020 at 854 TWh.
The UK’s gas storage capacity has always been low by European standards, reflecting its once-privileged access to production reserves in the North Sea, and more recently, the closure of the main storage site, the offshore Rough Gas Storage Facility, 30 TWh, and a related strategic policy decision to rely on just-in-time deliveries of shipped LNG.
Rough and two neighbouring depleted gas fields, Deborah and Baird, are in the HyUSPRe long list of 140 potential porous reservoir sites for hydrogen storage in the future. These three sites along with two small onshore operational sites, Humbly Grove and Hatfield Moor, can potentially provide 22 to 29 TWh of hydrogen storage capacity.
Central Europe
Introduction to region
The Central region has 22 storage sites across Austria, Croatia, Czechia and Slovakia: 21 depleted gas fields and only one aquifer, Lobodice. Their combined hydrogen storage potential is between 46 and 54 TWh. The western Austrian sites are clustered with the southern German sites of the northwestern region.
Austria
The natural gas storage capacity of Austria, 100% of annual demand, reflects its role as a transit hub for natural gas from the east. The gas is stored over the summer and distributed to central and western Europe in the winter. Only a fraction of the capacity is for domestic use. The country has nine operational gas storage sites, all of which are depleted gas fields. In the northwest, close to the German border, six sites are grouped into three localities: Puchkirchen, 17 TWh; Haidach, 31 TWh, and 7 Fields, 20 TWh. All six sites are operated by RAG. Combined with storage in the northeast, operated by OMV, this sums to a total storage capacity for natural gas of 95 TWh. Additional storage capacity can potentially be created in neighbouring depleted gas fields. The potential capacity for hydrogen is between 24-29 TWh.
Croatia
Croatia has one depleted gas field, Okoli, 5 TWh, operational since 1988, and a small, neighbouring planned site, 0.29 TWh. The potential for hydrogen storage is 1.5-2 TWh.
Czech Republic
Czechia has twelve operational gas storage sites: one aquifer with 2 TWh storage capacity, and eleven depleted hydrocarbon fields, with a total storage capacity of 43 TWh. The eleven hydrocarbon fields are a mixture of gas fields and oil fields with gas caps, mainly clustered in the southeast. A small 0.43 TWh expansion is planned for one depleted gas field, at Uhřice. The potential storage capacity for hydrogen is between 10 and 12 TWh.
Slovakia
Slovakia has two depleted gas field sites at Láb, 43 TWh, close to the western border and part of the large Central cluster. A depleted gas field site, 4 TWh, is planned on the eastern border. The potential hydrogen capacity is between 12 and 21 TWh.
Eastern Europe
Introduction to region
The Eastern region has 41 operational and planned storage sites across Bulgaria, Hungary, Latvia, Poland, Serbia and Ukraine with a potential for hydrogen storage that lies between 132 and 160 TWh. The region has 38 depleted gas fields and 3 aquifers.
Bulgaria
Bulgaria has a single storage site, Chiren, near the northwest border: a depleted gas field, 6 TWh, with a 5 TWh expansion planned. The potential hydrogen storage capacity lies between 3 and 4 TWh.
Hungary
Hungary has five storage sites, all depleted gas fields, total natural gas storage capacity of 70 TWh. Hajdúszoboszló in the northeast, 18 TWh; Pusztaederics in the west, 4 TWh; and three sites close to the southeastern border including two large sites, Zsana, 24 TWh; and Szöreg, 20 TWh. The potential storage capacity for hydrogen is between 18 and 21 TWh.
Latvia
Latvia has one site, Inčukalns, a large aquifer store inland from Riga, 24 TWh. The site historically buffered gas supplies from Ukraine for the Baltic region in the Soviet era. The site continues to stabilise seasonal supplies in the region, meeting domestic winter demand for Latvia, Estonia, northwestern Russia, and, to a lesser degree, Lithuania. The potential hydrogen storage capacity lies between 6 and 7 TWh.
Poland
Poland has seven depleted gas field storage sites and three salt caverns. Three of the seven depleted gas field storages are situated in the west of the country between the Baltic Sea and Wroclaw in the south. Four are clustered in the southeast of country near the Ukrainian border. Four of the sites are relatively small at less than 3 TWh compared to the European average of 9 TWh. One site, Wierzchowice, 15 TWh, accounts for half the country’s porous reservoir storage. The potential hydrogen storage capacity lies between 7 and 12 TWh.
Romania
Romania has six operational storage sites, all depleted gas fields, with a total storage capacity of 33 TWh. Three are clustered around the capital, Bucharest, including the largest site, Bilciuresti, 14 TWh. Two are in the northwest, and one in the south, with one planned in the north. Three of the existing sites have expansions planned, 8 TWh. The potential hydrogen storage capacity lies between 11 and 14 TWh.
Serbia
Serbia has one storage site, Banatski Dvor, 5 TWh, a depleted gas field between Belgrade and the Hungary cluster to the north. Two expansions are planned, 5 TWh. The potential hydrogen storage capacity lies between 2.5 and 3 TWh.
Ukraine
Ukraine has the largest natural gas storage capacity in Europe at 339 TWh. The large capacity speaks to its long history of gas production and the two markets it serves in the east and west.
The inventory consists of two aquifer stores in the north, close to the borders with Belarus and Russia, and eleven depleted gas fields: a cluster of five in the northwest, close to the border with Poland; five sites dispersed across the eastern half of the country, and one site located near the Black Sea on the Crimean peninsula.
The western cluster contains the largest storage site in Europe, Bilche-Volytsko-Uherske, 179 TWh. The four other sites in the cluster are all larger than 20 TWh. The potential hydrogen capacity for Ukraine is between 85 and 101 TWh.
Southern Europe
Introduction to region
The Southern region includes France, Greece, Italy, Spain, and Turkey. This is the only region with a large number of aquifers, primarily in France. The region is also notable for a large number of planned additional methane gas storage sites, primarily in Italy. The Southern inventory consists of 14 aquifers and 34 depleted gas fields with a potential hydrogen storage capacity that lies between 115 and 138 TWh.
France
France has the fourth largest porous reservoir storage inventory in Europe and is dominated by large aquifer sites. There are 11 operational aquifer stores, 130 TWh, two closed aquifers abd one closed depleted gas field: Serene Sud, Soings-en-Sologne and Trois Fontaines l’Abbaye. The predominance of aquifer storage is potentially explained by the country’s historic access to abundant and low-cost domestic natural gas during the planning and construction phase of their aquifer stores, which as strategic national infrastructure, were subsidised by the state. The potential hydrogen storage capacity of the French aquifer storage sites lies between 33 and 39 TWh.
Outside of France, a small number of countries have one aquifer site: Latvia, Belgium, Denmark, Spain, and Czechia. Germany has five small aquifer storage sites situated between the salt caverns of the north and large depleted gas field sites of the northwest and southeast.
Greece
Greece has planned a small methane gas storage site, South Kavala, 4 TWh, on its northeast coast, with a hydrogen storage potential of 1 TWh.
Italy
Italy has Europe’s second largest porous reservoir inventory: 197 TWh of natural gas storage capacity in 13 depleted gas fields, with another 49 TWh in planned expansions, also in depleted gas fields. This high storage provision – one of only four countries in the European Union with more than 100 TWh of operational gas storage in porous reservoirs – reflects Italy’s domestic natural gas demand; Italy is the third largest consumer of natural gas in Europe after Germany and the UK, and the second largest importer after Germany. Storage is clustered close to the upper Po valley industrial hub and the densely populated Lombardy.
Large storage sites are also strategically located in the northeast, to buffer networked gas from the east, and along the Adriatic coast, close to land-fall ports for shipped LNG, mostly from Algeria. The potential hydrogen storage capacity lies between 61 and 74 TWh.
Spain
Spain has a small number of strategically located storage sites: three depleted gas fields and one aquifer, with a combined natural gas capacity of 34 TWh. Spain has an annual domestic demand of 360 TWh and imports much of its natural gas, with a roughly equal share between networked gas and LNG. Storage capacity is relatively low for Europe at 9% of demand. Two sites were constructed in the early 1990s: Serrablo in the Pyrenees, 8 TWh, and Gaviota, 8 km offshore in the Bay of Biscay, 11 TWh. Two more sites were added in 2012: Yela, the only aquifer site, 12 TWh, is situated close to centre of the network; and Marismas on the southern Atlantic coast, 3 TWh. The potential hydrogen storage capacity lies between 9 and 11 TWh.
Turkey
Turkey has a large, depleted gas field store, Silivri Marmara, 29 TWh, operating since 2010 in the Marmara Sea near Istanbul. The potential hydrogen capacity is between 11 and 13 TWh.
Cluster Analysis
The longlist of 140 sites is used for cluster analysis and shortlist selection of so-called ‘exemplars’ and ‘prototypes’ (explained further down).
The map below identifies a number of clusters for the European distribution of existing storage with hydrogen storage potential. The seven largest clusters are found across the Northwestern, Central, Eastern and Southern regions. Clusters with dashed outlines are not included in the analysis. Hydrogen storage (research or pilot) projects are also shown on the map with blue "H 2 " symbol (GIE, 2021). They are mostly in the very early stages of development, with the exception of the ongoing Underground Sun Storage 2030 pilot project ( USS2030 ) with pure hydrogen in Austria. Sites within each cluster were scrutinized for available metrics, including depth, temperature, pressure, and permeability, going beyond the basic capacity and location data archived in the longlist. These allow the clusters to be profiled for norms, outliers, and anomalies.
Representative sites for each cluster are selected as ‘exemplars’, and the average values used to construct a profile for a ‘prototype’ site, which gives a reasonable indication of how representative the exemplar is of the cluster. The exemplars and prototypes are intended as an aid to locating and estimating the size of additional sites for existing clusters, and as a general indication of how a region may address gaps between future hydrogen storage demand and existing storage with conversion potential.
Shortlist
The longlist analysis concluded that regional distributions were frequently clustered in areas of significant storage capacity that bridged country borders. As such, the shortlist applies a cluster analysis to identify similarities and differences in these regionally significant concentrations of storage sites.
The short list of 10 exemplars and 10 prototypes are derived from the HyUSPRe longlist that looks forward to the possible location, capacity, and characteristics of future hydrogen storage sites. The veracity of these indications is dependent on our main assumption, which is that the hydrogen storage network will closely resemble the natural gas storage network, both with respect to capacity, distribution, and common storage characteristics.
The shortlisted exemplars (10 sites) are shown on the map below with green and blue circles for depleted gas fields and aquifers. The remaining sites (130) are highlighted with grey circles.
The shortlisted exemplars and prototypes are summarised in the tables below, taken from deliverable D1.5 ( link ), with the upper and lower values for each parameter shaded. Non-public data is indicated with hashtags (#). The main outcome is that many of the clustered sites are similar with respect to capacity and depth. The exceptions are the large, deep sites exemplified by the northwest, and the shallow depleted gas fields of the central and eastern clusters, and shallow aquifers of France. The latter are notable for low temperatures, and high permeabilities. With the exception of temperature, the metrics tend to have discrete ranges. Three prototypes, B, C, and G are labelled as ‘typical’, with similar capacities, 3 TWh, and storage depths of approximately 1.5 km, both close to the European average. The prototypes indicate minor variations for depth (shallow, D and F), temperature (hot, H), capacity (small, E), field size (area, I) and type (aquifer, J).
EU capacity scenarios
According to deliverable D1.3 ( link ) of HyUSPRe, for the low-to-mid-range demand scenarios, a European hydrogen economy may require 250 to 500 TWh of storage capacity. This could be up to 1,200 TWh for 'high demand' scenario. To fulfill this storage capacity requirement, the portfolio of existing gas storage sites represents a highly mature contingent resource of 320 to 415 TWh. However, considering that only a fraction of this resource (15% according to DNV-GL , our 'low supply' scenario) might actually be converted to hydrogen storage before 2050, additional storage sites must be developed to close the gap between future hydrogen storage demand and existing storage with conversion potential.
As an example, we assume a high demand-low supply scenario (HDLS) in 2050, for which 400 additional sites (1000 TWh) would be required to match 30% of annual demand. By combining some general observations from the longlist and shortlist analyses we can speculate on the scale and distribution of hydrogen storage in 2050 for this scenario, which may be considered an edge case. As explained before, we assume that the mature storage network for hydrogen may have a similarly distribution to that of natural gas storage, with a small number of large sites and large number of small sites. This is actually reflected in the cluster analysis, which ranges from 2-5 TWh for nine of the prototypes and 16 TWh for just one of the prototypes (see tables above).
The figure below shows the HDLS capacity curve for adding 1000 TWh of storage capacity in porous reservoirs (400 hydrogen storage sites) overlain on the map of the HDLS cluster distribution. The log-normal trend in the hydrogen network shows that 70% of the storage capacity is in just 30% of the sites and 90% in just over 50% of the sites (orange dashed lines). Bubbles are scaled with hydrogen storage capacity, the smallest representing 10 TWh or 1% and the largest, 150 TWh or 15% of HDLS. Mid-demand and low-demand scenarios of 500 and 250 TWh have the same distribution for 200 and 100 sites respectively.
Supply corridors, as envisioned by the EHB initiative ( EHB, 2022 ), are depicted as arrows. It is notable that the storage distribution maps well to these supply corridors for hydrogen transport from regions of high production to areas of high demand. The concentration of existing sites and network connections into discrete clusters suggests that these locations will see the first full-scale hydrogen storage sites.
About HyUSPRe
For more information about HyUSPRe projects, please visit our website.
Project Partners
Acknowledgement
The analysis has relied on publicly available data, especially the GIE storage database (GIE, 2021) and IGU database (IGU, 2022). We are grateful to these organizations for their efforts to communicate detailed technical information transparently.
The HyUSPRe project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under grant agreement No 101006632. This Joint Undertaking receives support from the European Union’s Horizon 202 research and innovation programme, Hydrogen Europe and Hydrogen Europe Research
Disclaimer
This story map reflects the views of the author(s) and does not necessarily reflect the views or policy of the European Commission. Whilst efforts have been made to ensure the accuracy and completeness of this story map, the HyUSPRe consortium shall not be liable for any errors or omissions, however caused.
