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Power-to-methanol is seen as a key energy storage technology in contributing to reach climate targets and unleash the great potential for renewable electricity. This study conducted dynamic simulations that focuses on the feed gas composition effects and surrogate modeling by using the nonlinear autoregressive exogenous (NARX) model for the green methanol production. The modeling results showed obvious influences of feed gas composition on the process efficiency and CO2 conversion, which were predicted by the NARX model with promising accuracy.

This report describes the fundamental rigorous modeling of the heat pump systems used in the EUDP-project Local Heating Concepts project developed. The models were developed at Department of Energy Technology, Section of Thermal Systems using the tools EES (Engineering Equation Solver) and MATLAB.

Part of the final reporting of Dansk Energi, Elforsk PSO 350 – 007 describing the long-term testing of the Adiabatic Cooling Aggregate.

In this study, a single proton exchange membrane fuel cell electrical performance is tested and modelled. The aim is to investigate the effect of reactants and membrane humidity on cell electrical performance. We discuss cell performance in terms of various variables affecting water transport in the membrane, such as electro-osmotic drag, water diffusion and ionic conductivity. The experimental results show that membrane hydration mainly affects ohmic losses and especially when humidity at cathode side is reduced. The developed model can estimate the contribution of different overpotentials and the impact of cell hydration on ohmic resistance.

In this paper, a theoretical analysis of an ejector for micro combined heat and power systems based on Solid Oxide Fuel Cell (SOFC) for small-scale residential applications is presented. A novel detailed procedure for the ejector designing is provided and its effectiveness is validated through a comparison with testing results. The ejector geometry is analysed in terms of component efficiency. The SOFC system performance with regard the recirculation of anode gas is finally discussed. Results show that fuel inlet temperature and the diameter of the ejector mixing chamber of the ejector largely affect the ejector performance. A large mixing chamber diameter allows a high entrainment ratio but causes a worse ejector efficiency suggesting a highest efficiency still ensuring the required entrainment ratio. At system level, it is shown that the degree of fuel pre-reforming affects the recirculation ratio. Besides, if anode gas recirculation is implemented the system capital cost decreases due to reduction in size of ancillary components. The high electrical efficiency achieved by the system reduces the heat output and makes it more attractive when less heat is demanded.

This background report describes on the different fuel pathways for the transport sector were created and compared. The study highlights the unique issues that need to be resolved for the transport sector such as the large growth in demand, the need for energy-dense fuels, and the concerns about the availability of sustainable resources.The results indicate that electricity should be prioritised as much as is economically possible in the transport sector, which is primarily for cars and rail. Other modes, such as trucks, ships, and aeroplanes will require fuels with a high energy density. Replacing oil in these modes with existing biofuels is likely to result in an over-consumption of biomass, thus resulting in an unsustainable solution. In this study, new electrofuel pathways are created outlining how electricity can be combined with biomass to create new fuels for these modes. The amount of electrofuel that can be incorporated into the energy system in the future will be very dependent on the technological develop of some key technologies, such as biomass gasification, carbon capture and recycling, and electrolysers, as well as on the amount of sustainable biomass that can be harnessed in the energy system.

The transition towards a 100 % fossil-free energy system, while achieving extreme penetration levels of intermittent wind and solar power in electricity generation, requires demand-side technologies that are smart (intermittency-friendly) and efficient.The integration of Smart Grid enabling technologies has been widely acknowledged by the industry and academia as the key to achieve a more reliable, efficient and secure grid. However, there is a lack of information about real flexibility with an active participation from customers. In this paper, we combine techno-economical modelling results with an empirical study in order to achieve a number of recommendations with respect to technology concepts and control strategies that would allow residential vapor-compression heat pumps to support large-scale integration of intermittent renewables.The analysis is based on data gathered over a period of up to 3 years for 283 residential heat pumps installed and operating in Denmark. The results are used to assess the flexibility of domestic heat pumps and their ability to follow production.

The transition to 100% renewable energy systems will require a more integrated energy system. Connecting the electricity sector to transport is one of the major challenges in this transition, especially for long-distance and heavy-duty transport. Hydrogen is one potential solution to this challenge, by either using it directly in vehicles or indirectly via the production of synthetic fuels. Electrolysers are necessary to convert electricity to hydrogen and so they will have an essential role in the future smart energy system. However, at present there is a lot of uncertainty in relation to the current and forecasted development of electrolysers. The aim in this report is to reduce this uncertainty by gathering and aligning current knowledge in relation to the technical and economic potential of electrolysers. The results highlight existing and forecasted costs and efficiencies for alkaline, polymer electrolyte membrane (PEM), and solid oxide (SOEC) electrolysers between 2012 and 2050. These inputs can be used for analysing energy systems that include electrolysers.

A proposed residential energy system based on the PBI (Polybenzimidazole) fuel cell technology is analyzed in terms of operational performance. Conventional operational strategies, such as heat-led and electricity-led, are applied to the simulated system to investigate their performance characteristics. Based on these findings, an improved operational strategy is formulated and applied in an attempt to minimize the shortcomings of conventional strategies. System parameters, such as electrical and thermal efficiencies, heat dumping, and import/export of electricity, are analyzed. The applied load profile is based on average data for a single-family household in Denmark and includes consumption data for electricity and heat demands. The study analyzes the potential of the proposed system on market penetration in the area of residential heat-and-power generation and whether this deployment can be justified as compared to other micro-CHP system technologies. The most important findings of this research study indicate that in comparison to non-fuel cell-based micro-CHP systems, such as Stirling Engine-based systems, the proposed system has significantly higher efficiencies. Moreover, the lower heat-to-power ratios allow the system to avoid high thermal surpluses throughout the whole annual operational profile.

The aim of this research work is to describe in qualitative and quantitative form the performance of a micro Combined Heat and Power system for residential application based on Solid Oxide Fuel Cell fueled by natural gas with two different types of pre-reforming systems, namely Steam Reforming and Partial Oxidation and recirculation of anode and cathode gas. The comparative analysis among the different configurations will lead us to conclude that maximum efficiency is achieved when cathode and anode gas recirculation are used along with steam methane reforming. Further Steam Methane Reforming process produces a higher electrical system efficiency compared to Partial oxidation reforming process. Efficiency is affected when running the system in part load mode mainly due to heat loss, additional natural gas supplied to the burner to satisfy the required heat demand inside the system, and ejector efficiency drop in the recirculation system. Due to high temperature of operation heat loss strongly affects the system efficiency especially at part load operation.

This report presents a summary of results of the strategic research project “Coherent Energy and Environmental System Analysis” (CEESA) which was conducted in the period 2007-2011 and funded by the Danish Strategic Research Council together with the participating parties. The project was interdisciplinary and involved more than 20 researchers from 7 different university departments or research institutions in Denmark. Moreover, the project was supported by an international advisory panel. The results include further development and integration of existing tools and methodologies into coherent energy and environmental analysis tools as well as analyses of the design and implementation of future renewable energy systems. For practical reasons, the work has been carried out as an interaction between five work packages, and a number of reports, papers and tools have been reported separately from each part of the project. A list of the separate work package reports is given at the end of this foreword while a complete list of all papers and reports can be found at the end of the report as well as at the following website: www.ceesa.dk. This report provides a summary of the results of the different project parts in a coherent way by presenting tools and methodologies as well as analyses of the design and implementation of renewable energy systems – including both energy and environmental aspects.

This report presents a summary of results of the strategic research project “Coherent Energy and Environmental System Analysis” (CEESA) which was conducted in the period 2007-2011 and funded by the Danish Strategic Research Council together with the participating parties.The project was interdisciplinary and involved more than 20 researchers from 7 different university departments or research institutions in Denmark. Moreover, the project was supported by an international advisory panel.The results include further development and integration of existing tools and methodologies into coherent energy and environmental analysis tools as well as analyses of the design and implementation of future renewable energy systems.For practical reasons, the work has been carried out as an interaction between five work packages, and a number of reports, papers and tools have been reported separately from each part of the project. A list of the separate work package reports is given at the end of this foreword while a complete list of all papers and reports can be found at the end of the report as well as at the following website: www.ceesa.dk.This report provides a summary of the results of the different project parts in a coherent way by presenting tools and methodologies as well as analyses of the design and implementation of renewable energy systems – including both energy and environmental aspects.The authors listed in the report represent those who have contributed directly as well as indirectly via the work of the different work packages. By nature this means that each individual author cannot be responsible for every detail of the different reports and papers of work packages conducted by others. Such responsibility relies on the specific authors of the sub-reports and papers. Moreover, individual participants may have personal views that differ from parts of the recommendations of this main report.List of CEESA Background Reports:Part 1: CEESA 100% Renewable Energy Scenarios towards 2050Part 2: CEESA 100% Renewable Energy Transport Scenarios towards 2050Part 3: Electric power systems for a transition to 100% Renewable Energy Systems in Denmark before 2050Part 4: Policies for a Transition to 100% Renewable Energy Systems in Denmark before 2050Part 5: Environmental Assessment of Renewable Energy Scenarios towards 2050

The potential offered by biomass for solving some of the world's energy problems is widely recognized. The energy contained in biomass can be utilized either directly as in combustion or by converting the biomass into a liquid fuel for transportation. The Catliq® (catalytic liquid conversion) process is a second generation process for the production of bio-oil from different biomass-based waste materials. The process is carried out at subcritical conditions (280-350 °C and 180-250 bar) and in the presence of homogeneous (KOH) and heterogeneous (ZrO2) catalysts. The great advantage with the CatLiq® process compared with combustion is that also wet material can be processed. In the process, the waste is transformed to bio-oil, combustible gases and water-soluble organic compounds. The raw material used in this study was DDGS (Dried Distilled Grain with Solubles), a residual product in 1st generation ethanol production, available in huge quantities. DDGS is today used as animal feed but in a future with increasing production of DDGS, converting it into bio-oil may be an attractive alternative. The bio-oil can be used for green electricity production or it can be upgraded to bio-diesel. In the current work, catalytic conversion of DDGS was performed in a pilot plant with a capacity of 10-20 L/h of wet biomass. The oil obtained was characterized using FTIR and GC-MS for both qualitative and quantitative analysis of the product. The potential offered by biomass for solving some of the world's energy problems is widely recognized. The energy contained in biomass can be utilized either directly as in combustion or by converting the biomass into a liquid fuel for transportation. The Catliq® (catalytic liquid conversion) process is a second generation process for the production of bio-oil from different biomass-based waste materials. The process is carried out at subcritical conditions (280-350 °C and 180-250 bar) and in the presence of homogeneous (KOH) and heterogeneous (ZrO2) catalysts. The great advantage with the CatLiq® process compared with combustion is that also wet material can be processed. In the process, the waste is transformed to bio-oil, combustible gases and water-soluble organic compounds. The raw material used in this study was DDGS (Dried Distilled Grain with Solubles), a residual product in 1st generation ethanol production, available in huge quantities. DDGS is today used as animal feed but in a future with increasing production of DDGS, converting it into bio-oil may be an attractive alternative. The bio-oil can be used for green electricity production or it can be upgraded to bio-diesel. In the current work, catalytic conversion of DDGS was performed in a pilot plant with a capacity of 10-20 L/h of wet biomass. The oil obtained was characterized using FTIR and GC-MS for both qualitative and quantitative analysis of the product.

Fuel cell-based combined heat and power (CHP) systems have received increasing attention during the last decade. This is mainly due to the high efficiencies obtainable on even a small-scale system basis. The current paper focuses on the development of a complete model of a system consisting of the high-temperature proton exchange membrane (HTPEM) fuel cell stack based on PBI membranes, steam-reforming reactor, burner, heat reservoir and other auxiliary equipment included in a typical reforming-based fuel cell system. The model is implemented in the MatlabsSimulink environment enabling both static system integration as well as dynamical control strategies to be evaluated. All results of the submodels correspond well with experimental results obtained. Additionally, a novel system integration of an HTPEM fuel cell and a steam reforming-based fuel processing unit is presented. The total energy utilization efficiency of the system modeled is as high as 902100%LHV depending on the operating point chosen, whereas the electrical efficiency can be up to 45%LHV. This is more than 30% better than the best low-temperature PEM-based systems demonstrated today. Udgivelsesdato: APR Fuel cell-based combined heat and power (CHP) systems have received increasing attention during the last decade. This is mainly due to the high efficiencies obtainable on even a small-scale system basis. The current paper focuses on the development of a complete model of a system consisting of the high-temperature proton exchange membrane (HTPEM) fuel cell stack based on PBI membranes, steam-reforming reactor, burner, heat reservoir and other auxiliary equipment included in a typical reforming-based fuel cell system. The model is implemented in the MatlabsSimulink environment enabling both static system integration as well as dynamical control strategies to be evaluated. All results of the submodels correspond well with experimental results obtained. Additionally, a novel system integration of an HTPEM fuel cell and a steam reforming-based fuel processing unit is presented. The total energy utilization efficiency of the system modeled is as high as 902100%LHV depending on the operating point chosen, whereas the electrical efficiency can be up to 45%LHV. This is more than 30% better than the best low-temperature PEM-based systems demonstrated today.

When using pressurized hydrogen to fuel a fuel cell, much space is needed for fuel storage. This is undesirable especially with mobile or portable fuel cell systems, where refuelling also often is inconvenient. Using a reformed liquid carbonhydrate can reduce this fuel volume considerably. Nafion based low temperature PEM (LTPEM) fuel cells are very intolerant to reformate gas because of the presence of CO. PBI based high temperature PEM (HTPEM) fuel cells can operate stable at much higher CO concentrations. This makes the HTPEM very suitable for applications using a reformer, and could simplify reformer design because CO removal is not needed. A fuel like methanol would be a preferable choice for reforming when using HTPEM fuel cells because of its high energy density and low reforming temperatures. The thermal integration and use of HTPEM fuel cells with methanol reformers show promising results. This work demonstrates the use of HTPEM fuel cells (HTPEM) in a 400 W fuel cell power pack. The fuel cell system concept uses a 30 cell HTPEM fuel cell stack designed at the Institute of Energy Technology, Aalborg University. The MEAs employed are Celtec P-series by Pemeas, with an active area of 45cm². The development of the bipolar plates and the stack design itself is an ongoing activity using CFD and optimizing for low pressure drop. Later versions of the stack design is expected to result in a much shorter stack. When using pure H2, the hydrogen circuit is running dead end with occasional purging. Single cell life time tests indicate that very infrequent purging does not accelerate degradation severely. This is a great advantage compared to the LTPEM which often has problems with flooding when not purged. The air supply is realized using a low power axial fan with a high turn down ratio. The stack is placed in an insulation box and the temperature controlled by electrical heating elements. When loading the stack at its nominal load of 400 W it produces enough heat to keep this temperature. For control system design and location of optimal operating conditions, a system model is made, including a HTPEM fuel cell model, expressing the cell voltage as a function of the current density, temperature, CO concentration and stoichiometries. Simulation results from this model are shown. The system model and control design is verified with the actual setup in the lab. For the use of the fuel cell stack in a power pack, a high efficiency DC/DC-converter is designed. The overall control of the power conditioning and the power pack itself is also derived from modelling of the DC/DC converter. Comparing the LTPEM and the HTPEM, the HTPEM fuel cell has a lower cell voltage than the LTPEM, but the developed power pack demonstrates some of the advantages by using a HTPEM fuel cell. This initial system is very simple and there is no need for humidification of the species like in a LTPEM fuel cell system. The use of the HTPEM fuel cell makes it possible to use reformed gas at high CO concentrations without, still with a stable performance.

Der er foretaget en hurtig screening af leverandører af naturgasreformere i størrelsen omkring 2kWe. Der er identificeret 13 navngivne aktører på området, der efterfølgende er opdelt i 3 segmenter med henblik på udvælgelse af producenter til nærmere undersøgelse. I segmentet: Leverandører af fleksible prototypereformere med mulighed for produkttilpasning blev Catator og HyGear identificeret og valgt til nærmere undersøgelse. Der ud over er Osaka Gas's reformerteknologi vurderet som produktionsmodnet og velafprøvet med stort potentiale primært i kraft af meget lave CO koncentrationer i syntesegassen på under 1 ppm. Både Catator og HyGear har bekræftet, at de kan levere reformere i den ønskede størrelse til såvel høj- som lavtemperatur PEM inden for henholdsvis 8 og 16 uger til en pris omkring 200,000 kr for enkeltstyk. Der er ikke bekræftet mulighed for leverance fra Mitsui & Co, som sælger reformeren fra Osaka Gas på licens. Catator og HyGear har allerede leveret flere reformere til Danmark og overholdt de lovede betingelser og specifikationer. Ved store styktal forventes en pris omkring 5000 kr for 2kWe. Catator og HyGear har bekræftet, at videreudvikling og produktion på licens er muligt. Særligt Catator's teknologi og forretningsstrategi vurderes velegnet til en eventuel videreudvikling på licens. Den anvendte wire-mesh katalysator er attraktiv på grund af kompakt og fleksibelt design, god dynamik, hurtig opstart samt ingen krav om nitrogen eller naturgas til opstart og nedlukning. Haldor Topsøe har udtrykt interesse i at stille reformerkoncept til rådighed for udvikling og markedsmodning, hvis der i projektet deltager systemudvikler(e), som vil modne konceptet til et salgbart og produktionsmodnet system og stå for den efterfølgende produktion baseret på leverancer og licens fra Haldor Topsøe A/S.

The objective of this doctoral thesis was to develop reliable steady-state and transient component models suitable to asses-, develop- and optimize proton exchange membrane (PEM) fuel cell systems. Several components in PEM fuel cell systems were characterized and modeled. The developed component- and system models match experimental data from the literature. However, limited data were available for verification so further work is necessary to confirm detailed aspects of the models. It is nonetheless expected that the developed models will be useful for system modeling and optimization of PEM fuel cell systems. Consequences of indirectly fueling PEM stacks with hydrocarbons using reforming technology were investigated using a PEM stack model including CO poisoning kinetics and a transient Simulink steam reforming system model. Aspects regarding the optimization of PEM fuel cell systems are discussed and heat integration of a steam reforming system using pinch technology and a simultaneous optimization approach solving a MINLP problem is described.