Potential Storage Capacity Research Articles

Advanced computational screening of X2CaH4 (X = Rb and Cs) for hydrogen storage applications

Utilizing cutting-edge computational screening methods, this study explores the hydrogen storage capacity of two complex metal hydrides, Cs2CaH4 and Rb2CaH4. We perform a thorough analysis of their structural, electrical, optical, and hydrogen storage properties using density functional theory (DFT). Within the I4/mmm space group, both compounds display stable tetragonal crystal structures, and their thermodynamic stability is confirmed by their formation energies. Notably, compared to Rb2CaH4, Cs2CaH4 is more stable. With band gaps of 2.99 eV for Cs2CaH4 and 3.28 eV for Rb2CaH4, the electronic properties show insulating behavior, which is beneficial for reducing electronic interference during hydrogen absorption and desorption. A comparative research reveals that the potential gravimetric hydrogen storage capacities of Cs2CaH4 (1.28%) and Rb2CaH4 (1.86%) are comparable to, albeit marginally less than, those of materials that are frequently explored, such as lithium borohydride. With their individual absorption and reflectivity peaks, the optical characteristics offer more information about how they interact with electromagnetic radiation, information that may be useful for improving their performance in real-world applications. Our results imply that Cs2CaH4and Rb2CaH4 have considerable potential for use in practical hydrogen storage systems, especially in situations where stability and minimal electronic interference are essential. Subsequent research endeavors may concentrate on enhancing the hydrogen storage capacity of these materials, so rendering their incorporation into existing hydrogen storage methods more feasible.

Influence of Growing Substrates on the Production Potential and Post-Harvest Storage Capacity of Tomato Fruits from the Buzău 1600 Variety

Influence of Growing Substrates on the Production Potential and Post-Harvest Storage Capacity of Tomato Fruits from the Buzău 1600 Variety

Disentangling soil-based ecosystem services synergies, trade-offs, multifunctionality, and bundles: A case study at regional scale (NE Italy) to support environmental planning

The explicit use of ecosystem services (ESs) assessments has been called as a way to guide environmental decision making, yet the promise of the ES approach lies behind its potential. A way to consolidate the approach could be to introduce some aspects into the ESs assessments which might have been neglected so far. Such aspects are mainly: (1) a focus on the complex ESs relations (such as synergies and trade-offs) that can impact the supply of multiple SESs (soil ecosystem services), and (2) focus on potential drivers of SESs relations. We applied bivariate and multivariate approaches to SESs indicators derived from a solid pedological knowledge of the Emilia-Romagna study area in NE Italy. We focused on 7 SES: (1) habitat for soil organisms, (2) filtering and buffering capacity, (3) contribution to microclimate regulation, (4) carbon sequestration, (5) food provision potential, (6) water regulation, and (7) water storage capacity. These SESs were estimated through a combination of point observations, and pedotransfer functions (PTF) estimates spatialised over the area of interest with geostatistical simulation techniques. We found that SESs bivariate spatial relations could be categorised mainly in three types of patterns at regional scale, either: (1) synergistic SESs relations dominating at the region level, (2) trade-offs dominating, or (3) both kind of relations more or less equally frequent. Interestingly, in some cases the dominant regional SESs relation switched at a local level, and such switch was driven by soil properties. For the multivariate case (>2 SESs), two main results are highlighted. First, the combination of properties of some soils is so characteristic that they conform a single SESs bundle, as in the case of the rich SOM soils of alluvial origin in the NE of the region with low agricultural productivity, but high value in regulating SESs. Secondly, some SESs such as potential food provision and water regulation are more important than others to determine locations with high multi-services value at a regional level. This suggests that attention must be paid when ascribing high multi-services value locations as this is not independent of SESs relations. Overall, our results highlight the importance of soils in the potential supply of ESs and show that SESs relations are useful in the implementation of the concept in environmental assessments.

A Review of Greenhouse Gas Emissions from Agricultural Soil

Greenhouse gases (GHGs) like nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) are both emitted and removed by soils. Accurate worldwide allocations of carbon budget are essential for land use planning, global climate change, and climate-related research. Precise measurements, drivers, and mitigation strategies are necessary, given agricultural soil’s significant potential storage and emission capacities. Different agricultural management practices cause greenhouse gas (GHG) emissions into the atmosphere and contribute to anthropogenic emissions. Agricultural soils can generate 70% of the world’s manmade N2O emissions and also behave as a CO2 sink and a source of organic carbon and as producers and consumers of CH4. When it comes to agronomic management, the source and sink of all these GHGs are distinct. Therefore, several approaches to measuring GHG emissions from agricultural soils are available and can be categorized into chamber systems and remote sensing approaches. Sustainable agriculture stands out as a viable and transformative approach to increase agricultural efficiency while addressing the challenge of GHG emissions. Incorporating advanced technologies, precise data analytics, and site-specific management practices can offer a pathway to mitigate GHG emissions, thereby reducing the global warming potential (GWP). Therefore, this review paper focuses solely on the drivers influencing and involving soil emissions and on quantification approaches for GHG emissions. In addition, mitigation practices aimed at optimizing GHG emissions from agricultural soils are highlighted.

Influence of Silica Nanoparticles on the Physical Properties of Random Polypropylene

Influence of Silica Nanoparticles on the Physical Properties of Random Polypropylene

Building a carbon dioxide storage portfolio for the Barrow-Dampier sub-basins through regional screening – an integrated geoscience approach

Safe geological carbon dioxide (CO2) storage (GCS) requires rocks with suitable injectivity, capacity and sealing properties to ensure secure long-term containment of injected CO2. A regional understanding of the subsurface is essential to determine the potential for GCS of a basin and to select target sites. This is best addressed by integrating the basin’s tectono-stratigraphic evolution, its gross depositional environment, and its hydrodynamic, thermal and stress regimes. A basin-scale GCS assessment for the Barrow-Dampier sub-basins was conducted by Geoscience Australia and SLB. The objective of the study is to high-grade geological intervals and sites for potential GCS and to understand potential storage capacity and key risk factors. Stratigraphic and structural mapping of key storage intervals was performed using the reprocessed seismic volume and well database associated with the project. Analysis of critically stressed faults was used to estimate the likelihood of reactivation based on the far-field regional stress field and fault mechanical properties. Pressure, temperature, porosity, permeability, and water geochemistry data have been screened for >500 wells for assessing the storage unit intervals and predicting the hydrodynamic regime. Calibrated 2D basin models provide information on the regional pressure-temperature regime, porosity/permeability distribution, and sealing effectiveness. Potentiometric surface maps for the aquifer systems inform the distribution of potential CO2 plume migration. Results of this integrated regional basin study are used to quantify the risk of identified storage containers and to map the chance of success for GCS at a regional scale. The project results are publicly available via NOPIMS.

Sulphonated coal tar pitch as a carbon source to develop the storage capacity of Fe2O3@C materials

Utilizing metal oxides as substitutes for carbon anodes is imperative in advancing LIBs. Recently, the researchers regarding to the Fe2O3 have become very popular owing to its advantages such as a high theoretical capacity (1007 mAh g−1), cost-effectiveness and sustainability. In our present studies, the Fe2O3@SCTPC (Fe2O3 nanosphere coated by carbons which are obtained by the carbonizations using the sulphonated coal tar pitches) materials are firstly and successfully fabricated by a one-step hydrothermal method using the Fe(NO3)3·9 H2O and sulphonated coal tar pitches (SCTPs). An intriguing observation is that the nanosphere Fe2O3 is encapsulated by carbons with a core-shell structure. This specific core-shell structure effectively mitigates the volume expansion of Fe2O3, and exhibits a notable enhancement in conductivity. Thanks to this unique structure, the Fe2O3@SCTPC electrode has a maximum capacity of 1106.74 mAh g−1 after 100 cycles at a current density of 0.1 A g−1 and a high reversible specific capacity of 373.5 mAh g−1 after 500 cycles at a current density of 2 A g−1, when it is used as an anode material for Li-ion battery. These results suggest that adjusting the structures of carbons is crucial to develop the potential storage capacity of the covered Fe2O3.

Hydro-sedimentological drivers of fine sediment ingress in a gravel-bed river

Most studies investigating fine sediment ingress in gravel-bed rivers have been conducted at the laboratory scale, and even fewer have explored the ingress processes of flocculated particles. Here, an extensive in-situ sampling programme was undertaken to investigate hydro-sedimentological drivers of interstitial fine sediment accumulation and to evaluate fine sediment ingress directional mechanisms in a gravel-bed river located on the eastern slopes of the Rocky Mountains in southern Alberta. Three sediment trap designs were installed across seven deployment cycles at four sites along the river. Instantaneous discharge, suspended solids concentration, and particle size distributions (of suspended and ingressed particles) were measured, while relevant hydraulic parameters were modelled with a flow model (MOBED). Distinct patterns of ingress dynamics between non-cohesive and cohesive fractions of fine sediment were observed. While the assessed hydro-sedimentological parameters did not statistically explain the ingress rates of non-cohesive 0.5 – 2 mm particles, the opposite was observed for < 0.5 mm particles, which were mostly transported in flocculated form. For flocculated sediment, horizontal ingress accounted for ∼ 60 % of interstitial accumulation. Directional ingress mechanisms, however, were dependent on flow conditions for both particle size fractions, with vertical and horizontal accumulations becoming more important during higher and lower energy flows, respectively. Our observations demonstrate the importance of ingress for the interstitial accumulation of fine sediment, even during events with flow above the critical threshold conditions for fine sediment gravitational deposition. Despite the comparable ingress rates to other studies, no interstitial clogging was observed in this study, demonstrating the channel potential storage capacity, which has implications for legacy impacts from landscape disturbances in the Crowsnest River catchment.

Phase-Field Simulation of a Dynamic Protective Layer for the Inhibition of Dendrite Growth in Zinc Metal Batteries.

Metallic zinc (Zn) has been considered one of the most promising anode materials for next-generation aqueous Zn batteries due to its low redox potential and high storage capacity. However, excessive dendrite formation in Zn metal, corrosion, the evolution of hydrogen gas during the cycling process, and the poor Zn-ion (Zn2+) transport from the electrolyte to the electrode limit its practical application. One of the most effective strategies to suppress Zn dendrite growth and promote Zn2+ transport is to introduce suitable protective layers between the Zn metal electrode and the electrolyte. Herein, we mathematically simulated the dynamic interactions between the Zn deposition on the anode and the resulting displacement of a protective layer that covers the anode, the latter of which can simultaneously inhibit Zn dendrite growth and enhance the Zn2+ transport through the interface between the Zn anode and the protective layer. Our simulation results indicate that a protective layer of high Zn2+ diffusivity not only improves the deposition rate of the Zn metal but also prevents dendrite growth by homogenizing the Zn2+ concentration at the anode surface. In addition, it is revealed that the anisotropic Zn2+ diffusivity in the protective layer influences the 2D diffusion of Zn2+. Higher Zn2+ diffusivity perpendicular to the Zn metal surface inhibits dendrite growth, while higher diffusivity parallel to the Zn metal surface promotes dendrite growth. Our work thus provides a fundamental understanding and a design principle for controlling anisotropic Zn2+ diffusion in the protective layer for better suppression of dendrite growth in Zn metal batteries.

Carbon sequestration and soil nitrogen enrichment in Robinia pseudoacacia L. post-mining restoration plantations

Robinia pseudoacacia L. (black locust) has been extensively used for restoring degraded lands, following anthropogenic interventions like coal mining. Here we have addressed the contribution of black locust restoration plantations, established on overburden post-mining material, to carbon storage and to soil nitrogen enrichment at the largest lignite center in Greece. Carbon stocks and fluxes in all pools of the ecosystem, as well as the foliar nitrogen resorption efficiency and soil N stocks were quantified and the effect of plantations’ age was tested. The young age of the plantations (4–24 years) resulted in a relatively low total ecosystem C stock (56.7 t ha−1), which was partitioned among the different pools in the following order: above-ground biomass (50%) &amp;gt; black locust-derived SOC (24%) &amp;gt; coarse roots (14%) &amp;gt; deadwood (6%) &amp;gt; forest floor (5%) &amp;gt; fine roots (less than 1%). Litterfall started early in the growing season and together with fine roots that had a turnover rate of 0.62 yr−1, fueled soil organic carbon. SOC accrual, referring to the accumulation of SOC derived by black locust, declined with age. However, further SOC accumulation is expected, based on the potential SOC storage capacity of soil at the area. C stocks in above- and below-ground biomass increased linearly with age. The same response was observed for soil N stock and NRE, indicating that despite the N2-fixing capacity of black locust, there was still a poor pedospheric N supply and a need for efficient N cycling. Overall, the studied restoration plantations have a considerable contribution to C and N accumulation at the degraded post-mining sites. These positive effects are expected to further increase at least until the plantations reach maturity.

A rGO/Cu0.7Fe0.3S2 composite electrode for asymmetric supercapacitor prepared via MIL-101 template strategy

As a branch of MOF, MIL has attracted much attention in the field of electrochemistry because of its high porosity and potential high charge storage capacity. Graphene oxide is considered as an ideal supercapacitor material because of its high electrical conductivity, high specific surface area and rich surface functional groups. The metal sulfides prepared with MIL as template not only inherit the structural characteristics of MIL, but also improve the electrical conductivity of the materials, which thus show excellent energy storage properties. In this work, the rGO/Cu0.76Fe0.24S2 composite was prepared through in-situ growth of MIL-101 on the surface of GO followed by copper nitrate etch, high temperature carbonization and hydrothermal sulfurization. To the best of our knowledge, it is the first time to report that rGO/Cu0.7Fe0.3S2 is used as the electrode of supercapacitor and tested for energy storage. The optimized rGO/Cu0.7Fe0.3S2 electrode exhibited good capacitive performances, including high specific capacitance of 661.2 F g−1 at 1 Ag−1 and remarkable cycle stability with 69 % after 5000 cycles. Employing the as-prepared rGO/Cu0.7Fe0.3S2 composites as positive electrode, the hybrid supercapacitor device displayed spectacular capacity of energy density (54.37 Wh kg−1), great power density (887.75 W kg−1) and impressive long-term stability of 70 % retention after 5000 cycles. The results show that the composite prepared with graphene oxide as substrate and MIL-101 (Fe) as template should be a promising materials for fabricating high-performance supercapacitor.

MnO2 regulated potential window and storage capacity of CoxNi1-x(OH)2@MnO2 freestanding electrode for promoted membrane-less and decoupled water splitting

The realization of membrane-less and decoupled water splitting holds immense significance in facilitating cost-efficient and substantial H2 supply. In this study, a two-step hydrothermal reaction was employed to synthesize a CoxNi1-x(OH)2@MnO2 freestanding electrode, utilizing nickel foam (NF) as the substrate, MnO2 as the seed layer, and CoxNi1-x(OH)2 nanofiber as the surface layer. This fabrication approach resulted in a buffer electrode with an expanded potential window and enhanced charge storage capacity. Notably, the optimized CoxNi1-x(OH)2@MnO2@NF electrode functioned as an effective charge mediator, successfully decoupling the synchronous oxygen and hydrogen evolution reactions (OER and HER). Consequently, the need for separators was eliminated, introducing a novel two-step water electrolysis hydrogen production technology. Remarkably, the initial HER process at the cathode exhibited robust performance, sustaining a current of 100 mA for an impressive duration of 1500 s. Simultaneously, the CoxNi1-x(OH)2@MnO2 mediator underwent oxidation, attaining its corresponding oxidation state and yielding a commendable applied potential of 1.564 V. Subsequently, the OER step entailed the revival of the buffer electrode, enabling the facilitated production of anodic O2 at an operating potential of 0.392 V. Beyond that, the integration of an oxidizing buffer medium and a zinc foil enabled the development of a battery configuration, effectively replacing the second step of OER. This pioneering integration facilitated the concurrent realization of persistent H2 generation and battery discharging, presenting an innovative approach to hydrogen production that circumvents reliance on an external power supply. Thus, this decoupled HER-OER apparatus offers a propitious strategy for effectively converting renewable resources into hydrogen.

Bimetal Metal-Organic Framework-Derived Ni-Mn@Carbon/Reduced Graphene Oxide as a Cathode for an Asymmetric Supercapacitor with High Energy Density.

As is known, metal-organic frameworks (MOFs) are a versatile class of materials in energy storage applications including supercapacitors. However, the individual kind of metal nodes connected by organic ligands to form a topological structure still limits the potential storage capacity of MOFs. Herein, a bimetal-based Ni-Mn MOF composite is configured with a one-pot hydrothermal method to derive a composite with a synergic effect to maximize the properties. Moreover, reduced graphene oxide (rGO) sheets are added as a conductive network to anchor the MOF-derived composite of Ni-Mn@C/rGO, which is expected to increase the conductivity of the materials system. The resulting composite exhibited a high specific capacitance of 1674 F g-1 at a current density of 0.3 A g-1, suggesting excellent energy storage performance. The composite was then integrated as the cathode in an asymmetrical supercapacitor with a 3D rGO aerogel anode, resulting in energy densities of 24.1 and 17.5 W h kg-1 at power densities of 88.9 and 444.4 W kg-1, respectively. Additionally, the device demonstrated remarkable long-term stability, with 90% capacitance retention after 10 000 charge-discharge cycles at 10 A g-1.

Optimized Charge Storage in Aza-Based Covalent Organic Frameworks by Tuning Electrolyte Proton Activity.

Proton activity in electrolytes plays a crucial role in deciding the electrochemical performance of aqueous batteries. On the one hand, it can influence the capacity and rate performance of host materials because of the high redox activity of protons. On the other hand, it can also cause a severe hydrogen evolution reaction (HER) when the protons are aggregated near the electrode/electrolyte interface. The HER dramatically limits the potential window and the cycling stability of the electrodes. Therefore, it is critical to clarify the impact of electrolyte proton activity on the battery macro-electrochemical performance. In this work, using an aza-based covalent organic framework (COF) as a representative host material, we studied the effect of electrolyte proton activity on the potential window, storage capacity, rate performance, and cycle stability in various electrolytes. A tradeoff relationship between proton redox reactions and the HER in the COF host is revealed by utilizing various in situ and ex situ characterizations. Moreover, the origin of proton activity in near-neutral electrolytes is discussed in detail and is confirmed to be related to the hydrated water molecules in the first solvation shell. A detailed analysis of the charge storage process in the COFs is presented. These understandings can be of importance for utilizing the electrolyte proton activity to build high-energy aqueous batteries.

Reversible Solid Oxide Cells for Energy Storage in the Netherlands: Thermodynamics and Fuel Selection

We investigated a large-scale energy storage system based on reversible solid oxide cells, for a future Dutch electrical grid powered entirely by intermittent renewables. Three fuels — hydrogen, ammonia and methane — were investigated for such a system, to find the most suitable one in terms of minimizing the required fuel storage and renewable power generation capacity. The required sizes of fuel storage and power generation using each fuel were estimated using process models of rSOC systems, and a mathematical model of a storage-supported power grid. The results show that the use of hydrogen would lead to the smallest power generation requirement. It is found that the potential storage capacity in the Netherlands exceeds the requirement for storing any fuel, while the renewable power capacity planned for 2030 is insufficient to meet the demand. Under these conditions and assumptions, we find hydrogen to be the appropriate fuel for the Netherlands.

Success factors in the creation of a CCS Hub

Carbon capture and storage (CCS) has the potential to significantly reduce emissions from industrial processes including gas processing and heavy industry. INPEX has a corporate goal to reduce scope 1 and 2 emissions intensity by 30% or more by 2030 on a path to net zero by 2050. Central to these goals is reduction of emissions associated with the Ichthys LNG operation, located on the Middle Arm of Darwin Harbour. Key to the reduction of emissions from Ichthys LNG is the development of a large-scale efficient CCS facility close to Darwin. To this end, INPEX (as Operator) and Joint Venture participants TotalEnergies and Woodside Energy were recently awarded the G-7-AP block in the promising Petrel Sub-basin. The work program associated with this bid includes new 3D seismic, a two-well-appraisal drilling campaign and a comprehensive post-well analysis program to prove up the previously identified storage intervals and allow INPEX to determine the potential storage capacities of these intervals. Scale is a critical driver of the efficiency of a storage solution, so INPEX is working collaboratively with wider industry, government and the CSIRO on the development of the Northern Territory Low Emissions Carbon Capture, Utilisation and Storage Hub business case which seeks to identify and map the pathway for the development of a large-scale multi-sink carbon storage network. This paper will provide an update on INPEX’s vision for the role it intends to play in the development of this Hub.

Aboveground Carbon Stock in a Bottomland Hardwood Forest in the Southeastern United States

Bottomland Hardwood Forests (BHFs) are commonly acknowledged worldwide for their vast carbon sequestration potential and carbon storage capacity. However, the paucity of forest carbon stock data from BHFs along the Lower Mississippi Alluvial Valley (LMAV) in Northeast Louisiana is an existing knowledge gap in understanding the carbon sequestration and storage dynamics across the region. This study was carried out in the Russell Sage Wildlife Management Area (RSWMA) in Northeast Louisiana using a protocol modified from the Terrestrial Carbon Observations Protocol for Vegetation Sampling. Comprehensive analyses of carbon stocks in trees, woody shrubs and seedlings, herbaceous vegetation, downed woody debris, leaf litter, and soil were carried out to quantify the carbon stored in each ecosystem component. Trees accounted for a carbon stock of 132.4 Mg C ha−1, approximately 99% of the total stock for the area. Woody shrubs and seedlings and leaf litter stored 0.4% (0.62 Mg C ha−1) and 0.3% (0.4 Mg C ha−1), respectively. Considering the sparse understory in a BHF, the carbon stored per hectare is comparable to other temperate forests in the conterminous United States. These findings highlight the importance of the BHF ecosystem in carbon storage and their overall role in regional and global ecosystem management in light of climate change.

Control of complex lithofacies on the shale oil potential in ancient alkaline lacustrine basins: The Fengcheng Formation, Mahu Sag, Junggar basin

The study of ultra-deep (>4500 m) oil and gas reservoirs in hydrocarbon-bearing basins is a hot spot for oil and gas exploration in the world today, the heterogeneity of lithofacies is a key factor influencing the potential of deep-buried shale oil. It is highly important to better understand the control of complex rock on the shale oil potential for shale oil exploration and development. The Fengcheng Formation (P1f) in the Mahu Sag is a type of ancient alkaline lacustrine shale oil, which was chosen as a research example in this paper. Four lithofacies were identified based on mineralogy: felsic, lime, dolomitic and mixed shale lithofacies. P1f exhibits a very high shale oil potential, and the oil saturation index (OSI) can reach 176 mg HC/g TOC, far exceeding the lower limit of effective benefits. The shale lithofacies of P1f is complex, and the complex lithofacies has a controlling effect on shale oil potential, specifically in terms of hydrocarbon generation, storage and hydrocarbon migration. The different lithofacies differ in various aspects and are controlled by different factors. Felsic shale is an enriched oil shale with a high hydrocarbon generation potential and high storage capacity that can receive foreign hydrocarbons. Mixed shale is a self-generating and self-accumulating oil shale with a low hydrocarbon production potential and low storage capacity. Lime shale is a partial reservoir-type oil shale with a low hydrocarbon production capacity and satisfactory storage capacity that can receive foreign hydrocarbons. Dolomite shale is a partial source rock-type oil shale exhibiting a high hydrocarbon generation capacity and low storage capacity, which can expel hydrocarbons. Studies have indicated that felsic shale exhibits a notable hydrocarbon generation potential, high storage capacity, easy foreign hydrocarbon migration, high brittle mineral content, and easy fracture production. This shale type is the most favorable shale oil exploration target in P1f within the Mahu Sag. In addition, this study reveals the relationship between rock lithofacies and shale oil potential, which provides a new idea for the potential evaluation of similar lacustrine shale oil.

Primary and potential secondary risks of landslide outburst floods

Outburst floods triggered by breaching of landslide dams may cause severe loss of life and property downstream. Accurate identification and assessment of such floods, especially when leading to secondary impacts, are critical. In 2018, the Baige landslide in the Tibetan Plateau twice blocked the Jinsha River, eventually resulting in a severe outburst flood. The Baige landslide remains active, and it is possible that a breach happens again. Based on numerical simulation using a hydrodynamic model, remote sensing, and field investigation, we reproduce the outburst flood process and assess the hazard associated with future floods. The results show that the hydrodynamic model could accurately simulate the outburst flood process, with overall accuracy and Kappa accuracy for the flood extent of 0.956 and 0.911. Three future dam break scenarios were considered with landslide dams of heights 30 m, 35 m, and 51 m. The potential storage capacity and length of upstream flow back up in the upstream valley for these heights were 142 × 106m3/32 km, 182 × 106m3/40 km, and 331 × 106m3/50 km. Failure of these three dams leads to maximum inundation extents of 0.18 km2, 0.34 km2, and 0.43 km2, which is significant out-of-bank flow and serious infrastructure impacts. These results demonstrate the seriousness of secondary hazards associated with this region.

Hydrogen Absorption Reactions of Hydrogen Storage Alloy LaNi5 under High Pressure.

Hydrogen can be stored in the interstitial sites of the lattices of intermetallic compounds. To date, intermetallic compound LaNi5 or related LaNi5-based alloys are known to be practical hydrogen storage materials owing to their higher volumetric hydrogen densities, making them a compact hydrogen storage method and allowing stable reversible hydrogen absorption and desorption reactions to take place at room temperature below 1.0 MPa. By contrast, gravimetric hydrogen density is required for key improvements (e.g., gravimetric hydrogen density of LaNi5: 1.38 mass%). Although hydrogen storage materials have typically been evaluated for their hydrogen storage properties below 10 MPa, reactions between hydrogen and materials can be facilitated above 1 GPa because the chemical potential of hydrogen dramatically increases at a higher pressure. This indicates that high-pressure experiments above 1 GPa could clarify the latent hydrogen absorption reactions below 10 MPa and potentially explore new hydride phases. In this study, we investigated the hydrogen absorption reaction of LaNi5 above 1 GPa at room temperature to understand their potential hydrogen storage capacities. The high-pressure experiments on LaNi5 with and without an internal hydrogen source (BH3NH3) were performed using a multi-anvil-type high-pressure apparatus, and the reactions were observed using in situ synchrotron radiation X-ray diffraction with an energy dispersive method. The results showed that 2.07 mass% hydrogen was absorbed by LaNi5 at 6 GPa. Considering the unit cell volume expansion, the estimated hydrogen storage capacity could be 1.5 times higher than that obtained from hydrogen absorption reaction below 1.0 MPa at 303 K. Thus, 33% of the available interstitial sites in LaNi5 remained unoccupied by hydrogen atoms under conventional conditions. Although the hydrogen-absorbed LaNi5Hx (x < 9) was maintained below 573 K at 10 GPa, LaNi5Hx began decomposing into NiH, and the formation of a new phase was observed at 873 K and 10 GPa. The new phase was indexed to a hexagonal or trigonal unit cell with a ≈ 4.44 Å and c ≈ 8.44 Å. Further, the newly-formed phase was speculated to be a new hydride phase because the Bragg peak positions and unit cell parameters were inconsistent with those reported for the La-Ni intermetallic compounds and La-Ni hydride phases.