On-board Hydrogen Storage Systems Research Articles

Automotive storage of hydrogen in alane

Abstract Although alane (AlH 3 ) has many interesting properties as a hydrogen storage material, it cannot be regenerated on-board a vehicle. One way of overcoming this limitation is to formulate an alane slurry that can be easily loaded into a fuel tank and removed for off-board regeneration. In this paper, we analyze the performance of an on-board hydrogen storage system that uses alane slurry as the hydrogen carrier. A model for the on-board storage system was developed to analyze the AlH 3 decomposition kinetics, heat transfer requirements, stability, startup energy and time, H 2 buffer requirements, storage efficiency, and hydrogen storage capacities. The results from the model indicate that reactor temperatures higher than 200 °C are needed to decompose alane at reasonable liquid hourly space velocities, i.e., > 60 h −1 . At the system level, a gravimetric capacity of 4.2 wt% usable hydrogen and a volumetric capacity of 50 g H 2 /L may be achievable with a 70% solids slurry. Under optimum conditions, ∼80% of the H 2 stored in the slurry may be available for the fuel cell engine. The model indicates that H 2 loss is limited by the decomposition kinetics rather than by the rate of heat transfer from the ambient to the slurry tank.

State of the Art: Hydrogen storage

Hydrogen is often considered to be the ultimate energy source for vehicles. However, if hydrogen is to fuel practical vehicles, then the development of fuel cell and hydrogen fueled engine technology must be accompanied by significant improvements in hydrogen storage techniques. Compressed hydrogen storage tanks, liquid hydrogen storage tanks, and containment systems for hydrides are examined to compare their advantages, disadvantages, and potential for onboard and stationary hydrogen storage systems. Each technique reviewed possesses specific shortcomings; thus, none can adequately satisfy the requirements of a hydrogen based economy.

Hydrogen storage systems for automotive applications: project StorHy

Around two thirds of world's oil usage is associated with transportation with road vehicles consuming around 40%. Also, transportation accounts for around 25% of greenhouse emissions worldwide, with around 90% coming from road vehicles. This situation is further complicated by the fact that oil reserves are running out. For this reason, the automotive industry supported by relevant governing bodies is rapidly exploring alternative propulsion solutions (such as hybrid, electric and hydrogen powered vehicle technologies). This paper presents the main objectives and progressive findings of an EU funded research project titled 'StorHy ? Hydrogen Storage Systems for Automotive Applications'. This research project was conducted in partnership between a number of participating organisations under the auspice of the EU Thematic Priority 6 program titled 'Sustainable development, global change and ecosystems'. The integrated project, StorHy, aims to develop robust, safe and efficient on-board vehicle hydrogen storage systems suitable for use in hydrogen-fuelled fuel cell or internal combustion engine vehicles. Research work covering the whole spectrum of hydrogen storage technologies (compressed gas, cryogenic liquid and solid materials) is carried out with a focus on automotive applications. The aim is to develop economically and environmentally attractive solutions for all three storage technologies.

ISO Technical Specification for Hydrogen Fuel Quality: Status and Path Forward

Hydrogen fuel quality specifications must be quantified at the vehicle-station interface and must consider how the presence of small amounts of contaminants affect the performance and durability of fuel cells and balance of plant; material compatibility of on-board and stationary hydrogen storage systems; and the operation and maintenance of hydrogen production, purification, and delivery systems. Preliminary fuel quality guidelines based on available data and information have been prepared by ISO (1) and SAE (2). Before these guidelines can become international and national standards, respectively, a comprehensive, structured R&D and testing effort is needed to determine the effects, especially degradation mechanisms, of various contaminants on fuel cell electrodes and membranes. Implications of fuel quality on the complexity, performance, and durability of fuel cell systems and upstream infrastructure as well as on the cost of fuel must be understood so that critical trade-offs can be assessed.

1 kW e sodium borohydride hydrogen generation system : Part I: Experimental study

A 1 kW e hydrogen generation system using hydrolysis of sodium borohydride (NaBH 4) has been designed and built. The effects of flow rate, fuel concentration, inlet temperature and operating pressure on chemical conversion have been systematically investigated. A 10-point thermocouple profile probe was used to measure the temperature distribution inside the catalyst bed. Chemical conversion was also qualitatively evaluated via the temperature profile. For the present adiabatic reactor, a large temperature gradient at the outlet implies low conversion, while a small temperature gradient at the outlet implies high conversion. In order to obtain accurate measurements of hydrogen flow rate, water vapor carried in the product stream was removed by a custom hydrogen conditioning station. Using 15% concentration NaBH 4 aqueous solution, this system generated hydrogen up to 20 SLPM with a reasonably high chemical conversion (95%). Discharge products from using NaBH 4 concentrations above 15% crystallized upon cooling to room temperature. Such products would be difficult to remove from the discharge tank in a practical setting. Considering the practical difficulties in heating the discharge product to prevent crystallization, the highest usable concentrations would likely fall in the range of 10–15%. The resulting maximum material gravimetric density is 3.1 wt% of hydrogen and falls short of the DOE on-board hydrogen storage system target of 6 wt% for year 2010.

The U.S. Department of Energy's National Hydrogen Storage Project: Progress towards meeting hydrogen-powered vehicle requirements

Hydrogen storage is widely recognized as a critical enabling technology for the successful commercialization and market acceptance of hydrogen powered vehicles. Storing sufficient hydrogen on-board a wide range of vehicle platforms, while meeting all consumer requirements (driving range, cost, safety, performance, etc.), without compromising passenger or cargo space, is a tremendous technical challenge. The U.S. Department of Energy (DOE), in collaboration with automotive industry partners, established specific technical targets for on-board hydrogen storage systems to focus R&D and to stimulate research on hydrogen storage. In order to achieve these long-term targets, DOE launched a “Grand Challenge” to the scientific community in 2003. Based on a competitively selected portfolio, DOE established a “National Hydrogen Storage Project” in the U.S. for R&D in the areas of advanced metal hydrides, chemical hydrogen storage, carbon-based and high surface area sorbent materials, as well as new materials and concepts. The current status of vehicular hydrogen storage is reviewed and research associated with the National Hydrogen Storage Project is discussed. Future DOE plans through the International Partnership for the Hydrogen Economy (IPHE) are also presented.

Importance of Turning to Renewable Energy Resources with Hydrogen as a Promising Candidate and on-board Storage a Critical Barrier

AbstractThe majority of the world energy consumption is derived from fossil fuels. Furthermore, the United States (US) consumption of petroleum vastly exceeds its production, with the majority of petroleum being consumed in the transportation sector. The increasing dependency on foreign fuel resources in conjunction with the severe environmental impacts of a petroleum-based society dictates that alternative renewable energy resources be developed. The US Department of Energy's (DOE's) Office of Energy Efficiency and Renewable Energy and the Office of Basic Energy Sciences are currently promoting a vehicular hydrogen-based energy economy. However, none of the current on-board storage technologies are suitable for practical and safe deployment. Significant scientific advancement is therefore still required if a viable on-board storage technology is to be developed. A detailed discussion of the benefits of transitioning to a hydrogen-powered automotive fleet as well as the tremendous technical hurdles faced for the development of an on-board hydrogen storage system are provided here. A novel class of theoretically predicted nanostructured materials that could revolutionize hydrogen storage materials is also presented.

Enhancement of hydrogen storage capacity of Ti?V?Cr?Mn BCC phase alloys

The phase structures and hydrogen absorption–desorption properties of Ti–V–Cr–Mn alloys were investigated. It is found that the increasing V content is effective for enhancing the hydrogen absorption capacity and flattening the hydrogen desorption plateau, while it depresses the hydrogen desorption plateau pressure. With the increase of V content, two phases of BCC and C14 Laves of the alloys transform into a single BCC phase. The maximum and effective hydrogen storage capacities among studied alloys are 3.98 and 2.51 wt.%, respectively, which open the hope to bring Ti–V-based alloy into the reach of practical application for onboard hydrogen storage systems in fuel cell powered vehicles.

Enhancement of hydrogen storage capacity of Ti–V–Cr–Mn BCC phase alloys

The phase structures and hydrogen absorption–desorption properties of Ti–V–Cr–Mn alloys were investigated. It is found that the increasing V content is effective for enhancing the hydrogen absorption capacity and flattening the hydrogen desorption plateau, while it depresses the hydrogen desorption plateau pressure. With the increase of V content, two phases of BCC and C14 Laves of the alloys transform into a single BCC phase. The maximum and effective hydrogen storage capacities among studied alloys are 3.98 and 2.51 wt.%, respectively, which open the hope to bring Ti–V-based alloy into the reach of practical application for onboard hydrogen storage systems in fuel cell powered vehicles.

Hydrogen storage in Ti–V-based body-centered-cubic phase alloys

The hydrogen storage performance of a single body-centered-cubic phase Ti-40V-10Cr-10Mn alloy was investigated. A hydrogen absorption capacity of 4.2 wt.% (H/M = 2.1), which is the highest value at room temperature reported so far, was achieved at 293 K under modest pressure (3 MPa) for this as-cast alloy. The effective hydrogen capacities of this alloy were 2.6, 2.8, and 3.2 wt.%, respectively, at 353, 393, and 523 K, which gave hope of bringing Ti-V-based alloys into the reach of practical application for onboard hydrogen storage systems in fuel cell-powered vehicles.

Dynetek to supply 60 H 2 storage systems to DaimlerChrysler

Calgary-based Dynetek Industries, which manufactures lightweight storage cylinders for compressed hydrogen and natural gas, is to deliver 60 of its certified 350 bar (5000 psi) on-board hydrogen storage systems to DaimlerChrysler for its F-Cell car fleet. Visit www.re-focus.net for the latest renewable energy news

Hydrogen storage in carbon nanotubes

Hydrogen is the cleanest, sustainable and renewable energy carrier, and a hydrogen energy system is expected to progressively replace the existing fossil fuels in the future, the latter are being depleted very fast and causes severe environmental problems. In particular, one potential use of hydrogen lies in powering zero-emission vehicles via a proton exchange membrane fuel cell to reduce atmosphere pollution. To achieve this goal feasible onboard hydrogen storage systems have to be developed. The recent discovery of the high and reversible hydrogen storage capacity of carbon nanotubes makes such a system very promising. In this overview, theoretical predictions and experimental results on the hydrogen uptake of carbon nanotubes and nanofibers are summarized, and we point out that, in order to accelerate the development of carbon nanotubes and nanofibers as a practical hydrogen storage medium in fuel cell-driven vehicles, many efforts have to be made to reproduce and verify the results both theoretically and experimentally, and to investigate their volumetric capacity, cycling characteristics and release behavior.

Development of catalytically enhanced sodium aluminum hydride as a hydrogen-storage material

The dehydriding of sodium aluminum hydride, NaAlH4, is kinetically enhanced and rendered reversible in the solid state upon doping with selected titanium compounds. Following the initial reports of this catalytic effect, further kinetic improvement and stabilization of the cyclable hydrogen capacity have been achieved upon variation in the method of the introduction of titanium and particle-size reduction. Rapid evolution of 4.0-wt % hydrogen at 100 °C has been consistently achieved for several dehydriding/rehydriding cycles. An improved, 4.8-wt % cyclable capacity has been observed in the material doped with a combination of Ti and Zr alkoxide complexes. Doping the hydride with Ti(OBun)4 and Fe(OEt)2 also produces a synergistic effect, resulting in materials that can be rehydrided to 4 wt % at 104 °C and 87 atm of hydrogen within 17 h. The improved kinetics allowed us to carry out constant-temperature, equilibrium-pressure studies of NaAlH4 that extended to temperatures well below the melting point of the hydride. The 37-kJ/mol value determined for enthalpy of the dehydriding of NaAlH4(s) to Na3AlH6 and Al and the hydrogen plateau pressure of 7 atm at 80 °C are in line with the predictions of earlier studies. The nature of the active catalyst and the mechanism of catalytic action are unknown. The catalytically enhanced hydrides appear to be strong candidates for development as hydrogen carriers for onboard proton exchange membran (PEM) fuel cells. However, further research and development in the areas of rehydriding catalysts, large-scale, long-term cycling, safety and adjustment of the plateau hydrogen pressure associated with dehydriding of AlH6- are required before these materials can be utilized in commercial onboard hydrogen-storage systems.

On-board hydrogen storage systems for automotive application

The potential of hydrogen in the emerging energy-environment scene as a promising alternative for simultaneously solving the two problems concerning the protection of the environment and optimum energy utilization, has by now, been very clearly understood. However, while considering hydrogen for automotive applications two important factors must be carefully viewed. Firstly, the fuel metering system should be capable of supplying the desired quantity of fuel to the engine at the appropriate point in the engine cycle so as to ensure sustained engine operation without any symptoms of undesirable combustion. The other practical aspect which has delayed the regular implementation and commercialization of hydrogen fuel for vehicular application centres round the problem of onboard storage. This paper discusses various possible storage techniques for hydrogen use in the automobile sector.

Hydrogen as a fuel

Hydrogen, used as fuel, has a number of attractive features that make it a leading candidate in the search for an alternative to the dwindling and progressively less reliable supply of fluid hydrocarbon fuels. Hydrogen produced by electrolysis using hydro- or nuclear-generated electricity will be available in Canada at prices competitive with other portable forms of energy before the end of the century. This paper examines the use of carbon-free electrolytic hydrogen as a motor vehicle fuel and as a fuel for fuel cells. A review of onboard hydrogen storage systems indicates that the propulsion power unit of hydrogen-fueled vehicles must be considerably more efficient than present gasoline-fueled internal combustion engines in order to compensate for the larger size and greater weight of hydrogen storage systems. Hydrogen-fueled internal combustion engines are more efficient than similar gasoline-fueled engines, but the improvement is not sufficient to offset the storage system limitation. Fuel cells operate with much higher efficiency than internal combustion engines, especially at partial loads. A comparison between H 3PO 4 and KOH fuel cells show that where carbon-free hydrogen is available from the onboard storage system, the KOH fuel cell offers the higher level of performance.