A detailed comparative performance study of underground storage of natural gas and hydrogen in the Netherlands

With the expected increase in the use of hydrogen as an energy carrier, large-scale underground storage sites will be needed. Unlike underground natural gas storage (UGS), many aspects on the performance of underground hydrogen storage (UHS) are not well understood, as there is currently no UHS in use for energy supply. Here we present the results of a detailed comparative performance study of UGS and UHS, based on an inflow/outflow nodal analysis. Three UGS sites in depleted gas fields and one in a salt cavern cluster in the Netherlands are used as case studies. The results show that although hydrogen can be withdrawn/injected at higher rates than natural gas, this can be limited by technical constraints. It also indicates that wider ranges of working pressures are required to increase the storage capacity and flow performance of an UHS site to compensate for the lower energy density of hydrogen.     

A review on worldwide underground hydrogen storage operating and potential fields

Overreliance on fossil fuels for human energy needs, combined with the associated negative environmental consequences in terms of greenhouse gas emissions, has shifted our focus to renewable energy sources. Hydrogen has been identified by researchers as an energy source. Hydrogen is a non-carbon-based energy resource that has the potential to replace fossil fuels. This resource is seen as an alternative fuel since it may be produced using environmentally friendly methods.Hydrogen storage is a critical component of the hydrogen economy, particularly when hydrogen utilization on a large scale is required. This paper presents a review of worldwide underground operating and potential sites to provide a clear understanding of the current status of hydrogen storage in the world.The literature survey indicated that underground geological structures have been used to successfully store hydrogen. Some of the criteria used to select these sites for underground hydrogen storage include but are not limited to geological conditions, storage location, availability of brine, presence of insoluble impurities such as dolostone, limestone, or shale, and socio-economic characteristics.The key issues with the hydrogen storage in the subsurface geological structures include but are not limited to microbial, hydrogeological, hydrodynamics, geomechanics, and geochemical facilitated by injected hydrogen which significantly impact the success and operational efficiency of the projects.     

Hydrogen tightness evaluation in bedded salt rock cavern: A case study of Jintan,China

Hydrogen is regarded as one of the most important energy sources for the future. Safe, large-scale storage of hydrogen contributes to the commercial development of the hydrogen industry. Use of bedded salt caverns for natural gas storage in China provides a new option for underground hydrogen storage (UHS). In this study, the physical properties of multicomponent gases in UHS and salt rock are reviewed and discussed, along with the flow of hydrogen in the surrounding salt rock. Mathematical models of the two-phase multicomponent flow of the gas–brine system in the UHS were established. A numerical model of a simplified elliptical salt cavern was built to simulate the migration of the gas–brine system in the UHS. The hydrogen tightness of the UHS was evaluated through simulation with different storage strategies, salt rock and interlayer permeabilities, and gas components. The results indicate that: (1) Cyclic injection and withdrawal facilitate hydrogen leakage, which is accelerated by increasing the frequency. (2) The huff-n-puff of hydrogen gas in the injection and withdrawal cycles forces the gas into pore space and enhances the relative permeability of the gas phase. The migration of hydrogen and brine weakens the hydrogen tightness. Brine saturation is an important index for evaluating the hydrogen tightness of UHS. (3) The leakage rate of UHS increases with an increase in the permeability of the salt rock and interlayer and the total thickness of the interlayers. The average permeability K_wa weighted by the thickness of layers for the bedded salt formation is proposed to integrate three variables to facilitate field application of the simulation results. The critical K_wa is less than 3.02 × 10⁻¹⁷ m² if the recommended annual hydrogen leakage rate is less than 1%. (4) The difference between hydrogen and other gas species is another important factor in the leakage rate and should be considered. This study provides theoretical guidance for evaluating the feasibility of UHS in salt caverns and site selection in China.     

Underground hydrogen storage to balance seasonal variations in energy demand: Impact of well configuration on storage performance in deep saline aquifers

Grid-scale underground hydrogen storage (UHS) is essential for the decarbonization of energy supply systems on the path towards a zero-emissions future. This study presents the feasibility of UHS in an actual saline aquifer with a typical dome-shaped anticline structure to balance the potential seasonal mismatches between energy supply and demand in the UK domestic heating sector. As a main requirement for UHS in saline aquifers, we investigate the role of well configuration design in enhancing storage performance in the selected site via numerical simulation. The results demonstrate that the efficiency of cyclic hydrogen recovery can reach around 70% in the short term without the need for upfront cushion gas injection. Storage capacity and deliverability increase in successive storage cycles for all scenarios, with the co-production of water from the aquifer having a minimal impact on the efficiency of hydrogen recovery. Storage capacity and deliverability also increase when additional wells are added to the storage site; however, the distance between wells can strongly influence this effect. For optimum well spacing in a multi-well storage scenario within a dome-shaped anticline structure, it is essential to attain an efficient balance between well pressure interference effects at short well distances and the gas uprising phenomenon at large distances. Overall, the findings obtained and the approach described can provide effective technical guidelines pertaining to the design and optimization of hydrogen storage operations in deep saline aquifers.     

Underground hydrogen storage in a naturally fractured gas reservoir: The role of fracture

As hydrogen provides a high heating value with the least environmental impact, it can be considered as an energy carrier pioneer in following the global zero-carbon policies. Then, since storing hydrogen in large quantities can also be a valuable technique for alleviating energy shortages due to energy consumption fluctuations, underground hydrogen storage (UHS) is being explored further in today's world. To the best of our knowledge, the role of fracture on underground hydrogen storage performance has not comprehensively been evaluated. For the first time, in this study, the effects of fracture on hydrogen storage and production were investigated in a naturally fractured gas reservoir in the Middle East using a numerical simulation. Then, to determine whether the fracture was able to accelerate hydrogen production, UHS was evaluated under various conditions, including the fracture system, condensate presence, Initial hydrogen injection stage, cushion gas type, hydrogen storage commence time and different injection/production cycle duration. The results of this study proves that although a huge amount of hydrogen is invaded into the matrix during hydrogen injection, the fracture accelerates hydrogen production, resulting in higher hydrogen recovery and purity, which indicates fractures are suitable media for hydrogen storage. However, it should be noted that the purity of hydrogen produced from naturally fractured reservoirs (NFR) decreases more rapidly than a conventional one during a single cycle due to the higher mixing of gases in the fracture. In the case of the initial stage of hydrogen injection, fractures are not found to be attractive as storage media. Therefore, it is necessary to analyze the fracture effects as a storage media under various situations and stages. In addition, alternative gas injection revealed that nitrogen injection into cushion gas resulted in the highest hydrogen production in the entire porous media, whereas methane injection led to the highest hydrogen recovery in the fracture media. Also, the rapid injection/production cycle duration improved hydrogen recovery, indicating that the required time for high hydrogen invasion into the matrix is not provided during hydrogen injection.     

Impact of experimentally measured relative permeability hysteresis on reservoir-scale performance of underground hydrogen storage (UHS)

Underground Hydrogen Storage (UHS) is an emerging large-scale energy storage technology. Researchers are investigating its feasibility and performance, including its injectivity, productivity, and storage capacity through numerical simulations. However, several ad-hoc relative permeability and capillary pressure functions have been used in the literature, with no direct link to the underlying physics of the hydrogen storage and production process. Recent relative permeability measurements for the hydrogen-brine system show very low hydrogen relative permeability and strong liquid phase hysteresis, very different to what has been observed for other fluid systems for the same rock type. This raises the concern as to what extend the existing studies in the literature are able to reliably quantify the feasibility of the potential storage projects. In this study, we investigate how experimentally measured hydrogen-brine relative permeability hysteresis affects the performance of UHS projects through numerical reservoir simulations. Relative permeability data measured during a hydrogen-water core-flooding experiment within ADMIRE project is used to design a relative permeability hysteresis model. Next, numerical simulation for a UHS project in a generic braided-fluvial water-gas reservoir is performed using this hysteresis model. A performance assessment is carried out for several UHS scenarios with different drainage relative permeability curves, hysteresis model coefficients, and injection/production rates. Our results show that both gas and liquid relative permeability hysteresis play an important role in UHS irrespective of injection/production rate. Ignoring gas hysteresis may cause up to 338% of uncertainty on cumulative hydrogen production, as it has negative effects on injectivity and productivity due to the resulting limited variation range of gas saturation and pressure during cyclic operations. In contrast, hysteresis in the liquid phase relative permeability resolves this issue to some extent by improving the displacement of the liquid phase. Finally, implementing relative permeability curves from other fluid systems during UHS performance assessment will cause uncertainty in terms of gas saturation and up to 141% underestimation on cumulative hydrogen production. These observations illustrate the importance of using relative permeability curves characteristic of hydrogen-brine system for assessing the UHS performances.     

Analysis of the problem of optimal placement and capacity of the hydrogen energy storage system in the power system

Nowadays the trend of increasing the generation units based on renewable energy sources in the electric power system can be observed. Obviously, this is due to the intensifying level of consumer load and demand for electricity. However, renewable generation is characterized by intermittent energy production, which can cause and potential imbalance between generation and demand, especially during off-peak periods. Therefore, in order to ensure a reliable power supply to consumers, it is necessary to use a maneuverable reserve of capacity, such as energy storage systems, in conjunction with the renewable energy source unit. Over the past 10 years, the energy storage market has grown by almost 50%: the installed capacity of energy storage system in the world is about 5 GW. Analysis of the literature on the subject determines the need to study the impact of these devices on the parameters of electric power systems and one of the primary tasks is to determine the optimal location and capacity of energy storage system in the power system. This paper presents the result of solving the task of determining the optimal parameters of a hydrogen energy storage system using the particle swarm optimization method for example a test scheme radial distribution system – 33 bus IEEE. The choice of the type of energy storage is based on such advantages of a hydrogen energy storage system as environmental friendliness, high energy capacity and the ability to store electricity for a long period of time. In addition, compared to lithium-ion batteries, hydrogen energy storage systems have a long life time of about 25 years, during this period of time there is no degradation and significant deterioration of its properties. All these advantages of hydrogen as an energy carrier allow to take into account not only the criterion of total value of active power losses and its maximum reduction respectively, but the possibility and economic efficiency of partial use of the stored hydrogen for other needs when determining the optimal scenario of their operation in the process of discharge.     

Feasibility study of large scale hydrogen power-to-gas applications and cost of the systems evolving with scaling up in Germany,Belgium and Iceland

The use of hydrogen to store electricity is no longer utopian nor merely theoretical. Hydrogen applications such as Power-to-Gas systems are entering the market and some of them are ready to compete with other options in the near future. This means they have indeed a potential for profitability, especially if seen as large-scale storage solutions for the electricity surplus produced by variable renewable energy sources.In this study Power-to-Industry, Power-to-Mobility and Power-to-Power applications are chosen to be investigated and compared through levelized cost of hydrogen to identify the main cost drivers and consequently understand the possible solutions to reduce costs. The feasibility of the applications is discussed and analyzed in Germany, Belgium and Iceland, with mid and long-term perspectives, focusing the analysis on the advantage of scaling up.     

A conceptual chemical looping combustion power system design in a power-to-gas energy storage scenario

Increasing global energy demand and the continued reliance on non-renewable energy sources, especially in developing countries, will cause continued increases in greenhouse gas emissions unless alternative electricity generation methods are employed. Although renewable energy sources can provide a clean way to produce electricity, the intermittent nature of many existing renewable energy sources, such as energy from the wind or sun, can cause instability in the energy balance. Energy storage systems such as power-to-gas may provide a clean and efficient way to store the overproduced electricity. In this work, a power-to-gas energy storage system coupled with a chemical looping combustion combined-cycle power generation system is proposed to provide base and intermediate load power from the unused electricity from the grid. Enhanced process integration was employed to achieve optimal heat and exergy recovery. The simulation results using ASPEN Plus V8.8 suggest that electric power generation with an overall energy efficiency of 56% can be achieved by using a methane chemical looping combustion power generation process with additional hydrogen produced from a solid oxide electrolysis cell. The proposed system was also evaluated to further improve the system's total energy efficiency by changing the key operating parameters.     

Hydrogen energy storage systems to improve wind power plant efficiency considering electricity tariff dynamics

One of the limitations of the efficiency of renewable energy sources is the stochastic nature of generation; consequently, it is necessary to use high-capacity energy storage systems such as hydrogen storage for its integration into existing power networks. At the same time, electricity market tariffs for large enterprises change during the day. Therefore, it can be assumed that storing energy during cheaper hours and usage in more expensive hours allows increasing the efficiency of renewable energy sources. Evaluation of the economic efficiency of an energy storage system requires simulation with a step of at least 1 h for several years since the use of averaged production volume and averaged electricity tariffs will not allow obtaining an adequate to the task accuracy. A simulation model and software have been implemented to perform simulations and calculate the economic efficiency of a wind turbine with and without a hydrogen storage device. The methodology has been approved on three-year real data of wind speeds and electricity tariffs in the Novosibirsk region and Krasnodar Territory (Russian Federation).     

Comprehensive study of the underground hydrogen storage potential in the depleted offshore Tapti-gas field

Hydrogen is becoming an alternative for conventional energy sources due to absence of any Greenhouse Gases (GHG) emissions during its usage. Geological storage of hydrogen will be potential solution for dealing with large volume requirement to manage uninterrupted Hydrogen supply-chain. Geological Storages such as depleted reservoirs, aquifers and salt caverns offer great potential option for underground hydrogen storage (UHS). There are several depleted gas fields in India. One of such field is located in Tapti-Daman formation. A comprehensive study is conducted to assess the possibility of hydrogen storage in this Indian field which is first of its kind. The geological characteristic of this site is assessed for its viability for storage. Additionally, several aspects including storage capacity, sealability, chemical and micro-biological stability, reservoir simulation, and production viability are assessed using various analytical and numerical models.The qualitative analysis of the Tapti-gas field suggests that the integrity of the storage site will be intact due to existing anticlinal four-way closed structure. The chemical and micro-biological losses are minimal and will not lead to major loss of hydrogen over time. The reservoir modeling results show that optimum gas production-injection scheme needs to be engineered to maintain the required reservoir pressure level in the Tapti-gas field. Also, the deliverability of the various seasonal storage time show that 80 days production scheme will be suitable for efficient operation in this field. Finally, a synergistic scheme to enable green energy production, storage, and transportation is proposed via implementation of UHS in the offshore Tapti-gas field.     

Geochemical reactions-induced hydrogen loss during underground hydrogen storage in sandstone reservoirs

Underground hydrogen storage (UHS) appears to be an important means as a large-scale and long-term energy storage solution. A primary concern of UHS is the in-situ geochemical reactions-induced hydrogen loss. In this context, we performed geochemical modelling to examine the hydrogen loss associated with hydrogen dissolution and fluid-rock interactions using PHREEQC (Version 3) as a function of temperature and pressure. We also performed geochemical modelling with kinetics to investigate the potential hydrogen loss in two commercial gas storage reservoirs (Tubridgi and Mondarra) in Western Australia against the reservoir mineralogy, fluid properties, depth and temperature.Our results show that increasing pressure and temperature only slightly increases hydrogen solubility in brines without minerals. Increasing salinity slightly decreases the solubility of hydrogen in brines. The saturated hydrogen aqueous solution almost does not react with silicate and clay minerals, which is favorable for underground hydrogen storage in quartz-rich sandstone reservoirs. However, unlike silicate and clay minerals, carbonates like calcite triggers up to 9.5% hydrogen loss due to calcite dissolution induced hydrogen dissociation process. Kinetic simulations show that Tubridgi only leads to 0.72% of hydrogen loss, and Mondarra causes 2.76% of hydrogen loss as a result of reservoir calcite dissolution and hydrogen dissociation in brines in 30-year time. Nearly over 87% of calcite cement from Mondarra may be dissolved in 30-year, suggesting potential risks associated with wellbore stability. In conclusion, geochemical reactions-induced hydrogen loss would be minor for UHS in porous media, and we argue that deep calcite-free reservoirs together with calcite-free caprocks would be preferable for underground hydrogen storage.     

GIS-based analysis of rock salt deposits’ suitability for underground hydrogen storage

The paper discusses the suitability of bedded salt deposits for underground hydrogen storage facilities. The presented research is an example of multi-criteria decision analysis coupled with spatial data analysis undertaken using GIS (Geographic Information System). The aim of this study is to develop a methodology for selecting the best locations for hydrogen storage in salt caverns. In the analysis, we take into account the results of previous studies of the storage capacity of rock salt deposits. The presented methodology allows the creation of rock salt deposit suitability maps for underground hydrogen storage. The results show that the applied method significantly influences the resulting map image, helping to identify optimal locations for hydrogen storage facilities. The presented approach may be of value to governmental institutions considering underground hydrogen storage, geological services, power plants producing electricity from renewable energy sources, and chemical and petrochemical plants.     

Integration of large-scale hydrogen storages in a low-carbon electricity generation system

This study investigates the overall feasibility of large energy storages with hydrogen as energy carrier onsite with a pre-combustion carbon capture and storage coal gasification plant and assesses the general impacts of such a backup installation on an electricity generation system with high wind power portion. The developed system plant configuration consists of four main units namely the gasification unit, main power unit, backup power unit including hydrogen storage and ancillary power unit. Findings show that integrating a backup storage in solid or gaseous hydrogen storage configuration allows to store excessive energy under high renewable power output or low demand and to make use of the stored energy to compensate low renewable output or high power demand. The study concludes that the developed system configuration reaches much higher load factors and efficiency levels than a plant configuration without backup storage, which simply increases its power unit capacity to meet the electricity demand. Also from an economical point of view, the suggested system configurations are capable to achieve lower electricity generation costs.     

Increasing renewable energy sources in island energy supply: case study Porto Santo

While the energy supply of most islands depends mainly on expensive oil derivatives’ importation, the others are linked by usually a weak electricity grid connection to the mainland. Due to high energy costs the islands are proving to be excellent test beds for the introduction of new technologies, and some islands are trying to become so-called renewable islands, to satisfy their energy demand mainly or entirely from indigenous and renewable sources, thus increasing the security of supply, and employment opportunities, without necessarily increasing the costs. Islands that have energy sources, such as hydro or geothermal energy, can easily integrate them into the power system, but those with mainly intermittent renewable energy sources are confronted with the necessity of energy storage. The most promising technologies are reversible hydro where geography allows, and storing hydrogen where it does not. The stored hydrogen can later be used for electricity production, and also for transport. This paper describes the H₂RES model for optimisation of integration of hydrogen usage with intermittent renewable energy sources on the example of an isolated island in the Madeira archipelago, Porto Santo. It shows that it is possible to significantly increase the penetration of renewable energy sources, albeit at a relatively high cost, with hydrogen storage technology. The H₂RES model, which includes reversible hydro and batteries as storage technologies, can serve as a valuable tool for island energy planning.     

Experimental study of hydrogen storage with reaction heat recovery using metal hydride in a totalized hydrogen energy utilization system

Experimental results for hydrogen storage tanks with metal hydrides used for load leveling of electricity in commercial buildings are described. Variability in electricity demand due to air conditioning of commercial buildings necessitates installation of on-site energy storage. Here, we propose a totalized hydrogen energy utilization system (THEUS) as an on-site energy storage system, present feasibility test results for this system with a metal hydride tank, and discuss the energy efficiency of the system. This system uses a water electrolyzer to store electricity energy via hydrogen at night and uses fuel cells to generate power during the day. The system also utilizes the cold heat of reaction heat during the hydrogen desorption process for air conditioning. The storage tank has a shell-like structure and tube heat exchangers and contains 50 kg of metal hydride. Experimental conditions were specifically designed to regulate the pressure and temperature range. Absorption and desorption of 5,400 NL of hydrogen was successfully attained when the absorption rate was 10 NL/min and desorption rate was 6.9 NL/min. A 24-h cycle experiment emulating hydrogen generation at night and power generation during the day revealed that the system achieved a ratio of recovered thermal energy to the entire reaction heat of the hydrogen storage system of 43.2% without heat loss.     

Preparation of hydrogen from metals and water without CO2 emissions

Considering the high calorific value and low-carbon characteristics of hydrogen energy, it will play an important role in replacing fossil energy sources. The production of hydrogen from renewable energy sources for electricity generation and electrolysis of water is an important process to obtain green hydrogen compared with classic low-carbon hydrogen production methods. However, the challenges in this process include the high cost of liquefied hydrogen and the difficulty of storing hydrogen on a large scale. In this paper, we propose a new route for hydrogen storage in metals, namely, electricity generation from renewable energy sources, electrolysis to obtain metals, and subsequent hydrogen production from metals and water. Metal monomers facilitate large-scale and long-term storage and transportation, and metals can be used as large-scale hydrogen storage carriers in the future. In this technical route, the reaction between metal and water for hydrogen production is an important link. In this paper, we systematically summarize the research progress, development trend, and challenges in the field of metal to hydrogen production. This study aim to aid in the development of this field.     

Role of hydrogen in future North European power system in 2060

The Balmorel model has been used to calculate the economic optimal energy system configuration for the Scandinavian countries and Germany in 2060 assuming a nearly 100% coverage of the energy demands in the power, heat and transport sector with renewable energy sources. Different assumptions about the future success of fuel cell technologies have been investigated as well as different electricity and heat demand assumptions. The variability of wind power production was handled by varying the hydropower production and the production on CHP plants using biomass, by power transmission, by varying the heat production in heat pumps and electric heat boilers, and by varying the production of hydrogen in electrolysis plants in combination with hydrogen storage. Investment in hydrogen storage capacity corresponded to 1.2% of annual wind power production in the scenarios without a hydrogen demand from the transport sector, and approximately 4% in the scenarios with a hydrogen demand from the transport sector. Even the scenarios without a demand for hydrogen from the transport sector saw investments in hydrogen storage due to the need for flexibility provided by the ability to store hydrogen. The storage capacities of the electricity storages provided by plug-in hybrid electric vehicles were too small to make hydrogen storage superfluous.     

Large-scale hydrogen energy storage in salt caverns

Large-scale energy storage methods can be used to meet energy demand fluctuations and to integrate electricity generation from intermittent renewable wind and solar energy farms into power grids. Pumped hydropower energy storage method is significantly used for grid electricity storage requirements. Alternatives are underground storage of compressed air and hydrogen gas in suitable geological formations. Underground storage of natural gas is widely used to meet both base and peak load demands of gas grids. Salt caverns for natural gas storage can also be suitable for underground compressed hydrogen gas energy storage. In this paper, large quantities underground gas storage methods and design aspects of salt caverns are investigated. A pre-evaluation is made for a salt cavern gas storage field in Turkey. It is concluded that a system of solar-hydrogen and natural gas can be utilised to meet future large-scale energy storage requirements.     

Relevance and costs of large scale underground hydrogen storage in France

The study analyzes the techno-economic feasibility and business case of large-scale hydrogen underground storage in France. Potential regions for locating the storage cavity were assessed, as well as the anticipated hydrogen demand and renewable energy developments. The business case of salt caverns storage facility has been assessed both in 2025 and 2050, looking at several demand sectors, including mobility (FCEVs), hydrogen-consuming industries and what is defined as “Power-to-Gas”. The hourly operation of the cavern has been modeled. The electricity supply is restricted to wind and grid electricity only.The mobility market is clearly the key driver, both in quantity and economic terms, with an easier to achieve target cost (€4/kgH2, ex-storage). High utilization rates of electrolysers are necessary to reach profitability. A need for massive storage begins for a renewable penetration rate of 50%. The hydrogen costs varies from €4.5/kg to €6.6/kg H2, and the underground mass storage cost remains always under 5% of the overall costs.