A detailed thermo-economic model combining thermodynamics with economic analysis and considering different technological alternatives for the thermochemical production of liquid fuels from ...lignocellulosic biomass is presented. Energetic and economic models for the production of Fischer–Tropsch fuel (FT), methanol (MeOH) and dimethyl ether (DME) by means of biomass drying with steam or flue gas, directly or indirectly heated fluidized bed or entrained flow gasification, hot or cold gas cleaning, fuel synthesis and upgrading are reviewed and developed. The process is integrated and the optimal utility system is computed. The competitiveness of the different process options is compared systematically with regard to energetic, economic and environmental considerations. At several examples, it is highlighted that process integration is a key element that allows for considerably increasing the performance by optimal utility integration and energy conversion. The performance computations of some exemplary technology scenarios of integrated plants yield overall energy efficiencies of 59.8% (crude FT-fuel), 52.5% (MeOH) and 53.5% (DME), and production costs of 89, 128 and 113
€
MWh
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on fuel basis. The applied process design approach allows to evaluate the economic competitiveness compared to fossil fuels, to study the influence of the biomass and electricity price and to project for different plant capacities. Process integration reveals in particular potential energy savings and waste heat valorization. Based on this work, the most promising options for the polygeneration of fuel, power and heat will be determined in a future thermo-economic optimization.
The paper evaluates the thermodynamic performances and the energy integration of alternative schemes of a methanol absorption based acid gas removal process designed for CO2 Capture and Storage.
More ...precisely, this work focuses the attention on the Rectisol® process specifically designed for the selective removal of H2S and CO2 from syngas produced by coal gasification.
The study addresses the following issues: (i) perform a review of the Rectisol® schemes proposed by engineers and researchers with the purpose of determining the best one for CO2 capture and storage; (ii) calibrate the PC-SAFT equation of state for CH3OH–CO2–H2S–H2–CO mixtures at conditions relevant to the Rectisol® process; (iii) evaluate the thermodynamic performances and optimize the energy integration of a “Reference” scheme derived from those available in the literature; (iv) identify and assess alternative Rectisol® schemes with optimized performance for CO2 Capture and Storage and Heat Integration with utilities. On the basis of the analysis of the Composite Curves of the integrated process, we propose some possible improvements at the level of the process configuration, like the introduction of mechanical vapor recompression and the development of a two stage regeneration arrangement.
•Comprehensive review of the Rectisol® process configurations and applications.•Calibration of PC-SAFT equation of state for Rectisol®-relevant mixtures.•Detailed process simulation and optimized Heat Integration, and utility design.•Development of alternative Rectisol® schemes optimized for CO2 Capture.
Environmental impact assessment will soon become a compulsory phase in future potable water production projects, especially when alternative treatment processes such as desalination are considered. ...An impact assessment tool is therefore developed for the environmental evaluation of potable water production. The evaluation method used is the life cycle assessment (LCA) method. The quick and easy assessment of energetic and environmental performances contributes to determine the weak points of potable water production processes or the best suited treatment in a specific context. Studies of some potable water supply scenarios (groundwater treatment, ultrafiltration, nanofiltration, seawater reverse osmosis and thermal distillation associated to water transfer) are presented in order to illustrate the environmental information drawn from this tool. The main source of impacts is shown to be electricity production for plant operation. Improvement levers are presented for impact reduction and for the objective comparison between alternative and conventional water treatment processes.
In the context of stationary power generation, fuel cell-based systems are being foreseen as a valuable alternative to thermodynamic cycle-based power plants, especially in small scale applications. ...As the technology is not yet established, many aspects of fuel cell development are currently investigated worldwide. Part of the research focuses on integrating the fuel cell in a system that is both efficient and economically attractive. To address this problem, we present in this paper a thermo-economic optimization method that systematically generates the most attractive configurations of an integrated system. In the developed methodology, the energy flows are computed using conventional process simulation software. The system is integrated using the pinch based methods that rely on optimization techniques. This defines the minimum of energy required and sets the basis to design the ideal heat exchanger network. A thermo-economic method is then used to compute the integrated system performances, sizes and costs. This allows performing the optimization of the system with regard to two objectives: minimize the specific cost and maximize the efficiency. A solid oxide fuel cell (SOFC) system of 50
kW integrating a planar SOFC is modeled and optimized leading to designs with efficiencies ranging from 34% to 44%. The multi-objective optimization strategy identifies interesting system configurations and their performance for the developed SOFC system model.
The methods proves to be an attractive tool to be used both as an advanced analysis tool and as support to decision makers when designing new systems.
•Biomass gasification combined with SOFC–GT hybrid system was studied.•Syngas hot cleaning unit is used in order to improve the efficiency of the system.•Energy integration in order to recover the ...maximum heat available inside the process.•Multi-objective optimization maximizing the efficiency and minimizing the capital investment costs.
Within the context of sustainable energy supply and CO2 emissions reduction a Solid Oxide Fuel Cell (SOFC) – gas turbine hybrid system, fuelled with gasified woody biomass is studied in detail for small and medium scale applications (100kWth,BM and 8MWth,BM of dry biomass input). The system consists of an air dryer unit, a gasifier, a hot cleaning section made of a particulate removal unit (cyclone and candle filter) and a two-stage tar removal unit, a SOFC and a gas turbine with optional CO2 capture. This modern technology has the advantage of using a renewable and CO2-neutral source and to be economically competitive at medium scales. The competitiveness of different process options is systematically compared by applying a coherent approach combining flowsheeting, energy integration and economic evaluation in a multi-objective optimization framework. This analysis reveals the importance of process integration maximizing the heat recovery and valorizing the waste heat, by cogeneration for example. The studied process options include direct and indirect circulating fluidized bed gasifier (using respectively oxygen or steam as gasification agent) and Viking gasifier, atmospheric or pressurized systems and optional pre-reforming in the hot gas cleaning. To close the thermal energy balance, a fraction of the produced syngas can be burnt. The energy integration results reveal that the steam production for the gasification and reforming are key parameters (S/B and S/C ratio) defining the process performance. A multi-objective optimization maximizing the efficiency and minimizing the capital investment costs is performed with respect to the operating conditions and the process configuration in order to assess the trade-offs and identify optimal process designs. The analysis shows the potential of the system converting woody biomass into electricity with an energy efficiency greater than 70%.
A geographical information system has been developed to model the energy requirements of an urban area. The purpose of the platform is to model with sufficient detail the energy services requirements ...of a given geographical area in order to allow the evaluation of the integration of advanced integrated energy conversion systems. This tool is used to study the emergence of more efficient cities that realize energy efficiency measures, integrate energy efficient conversion technologies and promote the use of endogenous renewable energy. The model is illustrated with case studies for the energetic planning of the Geneva district (Switzerland).
Les récentes lois (EGALIM, Climat et Résilience…) imposent dorénavant à l’acheteur public de procéder à des achats dits responsables. Ces lois sont même parfois présentées comme une possibilité de ...favoriser l’achat public local. Conséquence implicite d’un achat plus respectueux des considérations environnementales ou objectif explicite de l’acheteur public qui instrumentalise l’achat vert, l’achat local doit être analysé. Après avoir détaillé le cadre législatif en vigueur en France, nous présentons tout d’abord les arguments théoriques permettant d’analyser le lien entre achat local et achat responsable. Nous présentons ensuite les différents jeux de données ouvertes (disparates et incomplètes) de la commande publique, nous permettant de mener une analyse empirique dont les résultats suggèrent qu’on ne puisse pas exclure l’hypothèse que l’achat local ait des fondements de natures protectionnistes et ne soit pas nécessairement la conséquence d’une préoccupation environnementale annoncée.
Internal combustion engines are the most applied energy converters in passenger cars. In order to increase their efficiency, energy integration techniques are used to recover waste heat. An adapted ...methodology is required to design the organic Rankine cycle (ORC) as a waste heat recovery technology and to test the influence of the external temperature on its efficiency. The idea is to cluster the external temperature profile on typical external temperature multi‐periods. The energy system design is then tested on these typical multi‐periods.
In this article the methodology is applied on a vehicle with a diesel engine, in order to define the energy integrated configuration of the vehicle and to estimate the cost of the additional equipment. The performance indicators of the energy integration technology of the internal combustion engine is done and discussed, according to the multi‐periods. The energy recovery potential of a single stage ORC for a diesel engine is assessed for different temperature profiles. The ORC equipment is simultaneously pre‐sized and its cost is estimated.
The present study evaluates a sugarcane biorefinery producing ethanol through juice fermentation and methanol via gasification of sugarcane lignocellulosic residues and liquid fuel synthesis. Two ...technologies of gasification named entrained flow and circulating fluidized bed are compared. Flowsheet modeling and thermo-economic analysis methods are applied, followed by a multi-objective optimization based on a genetic algorithm. The optimum Ethanol–Methanol biorefinery design options are compared with other previously studied sugarcane biorefineries. The results show that the biorefinery's energy efficiency increases significantly with the integration of a methanol production plant in a conventional ethanol distillery. The configuration using an entrained flow gasifier presents lower conversion efficiency than the one using a circulating fluidized bed gasifier. However, for the entrained flow gasifier configuration, the size of the methanol production process could be bigger since more heat is available for the ethanol process favouring the integration with the ethanol plant. Higher energy efficiency due to increase of methanol production leads to a higher total investment for both gasification technologies. The cost analysis shows that the calculated methanol production cost is 30% higher than its current market price. Environmental incentives for biofuels could change this scenario but are not in the scope of this study.
•A sugarcane biorefinery producing methanol and ethanol was investigated.•Sugarcane bagasse was gasified and syngas was converted to methanol.•The EF gasifier presented better thermal integration with the biorefinery.•Methanol production cost at the biorefinery is higher than the market price.
A process optimization method has been developed for the design of reverse osmosis (RO) processes. RO process configurations are systematically generated using a flexible superstructure and evaluated ...by economical (investment and operating costs), technical (energy requirement, water recovery rate) and environmental performance indicators (Life Cycle Assessment). The simultaneous optimization of the RO process layout and operating conditions constitutes a mixed-integer nonlinear programming (MINLP) problem, which is solved using a multi-objective optimization (MOO) approach. The MOO identifies the best technological alternatives for the set of selected objectives. In a given context, it allows to define a set of optimal solutions representing the trade-off between conflicting objectives such as economical costs and environmental impacts. As a case study, the methodology is applied on a brackish water reverse osmosis (BWRO) desalination project, for which the optimal design is characterized depending on the economical conditions.
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