Quantitative risk analysis of life safety and financial loss for road accident of fuel cell vehicle

Vehicular use of hydrogen is the first attempt to apply hydrogen energy in consumers’ environment in large scale and has raised safety concerns in both public authorities and private bodies such as fire services and insurance companies. This paper analyzes typical accident progressions of hydrogen fuel cell vehicles in a road collision accident. Major hydrogen consequences including impinging jet fires and catastrophic tank ruptures are evaluated separately in terms of accident duration and hazard distances. Results show that in a 70 MPa fuel cell car accident, the hazards associated with hydrogen releases would normally last for no more than 1.5 min due to the empty of the tank. For the safety of general public, a perimeter of 100 m is suggested in the accident scene if no hissing sound is heard. However, the perimeter can be reduced to 10 m once the hissing sound of hydrogen release is heard. Furthermore, risks of fatalities, injuries, and damages are all quantified in financial terms to assess the impacts of the accident. Results show that costs of fatalities and injuries contribute most to the overall financial loss, indicating that the insurance premium of fatalities and injuries should be set higher than that of property loss.     

Comparative risk study of hydrogen and gasoline dispensers for vehicles

This paper describes an investigation into the acceptability of installing hydrogen dispensers in public areas based on risk assessments. Because gasoline dispenser risks have been widely accepted for many years, they were used as a benchmark in this study to analyze the risks of hydrogen dispensers. More specifically, we performed risk assessments for both hydrogen and gasoline dispensers and then compared and analyzed the results. We began the process by creating models for both hydrogen and gasoline dispensers that represented their various specifications and elements. Next, potential accident scenarios for each dispenser model were identified by failure mode effect analysis (FMEA) and hazard and operability study (HAZOP). The risks of each scenario were then qualitatively evaluated and the results were organized into risk matrices. By comparing the results of both hydrogen and gasoline dispensers with and without existing safety measures, the appropriateness of their safety measures were validated. Furthermore, by comparing the results of hydrogen and gasoline dispenser safety measures, it was confirmed that the risk levels of the two types were practically equivalent. Therefore, we concluded that the risks involved with installing hydrogen dispensers in public areas can be considered acceptable.     

Strategic cogeneration — fresh horizons for the development of cogeneration in Brazil

An earlier study (Szklo A, Soares J, Tolmasquim M. Economic potential of natural gas-fired cogeneration in Brazil: two case studies. Applied Energy 2000;67(3):245–67) that assessed the economic feasibility of gas-fired cogeneration systems in Brazil, indicated that the use of cogeneration in Brazilian malls tends to be small in the short-term. However, current experience is opening up the possibility of investments in cogeneration plants — despite their lack of economic feasibility — as part of the strategic actions of utilities in the energy market. The earlier study made no attempt to analyze this possibility, focusing solely on economic feasibility. This article supplements its predecessor by analyzing a type of cogeneration rated as strategic. This is a recent phenomenon prompted by the deregulation of Brazil's energy market. Within this new context, power utilities are taking up a defensive behavior as they battle to preserve their markets, in parallel to aggressive behaviors designed to expand and diversify their activities. This means that they may well invest in cogeneration for strategic reasons that may not be clearly reflected through an economic-feasibility assessment.     

Risk identification for the introduction of advanced science and technology: A case study of a hydrogen energy system for smooth social implementation

A method of risk identification is developed by comparing existing and advanced technologies from the viewpoint of comprehensive social risk. First, to analyze these values from a multifaceted perspective, we constructed a questionnaire based on 24 individual values and 26 infrastructural values determined in a previous study. Seven engineering experts and six social science experts were then asked to complete the questionnaire to compare and analyze a hydrogen energy system (HES) and a gasoline energy system (GES). Finally, the responses were weighted using the analytic hierarchy process. Three important points were identified and focused upon: the distinct disadvantages of the HES compared to the GES, judgments that were divided between experts in the engineering and social sciences fields, and judgments that were divided among experts in the same field. These are important risks that should be evaluated when making decisions related to the implementation of advanced science and technology.     

Trade-off study between risk and benefit in safety devices for hydrogen refueling stations using a dynamic physical model

As hydrogen refueling stations become increasingly common, it is clear that a high level of economic efficiency and safety is crucial to promoting their use. One way to reduce costs is to use a simple orifice instead of an excess flow valve, which Japanese safety regulations have identified as a safety device. However, there is concern about its effect on refueling time and on risk due to hydrogen leakage. To clarify the effect, we did a study of model-based refueling time evaluation and quantitative risk assessment for a typical refueling station. This study showed that an orifice is an effective alternative safety device. The increase in refueling time was less than 10%, based on simulations using a dynamic physical model of the station. Neither was there a significant difference in the risk between a configuration with excess flow valves and one with an orifice.     

Renewable energy in India — a modelling study for 2020–2021

The energy requirement in India is steadily increasing and this requirement is being met by both commercial and renewable energy sources. Due to the non-availability of sufficient resources and a considerable amount of emission of pollutants from commercial energy, it is now being felt that renewable energy has to be utilized to a greater extent. An optimization model was developed to determine the optimum allocation of renewable energy in various end-uses in 2020–2021, taking into account commercial energy requirement. In lighting end-use renewable energy to an extent of 1.27×10¹⁵ kJ can be utilized. Scenarios were developed for various parameters and sensitivity analysis was performed on the model. It was found that for a 3% increase in social acceptance of bio resources, there was 65% decrease in solar PV utilization and to that extent bioresources were introduced. Similar analysis was performed on the model by changing the demand, potential, reliability, emission and employment factors. The analysis revealed the critical parameters for the utilization of a renewable energy source. Using the critical parameters, appropriate policies can be formulated for promoting renewable energy sources.     

Integrating safety and economics in designing a steam methane reforming process

The recent explosion at a steam reforming facility producing hydrogen in California, U.S., suggests the need to revisit the design of the traditional steam methane reforming (SMR) process from a safety perspective to further enable the growth of the hydrogen economy. Specifically, it is important to analyze the interaction between process, economic and safety variables within the SMR process through an integrated model approach to maintain positive economics of hydrogen production while making the process safer. The integrated model described within this study consists of process synthesis, quantitative risk assessment and economic analysis sub-models facilitating a holistic design for the SMR process. The usefulness of the integrated model is demonstrated by evaluating alternatives based on the inherently safer design philosophy. For the considered base design, it was found that decreasing the pressure of purge gas exiting the purge gas compressor leads to a reduction in the jet-fire axial risk distance of purge gas with minor economic benefits. Also, increasing the temperature of syngas entering the condensation unit leads to a reduction in the jet-fire axial risk distance for both purge gas and syngas with slight decrease in process economics.     

A dynamical downscaling of ERA‐Interim in the North Sea using WRF with a 3 km grid—for wind resource applications

Large offshore wind energy projects are being planned and installed in the North Sea, and there is an urgent demand for high‐resolution atmospheric statistics to assess potential power production and revenue. Meteorological observations are too sparse to obtain those statistics, and global reanalyses like ERA‐Interim have a resolution too coarse in space and time to capture important small‐scale and terrain‐driven features of the atmospheric flow. We therefore dynamically downscale ERA‐Interim with the mesoscale model Weather Research and Forecasting to a 3 km grid to capture those unresolved features, for the period 1999–2008. The large‐scale flow is conditioned by spectral nudging, and we make use of observation nudging towards QuikSCAT near‐surface winds. The downscaling results in 100 m wind‐speed distributions and mean wind speeds, which are closer to the observations than ERA‐Interim, while the accuracy in terms of root‐mean‐square error decreases. The observation nudging partially counteracts this latter effect, improving the root‐mean‐square error of wind speed and direction by 0.5 m s^?1 and ~10°, respectively. We also introduce the power skill score, specifically designed to evaluate model performance within wind resource mapping. The power skill score confirms that the dynamical downscaling improves the distribution of wind speed in ranges where high accuracy is important for wind resource assessment. Copyright © 2016 John Wiley & Sons, Ltd.     

Assessment of risk factors and effects in hydrogen logistics incidents from a network modeling perspective

The use of hydrogen as an environmentally friendly fuel for the future is attracting more attention among the scientific community. However, hydrogen has its drawbacks such as its fast burning speed. This suggest that studies should be conducted in order to assess and minimize the associated risks. Hence, this study aims to analyze the risk factors that lead to hydrogen logistics incidents by capturing the complexity of interdependencies in a network modeling approach. In this study, facts and figures from incident cases were acquired, and the assessment was enhanced by considering incident chains and the interdependencies among factors and effects. Then, network analysis was used to identify significant factors and significant effects in the occurrence of hydrogen logistics incidents. The results reveal that each factor plays its own role in the occurrence of an effect. The occurrence of a hydrogen logistics incident cannot be truly reduced by only considering the factors, it must consider both the factors and the effects. Tackling the occurrence of a significant factor and effect is effective for controlling and reducing the occurrence of hydrogen logistics incidents. By modeling and analyzing the interdependencies, this study contributes in revealing the topological structures and characteristics of each factor and effect in the occurrence of hydrogen logistics incidents, and the network diagrams with probabilistic estimations are useful for enhancing safety in hydrogen logistics as well as developing associated precautions.     

Creep crack growth data and prediction for a P91 weld at 650 °C

Creep crack growth tests have been carried out on compact tension (CT) specimens machined from a P91 weldment. Four of these specimens were cut from the parent material side of the weld and another seven specimens were cut across the weld. For the cross-weld specimens, starter cracks were positioned into (or close to) the Type IV region. The creep tests were carried out under constant loads, at 650 °C. The results obtained showed that, the creep crack growth rates for parent material specimens are about ten times lower than those for the cross-weld specimens and that the scatter in the data is relatively high. In this respect, the accuracy of the crack tip location, in the cross-weld CT specimens, plays an important role. Finite Element (FE) analyses were carried out, on notched bar and CT models, using damage mechanics material behaviour models. These analyses were used to estimate the triaxial stress factor, α, for the parent material (PM), the weld metal (WM) and the heat affected zone (HAZ). FE analyses were then used to predict the creep crack growth in the CT specimens. Results from the FE analyses for both the PM and the cross-weld CT specimens were in good agreement with the corresponding experimental results. The effect of the potential drop versus crack length calibration on the calculated C* values was also investigated.     

“FRAC ” — A simulation code for forced fluid flow and transport in fractured, porous rock

The 3D Finite Element Program FRACTure was developed with the specific aim of studying the coupling of interactive mechanisms in geoscience and in particular those relevant to the long term behaviour of a Hot Dry Rock reservoir. The flexible modular structure facilitates the addition of further processes and elements to the existing library and the handling of linear and non-linear constitutive laws and the calculation of their interactions. The Hot Dry Rock applications involve essentially forced fluid flow of cool fluid injected into a hot fractured rock matrix. A study of the relevant processes required finite element solutions for the hydraulic, thermal and elastic fields and especially their interactions. Particular attention has been paid to modelling the perturbations arising from poro-elastic and thermo-elastic effects in the rock matrix and of a non-linear, stress dependent joint closure law. The fracture network is designed in a way to represent nature as realistically as possible: fracture flow takes place along planes or in pipes (fracture intersections), porous matrix flow in 3D bodies. In devising the coupling scheme careful thought has been given to the different time constants for each physical process. Apart of simulating the coupled Hot Dry Rock behaviour, the code has been successfully practised in a variety of applications in geoscience: analysis of geoelectric measurements, radon transport, solute tracer tests, simulations of heat probe operations and hydrogeologic system modelling.     

Epi-n-IZO thin films/1 0 0 Si, GaAs and InP by L-MBE––a novel feasibility study for SIS type solar cells

High quality epitaxial indium zinc oxide (heavily indium oxide doped) (epi-n-IZO) thin films were optimized by laser-molecular beam epitaxy (L-MBE) i.e., pulsed laser deposition (PLD) technique for fabricating novel iso- and hetero-semiconductor–insulator–semiconductor (SIS) type solar cells using Johnson Matthey “specpure”- grade 90% In₂O₃ mixed 10% ZnO (as commercial indium tin oxide (ITO) composition) pellets. The effects of substrate temperatures, substrates and heavy indium oxide incorporation on IZO thin film growth, opto-electronic properties with 1 0 0 silicon (Si), gallium arsenide (GaAs) and indium phosphide (InP) wafers were studied. As well as the feasibility of developing some novel models of iso- and hetero-SIS type solar cells using epi-IZO thin films as transparent conducting oxides (TCOs) and 1 0 0 oriented Si, GaAs and InP wafers as base substrates was also studied simultaneously. The optimized films were highly oriented, uniform, single crystalline approachment, nano-crystalline, anti-reflective (AR) and epitaxially lattice matched with 1 0 0 Si, GaAs and InP wafers without any buffer layers. The optical transmission T (max) 95% is broader and absolute rivals that of other TCOs such as ITO. The highest conductivity observed is σ=0.47×10³ Ω⁻¹ cm⁻¹ (n-type), carrier density n=0.168×10²⁰ cm⁻³ and mobility μ=123 cm²/V s. From opto-electronic characterizations, the solar cell characteristics and feasibilities of fabricating respective epi-n-TCO/1 0 0 wafer SIS type solar cells were confirmed. Also, the essential parameters of these cells were calculated and tabulated. We hope that these data be helpful either as a scientific or technical basis in semiconductor processing.     

Techno-economic analysis of fuel conversion and power generation systems — the development of a portable chemical process simulator with capital cost and economic performance analysis capabilities

The development is described of ECLIPSE, a suite of programs written in C for IBM PC compatible computers, which permits the full technical and economic analysis of current and proposed fuel conversion and power generation systems. A large advantage is the flexibility of approach which is possible and the degree of integration of the technical and economic aspects of the problem. The package includes extensive chemical properties, utilities and capital costing databases which can be modified by the user.     

Performance analyses and improvement guidelines for organic Rankine cycles using R600a/R601a mixtures driven by heat sources of 100°C to 200°C

R600a/R601a mixtures are promising to be widely used in organic Rankine cycle (ORC) systems and also can promote the popularization of ORC technology. While, most of existing studies on ORC systems using R600a/R601a mixtures are based on certain heat source temperatures (generally below 150°C) and saturated vapor at the evaporator outlet. Variations in the optimal mixture composition and superheat degree of R600a/R601a mixtures with increasing heat source temperature remain indeterminate thus far, especially for heat sources above 150°C. Suitable approaches to further improve the system thermodynamic performance are also unclear. This study carried out a systematized analysis for subcritical ORC systems using R600a/R601a mixtures driven by heat sources of 100°C to 200°C, based on the first and second law analysis methods. Guidelines for selections of optimal mixture composition and cycle parameters were provided. Characteristics of exergy loss distribution were revealed to point out the crucial process to further improve the system thermodynamic performance. Results show that the effects of critical parameters on the selections of optimal mixture composition and evaporation pressure become remarkable for heat sources above approximately 160°C. A minimum superheat degree is optimal for heat sources below 170°C, whereas the optimal superheat degree may increase with increasing heat source temperature and R600a mass fraction for heat sources above 170°C. Moreover, reducing the exergy losses in the heat absorption process, turbine, and condenser is vital to further increase the heat‐work conversion efficiency for heat sources of approximately 100°C to 160°C, 170°C to 190°C, and 200°C, respectively.     

European perspective on absorption cooling in a combined heat and power system – A case study of energy utility and industries in Sweden

Mankind is facing an escalating threat of global warming and there is increasing evidence that this is due to human activity and increased emissions of carbon dioxide. Converting from vapour compression chillers to absorption chillers in a combined heat and power (CHP) system is a measure towards sustainability as electricity consumption is replaced with electricity generation. This electricity produced in Swedish CHP-system will substitute marginally produced electricity and as result lower global emissions of carbon dioxide. The use of absorption chillers is limited in Sweden but the conditions are in fact most favourable. Rising demand of cooling and increasing electricity prices in combination with a surplus of heat during the summer in CHP system makes heat driven cooling extremely interesting in Sweden. In this paper we analyse the most cost-effective technology for cooling by comparing vapour compression chillers with heat driven absorption cooling for a local energy utility with a district cooling network and for industries in a Swedish municipality with CHP. Whilst this case is necessarily local in scope, the results have global relevance showing that when considering higher European electricity prices, and when natural gas is introduced, absorption cooling is the most cost-effective solution for both industries and for the energy supplier. This will result in a resource effective energy system with a possibility to reduce global emissions of CO₂ with 80%, a 300% lower system cost, and a 170% reduction of the cost of producing cooling due to revenues from electricity production. The results also show that, with these prerequisites, a decrease in COP of the absorption chillers will not have a negative impact on the cost-effectiveness of the system, due to increased electricity production.     

Total planning of combined district heating,cooling and power generation systems for a new town—Part II

The objective of this study is to introduce one of the main results of the project for studying energy conservation technologies in a new airport town, which is organized by the Osaka Science and Technology Center, Japan. First, based on the estimated energy demands in the new town, technological aspects are investigated for the district heating, cooling and hot water supply system. Then, the economic and energy saving characteristics are compared for several alternative systems according to the differences of the type of absorption refrigerating machine and so forth. Assuming that a combined heat and power plant is used as the heat source plant of the district thermal distribution system, the optimal combined district heating, cooling and power generation system has been selected from a comprehensive economic viewpoint. Lastly, it is ascertained that if fuel costs continue to rise at the rate of 8 per cent per year, the best energy conservation system becomes superior economically to the conventional district thermal distribution system.     

Evaluation of PMSG‐based drivetrain technologies for 10‐MW floating offshore wind turbines: Pros and cons in a life cycle perspective

This paper presents an in depth evaluation and comparison of three different drivetrain choices based on permanent‐magnet synchronous generator (PMSG) technology for 10‐MW offshore wind turbines. The life cycle approach is suggested to evaluate the performance of the different under consideration drivetrain topologies. Furthermore, the design of the drivetrain is studied through optimized designs for the generator and gearbox. The proposed drivetrain analytical optimization approach supported by numerical simulations shows that application of gearbox in 10‐MW offshore wind turbines can help to reduce weight, raw material cost, and size and simultaneously improve the efficiency. The possibility of resonance with the first torsional natural frequency of drivetrain for the different designed drivetrain systems, the influence of gear ratio, and the feasibility of the application for a spar floating platform are also discussed. This study gives evidence on how gearbox can mitigate the torque oscillation consequences on the other components and how the latter can influence the reliability of drivetrain.     

Creep crack growth in welded components — a numerical study and comparison with the R5 procedures

In the present study, creep crack growth (CCG) in a circumferentially welded low alloyed pipe is numerically investigated for a number of different combinations of weldment constituent material properties. A creep ductility based damage model describes the accumulation of creep damage ahead of the crack tip where a constraint parameter and the creep strain rate perpendicular to the crack plane are used as characterising parameters. It is assumed that a fully circumferential creep crack, located in the heat affected zone with a depth of one quarter of the pipe thickness, is growing at a constant rate from the outer surface towards the inside. The numerical results reveal that not only the properties of the zone containing the crack, but also the deformation properties of the surrounding material influence the CCG behaviour. This influence can be noted on the characterising parameters used for the CCG rate predictions as well as on the CCG rate itself. The mismatch influence on corresponding C^* values is, however, marginal. This indicates that determination of the CCG rate in weldments, based on the C^* value only, may result in uncertain estimates.The numerically investigated cases are also assessed by use of the R5 procedures for the sake of comparison. Considering the stress re-distribution, due to the mismatch effect, the CCG rate is determined for the different weldment configurations. The comparison shows that the assumption of plane strain or plane stress conditions in the R5 analysis is essential for the agreement of the results between R5 and the two-parameter approach. Assuming plane stress conditions at the crack tip results in a relatively good agreement for the axial stress dominated cases investigated. However, for the hoop stress dominated cases, the R5 procedures predict higher CCG rates by an order of magnitude.