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In this paper, the performances of two iron-based syngas-fueled chemical looping (SCL) systems for hydrogen (H2) and electricity production, with carbon dioxide (CO2) capture, using different reactor configurations were evaluated and compared. The first investigated system was based on a moving bed reactor configuration (SCL-MB) while the second used a fluidized bed reactor configuration (SCL-FB). Two modes of operation of the SCL systems were considered, namely, the H2 production mode, when H2 was the desired product from the system, and the combustion mode, when only electricity was produced. The SCL systems were modeled and simulated using Aspen Plus software. The results showed that the SCL system based on a moving bed reactor configuration is more efficient than the looping system with a fluidized bed reactor configuration. The H2 production efficiency of the SCL-MB system was 11 % points higher than that achieved in the SCL-FB system (55.1 % compared to 44.0 %). When configured to produce only electricity, the net electrical efficiency of the SCL-MB system was 1.4 % points higher than that of the SCL-FB system (39.9 % compared to 38.5 %). Further, the results showed that the two chemical looping systems could achieve >99 % carbon capture efficiency and emit ~2 kg CO2/MWh, which is significantly lower than the emission rate of conventional coal gasification-based plants for H2 and/or electricity generation with CO2 capture.

The transition to a low carbon future is starting to affect landscapes around the world. In order for this landscape transformation to be sustainable, renewable energy technologies should not cause critical trade-offs between the provision of energy and that of other ecosystem services such as food production. This literature review advances the body of knowledge on sustainable energy transition with special focus on ecosystem services-based approaches and methods. Two key issues emerge from this review: only one sixth of the published applications on the relation between renewable energy and landscape make use of the ecosystem service framework. Secondly, the applications that do address ecosystem services for landscape planning and design lack efficient methods and spatial reference systems that accommodate both cultural and regulating ecosystem services. Future research efforts should be directed to further advancing the spatial reference systems, the use of participatory mapping and landscape visualizations tools for cultural ecosystem services and the elaboration of landscape design principles.

The Vietnamese Mekong Delta (VMD) is one of the world’s most vulnerable deltas to climate change and sea level rise. Adequate understandings of future hydrological changes are crucial for effective water management and risk-proofing, however, this knowledge body is currently very limited. This study quantifies the responses of the VMD’s river flow regime to multiple stimuli, namely future upstream inflow variation, local climate change, and sea level rise. The one-dimensional hydrodynamic model MIKE 11 was used to simulate discharges and water levels across the delta. We developed four scenarios to represent changes in the upstream discharges, precipitation changes and sea level rise, covering the 2036–2065 period. We downscaled climate data and applied three bias-correction methods for five General Circulation Models (GCM), and two Representative Concentration Pathways (RCPs). The climate change projections show similar trends of increasing wet season precipitation and decreasing dry season precipitation. However, cross-scenario variations are sometimes large, depending on the individual GCMs, the RCPs and specific locations. The hydraulic simulation results indicate that, under discharge changes between −20% and +10%, combined with in-delta precipitation variations during the dry season, river discharges at the four representative stations could reduce substantially from −2.5% to −100.2%. During the wet season, the calculated river discharges show increase between 7.3% and 46.7% under four considered scenarios. Substantial changes in the VMD’s river flow regime could have potentially serious implications for water management, especially saltwater intrusion, and therefore calling for timely adaptation measures.

In the course of the “Energiewende,” the German electricity market is undergoing major changes. The state-aided priority of renewable generation has led to a significant decline in electricity prices. This reduces the profit margin of cogeneration units and increases the necessity of flexible operation to avoid electricity production when spot prices drop below marginal costs. In this work, a 100 MWel combined-cycle (CC) power plant supplying heat and power to a paper mill is investigated. Currently, the plant is operated heat-controlled and is therefore unable to react to changing electricity spot prices. With the integration of heat storage, the plant is enabled to switch to power-controlled mode. To evaluate the technical impact of the storage, the plant and a thermochemical MgO/Mg(OH)2 storage are modeled using the stationary process simulation tool ebsilon professional. Different operation modes are investigated and results are used to derive a mixed integer linear programming (MILP) model to optimize the operation of the plant/storage system. Using this method, the overall economic impact of the storage on the plant operation is quantified.

AbstractBackgroundCodes of ethics (CoE) are widely adopted in several professional areas, including that of Software Engineering. However, contemporary CoE do not pay sufficient attention to one of the most important trends to have appeared in the last years environmental issues.AimThe aim of this study is to establish a Green CoE for software engineering and Professional Practices (GreCo). Our intention is to cover a wide range of aspects related to sustainability, such as economic, environmental, social, and technical features. We are additionally interested in encouraging software engineers to adopt these aspects.MethodsThe Green CoE presented is the result of the interaction of several experts in the area. A first version of GreCo, whose starting point was a discussion at the GInSEng workshop, was created by identifying key principles and adapting them to the Green area. Next, various important CoE were reviewed so as to gather the existing references to sustainability or to detect new ones. These elements would then possibly be incorporated into the new code or stimulate the creation of new sustainable principles.ResultsThe final result is the GreCo code, which has been produced by modifying existing principles or by the introduction of new ones.

AbstractAlumosilicate minerals are suitable sorbents at high temperatures for removing alkalis in syngas. Thermogravimetric investigations of these sorbents usually focus on the reaction mechanisms. Herein, a crucible arrangement is described that allows evaporation of the alkali source and sorption of gaseous alkali components in one temperature zone. With this experimental setup, kinetic investigations of alkali sorption are possible in a conventional thermobalance. Experiments were performed with sodium chloride as the alkali source and kaolin as the getter material. The reaction rate increased with alkali concentration and showed an exponential dependence on temperature. Thus, the Arrhenius model approach and power law model were selected for mathematical description.

This paper presents the results of a thermodynamic and economic evaluation of a novel hybrid combination of a compressed air energy storage and a combined cycle power plant. The new cycle is modeled on basis of a GE LM6000 gas turbine model, an adiabatic compressor model, an air expander and a conventional dual pressure HRSG configuration. Furthermore, a detailed design of the recuperator is presented. With the simulated components, a storage efficiency of 60% is reached. In CHP configuration the total efficiency of the plant reaches up to 86.2%. The thermodynamic and economic performance is compared to a conventional LM6000 combined cycle. For the economic evaluation the German electricity day-ahead prices and average gas price of the year 2014 are used. Overall it is found that the CAES/CCPP concept exhibits far more operation hours per year and a higher profit margin than the compared CCPP. Taking into account the investment and operational costs, especially with steam extraction the net present value of the novel cycle is higher than that of the combined cycle, despite the challenging market environment for storage technologies in Germany.

Gas–solid fluidized bed reactors play an important role in many industrial applications. Nevertheless, there is a lack of knowledge of the processes occurring inside the bed, which impedes proper design and upscaling. In this work, numerical approaches in the Eulerian and the Lagrangian framework are compared and applied in order to investigate internal fluidized bed phenomena. The considered system uses steam/air/nitrogen as fluidization gas, entering the three-dimensional geometry through a Tuyere nozzle distributor, and calcium oxide/corundum/calcium carbonate as solid bed material. In the two-fluid model (TFM) and the multifluid model (MFM), both gas and powder are modeled as Eulerian phases. The size distribution of the particles is approximated by one or more granular phases with corresponding mean diameters and a sphericity factor accounting for their nonspherical shape. The solid–solid and fluid–solid interactions are considered by incorporating the kinetic theory of granular flow (KTGF) and a drag model, which is modified by the aforementioned sphericity factor. The dense discrete phase model (DDPM) can be interpreted as a hybrid model, where the interactions are also modeled using the KTGF; however, the particles are clustered to parcels and tracked in a Lagrangian way, resulting in a more accurate and computational affordable resolution of the size distribution. In the computational fluid dynamics–discrete element method (CFD–DEM) approach, particle collisions are calculated using the DEM. Thereby, more detailed interparticulate phenomena (e.g., cohesion) can be assessed. The three approaches (TFM, DDPM, CFD–DEM) are evaluated in terms of grid- and time-independency as well as computational demand. The TFM and CFD–DEM models show qualitative accordance and are therefore applied for further investigations. The MFM (as a variation of the TFM) is applied in order to simulate hydrodynamics and heat transfer to immersed objects in a small-scale experimental test rig because the MFM can handle the required small computational cells. Corundum is used as a nearly monodisperse powder, being more suitable for Eulerian models, and air is used as fluidization gas. Simulation results are compared to experimental data in order to validate the approach. The CFD–DEM model is applied in order to predict mixing behavior and cohesion effects of a polydisperse calcium carbonate powder in a larger scale energy storage reactor.