Steffen Møller-holst | Norwegian University of Science and Technology (original) (raw)

Papers by Steffen Møller-holst

Research paper thumbnail of Fundamental studies of the transient response of an alkaline fuel cell

This thesis addresses the dynamic behaviour of proton exchange membrane fuel cells (PEMFCs) and a... more This thesis addresses the dynamic behaviour of proton exchange membrane fuel cells (PEMFCs) and alkaline fuel cells (AFCs). For successful implementation in automotive vehicles and other applications with rapidly varying power demands, the dynamic behaviour of the fuel cell is critical. Knowledge of the load variation requirements as well as the response time of the cell at load change is essential for identifying the need for and design of a buffer system.The transient response of a PEMFC supplied with pure hydrogen and oxygen was investigated by load step measurements assisted by electrochemical impedance spectroscopy and chronoamperometry. Using an in-house designed resistance board, the uncontrolled response in both cell voltage and current upon step changes in a resistive load was observed. The PEMFC was found to respond quickly and reproducibly to load changes. Two transient processes limiting the fuel cell response were identified: i) A cathodic charge transfer process with a...

Research paper thumbnail of Hydrogenproduksjon ved småkraftverk

Research paper thumbnail of EVS 24 Stavanger , Norway , May 13-16 , 2009 Building a hydrogen infrastructure in Norway

Hydrogen is expected to become an integral part of the Norwegian energy system in the future, pri... more Hydrogen is expected to become an integral part of the Norwegian energy system in the future, primarily as a fuel for transportation. The NorWays project aims at providing decision support for introduction of hydrogen in the Norwegian energy system by modelling the energy system and hydrogen infrastructure build-up at various spatial levels. GIS-based regional hydrogen demand scenarios and hydrogen refuelling station networks have been generated, considering organic growth of regional hydrogen deployment and increasing density of hydrogen users over time. A regional model was used to optimise supply scenarios for these hydrogen refuelling station networks, including choice of production technology (biomass gasification, NG SMR, electrolysis, by-product hydrogen) and delivery (pipeline, truck, and onsite schemes) as well as integrated hydrogen delivery networks by truck and pipeline. The sensitivity to variations in energy price and GHG emission constraint scenarios on hydrogen produ...

Research paper thumbnail of Brenselceller i ASKOs distribusjonsbiler. Forprosjekt for å verifisere egnethet

Research paper thumbnail of In Situ Calorimetric Measurements in a Polymer Electrolyte Fuel Cell

The Geopig inspection tool provides pipeline operators with three-dimensional geographic and geom... more The Geopig inspection tool provides pipeline operators with three-dimensional geographic and geometric information of their pipeline system. This paper reviews two of the primary technologies onboard the NPS 8 Geopig that are used to provide such information: the inertial measurement unit (IMU), which provides structural and geographical characteristics of the pipeline, and the mechanical caliper arms, which capture the internal diameter of the pipeline. Recognizing the benefits of the tool and the data it can provide, Wascana Energy Inc. executed an inspection of a natural gas pipeline in Northern Alberta. The pipeline, which had buckled and sheared at a specific location, was inspected with the Geopig to further identify any other possible buckles, wrinkles or dents prior to re-commissioning. This paper reviews the inspection project undertaken, the data compiled by the Geopig, and the steps taken in the development of a predictive finite element model of the pipeline. BACKGROUND G eopia Inspection C apabilities The Geopig has traversed through many onshore and offshore oil and gas pipelines worldwide, inspecting their respective fitness for service levels from a pipe deformation perspective. Its' uniqueness as compared to standard caliper inspection tools is that it provides pipeline operators with a highly accurate, three-dimensional geographic and geometric representation of the pipeline. Both internal cross-sectional details and centerline axial data are obtained in a single inspection run. This allows operators to identify, characterize and locate pipeline dents, buckles, wrinkles, ovalities and bending strain to very high degrees of accuracy. The dynamics associated with such features (e.g. slope instability, subsidence, frost heave, upheaval buckling, river crossings, free spanning, overburden and pressure and

Research paper thumbnail of On the Measured PEMFC Anode and Cathode Reversible Heats

A recently constructed 2D calorimeter was used to measure the work and the total heat production ... more A recently constructed 2D calorimeter was used to measure the work and the total heat production of a single PEM fuel cell that is operated on hydrogen and oxygen at 50 °C and 1 bar. The cells had different membranes and catalyst layers, but the same porous transport layer and micro-porous layer. In this paper the distribution of the reaction entropy between the anode and the cathode, also known as the Peltier heats, was determined. This was done by the use of the measured heat through the anode and the cathode polarisation plates, the measured cell resistance, the measured overpotential and a fuel cell thermal model. The results show that the reaction entropy is almost solely related to the cathode and that the Peltier heat of the anode is near zero.© 2010 ASME

Research paper thumbnail of Building a hydrogen infrastructure in Norway

World Electric Vehicle Journal

Hydrogen is expected to become an integral part of the Norwegian energy system in the future, pri... more Hydrogen is expected to become an integral part of the Norwegian energy system in the future, primarily as a fuel for transportation. The NorWays project aims at providing decision support for introduction of hydrogen in the Norwegian energy system by modelling the energy system and hydrogen infrastructure build-up at various spatial levels. GIS-based regional hydrogen demand scenarios and hydrogen refuelling station networks have been generated, considering organic growth of regional hydrogen deployment and increasing density of hydrogen users over time. A regional model was used to optimise supply scenarios for these hydrogen refuelling station networks, including choice of production technology (biomass gasification, NG SMR, electrolysis, by-product hydrogen) and delivery (pipeline, truck, and onsite schemes) as well as integrated hydrogen delivery networks by truck and pipeline. The sensitivity to variations in energy price and GHG emission constraint scenarios on hydrogen production and delivery mix and average hydrogen costs was assessed, and conclusions on the effectiveness of policy measures were drawn.

Research paper thumbnail of Techno-economic analysis of freight railway electrification by overhead line, hydrogen and batteries: Case studies in Norway and USA

Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit

Two non-electrified railway lines, one in Norway and the other in the USA, are analysed for their... more Two non-electrified railway lines, one in Norway and the other in the USA, are analysed for their potential to be electrified with overhead line equipment, batteries, hydrogen or hydrogen-battery hybrid powertrains. The energy requirements are established with single-train simulations, including the altitude profiles of the lines, air and rolling resistances, and locomotive tractive-effort curves. The composition of the freight trains, in terms of the number of locomotives, battery wagons, hydrogen wagons, etc. is also calculated by the same model. The different technologies are compared by the criteria of equivalent annual costs, benefit–cost ratio, payback period and up-front investment, based on the estimated techno-economic parameters for years 2020, 2030 and 2050. The results indicate the potential of batteries and fuel cells to replace diesel on rail lines with low traffic volumes.

Research paper thumbnail of Water and ion transport in the cation exchange membrane systems NaClSrCl2 and KClSrCl2

Journal of Membrane Science, 1996

Water transference coefficients, water permeabilities and ionic transference numbers were investi... more Water transference coefficients, water permeabilities and ionic transference numbers were investigated for the cation exchange membrane CR61 AZL389. The membranes were equilibrated with aqueous solutions of NaC1 (KC1) and SrCI 2 of various compositions. No chloride ions were detected in the membranes. The water transference coefficients and the water permeabilities were determined from streaming potential measurements, whereas the ionic transference numbers were determined by a new emf method. When the membrane was in the pure KM, NaM or SrM 2 form, the water transference coefficients were close to 11, 14 and 20, respectively. The water permeability is about two times larger in NaM than in SrM 2. The water transference coefficient is not a linear function of the transference number of Na + (K +) in the membrane, as found earlier. The results are explained by a variation in the membrane polymer cross-binding caused by Sr2+-binding to ionic membrane site(s). The transport behaviors in the mixture of NaM(KM) and SrM 2 can all be understood by the Sr 2+ ion's strong interaction with the polymer membrane. The same technique also provide information on Present address: Norzink AS, N-5750 Odda, Norway. water permeabilities. We also report ionic transfer-Elsevier Science B.V. SSDI 0376-7388(95)00184-0

Research paper thumbnail of Transport and equilibrium properties of Nafion® membranes with H+ and Na+ ions

Journal of Electroanalytical Chemistry, 1998

Research paper thumbnail of Market penetration analysis of hydrogen vehicles in Norwegian passenger transport towards 2050

International Journal of Hydrogen Energy, 2010

Hydrogen cars a b s t r a c t The Norwegian energy system is characterized by high dependency on ... more Hydrogen cars a b s t r a c t The Norwegian energy system is characterized by high dependency on electricity, mainly hydro power. If the national targets to reduce emissions of greenhouse gases should be met, a substantial reduction of CO 2 emissions has to be obtained from the transport sector. This paper presents the results of the analyses of three Norwegian regions with the energy system model MARKAL during the period 2005e2050. The MARKAL models were used in connection with an infrastructure model H2INVEST. The analyses show that a transition to a hydrogen fuelled transportation sector could be feasible in the long run, and indicate that with substantial hydrogen distribution efforts, fuel cell cars can become competitive compared to other technologies both in urban (2025) and rural areas (2030). In addition, the result shows the importance of the availability of local energy resources for hydrogen production, like the advantages of location close to chemical industry or surplus of renewable electricity.

Research paper thumbnail of Pathways to a hydrogen fuel infrastructure in Norway

International Journal of Hydrogen Energy, 2010

Research paper thumbnail of Well-to-wheel study of passenger vehicles in the Norwegian energy system

Energy, 2007

For the evaluation of potential routes for production and application of hydrogen in a future ene... more For the evaluation of potential routes for production and application of hydrogen in a future energy system, well-to-wheel (WtW) methodologies provide a means of comparing overall impacts of technologies and fuels in a consistent and transparent manner. Such analysis provides important background information for decision makers when implementing political incentives for the conversion to more environmentally friendly energy production and consumption. In this study, a WtW approach was applied in order to evaluate the energetic and environmental impacts of introducing hydrogen in the transportation sector, in terms of energy efficiency and emissions of CO 2 and NO x , under conditions relevant for the Norwegian energy system. The hydrogen chains were compared to reference chains with conventional fuels. r

Research paper thumbnail of A calorimetric analysis of a polymer electrolyte fuel cell and the production of H2O2 at the cathode

Electrochimica Acta, 2010

A calorimeter has been constructed and used to measure the total heat production of a single poly... more A calorimeter has been constructed and used to measure the total heat production of a single polymer electrolyte fuel cell that is operated on hydrogen and oxygen at 50 • C and 1 bar. The cell had a SolviCore Catalyst Coated Backing and Nafion membranes 112, 115 and 117. We report that the total heat production plus the power production corresponds to the enthalpy of formation of water for cell potentials above 0.55 V. For cell potentials less than 0.55 V, we measured a linear decrease in the reaction enthalpy with decreasing cell potential. This effect was obtained independently of membrane thickness and current density. We propose therefore that the main power loss at low cell potentials and the inflection point in the polarisation curve is due to hydrogen peroxide formation at the cathode. The total heat production was decomposed into reversible and irreversible effects (non-ohmic and ohmic). The non-ohmic part was evaluated using Tafel plots. We show that it is possible to determine the overpotential of an electrode also from its thermal signature.

Research paper thumbnail of Calculation of reversible electrode heats in the proton exchange membrane fuel cell from calorimetric measurements

Electrochimica Acta, 2011

A calorimeter was used to measure the heat production in polymer electrolyte membrane (PEM) fuel ... more A calorimeter was used to measure the heat production in polymer electrolyte membrane (PEM) fuel cells operated on hydrogen and oxygen at 50 • C and 1 bar. Two cells were examined, one using a 35 m thick Nafion membrane and a catalyst loading of 0.6/0.4 mg Pt cm −2 , for the cathode and anode layer, respectively, the other using a 180 m thick Nafion membrane and loading of 0.4/0.4 mg Pt cm −2 . The cells investigated thus had different membranes and catalyst layers, but identical porous transport layers and micro-porous layers. The calorimeter is unique in that it provides the heat fluxes out of the cell, separately for the anode and the cathode sides. The corresponding cell potential differences, ohmic cell resistance and current densities are also reported. The heat fluxes through the current collector plates were decomposed by a thermal model to give the contributions from the ohmic and the Tafel heats to the total heat fluxes. Thus, the contributions from the reversible heat (the Peltier heats) to the current collectors were determined. The analysis suggests that the Peltier heat of the anode of these fuel cell materials is small, and that it is the cathode reaction which generates the main fraction of the total heat in a PEM fuel cell. The entropy change of the anode reaction appears to be close to zero, while the corresponding value for the cathode is near −80 J K −1 mol −1 .

Research paper thumbnail of Options for CO2-lean hydrogen export from Norway to Germany

Energy, 2008

Norway is a nation with an abundant supply of energy, both from fossil and renewable resources. D... more Norway is a nation with an abundant supply of energy, both from fossil and renewable resources. Due to limited domestic demand, Norway is today exporting large amounts of petroleum products. For the future, various options for export of CO 2 -lean energy exist, both from Northern and Southern Norway, and both from fossil sources (including carbon capture and storage), and renewable energies (particularly wind power). Transport vectors are hydrogen pipelines, liquid hydrogen ships and HVDC cables, and a plausible customer is central Europe due to its proximity, high population density and lack of domestic energy resources.

Research paper thumbnail of Fundamental studies of the transient response of an alkaline fuel cell

This thesis addresses the dynamic behaviour of proton exchange membrane fuel cells (PEMFCs) and a... more This thesis addresses the dynamic behaviour of proton exchange membrane fuel cells (PEMFCs) and alkaline fuel cells (AFCs). For successful implementation in automotive vehicles and other applications with rapidly varying power demands, the dynamic behaviour of the fuel cell is critical. Knowledge of the load variation requirements as well as the response time of the cell at load change is essential for identifying the need for and design of a buffer system.The transient response of a PEMFC supplied with pure hydrogen and oxygen was investigated by load step measurements assisted by electrochemical impedance spectroscopy and chronoamperometry. Using an in-house designed resistance board, the uncontrolled response in both cell voltage and current upon step changes in a resistive load was observed. The PEMFC was found to respond quickly and reproducibly to load changes. Two transient processes limiting the fuel cell response were identified: i) A cathodic charge transfer process with a...

Research paper thumbnail of Hydrogenproduksjon ved småkraftverk

Research paper thumbnail of EVS 24 Stavanger , Norway , May 13-16 , 2009 Building a hydrogen infrastructure in Norway

Hydrogen is expected to become an integral part of the Norwegian energy system in the future, pri... more Hydrogen is expected to become an integral part of the Norwegian energy system in the future, primarily as a fuel for transportation. The NorWays project aims at providing decision support for introduction of hydrogen in the Norwegian energy system by modelling the energy system and hydrogen infrastructure build-up at various spatial levels. GIS-based regional hydrogen demand scenarios and hydrogen refuelling station networks have been generated, considering organic growth of regional hydrogen deployment and increasing density of hydrogen users over time. A regional model was used to optimise supply scenarios for these hydrogen refuelling station networks, including choice of production technology (biomass gasification, NG SMR, electrolysis, by-product hydrogen) and delivery (pipeline, truck, and onsite schemes) as well as integrated hydrogen delivery networks by truck and pipeline. The sensitivity to variations in energy price and GHG emission constraint scenarios on hydrogen produ...

Research paper thumbnail of Brenselceller i ASKOs distribusjonsbiler. Forprosjekt for å verifisere egnethet

Research paper thumbnail of In Situ Calorimetric Measurements in a Polymer Electrolyte Fuel Cell

The Geopig inspection tool provides pipeline operators with three-dimensional geographic and geom... more The Geopig inspection tool provides pipeline operators with three-dimensional geographic and geometric information of their pipeline system. This paper reviews two of the primary technologies onboard the NPS 8 Geopig that are used to provide such information: the inertial measurement unit (IMU), which provides structural and geographical characteristics of the pipeline, and the mechanical caliper arms, which capture the internal diameter of the pipeline. Recognizing the benefits of the tool and the data it can provide, Wascana Energy Inc. executed an inspection of a natural gas pipeline in Northern Alberta. The pipeline, which had buckled and sheared at a specific location, was inspected with the Geopig to further identify any other possible buckles, wrinkles or dents prior to re-commissioning. This paper reviews the inspection project undertaken, the data compiled by the Geopig, and the steps taken in the development of a predictive finite element model of the pipeline. BACKGROUND G eopia Inspection C apabilities The Geopig has traversed through many onshore and offshore oil and gas pipelines worldwide, inspecting their respective fitness for service levels from a pipe deformation perspective. Its' uniqueness as compared to standard caliper inspection tools is that it provides pipeline operators with a highly accurate, three-dimensional geographic and geometric representation of the pipeline. Both internal cross-sectional details and centerline axial data are obtained in a single inspection run. This allows operators to identify, characterize and locate pipeline dents, buckles, wrinkles, ovalities and bending strain to very high degrees of accuracy. The dynamics associated with such features (e.g. slope instability, subsidence, frost heave, upheaval buckling, river crossings, free spanning, overburden and pressure and

Research paper thumbnail of On the Measured PEMFC Anode and Cathode Reversible Heats

A recently constructed 2D calorimeter was used to measure the work and the total heat production ... more A recently constructed 2D calorimeter was used to measure the work and the total heat production of a single PEM fuel cell that is operated on hydrogen and oxygen at 50 °C and 1 bar. The cells had different membranes and catalyst layers, but the same porous transport layer and micro-porous layer. In this paper the distribution of the reaction entropy between the anode and the cathode, also known as the Peltier heats, was determined. This was done by the use of the measured heat through the anode and the cathode polarisation plates, the measured cell resistance, the measured overpotential and a fuel cell thermal model. The results show that the reaction entropy is almost solely related to the cathode and that the Peltier heat of the anode is near zero.© 2010 ASME

Research paper thumbnail of Building a hydrogen infrastructure in Norway

World Electric Vehicle Journal

Hydrogen is expected to become an integral part of the Norwegian energy system in the future, pri... more Hydrogen is expected to become an integral part of the Norwegian energy system in the future, primarily as a fuel for transportation. The NorWays project aims at providing decision support for introduction of hydrogen in the Norwegian energy system by modelling the energy system and hydrogen infrastructure build-up at various spatial levels. GIS-based regional hydrogen demand scenarios and hydrogen refuelling station networks have been generated, considering organic growth of regional hydrogen deployment and increasing density of hydrogen users over time. A regional model was used to optimise supply scenarios for these hydrogen refuelling station networks, including choice of production technology (biomass gasification, NG SMR, electrolysis, by-product hydrogen) and delivery (pipeline, truck, and onsite schemes) as well as integrated hydrogen delivery networks by truck and pipeline. The sensitivity to variations in energy price and GHG emission constraint scenarios on hydrogen production and delivery mix and average hydrogen costs was assessed, and conclusions on the effectiveness of policy measures were drawn.

Research paper thumbnail of Techno-economic analysis of freight railway electrification by overhead line, hydrogen and batteries: Case studies in Norway and USA

Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit

Two non-electrified railway lines, one in Norway and the other in the USA, are analysed for their... more Two non-electrified railway lines, one in Norway and the other in the USA, are analysed for their potential to be electrified with overhead line equipment, batteries, hydrogen or hydrogen-battery hybrid powertrains. The energy requirements are established with single-train simulations, including the altitude profiles of the lines, air and rolling resistances, and locomotive tractive-effort curves. The composition of the freight trains, in terms of the number of locomotives, battery wagons, hydrogen wagons, etc. is also calculated by the same model. The different technologies are compared by the criteria of equivalent annual costs, benefit–cost ratio, payback period and up-front investment, based on the estimated techno-economic parameters for years 2020, 2030 and 2050. The results indicate the potential of batteries and fuel cells to replace diesel on rail lines with low traffic volumes.

Research paper thumbnail of Water and ion transport in the cation exchange membrane systems NaClSrCl2 and KClSrCl2

Journal of Membrane Science, 1996

Water transference coefficients, water permeabilities and ionic transference numbers were investi... more Water transference coefficients, water permeabilities and ionic transference numbers were investigated for the cation exchange membrane CR61 AZL389. The membranes were equilibrated with aqueous solutions of NaC1 (KC1) and SrCI 2 of various compositions. No chloride ions were detected in the membranes. The water transference coefficients and the water permeabilities were determined from streaming potential measurements, whereas the ionic transference numbers were determined by a new emf method. When the membrane was in the pure KM, NaM or SrM 2 form, the water transference coefficients were close to 11, 14 and 20, respectively. The water permeability is about two times larger in NaM than in SrM 2. The water transference coefficient is not a linear function of the transference number of Na + (K +) in the membrane, as found earlier. The results are explained by a variation in the membrane polymer cross-binding caused by Sr2+-binding to ionic membrane site(s). The transport behaviors in the mixture of NaM(KM) and SrM 2 can all be understood by the Sr 2+ ion's strong interaction with the polymer membrane. The same technique also provide information on Present address: Norzink AS, N-5750 Odda, Norway. water permeabilities. We also report ionic transfer-Elsevier Science B.V. SSDI 0376-7388(95)00184-0

Research paper thumbnail of Transport and equilibrium properties of Nafion® membranes with H+ and Na+ ions

Journal of Electroanalytical Chemistry, 1998

Research paper thumbnail of Market penetration analysis of hydrogen vehicles in Norwegian passenger transport towards 2050

International Journal of Hydrogen Energy, 2010

Hydrogen cars a b s t r a c t The Norwegian energy system is characterized by high dependency on ... more Hydrogen cars a b s t r a c t The Norwegian energy system is characterized by high dependency on electricity, mainly hydro power. If the national targets to reduce emissions of greenhouse gases should be met, a substantial reduction of CO 2 emissions has to be obtained from the transport sector. This paper presents the results of the analyses of three Norwegian regions with the energy system model MARKAL during the period 2005e2050. The MARKAL models were used in connection with an infrastructure model H2INVEST. The analyses show that a transition to a hydrogen fuelled transportation sector could be feasible in the long run, and indicate that with substantial hydrogen distribution efforts, fuel cell cars can become competitive compared to other technologies both in urban (2025) and rural areas (2030). In addition, the result shows the importance of the availability of local energy resources for hydrogen production, like the advantages of location close to chemical industry or surplus of renewable electricity.

Research paper thumbnail of Pathways to a hydrogen fuel infrastructure in Norway

International Journal of Hydrogen Energy, 2010

Research paper thumbnail of Well-to-wheel study of passenger vehicles in the Norwegian energy system

Energy, 2007

For the evaluation of potential routes for production and application of hydrogen in a future ene... more For the evaluation of potential routes for production and application of hydrogen in a future energy system, well-to-wheel (WtW) methodologies provide a means of comparing overall impacts of technologies and fuels in a consistent and transparent manner. Such analysis provides important background information for decision makers when implementing political incentives for the conversion to more environmentally friendly energy production and consumption. In this study, a WtW approach was applied in order to evaluate the energetic and environmental impacts of introducing hydrogen in the transportation sector, in terms of energy efficiency and emissions of CO 2 and NO x , under conditions relevant for the Norwegian energy system. The hydrogen chains were compared to reference chains with conventional fuels. r

Research paper thumbnail of A calorimetric analysis of a polymer electrolyte fuel cell and the production of H2O2 at the cathode

Electrochimica Acta, 2010

A calorimeter has been constructed and used to measure the total heat production of a single poly... more A calorimeter has been constructed and used to measure the total heat production of a single polymer electrolyte fuel cell that is operated on hydrogen and oxygen at 50 • C and 1 bar. The cell had a SolviCore Catalyst Coated Backing and Nafion membranes 112, 115 and 117. We report that the total heat production plus the power production corresponds to the enthalpy of formation of water for cell potentials above 0.55 V. For cell potentials less than 0.55 V, we measured a linear decrease in the reaction enthalpy with decreasing cell potential. This effect was obtained independently of membrane thickness and current density. We propose therefore that the main power loss at low cell potentials and the inflection point in the polarisation curve is due to hydrogen peroxide formation at the cathode. The total heat production was decomposed into reversible and irreversible effects (non-ohmic and ohmic). The non-ohmic part was evaluated using Tafel plots. We show that it is possible to determine the overpotential of an electrode also from its thermal signature.

Research paper thumbnail of Calculation of reversible electrode heats in the proton exchange membrane fuel cell from calorimetric measurements

Electrochimica Acta, 2011

A calorimeter was used to measure the heat production in polymer electrolyte membrane (PEM) fuel ... more A calorimeter was used to measure the heat production in polymer electrolyte membrane (PEM) fuel cells operated on hydrogen and oxygen at 50 • C and 1 bar. Two cells were examined, one using a 35 m thick Nafion membrane and a catalyst loading of 0.6/0.4 mg Pt cm −2 , for the cathode and anode layer, respectively, the other using a 180 m thick Nafion membrane and loading of 0.4/0.4 mg Pt cm −2 . The cells investigated thus had different membranes and catalyst layers, but identical porous transport layers and micro-porous layers. The calorimeter is unique in that it provides the heat fluxes out of the cell, separately for the anode and the cathode sides. The corresponding cell potential differences, ohmic cell resistance and current densities are also reported. The heat fluxes through the current collector plates were decomposed by a thermal model to give the contributions from the ohmic and the Tafel heats to the total heat fluxes. Thus, the contributions from the reversible heat (the Peltier heats) to the current collectors were determined. The analysis suggests that the Peltier heat of the anode of these fuel cell materials is small, and that it is the cathode reaction which generates the main fraction of the total heat in a PEM fuel cell. The entropy change of the anode reaction appears to be close to zero, while the corresponding value for the cathode is near −80 J K −1 mol −1 .

Research paper thumbnail of Options for CO2-lean hydrogen export from Norway to Germany

Energy, 2008

Norway is a nation with an abundant supply of energy, both from fossil and renewable resources. D... more Norway is a nation with an abundant supply of energy, both from fossil and renewable resources. Due to limited domestic demand, Norway is today exporting large amounts of petroleum products. For the future, various options for export of CO 2 -lean energy exist, both from Northern and Southern Norway, and both from fossil sources (including carbon capture and storage), and renewable energies (particularly wind power). Transport vectors are hydrogen pipelines, liquid hydrogen ships and HVDC cables, and a plausible customer is central Europe due to its proximity, high population density and lack of domestic energy resources.