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Abstract In this paper, a strategy is proposed in order to introduce in a realistic way wind generation into a transmission power system non sequential Monte Carlo adequacy study with economic dispatch. Thanks to the implemented solution, wind generation is consequently confronted to operational constraints related to high powered thermal units, nuclear parks or thermal machines with technical minimum value. Moreover, during each simulated system state, a DC load flow is also calculated in order to evaluate reinforcements optimizing the large scale integration of wind power production. The simulation tool modified during the present work is called Scanner© and is the property of Tractebel Engineering (Gaz de France – Suez) company. It has been here applied to an academic test system: the Roy Billinton Test System (RBTS).

The Community Energy Technology Support Programmes have been in operation since 1973 and the various regulations governing them require periodic evaluations to be carried out. This study presents the main results of the last evaluation that was performed as part of the THERMIE programme, concerning projects supported in the sector Renewable Energy Sources.

Abstract Recently, the impurity photovoltaic effect (IPV) was proposed to improve the solar cell performance. Free electron–hole pairs can be generated in a two-step process involving an impurity level in the energy gap and two lower-energy photons: first electrons are optically excited from the valence band to the defect level and then from the defect level to the conduction band. The IPV effect will thus enhance the long-wavelength response of the cell. A significant amount of theoretical work has been carried out on IPV effect in the literature, particularly on silicon solar cells with indium impurities as defect. However, the lack of an easily available solar cell simulator including the IPV effect is a handicap. In this work, the numerical solar cell simulator SCAPS of the ELIS group was extended to include IPV in collaboration between the ELIS and the LPDS groups. Also, some special features are implemented, such as the calculation of electron and hole photoemission cross-sections of the impurity using the model of Lucovsky. The functionality of new SCAPS version was checked against existing results in the literature. Also, new results are presented such as the evolution of solar cell parameters with the indium density. We find that increasing indium concentration can improve silicon solar cell parameters, especially the short-circuit current and the efficiency, without drastically decreasing the open-circuit voltage. This is possible if a suitable structure for the cell is chosen. The optimum indium density should be equal around the base region density to obtain a positive benefit from the IPV effect. Light trapping, which is related to the internal reflectance at the front and the back of the cell, is very important in the IPV study. Reflectivity at the front and the back should exceed 99.9% to obtain a real efficiency increase. We calculate an improvement of about 6 mA/cm 2 in the photocurrent, and about 2% for the efficiency, which is due to the enhancement of long-wavelength absorption by the IPV effect.

Abstract There is an increasing need for an alternative energy source within the electricity market to counterbalance the intermittent supply from renewable energy sources as their share in the market continues to grow. Anaerobic digestion could play a role in fulfilling this need through participation in the day-ahead electricity market. The potential for anaerobic digestion operators in Flanders, Belgium, and the impact of the current Flemish support policy framework on this potential are investigated by developing a non-linear optimization model that maximizes profits for the complete anaerobic digestion system, taking into account the current policy framework and a proposed alternative one. Our analysis indicates that there is a potential profit to be made for anaerobic digestion operators in the day-ahead market. However, the current framework of public support is not conducive to their participation. By allowing the same amount of support to be spread over a longer period of time, the use of flexible electricity production in the anaerobic digestion sector could be stimulated, and the profitability of this sector increased.

Abstract Renewable energy systems have a relevant land footprint, and their development can lead to land-use conflicts and trade-offs between energy supply and ecosystem services. Accordingly, this work identified the more suitable renewable energy development areas and discussed the potential trade-offs between energy supply and priority ecosystem services, combining the Geographic Information System-based suitability analysis and ecosystem service approach. The expert consultations were carried out to assess and identify the supply capacities of priority ecosystem services in South-Central Chile. The suitability maps for four renewable energy types were generated and spatially overlapped with priority ecosystem service maps to assess the trade-offs resulting from energy development. The results showed that suitable sites for solar, wind and biomass energy showed limited capacities to supply relevant provisioning and regulatory services and medium-to-low capacity to deliver cultural services. More than half of potential hydropower stations can be located on zones with a medium capacity to supply provisioning services and a high capacity for regulation and maintenance and cultural services. In most cases, sitting energy plants on areas of cultural relevance and other adverse impacts may cause social rejection toward their installation. This work provides valuable spatial information to support land-renewable energy planning, minimizing the environmental and social conflicts on ecosystem services.

Abstract The 2-parameter Weibull distribution is widely used, accepted, and recommended as probability law to describe and evaluate the wind speed frequency, which is especially useful for assessing wind resources. In this study, six popular parameter estimation methods are reviewed and compared with a new method that we call Modified Energy Pattern Factor (MEPF) method. The advantage of MEPF is that it is free from binning, linear least square problems or iterative procedures. All methods are compared via a thorough Monte Carlo simulation study with sample sizes varying from 100 to 100,000. The results indicate that the MEPF is a suitable alternative and comparable with the relatively best estimator of the Weibull parameters at each sample size. Consequently, we have used the MEPF to estimate the Weibull parameters of wind data from three regions in India, and we explain how to use these insights for the calculation and prediction of wind energy production. In particular, for harnessing the wind energy, both wind speed and direction are important. For the wind direction assessment, we have compared the conventional von Mises distribution to the new 4-parameter Kato-Jones distribution, and found that the latter approach provides better results.

Abstract In order to optimize the efficiency of multicrystalline silicon solar cells, the influence of specific process steps and sequences were studied. Therefore clean-room high efficiency as well as industrial screen-printed cells were fabricated. Benefits are found in choosing a substrate with lower base resistivity, using front and rear oxide passivation, using hydrogen passivation for bulk and surfaces, the use of Si3N4 with a double function i.e. as an anti-reflection and passivation layer and the use of mechanical V-grooving. Efficiencies of 17% are found on 4 cm2 clean-room fabricated cells and 15.2% has been obtained on 100 cm2 V-grooved screenprinted industrial cells.

Abstract Three-dimensional (3D) computational fluid dynamics (CFD) simulations were performed to study solids flow dynamics and solids back-mixing behavior in a screw reactor (designed for thermal conversion of dry biomass particles) based on the Eulerian-Eulerian method. Simulation results were compared against experimental data with respect to filling degree and mean residence time of particles. The mean deviations for filling degree and for mean residence time between simulation and experiment were about 0.01 and 11.4 s, respectively, which shows that the model is reasonably accurate in predicting solids flow behavior in the screw reactor. The solids flow dynamics inside the reactor were discussed. The solids residence time distribution (RTD) was calculated and the degree of solids back-mixing in the forward transportation direction of the reactor was analyzed. It was found that solids being flung over the shaft and solids back-leakage, resulting from the low solids forward transportation velocity at the clearance between the flight and the bottom shell of the screw reactor, were responsible for solids back-mixing. The degree of solids back-mixing can be reduced at higher screw rotating speeds when keeping inlet mass flow rate of solids constant.