United States

In this study the consequences of an accidental release of hydrogen within large scale (>15000 m3) facilities were modelled. To model the hydrogen release an LES Navier–Stokes CFD solver called fireFoam was used to calculate the dispersion and mixing of hydrogen within a large scale facility. The performance of the CFD modelling technique was evaluated through a validation study using experimental results from a 1/6 scale hydrogen release from the literature and a grid sensitivity study. Using the model a parametric study was performed varying release rates and enclosure sizes and examining the concentrations that develop. The hydrogen dispersion results were then used to calculate the corresponding pressure loads from hydrogen-air deflagrations in the facility.

Geodesign is a participatory planning approach in which stakeholders use geographic information systems to develop and vet alternative design scenarios in a collaborative and iterative process. This study is based on a 2019 geodesign workshop in which 17 participants from industry government university and non-profit sectors worked together to design an initial network of hydrogen refueling stations in the Hartford Connecticut metropolitan area. The workshop involved identifying relevant location factors rapid prototyping of station network designs and developing consensus on a final design. The geodesign platform which was designed specifically for facility location problems enables breakout groups to add or delete stations with a simple point-and-click operation view and overlay different map layers compute performance metrics and compare their designs to those of other groups. By using these sources of information and their own expert local knowledge participants recommended six locations for hydrogen refueling stations over two distinct phases of station installation. We quantitatively and qualitatively compared workshop recommendations to solutions of three optimal station location models that have been used to recommend station locations which minimize travel times from stations to population and traffic or maximize trips that can be refueled on origin–destination routes. In a post-workshop survey participants rated the workshop highly for facilitating mutual understanding and information sharing among stakeholders. To our knowledge this workshop represents the first application of geodesign for hydrogen refueling station infrastructure planning.

Natural gas (Methane) is currently the primary source of catalytic hydrogen production accounting for three quarters of the annual global dedicated hydrogen production (about 70 M tons). Steam–methane reforming (SMR) is the currently used industrial process for hydrogen production. However the SMR process suffers with insufficient catalytic activity low long-term stability and excessive energy input mostly due to the handling of large amount of CO2 coproduced. With the demand for anticipated hydrogen production to reach 122.5 M tons in 2024 novel and upgraded catalytic processes are desired for more effective utilization of precious natural resources. In this review we summarized the major descriptors of catalyst and reaction engineering of the SMR process and compared the SMR process with its derivative technologies such as dry reforming with CO2 (DRM) partial oxidation with O2 autothermal reforming with H2O and O2. Finally we discussed the new progresses of methane conversion: direct decomposition to hydrogen and solid carbon and selective oxidation in mild conditions to hydrogen containing liquid organics (i.e. methanol formic acid and acetic acid) which serve as alternative hydrogen carriers. We hope this review will help to achieve a whole picture of catalytic hydrogen production from methane.

Photoelectrochemical (PEC) water splitting is a promising technology for solar hydrogen production to build a sustainable renewable and clean energy economy. Given the complexity of the PEC water splitting processes it is important to note that developing in-situ techniques for studying PEC water splitting presents a formidable challenge. This review is aimed at highlighting advantages and disadvantages of each technique while offering a pathway of potentially combining several techniques to address different aspects of interfacial processes in PEC water splitting. We reviewed recent progress in various techniques and approaches utilized to study PEC water splitting focusing on spectroscopic and scanning-probe methods.

This US Hydrogen Road Map was created through the collaboration of executives and technical industry experts in hydrogen across a broad range of applications and sectors who are committed to improving the understanding of hydrogen and how to increase its adoption across many sectors of the economy. For the first time this coalition of industry leaders has convened to develop a targeted holistic approach for expanding the use of hydrogen as an energy carrier. Due to great variation among national and state policies infrastructure needs and community interests each state and region of the US will likely have its own specific policies and road maps for implementing hydrogen infrastructure. The West Coast for example has traditionally had progressive policies on reducing transportation emissions so it is likely that hydrogen will scale sooner for vehicles in this region especially California. Experts also acknowledge the role that hydrogen in combination with renewables can play in supplying microgrid-type power to communities with the highest risk of shut-offs during seasonal weather-related issues such as high temperatures or wildfire-related power interruptions. Some states have emphasized the need to decarbonize the gas grid so blending hydrogen in natural gas networks and using hydrogen as feedstock may advance more quickly in these regions. Other states are interested in hydrogen as a means to address power grid issues enable the deployment of renewables and support competitive nuclear power. The launch of hydrogen technologies in some states or regions will help to scale hydrogen in various applications across the country laying the foundation for energy security grid resiliency economic growth and the reduction of both greenhouse gas (GHG) emissions and air pollutants. This report outlines the benefits and impact of fuel cell technologies and hydrogen as a viable solution to the energy challenges facing the US through 2030 and beyond. As such it can serve as the latest comprehensive industry-driven national road map to accelerate and scale up hydrogen in the economy across North America

The availability of repair garage infrastructure for hydrogen fuel cell vehicles is becoming increasingly important for future industry growth. Ventilation requirements for hydrogen fuel cell vehicles can affect both retrofitted and purpose-built repair garages and the costs associated with these requirements can be significant. A hazard and operability (HAZOP) study was performed to identify key risk-significant scenarios related to hydrogen vehicles in a repair garage. Detailed simulations and modeling were performed using appropriate computational tools to estimate the location behaviour and severity of hydrogen release based on key HAZOP scenarios. This work compares current fire code requirements to an alternate ventilation strategy to further reduce potential hazardous conditions. It is shown that position direction and velocity of ventilation have a significant impact on the amount of flammable mass in the domain.

The present study describes hydrogen generation from N_aBH₄ in the presence of acid accelerator boric oxide or  B₂O₃ using seawater as a reactant. Reaction times and temperatures are adjusted using various delivery methods: bulk addition funnel and metering pump. It is found that the transition metal catalysts typically used to generate hydrogen gas are poisoned by seawater. B₂O₃ is not poisoned by seawater; in fact reaction times are considerably faster in seawater using  B₂O₃. Reaction times and temperatures are compared for pure water and seawater for each delivery method. It is found that using B2O3 with pure water bulk addition is 97% complete in 3 min; pump metering provides a convenient method to extend the time to 27 min a factor of 9 increase above bulk addition. Using  B₂O₃ with seawater as a reactant bulk addition is 97% complete in 1.35 min; pump metering extends the time to 23 min a factor of 17 increase above bulk. A second acid accelerator sodium bisulfate or NaHSO4 is investigated here for use with NaBH4 in seawater. Because it is non-reactive in seawater i.e. no spontaneous H₂ generation NaHSO₄ can be stored as a solution in seawater; because of its large solubility it is ready to be metered into NaBH₄. With N_aHSO₄ in seawater pump metering increases the time to 97% completion from 3.4 min to 21 min. Metering allows the instantaneous flow rate of H₂ and reaction times and temperatures to be tailored to a particular application. In one application the seawater hydrogen generator characterized here is ideal for supplying H₂ gas directly to Proton Exchange Membrane fuel cells in sea surface or subsea environments where a reliable source of power is needed.

Guidance on Sensor Placement was identified as the top research priority for hydrogen sensors at the 2018 HySafe Research Priority Workshop on hydrogen safety in the category Mitigation Sensors Hazard Prevention and Risk Reduction. This paper discusses the initial steps (Phase 1) to develop such guidance for mechanically ventilated enclosures. This work was initiated as an international collaborative effort to respond to emerging market needs related to the design and deployment equipment for hydrogen infrastructure that is often installed in individual equipment cabinets or ventilated enclosures. The ultimate objective of this effort is to develop guidance for an optimal sensor placement such that when integrated into a facility design and operation will allow earlier detection at lower levels of incipient leaks leading to significant hazard reduction. Reliable and consistent early warning of hydrogen leaks will allow for the risk mitigation by reducing or even eliminating the probability of escalation of small leaks into large and uncontrolled events. To address this issue a study of a real-world mechanically ventilated enclosure containing GH2 equipment was conducted where CFD modelling of the hydrogen dispersion (performed by AVT and UQTR and independently by the JRC) was validated by the NREL Sensor laboratory using a Hydrogen Wide Area Monitor (HyWAM) consisting of a 10-point gas and temperature measurement analyzer. In the release test helium was used as a hydrogen surrogate. Expansion of indoor releases to other larger facilities (including parking structures vehicle maintenance facilities and potentially tunnels) and incorporation into QRA tools such as HyRAM is planned for Phase 2. It is anticipated that results of this work will be used to inform national and international standards such as NFPA 2 Hydrogen Technologies Code Canadian Hydrogen Installation Code (CHIC) and relevant ISO/TC 197 and CEN documents.

Comparison of Computational Fluid Dynamics (CFD) predictions with measurements is presented for cryo-compressed hydrogen vertical jets. The stagnation conditions of the experiments are characteristic of unintended leaks from pipe systems that connect cryogenic hydrogen storage tanks and could be encountered at a fuel cell refuelling station. Jets with pressure up to 5 bar and temperatures just above the saturation liquid temperature were examined. Comparisons are made to the centerline mass fraction and temperature decay rates the radial profiles of mass fraction and the contours of volume fraction. Two notional nozzle approaches are tested to model the under-expanded jet that was formed in the tests with pressures above 2 bar. In both approaches the mass and momentum balance from the throat to the notional nozzle are solved while the temperature at the notional nozzle was assumed equal to the nozzle temperature in the first approach and was calculated by an energy balance in the second approach. The two approaches gave identical results. Satisfactory agreement with the measurements was found in terms of centerline mass fraction and temperature. However for test with 3 and 4 bar release the concentration was overpredicted. Furthermore a wider radial spread was observed in the predictions possibly revealing higher degree of diffusion using the k-ε turbulence model. An integral model for cryogenic jets was also developed and provided good results. Finally a test simulation was performed with an ambient temperature jet and compared to the cold jet showing that warm jets decay faster than cold jets.

A technoeconomic analysis of photoelectrochemical (PEC) and photovoltaic-electrolytic (PV-E) solar-hydrogen production of 10 000 kg H₂ day⁻¹ (3.65 kilotons per year) was performed to assess the economics of each technology and to provide a basis for comparison between these technologies as well as within the broader energy landscape. Two PEC systems differentiated primarily by the extent of solar concentration (unconcentrated and 10× concentrated) and two PV-E systems differentiated by the degree of grid connectivity (unconnected and grid supplemented) were analyzed. In each case a base-case system that used established designs and materials was compared to prospective systems that might be envisioned and developed in the future with the goal of achieving substantially lower overall system costs. With identical overall plant efficiencies of 9.8% the unconcentrated PEC and non-grid connected PV-E system base-case capital expenses for the rated capacity of 3.65 kilotons H₂ per year were $205 MM ($293 per m² of solar collection area (m_S⁻²) $14.7 W_H2P⁻¹) and $260 MM ($371 mS−2 $18.8 W_H2P⁻¹) respectively. The untaxed plant-gate levelized costs for the hydrogen product (LCH) were $11.4 kg⁻¹ and $12.1 kg⁻¹ for the base-case PEC and PV-E systems respectively. The 10× concentrated PEC base-case system capital cost was $160 MM ($428 m_S−2 $11.5 WH₂P⁻¹) and for an efficiency of 20% the LCH was $9.2 kg−1. Likewise the grid supplemented base-case PV-E system capital cost was $66 MM ($441 _mS⁻² $11.5 W_H2P⁻¹) and with solar-to-hydrogen and grid electrolysis system efficiencies of 9.8% and 61% respectively the LCH was $6.1 kg⁻¹. As a benchmark a proton-exchange membrane (PEM) based grid-connected electrolysis system was analyzed. Assuming a system efficiency of 61% and a grid electricity cost of $0.07 kWh⁻¹ the LCH was $5.5 kg⁻¹. A sensitivity analysis indicated that relative to the base-case increases in the system efficiency could effect the greatest cost reductions for all systems due to the areal dependencies of many of the components. The balance-of-systems (BoS) costs were the largest factor in differentiating the PEC and PV-E systems. No single or combination of technical advancements based on currently demonstrated technology can provide sufficient cost reductions to allow solar hydrogen to directly compete on a levelized cost basis with hydrogen produced from fossil energy. Specifically a cost of CO₂ greater than ∼$800 (ton CO₂)−1 was estimated to be necessary for base-case PEC hydrogen to reach price parity with hydrogen derived from steam reforming of methane priced at $12 GJ⁻¹ ($1.39 (kg H₂)⁻¹). A comparison with low CO₂ and CO₂-neutral energy sources indicated that base-case PEC hydrogen is not currently cost-competitive with electrolysis using electricity supplied by nuclear power or from fossil-fuels in conjunction with carbon capture and storage. Solar electricity production and storage using either batteries or PEC hydrogen technologies are currently an order of magnitude greater in cost than electricity prices with no clear advantage to either battery or hydrogen storage as of yet. Significant advances in PEC technology performance and system cost reductions are necessary to enable cost-effective PEC-derived solar hydrogen for use in scalable grid-storage applications as well as for use as a chemical feedstock precursor to CO₂-neutral high energy-density transportation fuels. Hence such applications are an opportunity for foundational research to contribute to the development of disruptive approaches to solar fuels generation systems that can offer higher performance at much lower cost than is provided by current embodiments of solar fuels generators. Efforts to directly reduce CO₂ photoelectrochemically or electrochemically could potentially produce products with higher value than hydrogen but many as yet unmet challenges include catalytic efficiency and selectivity and CO₂ mass transport rates and feedstock cost. Major breakthroughs are required to obtain viable economic costs for solar hydrogen production but the barriers to achieve cost-competitiveness with existing large-scale thermochemical processes for CO₂ reduction are even greater.