A model for a 100
kW class solid oxide fuel cell (SOFC) system running on biogas from a sewage sludge digestion plant was implemented in a process flow scheme using external steam reforming. The ...model stack consisted of planar anode supported cells operated at 800
°C displaying state-of-the-art electrochemical performance (0.15
W/cm
2 at 80% fuel utilisation). Real annual data from an existing sewage plant were used as input to the model. From the input of 43
m
3/h biogas (63% CH
4), equivalent to 269
kW (higher heating value, HHV), the SOFC stack was calculated to deliver 131
kW
el electricity (48.7%) using a steam-to-carbon ratio of 0.5. This would allow the sewage site to more than cover its own electrical needs, hence to depollute the waste stream at negative energy cost. In its current exploitation using a low efficient gas engine (130
kW), the site is only ≈50% self-sufficient. Special attention was given to the thermal balance of the stack. The stack developed heat (143
kW) could be balanced by endothermal reforming (78
kW) and by cathode excess air
λ (=3), allowing a temperature difference between stack inlet and outlet of 200
K. The case was compared to other fuel scenarios. Steam-added biogas behaves basically identically to steam-reformed methane. For partial oxidation of biogas or pure hydrogen feeding, electrical efficiency drops to under 43% while
λ needs to be raised to 4.5 to maintain the 200
K thermal gradient over the stack.
For efficient feedstock and energy utilization, integrated biorefinery processes are applied to furfural production from bagasse to convert furfural residue into 5-hydroxymethylfurfural (HMF)—an ...important intermediate building block for the production of various biochemicals. Here, a techno-economic analysis of the integrated processes of furfural and HMF production combined with electricity generation under different scenarios was performed to identify the most suitable process design. Simulations revealed that using the whole bagasse in the biorefinery plant and recycling 50% waste from the HMF production to recover unreacted sugar (scenario 2) achieved the maximum furfural and HMF production with minimum CO2 emission, compared with integrated processes without sugar recycling (scenario 1), with 80% (scenario 3) and 60% biomass (scenario 4) bypassed to the biorefinery, and with a standalone combined heat and power system (scenario 5). Moreover, heat integration improved the efficiency of biorefinery plant (scenario 2), with an energy recovery potential of 71%, leading to the maximum profit at 11% internal rate of return. However, the high operating cost associated with the requirement of solvents and catalysts for HMF production represents the largest cost distribution in the proposed integrated processes. Sensitivity analysis revealed that solvent cost was the most important parameter for economic benefit. In addition, improving technological efficiency in the pretreatment and HMF production phases can enhance product yield, thereby benefiting the profitability of this process.
•Integrated biorefinery processes are proposed for furfural and HMF production.•Energy recovery potential of 60–70% can be achieved through heat integration.•Integrated biorefinery of whole bagasse with sugar recycling offers the maximum profit.•HMF production cost produces the strongest effect on economic benefit.
This article investigates the techno-economic performance of large integrated biogas Solid Oxide Fuel Cell (SOFC) power plants. Both atmospheric and pressurized operation is analysed with CO2 vented ...or captured. The SOFC module produces a constant electrical power of 1 MWe.
Sensitivity analysis and multi-objective optimization are the mathematical tools used to investigate the effects of Fuel Utilization (FU), SOFC operating temperature and pressure on the plant energy and economic performances. FU is the design variable that most affects the plant performance. Pressurized SOFC with hybridization with a gas turbine provides a notable boost in electrical efficiency. For most of the proposed plant configurations, the electrical efficiency ranges in the interval 50–62% (LHV biogas) when a trade-off of between energy and economic performances is applied based on Pareto charts obtained from multi-objective plant optimization. The hybrid SOFC is potentially able to reach an efficiency above 70% when FU is 90%. Carbon capture entails a penalty of more 10 percentage points in pressurized configurations mainly due to the extra energy burdens of captured CO2 pressurization and oxygen production and for the separate and different handling of the anode and cathode exhausts and power recovery from them.
•Five large SOFC power plant configurations are evaluated.•SOFC is fuelled by digester gas from a wastewater treatment plant.•Fuel Utilization is the design variable that most influences the efficiency.•Gas turbine integration improves efficiency with optimal stack pressure at 4–5 bar.•Carbon capture entails a penalty of more 10% in pressurized configurations.
•Review of urban planning’s new requirements and goals to tackle energy issues.•Presentation of a systematic framework to map challenges hindering urban energy planning.•Review of tools and methods ...to manage “wicked problems”.•Application of the theoretical framework to a case-study in Switzerland.
Cities are expected to play a key role in achieving the ambitious energy targets set by the European Union. By looking at opportunities beyond the single building scale, urban planners can significantly contribute to shape energy-efficient and low-carbon cities. However, the complexity involved in such a broad task impedes the realization of any simple solution. This paper aims to make clear the many interrelated challenges and obstacles which hinder efficient urban energy planning. After reviewing the new requirements and goals of urban planning and its links with energy issues, a systematic framework to analyze the issues at stake is presented. The importance of such a structured and comprehensive definition and understanding of the problem is discussed, arguing that it is a necessary step to improve and develop adapted solutions which embrace the entirety of the problem. The approach is applied to a case-study in Switzerland, mapping out the different challenges and corresponding solutions related to energy planning encountered in an urban development project.
A small cogeneration system based on a Solid Oxide Fuel Cell (SOFC) fed on the renewable energy source biogas is presented. An existing farm biogas production site (35
m
3 per day), currently ...equipped with a SOFC demonstration stack, is taken for reference. A process flow diagram was defined in a software package allowing to vary system operating parameters like the fuel inlet composition, reforming technology, stack temperature and stack current (or fuel conversion). For system reforming simplicity, a base case parameter set was defined as the fuel inlet of 60% CH
4:40% CO
2 mixed with air in a 1:1 ratio, together with 800
°C operating temperature and 80% fuel conversion. A model stack, consisting of 100 series elements of anode supported electrolyte cells of 100
cm
2 each, was calculated to deliver 3.1
kW
el and 5.16
kW
th from an input of 1.5
N
m
3/h of biogas (8.95
kW LHV), corresponding to 33.8 and 57.6% electrical and thermal efficiencies (Lower Heating Values (LHVs)), respectively. The incidence on the efficiencies of the model system was examined by the variation of a number of parameters such as the CO
2 content in the biogas, the amount of air addition to the biogas stream, the addition of steam to the fuel inlet, the air excess ratio
λ and the stack operating temperature, and the results discussed.
Converting wood to grid quality methane allows to distribute a CO
2 free, renewable energy resource in a conventional energy distribution system and use it in transportation applications. Applying a ...multi-objective optimisation algorithm to a previously developed thermo-economic process model for the thermochemical production of synthetic natural gas from wood, the present paper assesses the prospect of integrating an electrolyser in conversion systems based on directly and indirectly heated gasification. Due to an inherent lack of hydrogen for complete conversion of wood into methane and the possibility for rational use of oxygen, it is shown that electrolysis is an efficient and economically interesting option for increasing the gas output of the process while storing electricity and producing fuel that mitigates CO
2 emissions.
The objective of the current work is to support the design of a pilot hydrogen and electricity producing plant that uses natural gas (or biomethane) as raw material, as a transition option towards a ...100% renewable transportation system. The plant, with a solid oxide fuel cell (SOFC) as principal technology, is intended to be the main unit of an electric vehicle station. The refueling station has to work at different operation periods characterized by the hydrogen demand and the electricity needed for supply and self‐consumption. The same set of heat exchangers has to satisfy the heating and cooling needs of the different operation periods. In order to optimize the operating variables of the pilot plant and to provide the best heat exchanger network, the applied methodology follows a systematic procedure for multi‐objective, i.e. maximum plant efficiency and minimum number of heat exchanger matches, and multi‐period optimization. The solving strategy combines process flow modeling in steady state, superstructure‐based mathematical programming and the use of an evolutionary‐based algorithm for optimization. The results show that the plant can reach a daily weighted efficiency exceeding 60%, up to 80% when considering heat utilization.
A model for planar solid oxide fuel cell repeat elements and stacks has been developed. Distribution of concentrations, reaction rates and temperatures (both gases and solids) are computed as well as ...overall performance results. Specific experiments provide inputs to the model by a parameter estimation method.
The modeling approach developed allows to compare several configurations. As the number of design parameters is large (from cell size, component thicknesses to gas flow configuration), the model is designed to change easily these parameters so as to explore as many cases as possible. This is particularly true for the flow configuration (inlet position, outlets) for which several options are considered.
This model assists in choosing a configuration and allows to perform sensitivity studies in an efficient way (without having to produce a new mesh such as for CFD tools) or to be combined with an optimization tool. A first validation with experimental results, performed on a particular stack design, is presented. Issues of model accuracy and sensitivity to uncertain inputs are discussed.
The dispersion potential of mechanical vectors is an important factor in the dissemination of pathogens. A mark–release–recapture experiment was implemented using two groups (unfed and partially fed) ...of the Tabanidae (Diptera) (Haematopota spp.) and biting Muscidae (Diptera) (Stomoxys calcitrans) most frequently collected in Belgium in order to evaluate their dispersion potential. In total, 2104 specimens of Haematopota spp. were collected directly from horses and 5396 S. calcitrans were collected in a cattle farm using hand‐nets. Some of these insects were partially fed in vitro and all were subsequently coloured. Overall, 67 specimens of S. calcitrans (1.2%) and 17 of Haematopota spp. (0.8%) were recaptured directly on horses. Stomoxys calcitrans flew maximum distances of 150 m and 300 m when partially fed and unfed, respectively. Haematopota spp. travelled maximum distances of 100 m and 200 m when partially fed and unfed, respectively. Segregation measures seem essential in order to reduce the risk for pathogen transmission. A distance of 150 m appears to be the minimum required for segregation to avoid the risk for mechanical transmission, but in areas of higher vector density, this should probably be increased.
The dispersion potential of mechanical vectors is an important factor in the dissemination of pathogens.
A mark–release–recapture experiment was implemented using unfed and partially fed Tabanidae (2104 Haematopota spp.) and biting Muscidae (5396 Stomoxys calcitrans) in Belgium.
A segregation distance of 150 m appears to be the minimum required to avoid mechanical transmission, but in areas of higher vector density, this should probably be increased.
Summary
Background Microsporum canis is a pathogenic dermatophyte that causes a superficial cutaneous mycosis, mainly in cats and humans. Proteolytic enzymes, including subtilisins, have been ...postulated to be key factors involved in adherence and invasion of the stratum corneum and keratinized epidermal structures.
Objectives To evaluate the importance of Sub3 as a M. canis virulence factor using a SUB3 RNA‐silenced strain.
Materials and methods The stability of a previously constructed RNA‐silenced strain IHEM 22957 was tested in three different ways. The involvement of Sub3 in the adherence process was evaluated using a new ex vivo adherence model of M. canis arthroconidia to feline epidermis. In order to investigate the contribution of Sub3 in epidermal invasion, the pathogenicity of the SUB3 silenced strain was compared with that of the control strain in a guinea pig model of experimental M. canis dermatophytosis.
Results The silenced strain was shown to be stable after four in vitro transfers and after the in vivo experimental infection. This strain has dramatic loss of adherence capacity to feline corneocytes when compared with the parental strain. In contrast, no significant differences were observed at any time during the infection between the control strain and the SUB3 silenced strain, indicating that Sub3 secretion is not required for invasion of epidermal structures.
Conclusions RNA interference is a useful tool to evaluate pathogenic mechanisms of M. canis. For the first time, a role in pathogenicity could be attributed to a protease of a dermatophyte, namely Sub3 from M. canis, which is required for adherence to but not for invasion of the epidermis.
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