European Curriculum on Fuel Cell and Hydrogen Technology

CONTENTS

1 INTRODUCTION

2 FUNDAMENTAL MODULES

2.1  MODULE THEORY OF FUEL CELLS

2.1.1  INTRODUCTORY STATEMENT

2.1.2  PREREQUISITE MATTER

2.1.3  CONTENTS OF THE MODULE

2.1.3.1  Thermodynamics (G: x hrs)

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Equilibrium and non-equilibrium. Thermodynamic quantities. Reversible and irreversible processes. References:

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Definition and relation to other thermodynamic potentials. Fundamental properties (correspondence between equilibrium state and a minimum in Gibbs free energy, maximum amount of work the system can perform on an external object being the difference in Gibbs free energy between final and initial states, at equilibrium the chemical potential is constant throughout the system). References:

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Chemical potential in an external electrical field. Molar quantities and the Faraday constant. References:

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Chemical potential of an ideal gas. Standard state. Non-ideal gasses (activity and fugacity). Activity of solutes and of pure solids/liquids. References:

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Chemical potential in systems with more than one particle species; partial pressure. Law of mass action. Standard reaction Gibbs free energy. The equilibrium constant. References:

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Electromotive force. Open circuit voltage. Nernst's equation. Standard potentials. References:

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The Carnot cycle. Carnot efficiency as limiting efficiency of all thermodynamic cycles. Lower heating value (LHV) and higher heating value (HHV) of a fuel. Only the HHV efficiency is thermodynamically relevant. Relation to Gibbs free energy and the standard enthalpy. Actual efficiency of a fuel cell. Voltage efficiency. Faradaic/current effiency. Fuel utilization. References:

2.1.3.2  Electrochemistry (G: x hrs)

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Electrochemical processes. Importance of surfaces. Anode. Cathode. Electrolyte. Three-phase boundaries. Anodic and cathodic currents. Polarization. Galvani and Volta potentials. References:

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Reduction and oxidation. Oxidation numbers. Charge transfer reactions. Half-reactions. References:

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Activation losses; fuel crossover. Electronic conductivity of electrolyte. Ohmic losses. Mass transport losses. Bubble formation. Activation overpotential. Reaction overpotential. Resistance overpotential. Concentration overpotential. Transfer overpotential. References:

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Transition states and energy barriers. Electrode and electrolyte double layers. Exchange current density. Butler-Volmer equation. Tafel plots. Rate determining steps. References:

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References:

2.1.3.3  Charge transport (G: x hrs)

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Current density. Conductivity and resistivity. Ohmic and non-ohmic transport. Area specific resistance. References:

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Time varying fields. The complex impedance. Ohmic, capacitive and inductive elements. Constant phase element. Impedance spectroscopy. References:

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Microscopics of electronic conduction. Mobility. Charge carrier density. Energy bands. Diffusion and the Einstein relation. Metals. Insulators. Semiconductors (intrinsic and extrinsic). Typical magnitude and temperature dependence of the conductivity for each class of materials. References:

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Mechanisms. Bulk and grain boundary transport. Typical magnitude and temperature dependence of the conductivity. Examples of materials. References:

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Mixed conduction. Transference number. Examples of materials. References:

2.1.3.4  Defect chemistry (G: x hrs)

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Point defects: intrinsic (Schottky, Frenkel), extrinsic. Dislocations. Grain boundaries. Notation: Kröger-Vink. References:

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2.1.3.5  Types of fuel cells (G: x hrs)

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Definitions: polymer electrolyte, electrolyte materials, electrode materials, operating temperature, high and low T PEM, direct methanol fuel cells, fuel requirements, performance characteristics. References:

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Definitions: solid oxide (ceramic) electrolyte, oxygen conducting and proton conducting SOFC, electrolyte materials, electrode materials, operation temperature, fuel requirements; performance characteristics. References:

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Molten carbonate fuel cell. Electrolyte and electrode materials. Performance characteristics. Phosphoric acid fuel cell. Electrolyte and electrode materials. Performance characteristics. Alkaline fuel cell. Electrolyte and electrode materials. Performance characteristics. Novel fuel cell concepts: formic acid fuel cell, fuel-cell-on-a-chip, direct carbon fuel cell, microbial fuel cells. References:

2.2  MODULE HYDROGEN TECHNOLOGY

2.2.1  INTRODUCTORY STATEMENT

2.2.2  PREREQUISITE MATTER

2.2.3  CONTENTS OF THE MODULE

2.2.3.1  Thermodynamic and physical properties of hydrogen (G: x hrs)

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Thermodynamic properties [1,2,3,4,5,6,7]: intensive properties (density, pressure, temperature, internal energy, entropy, chemical potential of a species, mole fraction of a species, mass fraction of a species) and extensive properties (volume, mass, kinetic energy, potential energy, internal energy (Joule's law [8]: in a perfect gas the internal energy is a function of the absolute temperature alone), enthalpy, entropy, Helmholtz energy, Gibbs energy). Thermodynamic property tables for the computation of the internal energy, enthalpy and entropy [9]. Statistical mechanical foundation of thermodynamic properties [10]: density and the Boltzmann distribution law, the internal energy and the partition function, Boltzmann's definition of entropy, connection between the Helmholtz energy and the partition function, the Helmholtz energy as a thermodynamic potential, derivation of all thermodynamic properties from the Helmholtz energy: internal energy from the Helmholtz energy, enthaly from the Helmholtz energy, the Gibbs energy from the Helmholtz energy, entropy from the Helmholtz energy. The rotational partition function [10]: ortho- and para-hydrogen. Phase boundaries [1,3,6]: boiling point, melting point, vapour pressure, sublimation vapour pressure, fusion curve, sublimation curve, vaporisation curve, triple point, critical point, critical properties. Phase diagrams [1,3,6]: the PT-diagram of a pure substance (solid region, liquid region, vapour region, gas region, fluid region), the PV-diagram of a pure substance (solid region, liquid region, liquid-vapour region, vapour region, gas region, super-heated vapor, sub-cooled liquid), the phase diagram of hydrogen [11]. Equations of state for the PVT-behaviour of pure substances and mixtures: ideal gas law [2,1,3], Noble-Abel equation of state [12,13], van der Waals equation of state [2,1,3,14], mixing rules for the van der Waals coefficients [1], the virial equations of state [2,1], extended virial equation of state (the Benedict-Webb-Rubin equation [1]), cubic equations of state (the van der Waals equation of state [2,1,7]), relation between the van der Waals constants and critical properties of a pure substance [2,7], the Redlich-Kwong equation of state [2,7], the Beattie-Bridgeman equation of state [7]. Corresponding-states correlations for gases: the two-parameter theorem of corresponding states, the acentric factor, the three-parameter theorem of corresponding states, the Pitzer correlations for the compressibility factor [1], the Pitzer correlations for the second virial coefficient [1], the Lee-Kesler equation, the Soave-Redlich-Kwong equation, the Peng-Robinson equation. Generalised correlations for liquids: Rackett's correlation [1], the Lydersen-Greenkorn-Hougen correlation [1]. Equations of state for para-hydrogen, normal hydrogen, and ortho-hydrogen [15]. References: Abbott & Van Ness (1972) [2], Atkins & de Paula (2006) [3], Metz (1976) [4], Moran & Shapiro (2000) [5], Smith, Van Ness & Abbott (2007) [1], Cengel & Boles (2007) [6], and Sonntag, Borgnakke & Van Wylen (2003) [7].

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Atomic structure. Spin of the atomic nuclei of a hydrogen molecule [16]: ortho-hydrogen, para-hydrogen, equilibrium between ortho-hydrogen and para-hydrogen (temperature dependence of the equilibrium [17,18], normal hydrogen), the release of heat accompanying ortho- to para-conversion [17,18], rate of the non-catalytic ortho- to para-hydrogen conversion [19]. States of matter. Gaseous (GH2), liquefied (LH2) and slush (SLH2) forms of hydrogen [17]. Viscosity. Examples of viscosities of gases, liquids, and liquid metals [20]. Molecular transport of momentum in a fluid: the hypothesis of a linear relationship between the momentum flux vector and the local velocity gradient (Newton's momentum law) [21], the proportionality constant (i.e. the dynamic viscosity) in Newton's momentum law as a measure of the internal friction opposing deformation of the fluid [21], positivity of the dynamic viscosity as a result of the momentum flux vector pointing in such a direction as to tend to eliminate the non-uniformity of the fluid velocity [21], the application of Newton's momentum law as an empirical expression for the tangential stresses (i.e. the off-diagonal components of the deviatoric stress tensor) in a fluid [21]. The kinematic viscosity (i.e. dynamic viscosity divided by the density) as a measure of the internal friction per mass unit of fluid [21]. The coefficient of bulk viscosity in the pure expansion of a fluid: distinction and independence between the shear viscosity and the bulk (dilatational) viscosity [20,22]. The concept of a Newtonian fluid [21]: effect of pressure and temperature on the viscosity of pure gases and gas mixtures [20,22,23], effect of high pressure on liquid viscosity [23], effect of temperature on liquid viscosity [23]. Non-Newtonian fluids [21,20,24]: time independent non-Newtonian fluids (Bingham plastics, pseudoplasic fluids, dilatant fluids), time dependent non-Newtonian fluids (thixotropic fluids, rheopectic fluids), viscoelastic fluids (Maxwell liquids). Empirical models for the viscosity of non-Newtonian fluids: the Bingham model [20], the Ostwald-de Waele model [20], the Eyring model [20], the Ellis model [20], the Reinier-Philippoff model [20]. Property tables for the computation of the viscosity of gases and gas mixtures [9,25]. Inter-comparison between models for the viscosity [26]. Thermal conductivity. Conduction heat transfer [27,28,29]: Fourier's law , thermal conductivity (examples of thermal conductivities of some metals, alloys, nonmetallic solids, liquids, gases [27,28]), the heat flux (heat transfer per unit area) and the heat rate by conduction [27], thermal resistance, analogy between thermal resistance and electrical circuits, plane walls in series and parallel [28], variation of thermal conductivity for gases and liquids [28], thermal contact resistance (temperature drop through contact resistance [28], effect of surface roughness [28], thermal contact resistance for metallic interfaces under vacuum conditions [28,30], effect of contact pressure on thermal contact resistance [28,30], effect of different interfacial fluids on thermal contact resistance [28,30], example: application of high conductivity pastes to mount electronic components to heat sinks). Effect of pressure and temperature on the viscosity of pure gases and gas mixtures [23]. Effect of temperature on the viscosity of liquids [23]. Property tables for the computation of the thermal conductivity of gases and gas mixtures [9,25]. Inter-comparison between models for the thermal conductivity [26]. Diffusion coefficient. Fick's law of diffusion [27,29]. Binary diffusion coefficient (mass diffusivity). Ordinary diffusion (motion of species due to concentration gradient). Other modes of diffusion [31,22]: pressure diffusion (motion of species due to pressure gradient), thermal diffusion (motion of species due to temperature gradient), forced diffusion (motion of species due to external force). Diffusion velocity [31]: definition with respect to mass average velocity, definition with respect to molar average velocity. Pressure and temperature dependence of mass diffusivity [31,22,27]. Conservation of species in a control volume: the species diffusion equation, the species convection-diffusion equation. Multi-component mixtures: the Stefan-Maxwell equations [31], the effective binary diffusivity of a species in a multi-component mixture [31], equation of continuity for each species in a multi-component mixture [31]. Effect of pressure and temperature on the diffusion coefficient of a species in a gas [23]. Effect of temperature on the diffusion coefficient in a liquids [23]. Property tables for the computation of binary diffusion coefficients of gases in gas mixtures [9]. Joule-Thompson inversion. Joule-Thompson inversion temperature [22,3]. Joule-Thompson coefficient [22,3]: molecular interpretation of the Joule-Thompson effect, calculation of the Joule-Thompson effect, application to isenthalpic expansion, derivation of the Joule-Thompson coefficient from the enthalpy state equation, measurement of the Joule-Thompson coefficient, calculation of the Joule-Thompson coefficient for pure gases and gas mixtures. Joule-Thompson inversion curve [22]. Reduced Joule-Thompson inversion curve [22]. References: Lanz, Heffel & Messer (2001) [16], NASA NSS 1740.16 (1997) [17], Zabetakis, Furno & Martindill (1961) [19], Batchelor (1994) [21], Bird, Stewart & Lightfoot (2002) [31], Atkins & de Paula (2006) [3], Hirschfelder, Curtiss & Bird (1967) [22], Reid, Prausnitz & Poling (1987) [23], Holman (1997) [32], Hottel & Sarofim (1967) [33], Incropera, De Witt, Bergman & Lavine (2006) [27], Kaviany (2002) [34], Kreith & Bohn (2001) [28], Pitts & Sissom (1977) [35], Welty, Wicks, Wilson & Rorrer (2001) [36] and Fried (1969) [30].

2.2.3.2  Hydrogen production for fuel cells (G: x hrs)

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2.2.3.3  Hydrogen storage (G: x hrs)

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2.2.3.4  Markets and infrastructure (G: x hrs)

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2.2.3.5  Other fuels for fuel cells (G: x hrs)

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2.3  MODULE APPLICATIONS OF FUEL CELLS AND HYDROGEN AS AN ENERGY CARRIER

2.3.1  INTRODUCTORY STATEMENT

2.3.2  PREREQUISITE MATTER

2.3.3  CONTENTS OF THE MODULE

2.3.3.1  Components of a fuel cell system (G: x hrs)

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2.3.3.2  Hydrogen combustion engine (G: x hrs)

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2.3.3.3  Vehicle propulsion (G: x hrs)

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2.3.3.4  Auxiliary power units (APU's) (G: x hrs)

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2.3.3.5  Micro-combined heat and power (m-CHP) (G: x hrs)

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2.3.3.6  Distributed generation (G: x hrs)

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2.3.3.7  Large power plants (G: x hrs)

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2.3.3.8  Battery replacement (G: x hrs)

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2.3.3.9  Reversible fuel cells (G: x hrs)

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2.3.3.10  Energy system considerations (G: x hrs)

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3 APPLIED MODULES

3.1  MODULE PROTON EXCHANGE MEMBRANE (PEM) FUEL CELLS

3.1.1  INTRODUCTORY STATEMENT

3.1.2  PREREQUISITE MATTER

3.1.3  CONTENTS OF THE MODULE

3.1.3.1  Theory of proton exchange membrane (PEM) fuel cells (G: x hrs)

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3.1.3.2  Low-temperature proton exchange membrane (LT-PEM) fuel cells (G: x hrs)

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3.1.3.3  High-temperature proton exchange membrane (HT-PEM) fuel cells (G: x hrs)

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3.1.3.4  Direct methanol fuel cells(G: x hrs)

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3.1.3.5  Materials (G: x hrs)

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3.1.3.6  Manufacturing methods (G: x hrs)

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3.1.3.7  Cell design (G: x hrs)

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3.1.3.8  Stack and system design (G: x hrs)

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3.1.3.9  Degradation mechanisms (G: x hrs)

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3.1.3.10  Open R&D issues (G: x hrs)

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3.2  MODULE SOLID OXIDE FUEL CELLS (SOFC)

3.2.1  INTRODUCTORY STATEMENT

3.2.2  PREREQUISITE MATTER

3.2.3  CONTENTS OF THE MODULE

3.2.3.1  Basics of solid oxide fuel cells (SOFC) fuel cells (G: x hrs)

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3.2.3.2  Cell design (G: x hrs)

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Thermal compatibility (TEC), mechanical strength, Anode/ Cathode / Metal / Electrolyte / Free-standing supported. References:

3.2.3.3  Cell components (G: x hrs)

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Ionic and electronic conductivity, catalytic activity, microstructure (porosity, particle sizes, percolation), graded structure, graded composition. Materials: cermets (Ni/YSZ), ceramic (mixed conductors (CGO, StTiNb), dual phase (CGO/YSZ, LaSrCrMn/YSZ), materials for proton-conducting SOFCs. References:

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Ionic and electronic conductivity, catalytic activity, microstructure (porosity, particle sizes, percolation), graded structure, graded composition. Materials: Dual phase (LSM/YSZ, LSCo/CGO, LSCF/CGO), mixed conductors (LSCo), materials for proton-conducting SOFCs. References:

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Ionic transfer number and conductivity, gas tightness, bulk and grain boundary conductivity, dependence on oxygen partial pressure. Materials: YSZ, CGO, LSGM, proton conductors References:

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Electronic conductivity, microstructure (porous, perforated sheets). Anode support: Ni/YSZ, STN. Cathode support: LSM. Metal: FeCr. Supports for m-SOFCs: Si, glasses. References:

3.2.3.4  Manufacturing methods (G: x hrs)

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Pecchini, drip pyrolysis, glycine-nitrate, solid state oxide. References:

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Slurry and paste preparation (binders, plasticizers, particle size distribution, viscosity, zeta potential). Shaping (tape casting, screen printing, spray deposition, calendaring, dip coating, slip casting, electrophoretic, extrusion, physical vapour deposition methods (PLD, Sputtering, plasma spray), chemical vapour deposition). References:

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Sintering mechanisms, debinding, sintering atmospheres (air, inert, hydrogen), sintering aids, sintering profiles, liquid phase sintering, characterization (dilatometry, TGA, DSC, XRD, microscopy). References:

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Processes, nitrates, nanoparticles. References:

3.2.3.5  Stack and system design (G: x hrs)

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Manifolding, flow patterns (fuel and air), current collection. References:

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Manifolding, flow patterns (fuel and air), current collection. References:

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Materials: metals, ceramics, dual phase, coatings. Corrosion mechanisms, geometries, shaping. References:

3.2.3.6  Degradation mechanisms (G: x hrs)

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Changes of microstructure, chemical reactions, impurities, redox, mechanical failure (cracks, delamination), corrosion (cell support), mitigation strategies. References:

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Mechanical failure (vibration, thermal stresses, cracks, loss of electrical contact), leaking, seal degradation, corrosion, Cr-evaporation, mitigation strategies. References:

3.2.3.7  Open R&D issues (G: x hrs)

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Reaction mechanisms, correlation between microstructure and performance, new in situ methods, predictive methods for improved materials. References:

3.3  MODULE MOLTEN CARBONATE FUEL CELLS (MCFC) AND OTHER TYPES

3.3.1  INTRODUCTORY STATEMENT

3.3.2  PREREQUISITE MATTER

3.3.3  CONTENTS OF THE MODULE

3.3.3.1  Molten carbonate fuel cells (G: x hrs)

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3.3.3.2  Phosphoric acid fuel cells (G: x hrs)

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3.3.3.3  Alkaline fuel cells (G: x hrs)

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3.3.3.4  Other fuel cells (G: x hrs)

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3.3.3.5  Open R&D issues (G: x hrs)

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3.4  MODULE EXPERIMENTAL METHODS

3.4.1  INTRODUCTORY STATEMENT

3.4.2  PREREQUISITE MATTER

3.4.3  CONTENTS OF THE MODULE

3.4.3.1  Materials characterization (G: x hrs)

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3.4.3.2  Impedance spectroscopy (G: x hrs)

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3.4.3.3  In situ methods (G: x hrs)

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3.4.3.4  Stack and system evaluation (G: x hrs)

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3.5  MODULE MODELLING

3.5.1  INTRODUCTORY STATEMENT

3.5.2  PREREQUISITE MATTER

3.5.3  CONTENTS OF THE MODULE

3.5.3.1  Electrode reactions (G: x hrs)

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3.5.3.2  Thermodynamic stability (G: x hrs)

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3.5.3.3  Mechanical modelling (G: x hrs)

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3.5.3.4  Stack modelling (G: x hrs)

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3.5.3.5  Systems modelling (G: x hrs)

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3.5.3.6  Solid state hydrogen storage (G: x hrs)

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3.6  MODULE SAFETY OF FUEL CELL AND HYDROGEN TECHNOLOGIES

3.6.1  INTRODUCTORY STATEMENT

3.6.2  PREREQUISITE MATTER

3.6.3  CONTENTS OF THE MODULE

3.6.3.1  Safety related hydrogen properties and combustion characteristics (G: x hrs)

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Density. Role of buoyancy after gaseous hydrogen releases (plume formation distance and formation of ceiling layers in enclosures [39,40,41,42,43,44,45], hydrogen removal by natural convection [46,47,48,49]). Pool spreading after liquefied hydrogen releases: on solid surfaces [50,51], on water [52,53] e.g. large spill in a harbour, canal or river). Boiling point. Heat of vaporisation. Flammability limits. Minimum ignition energy. Minimum ignition temperature. Auto-ignition temperature. Quenching distance. Flame temperature. Burning velocity. References: Swain & Swain (1996) [49], Swain, Filoso, Grilliot & Swain (2003) [48], Cleaver, Marshall & Linden (1994) [45], Morton (1959) [40], Turner (1969) [43], Baines & Turner (1969) [44], Rooney & Linden (1997) [42], Kaye & Hunt [41], Hunt & Linden (2001) [46], Hunt & Kaye (2001) [47], Zalosh (2006) [39], Verfondern & Dienhart (1997 [50], 2007 [51]), and Fay (2003) [53].

3.6.3.2  Hydrogen releases, mixing and dispersion

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Vessels for liquefied hydrogen storage [54]. Hydrogen losses due to initial vessel temperature during filling [54]. Accumulation of gaseous hydrogen due to evaporation [54]. References: Aceves (1998) [54] and Sherif (1997) [55].

3.6.3.3  Hydrogen combustion

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Combustion reaction of hydrogen in air: stoichiometric equation, global versus elementary reactions, relationship between reaction rate and chemical species concentration, the three-parameter Arrhenius form to describe the reaction-rate constant (activation energy, temperature exponent, pre-exponential factor), overall reaction rate expression, overall reaction order (effect of equivalence ratio and pressure on overall reaction order), overall activation energy (effect of equivalence ratio and pressure on overall activation energy). Heats of reaction (constant pressure combustion: equality of reactant and product enthalpies; constant volume combustion: equality of reactant and product internal energies). Adiabatic flame temperature: the frozen flame temperature (absence of product dissociation), adiabatic flame temperature with product dissociation (equilibrium constants, chemical affinity and chemical potential, equilibrium as the condition of zero chemical affinity, chemical affinity as the partial molar Gibbs function, criteria for equilibrium (Gibbs free energy for constant pressure processes, Helmholtz free energy for constant volume processes)). Calculation of the adiabatic flame temperature by the element potential method (constant pressure combustion: minimisation of the Gibbs free energy; constant volume combustion: minimisation of the Helmholtz free energy; examples of chemical equilibrium codes CANTERA, STANJAN, GASEQ; limitations imposed by the inclusion of the ideal gas law in chemical equilibrium codes; equations of state for high pressure effects up to 700 MPa: virial equations of state, Becker-Kistiakowsky-Wilson equation of state). Reaction mechanisms: forward elementary reactions, backward elementary reactions, the chemical equilibrium constant as the ratio between the forward and backward elementary reaction rates, detailed schemes (the Dougherty & Rabitz mechanism, the Miller, Mitchell, Smooke & Kee mechanism, the Marinov, Westbrook & Pitz mechanism, the O'Conaire, Curran, Simmie, Pitz & Westbrook mechanism, the Saxena & Williams mechanism), reduced mechanisms (example: a four-step reduced mechanism for hydrogen-air mixtures by Lu, Ju & Law). Chain branching: the concept of a chain carrier. Removal of chain carriers by a three-body collision with a third body. The crossover temperature. Falloff. The fall-off reaction rate: the Lindemann fall-off rate constant, the Stewart fall-off rate constant, the Troe fall-off rate constant. Chaperon efficiencies. Software tools for analysing detailed chemical kinetic mechanisms: CANTERA, CHEMKIN, FLAMEMASTER. Validation of kinetic mechanisms from critically-reviewed experiments including stretch-free laminar burning velocities, flow reactor species profiles, ignition delay times in shock tubes, etc. Surface reactions. Surface adsorption processes: relation to catalysis, improvement of the miners' safety lamp due to Henry in 1824 by the addition of platinum powder to the reacting surface, Faraday's view on the role of adsorption to the surface in catalysis, physiosorption, van der Waals adsorption, chemisorption, Langmuir's concept of the unimolecular layer, Langmuir's adsorption isotherm, monolayer adsorption, multi-layer adsorption, adsorption with dissociation, competitive adsorption. Surface reaction processes: reaction mechanism, the Langmuir-Hinselwood mechanism, the Langmuir-Rideal-Eley mechanism, the precursor mechanism, Unimolecular surface reactions. Bimolecular surface reactions. Desorption. Kinetic model of hydrogen-oxygen reaction on the platinum surface. Kinetic rates of hydrogen-oxygen reaction on the platinum surface. Application in hydrogen safety: the three explosion limits in the flammability diagram, dependence explosion limits of hydrogen-oxygen systems on containment shape, nature of surface, added inert gases (inertisation by steam), spontaneous ignition of hydrogen leaks. ignition by hot surfaces, catalytic recombiners, initial conditions for self-sustained detonation, boundary conditions for self-sustained detonation, prediction of detonation limits of hydrogen-air and hydrogen-oxygen mixtures, prevention of hydrogen ignition (electrical circuits, static electricity, hot surface, open fire, shock waves, (hot) gas jet, explosives, exothermic reaction, pyrophoric substances, lightning). Overview of hydrogen ignition mechanisms and relevant prevention techniques: electrical circuits, static electricity, hot surface, open fire, shock waves, (hot) gas jet, explosives, exothermic reaction, pyrophoric substances, lightning, etc. Autoignition and safety in hydrogen powered vehicles. Standard IEC 60079-10 'Electrical apparatus for explosive gas atmospheres - Part 10: Classification of hazardous areas'.

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Overview of governing equations (instantaneous equations, Reynolds and Favre decomposition, filtering) and turbulence concepts (closure problem, Reynolds stresses, Boussinesq hypothesis, subgrid-scale stresses) and modeling (Prandtl mixing length model, the k-epsilon model, Reynolds stress models, LES models). The equations of change for turbulent reacting flows and closure models. Large Eddy Simulation: mass weighted Favre averaging and the filtered balance equations for (non)-reacting flows, sub-grid scale models. Brief overview of applications to practical hydrogen safety provision (garages, parking places, tunnels, re-fuelling stations, liquefied hydrogen storage, fuel-cell storage, bursts of high-pressure vehicle tanks, pressure-release devices, post-release mitigation, accidental combustion, stand-off distances).

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Laminar premixed flames: phenomenology, structure of the reaction zone, laminar burning velocity and laminar flame thickness. Stabilisation of laminar premixed flames on burners. Flash-back, blow-off and flame quenching. Effect of equivalence ratio, diluent concentration, pressure and temperature on the laminar burning velocity. Cellular flame structure and flame wrinkling. Effect of flame stretch and flame curvature on the laminar burning velocity. Turbulence generated by flame front itself. Turbulent premixed flames: phenomenology, turbulent flame brush, turbulent burning velocity and turbulent flame thickness. Turbulence scales and the interaction between turbulence and flames. The Borghi-diagram and interpretation of combustion regimes. The closure problem in turbulent premixed combustion. Flamelet models and flame surface density models. Flame extinction by turbulence.

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Non-premixed flames. Laminar diffusion flames: passive scalars, mixture fraction, flame structure in the mixture fraction space, state relationships, the Burke-Schumann flame structure, Laminar jet flames in a uniform flow field and flame length. Turbulent diffusion flames: relationship between flame height and fuel flow rate, stable lifted flames and blow-out phenomenon, dependence of flame length and shape on jet direction, correlation between flame length and rate of heat release. Partially premixed combustion: triple flames, combustion of an inhomogeneous mixture in a closed vessel and pressure build up. Prediction of jet fire parameters: temperature, visibility, flame length and flame shape, radiation. Pool fire characteristics. Fireball characteristics. Case studies and analysis of experimental data on thermal effects of hydrogen fires. Thermal effects on people and construction elements: tolerance limits, fire resistance rating. Damage criteria for buildings, vehicles and people. Safety distances for hydrogen fires. Partially premixed flames. Non-uniform mixtures: triple flames. Insight into diffusion flame stabilisation on the burner. Application of mixture fraction concept to non-uniform mixtures.

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Micro-flames (characteristic flow rates, quenching limits, blow-off limits, relevant regulations, codes and standards). Hydrogen jet flame basics (laminar diffusion flames and turbulent non-premixed flames, dependence of flame length on Reynolds and Froude numbers, hydrogen flame visibility (infrared, visible, ultraviolet emissions), flame lengths, length to width ratio of jet fire). Dimensional flame length correlations. Dimensionless flame length correlations. Nomogram for hydrogen flame length calculation. Location of hydrogen flame tip. Effect of ignition source location on jet flame shape. Flame lift-off and blow-out phenomena (dependence of lift-off height on flow velocity, independence of lift-off height on nozzle diameter, flame blow-off pressure for different nozzle diameters). Separation distances from hydrogen jet fires (jet fire hot current, radiation from hydrogen flames, effect of buoyancy on reduction of the separation distance, effect of jet attachment on the separation distance, pressure effects of delayed ignition of hydrogen releases). Modelling and simulation of hydrogen jet fires. References:

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Phenomenology of deflagration. Explosion severity parameters: relationship between explosion severity parameters and flame propagation parameters, pressure and temperature dependence of explosion severity parameters, effect of obstacles on flame propagation, flame acceleration and pressure build up. Confined deflagrations: dynamics of flame front propagation, flame induced flow, flame instabilities and flame wrinkling, prediction of pressure build-up in closed space, the Mache effect. Unconfined large-scale deflagration dynamics: mechanisms of flame propagation acceleration and the role of instabilities, positive and negative phases of pressure dynamics, pressure wave decay in the atmosphere. Overview of hydrogen deflagration mitigation techniques : pressure containment, deflagration venting, suppressant barriers, suppressant injections, fast-acting valves, flame front diverters, inherently safe design, inertisation, deflagration flame arresters, quenching diameter, dependence of the quenching diameter on pressure and application in deflagration flame arresters, quenching on the wall.

Contents

Phenomenology of detonation. The Hugoniot curve: the Hugoniot relations, the Rankine-Hugoniot relation, the Rankine-Hugoniot diagram, the Rayleigh-line relation, the Chapman-Jouget points, the Chapman-Jouget detonation wave velocity. The detonation wave structure: the Zeldovich-von Neumann-Doring theory of detonation (one-dimensional wave structure), three-dimensional detonation wave structure. Detonation limits: confined and unconfined detonation limits, comparison between different fuels, effect of a problem scale. Detonation cell size: dependence on composition, temperature and pressure, comparison between hydrogen and hydrocarbon fuels, relationship between detonation initiation energy and detonation cell size, comparison between hydrogen, other fuels, and explosives, critical tube diameter for the onset of detonation. Deflagration to detonation transition (DDT): phenomenology of flame acceleration and DDT; effect of chemical composition, pressure, temperature, geometry, and physical size of the system. Autoignition delay times for hydrogen-air mixtures. Possible measures for reducing the potential of detonation wave generation: inhibition of flames, venting in the early stages of an explosion, quenching of the flame-shock complex, detonation flame arresters.

Contents

Structural response to explosion loadings: amplification factors for sinusoidal and blast loadings, P-I diagrams for ideal blast sources and non-ideal explosions, energy solutions, dimensionless P-I diagrams. Structural response times for plates. Damage criteria for buildings, vehicles and people. Fragmentation and missile effects: primary and secondary fragments; drag-type and lifting-type fragments; impact effects; trajectories and impact conditions.

3.6.3.4  Degradation and embrittlement of construction materials (G: x hrs)

Contents

Internal hydrogen embrittlement. External hydrogen embrittlement. States of hydrogen in steels: hydrogen in metallic solution, hydrogen in combined state. Gaseous hydrogen embrittlement: steel deterioration due to hydrogen in metallic solution, mechanism due to transport by dislocations, effect of temperature. Hydrogen attack: steel deterioration due to hydrogen in combined state, mechanism of formation of micro-cavities in steel because of the induced lack of carbon, effect of diffusional transport, effect of temperature. Influence of hydrogen pressure on crack growth rate. Test methods to investigate hydrogen embrittlement and hydrogen attack. Factors affecting hydrogen embrittlement: hydrogen purity, hydrogen partial pressure, temperature, exposure time, surface condition, nature of the material (critical concentration of hydrogen in the material, microstructure, chemical composition, mechanical properties). Mitigation of hydrogen embrittlement by the addition of vanadium and rare earth elements to ferritic steel, or, Ni, C, and Mn to austenitic stainless steels. Hydrogen embrittlement of other materials: brass and copper alloys, aluminum and aluminum alloys, Cu-Be (used in springs and membranes), Ni and high Ni alloys, Ti and Ti alloys. Mitigation of hydrogen attack: chemical composition (addition of Cr, Mo, Ti, W), heat treatment (stress relief treatment), level of stress (elimination of residual stresses by heat treatment). An overview of reported accidents and incidents caused by hydrogen embrittlement (hydrogen transport vessel, hydrogen cylinder bursts, hydrogen transport pipes, etc.). References: Ahmad (2006) [56], Gibala & Hehemann (2002) [57], Barthelemy (2005) [58], Barthelemy (2006) [59], Rogante, Battistella & Cesari (2006) [60], ASTM F519-08 (2008) [61],

3.6.3.5  Safety requirements of hydrogen storage (G: x hrs)

Contents

Storage tanks of type 1, 2, 3 & 4. Fire resistance of CGH2 storage tanks. Hydrogen storage fast filling and associated issues. Cryo-compressed hydrogen storage (effect ortho- to para-hydrogen conversion heat on the boil-off phenomenon). Physical storage of hydrogen in capillary systems. Effect of filling direction on vessel failure. Fire resistance of onboard storage. References:

Contents

Boil-off phenomenon. Enriched oxygen atmosphere formation at failure of external tank wall. Safety issues of unconverted liquefied hydrogen storage (evaporation due to conversion heat release). Potential hazard due to naturally occurring deuterium. Spills of LH2. Fire resistance of LH2 storage vessels. Fire resistance of onboard storage. References:

Contents

Pyrophoric properties of metal hydrides. Toxicity of metal hydrides. Hydrogenated hydrocarbons. Fire resistance of onboard storage. References:

3.6.3.6  Risk analysis (G: x hrs)

Contents

Deterministic risk analysis: assessment of effects of unscheduled releases, ignition, pressure and thermal effects in detailed, reasonable-worst- case, credible scenarios. Probabilistic risk analysis [62,63]: event tree analysis, frequency analysis, consequence analysis, frequency analysis, system analysis, statistical interference, uncertainty. Comparative risk analysis of hydrogen and hydrocarbon fuels at different levels of abstraction: Component, sub-system/installation, overall system level. Relation with workers' safety, public safety and spatial planning. Effectiveness of different mitigation techniques and procedures. Safety Management System [64]. Precursor analysis [65]. Risk perception and acceptance [66]. Examples of risk assessment of hydrogen applications. References: AICHE (1989) [64,62], Bedford & Cooke (2001) [63], Pasman & Vrijling (2003) [67], and Pasman, Körvers & Sonnemans (2004) [65].

Contents

Hazard identification and analysis methods [68]. Checklist analysis: methods based on lists of questions and points related to safety and environment. Hazard ranking methods (Class 1 methods: Hazard Index Methods that rank solely on the basis of substance properties, the NFPA Material Factor. Class 2 methods: Hazard Ranking Systems that rank on basis of properties of materials and quantities, threshold quantities for licensing. Class 3-4 methods: hazard ranking systems that rank on basis of properties of materials, quantities, process conditions, and (certain) preventive and protective measures, the Dow Fire & Explosion Index). FMEA. Hazard and operability studies (HAZOP)[66]. Incident data banks and other means of identification. What-if analysis (threats to or impact on: personnel, equipment, business interruption, environment) [69,70,71]. Event tree analysis (and its role as the central part of quantitative risk analysis). Layers of protection analysis [72,73]. References: AICHE (2001) [72], Crawley & Preston (2000) [66], EU ATEX 100 (1994) [74,75,76], EU ATEX 137 (1999) [77,78], Lees (1996) [69,70,71], Pasman, Schupp & Lemkowitz (2003) [73], and, Pasman (2006) [68].

Contents

Consequence analysis [68]. Source terms/emissions: outflow, release modes, selection of release models, outflow of compressed gases, vapour outflow. Outflow of pressurised liquefied gases: two phase flow, outflow of pressurised liquefied gas through holes, two-phase flow in piping. Outflow of liquids: outflow of liquid through a hole, liquid outflow through a pipe. Evaporation of liquids: phenomenon of pool evaporation, heat balance at evaporation, heat flux to boiling liquids from subsoil, heat flux to boiling liquids from a water surface, evaporation of non-boiling liquids (mass transfer of vapour in the air, pool spreading. Dispersion and transmission models [68]: the structure of the atmosphere and its relation to transmission of pollutants, behaviour of plumes. Dispersion models: critical Richardson number criterion, the Gaussian plume model, dense gas dispersion, the Ooms integral plume model [79,80], dispersion from a free turbulent gas jet, effect intensity calculations as inputs for determination of damage. Effect on people and structures: jet impact from high-momentum releases, damage by low temperature releases, asphyxiation by hydrogen, thermal effects from fires, pressure effects from explosions, blast wave strength from vapour cloud explosion, blast interaction with objects, [69,70,71], materials for hydrogen services [81]. Environmental effects of hydrogen accidents. References: Lees (1996) [69,70,71], Pasman (2006) [68], and Perry & Green (1997) [81].

Contents

Vulnerability and damage [68]: general response function given intensity of effect and time of exposure; fires and dose-response of heat radiation exposure; damage caused by blast waves, blast effects on people; toxic effects; domino effects. Failure frequency estimation: reliability engineering; reliability function; multiple failure modes/Markov model; mean life; repairs and availability; failure rate data: empirical (from experience), reliability data banks/literature, accelerated ageing tests; Fault Tree Analysis (FTA) [82,83,68]: minimum cut sets. Risk presentation, acceptance criteria and perception [68]: individual and group risk, and their application to external or public safety; perception of risk: rational or irrational?; a note on legal tolerability criteria for human risk elsewhere; uncertainty in risk assessment; future developments. Preliminary failure mode analysis. What-if analysis. Comprehensive identification and classification hazard analysis. Damage models. Probits for various types of damage [84]. Data bases. Probabilistic assessment [63]. Appropriate equivalent methodology. References: Bedford & Cooke (2001) [63], van den Braken (2005) [85], Green Book (1989) [84], Hauptmanns (2004) [82], Khan & Abbasi (2000) [83], and, Pasman (2006) [68].

Contents

Risk reduction and control [68]: management systems; history of accident frequency; the crucial role of management and human factor: Safety Management System (SMS); accident investigation. Risk reducing measures [68]: rapid ranking and the risk matrix; Layer of Protection Analysis (LOPA); Safety Instrumented Systems (SIS); other protective measures; maintenance; design methods and design safety reviews. Application of hazard identification techniques and layers of protection analysis to production, storage and distribution installations. Application of vulnerability analysis to the potential of an initial incident to inhibit or destroy mitigation technologies. Case studies and European Hydrogen Incident/Accident Database. References: Pasman (2006) [68].

3.6.3.7  Regulations codes and standards (G: x hrs)

Contents

Hydrogen safety and regulatory issues [86]. Public acceptance and safety [86]. Trans-national nature of safety regulations, codes and standards (RCS) [86]. Safety legislation: hierarchy in safety legislation; purpose of safety legislation (imposing duties, responsibilities and accountabilities on people and organisations); the meaning of codes, standards, guidance and regulations; the origin of codes (developed by industry or trade bodies), standards (developed by engineering or standard bodies), and regulations (issued by the State); the Approved Code of Practice. An overview of the key European safety legislation that applies to hydrogen [87]: EU ATEX Directives (ATEX 100 [74,75,76,88] (Product Directive) and ATEX 137 [77,78] (User Directive)). A detailed examination of the structured approach to safety demanded by the ATEX Directives [87] (substitution, preventing the formation of explosive atmospheres, containment, dilution through effective ventilation, preventing the ignition of explosive atmospheres, zone classification, mitigating the effects of an explosion, use of explosion resistant equipment, explosion relief, explosion suppression, prevention of explosion propagation, organisational measures to ensure explosion protection). Compliance of the EU ATEX Directives with the EMC Directive 89/336/EEC [89] (modified by 92/31/EEC [90] and 93/68/EEC [91,92] (the CE Marking Directive)), the Machine Directive 98/37/EC [93], and, the Low Voltage Directive 73/23/EEC (modified by 93/68/EEC). IEC Standard 61511 [94,95,96]: structure (Part 1: Framework, definitions, system, hardware and software requirements [94]; Part 2: Guidelines in the application of IEC 61511-1 [95]; Part 3: Guidance for the determination of the required safety integrity levels [96]), and, harmonisation (adoption of IEC 61511 as EN 61511 [94,95,96] by the European standards body CENELEC; implication: in each of the member states of the European Union the standard is published as a national standard; IEC 61511 [94,95,96] is not harmonised under any Directive of the European Commission), purpose (sets out what is good practice in the engineering of systems that ensure the safety of an industrial process through the use of instrumentation), and, scope (defines the functional safety requirements established by IEC 61508 [97,98,99,100,101,102,103,104] using process industry sector terminology; applicable to refineries, petrochemical, chemical, pharmaceutical, pulp and paper, and power plants; covers application of electrical, electronic and programmable electronic equipment; focuses attention on one type of instrumented safety system used within the process sector: the Safety Instrumented System (SIS); covers the design and management requirements for SIS's from cradle to grave: initial concept, design, implementation, operation, and maintenance through to decommissioning). IEC Standard 61508 [97,98,99,100,101,102,103,104]: structure (the standard has seven parts: parts 1-3 contain the requirements of the standard (normative), while 4-7 are guidelines and examples for development), scope (basic functional safety standard applicable to all kinds of industry), and, paradigm (risk is defined as function of frequency (or likelihood) of the hazardous event and the event consequence severity; zero risk can never be reached, safety must be considered from the beginning, and, non-tolerable risks must be reduced (ALARP)). Examples of how codes, standards and guidance may be used to manage risk and comply with the law. Approval of new hydrogen technologies by RCS (example of hydrogen road vehicles [105], the case of hydrogen refuelling stations [105]). References: European Commission Directive 94/9/EC (1994 [74], 2000 [75,76]), European Commission Directive 1999/92/EC (2000 [77,78]), Newsholme (2007) [86,87], and, Wurster (2006) [105].

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