ALBERT

Beschreibung: Hydrogen adsorption in porous nanostructured polyaniline (PANI) has been investigated to determine its potential as a hydrogen storage media. Residual gas analysis and thermogravimetric analysis were used to investigate the cyclical hydrogen adsorption in PANI. A hydrogen storage capacity of up to 3 wt % was obtained by charging the polymers at up to 3.0 × 10 6  Pa hydrogen at elevated temperature. Multiple charge and discharge cycles have been shown, with good retention beyond 10 6  sec. Hydrogen absorption with retention for greater than 10E6 sec and with multiple charge–discharge cycles has been shown in porous nanostructured polyaniline at the 3% absorption level.

Beschreibung: Wind power has seen a remarkable growth in China since the Renewable Energy Law came into force in the beginning of 2006. However, the contribution and the economic cost of wind power development to reduce carbon emission at the provincial level are still unclear. This research combined geographic information system analysis and levelized production cost calculation to provide provincial-level supply curve of carbon dioxide (CO 2 ) mitigation by wind power in China. The results showed that wind power could be a very competitive mitigation option in China, with a potential to contribute 500 million tons of CO 2 emission mitigation at an average abatement cost of 75 RMB/t of CO 2 mitigation. The emission abatement cost and the potential to reduce carbon emission in different provinces may be used for national planning as well as for the allocation of investments. Our results showed that wind power could be a very competitive mitigation option in China, with a potential to contribute 500 million tons of CO 2 emission mitigation at an average abatement cost of 75 RMB/t of CO 2 mitigation.

Beschreibung: Increasing the number of subcells in a multijunction or “spectrum splitting” photovoltaic improves efficiency under the standard AM1.5D design spectrum, but it can lower efficiency under spectra that differ from the standard if the subcells are connected electrically in series. Using atmospheric data and the SMARTS multiple scattering and absorption model, we simulated sunny day spectra over 1 year for five locations in the United States and determined the annual energy production of spectrum splitting ensembles with 2–20 subcells connected electrically in series or independently. While electrically independent subcells have a small efficiency advantage over series-connected ensembles under the AM1.5D design spectrum, they have a pronounced energy production advantage under realistic spectra over 1 year. Simulated energy production increased with subcell number for the electrically independent ensembles, but it peaked at 8–10 subcells for those connected in series. Electrically independent ensembles with 20 subcells produce up to 27% more energy annually than the series-connected 20-subcell ensemble. This energy production advantage persists when clouds are accounted for. As the solar spectrum varies over the course of a year, multijunction cells with series-connected subcells suffer efficiency losses as various subcells are over or under illuminated. Consequently, series-connected multijunction cells will produce fewer kW-hr of energy per year than equivalent ensembles with electrically independent subcells. We find that the energy production advantage of the electrically independent subcells increases with the number of junctions, from 4.9% for two junctions, 13.3% for six junctions, and up to 27.1% for 20 junctions.

Beschreibung: The global warming is directly related to the increased greenhouse gas emissions from both natural and anthropogenic origins. There has been a drastic rise in the concentration of CO 2 and other greenhouse gases since the industrial revolution primarily due to the intensifying consumption of fossil fuels. With the need to reduce carbon emissions and mitigate global warming certain strategies relating to carbon capturing and sequestration are indispensable. This paper comprehensively describes several physicochemical, biological and geological routes for carbon capture and sequestration. The trend of the increase in greenhouse gases over the years is illustrated along with the global statistics for fossil fuels usage and biofuels production. The physicochemical carbon capturing technologies discussed include absorption, adsorption, membrane separation and cryogenic distillation. The algal and bacterial systems, dedicated energy crops and coalbed methanogenesis have been vividly explained as the biological routes for carbon sequestration. The geological carbon sequestering route centers on biochar application and oceanic carbon storage. A systematic survey has been made on the origin and impact of greenhouse gases along with the potential for sequestration based on some fast-track and long-term sequestration technologies. The physicochemical carbon capture technologies discussed includes absorption, adsorption, membrane separation and cryogenic distillation. The algal and bacterial systems, dedicated energy crops and coalbed methanogenesis have been vividly explained as the biological routes for carbon sequestration. The geological carbon sequestering route centers on biochar application and oceanic carbon storage.

Beschreibung: The purpose of this study was to evaluate the effects of temperature and equivalence ratios (ERs) on the distribution of products (primary gases carbon monoxide [CO], H 2 , CH 4 , CO 2 ), gas phase contaminants (tar, NH 3 , HCN, H 2 S, HCl), char, carbon, and inorganics), and energy flows on an oxygen-blown bubbling fluidized bed gasifier system using loblolly pine. The goal and value of this study was to provide quantitative and qualitative performance analysis and data for process engineering and optimization of these fledgling biomass conversion systems. As temperature and ER increased, mass balance closures also increased from 94.73% to 96.72% for temperature and 89.82–96.93% for ER. In addition, the carbon closures ranged from 80.77% to 92.29% and from 79.09% to 87.13% as temperature and ER increased, respectively. Carbon conversion efficiency to gas product ranged from 72.26% to 84.32% as temperature increased and from 72.26% to 84.66% as ER increased. Carbon flow analysis showed that the char product streams retained 10.26–6.94% and 8.82–2.13% of the carbon fed to the gasifier as temperature and ER increased, respectively. The carbon content in the liquid condensate was minimal compared to the carbon in other product streams and accounted for less than 0.1% of the carbon input to the gasifier at all conditions. The cold and hot gas efficiencies increased from 56.12% to 67.45% and from 67.51% to 83.83% as temperature increased due to higher production of CO and hydrogen (H 2 ). In contrast, cold and hot gas efficiencies decreased from 63.85% to 52.84% and from 78.06% to 73.00% as ER increased, respectively, due to enhanced oxidation of gas products resulting in a net decrease in heating value. This study provides quantitative and qualitative performance analysis of biomass gasification using a fluidized bed reactor.

Beschreibung: Al 2 O 3 /TiO 2 double layer anti-reflection coating (ARC) film formed by spray pyrolysis was introduced for monocrystalline silicon solar cells as the nonvacuum processing method. The thickness of the Al 2 O 3 layer and TiO 2 compact layer was controlled by the volume of deposited precursor solution and confirmed by ellipsometry and scanning electron microscope. The average photovoltaic properties of photocurrent density ( J sc ), the open-circuit photovoltage ( V oc ), the fill factor ( FF ), and the photo energy conversion efficiency ( η ) were 37.0 mA/cm 2 , 590 mV, 0.712, and 15.5%, respectively. A significant improvement on J sc and η could be confirmed owing to the Al 2 O 3 /TiO 2 ARC. According to the results of Fourier transform infrared (FTIR) spectroscopy and optical simulation with modeling for the reflectance properties, it was confirmed that C-H-based organics remained after the deposition of thin films. Al 2 O 3 /TiO 2 double layer anti-reflection coating film formed by spray pyrolysis was introduced for monocrystalline silicon solar cells as a nonvacuum processing method. According to the results of Fourier transform infrared spectroscopy and optical simulation with modeling for the reflectance properties, it was confirmed that C-H-based organics remained after the deposition of thin films.

Beschreibung: This article presents a simple comparative model which has been developed for the estimation of the performance of photovoltaic (PV) products' cells in indoor environments. The model predicts the performance of PV solar cells, as a function of the distance from a spectrum of artificial (fluorescent light, halogen light, and light-emitting diodes) and natural light. It intends to support designers, while creating PV-integrated products for indoor use. For the model's validation, PV cells of 12 commercially available PV-powered products with power ranging from 0.8 to 4 mWp were tested indoors under artificial illumination and natural light. The model is based on the physical measurements of natural and artificial irradiance indoors, along with literature data of PV technologies under low irradiance conditions. The input data of the model are the surface of the solar cell (in m 2 ), the wavelength-dependent spectral response (SR) of the PV cell, the spectral irradiance indoors, and solar cell's distance from light sources. The model calculates solar cells' efficiency and power produced under the specific indoor conditions. If using the measured SR of a PV cell and the irradiance as measured indoors, the model can predict the performance of a PV product under mixed indoor light with a typical inaccuracy of around 25%, which is sufficient for a design process. Measurements revealed that under mixed indoor lighting of around 20 W/m 2 , the efficiency of solar cells in 12 commercially available PV products ranges between 5% and 6% for amorphous silicon (a-Si) cells, 4–6% for multicrystalline silicon (mc-Si) cells, and 5–7% for the monocrystalline silicon (c-Si) cells. This article describes a model which estimates the performance of PV cells at an indoor environment and under mixed indoor lighting. It intends to support designers, while creating PV-integrated products for indoor use. For the model's validation, PV cells of 12 commercially available PV-powered products with power ranging from 0.8 to 4 mWp were tested indoors. Measurements revealed that under mixed indoor lighting of around 20 W/m 2 , the efficiency of the tested PV products’ cells ranges between 5% and 6% for a-Si cells, 4–6% for mc-Si cells, and 5–7% for c-Si cells.

Beschreibung: We estimate the emissions of the two most important greenhouse gasses (GHG), carbon dioxide (CO 2 ) and methane (CH 4 ), from the use of modern high-efficiency heat pump water heaters compared to the most commonly used domestic hot water systems: natural gas storage tanks, tankless natural gas demand heaters, electric resistance storage tanks, and tankless electric resistance heaters. We considered both natural gas-powered electric plants and coal-powered plants as the source of the electricity for the heat pumps, the thermal electric storage tanks, and the tankless electric demand heaters. The time-integrated radiative forcing associated with using a heat pump water heater was always smaller than any other means of heating water considered in this study across all time frames including at 20 and 100 years. The estimated amount of CH 4 lost during its lifecycle was the most critical factor determining the relative magnitude of the climatic impact. The greatest net climatic benefit within the 20-year time frame was predicted to be achieved when a storage natural gas water heater (the most common system for domestic hot water in the United States) fueled by shale gas was replaced with a high efficiency heat pump water heater powered by coal-generated electricity; the heat pump system powered by renewable electricity would have had an even greater climatic benefit, but was not explicitly modeled in this study. Our analysis provides the first assessment of the GHG footprint associated with using a heat pump water heater, which we demonstrate to be an effective and economically viable way of reducing emissions of GHGs. We developed a web-based tool analyzing the emissions of the two most important greenhouse gasses (GHG), carbon dioxide and methane, from the use of modern high-efficiency heat pump water heaters compared to the most commonly used domestic hot water systems. The time-integrated radiative forcing associated with using a heat pump water heater was always smaller than any other means of heating water considered in this study. Our analysis provides the first assessment of the GHG footprint associated with using a heat pump water heater, which we demonstrate to be an effective and economically viable way of reducing emissions of GHGs.

Beschreibung: At present food production depends almost exclusively on direct use of stored energy sources, may perhaps they be nuclear-, petroleum-, or biobased. Arable land, artificial fertilizers, and fresh water resources are the base for our present food systems, but are limited. At the same time, energy resources in the form of waste heat are available in ample quantities. The European Spallation Source (ESS) will require approximately 270 GWh of power per year to operate, power that ultimately is converted to heat. This multidisciplinary case study details an alternative food production cooling chain, using low-grade surplus heat, and involving fermentation, aquaculture, nutrient recapture, and greenhouse horticulture including both use of low-grade surplus heat and recycling of society's organic waste that is converted to animal feed and fertilizer. The study indicates that by combining the use of surplus energy with harvest of society's organic side flows, for example, food waste and aquatic-based cash crops, sustainable food systems are possible at a level of significance also for global food security. The effects of the proposed heat reuse model are discussed in a system perspective and in the context of the UNSCD indicator framework. The potential sustainability benefits of such an effort are shown to be substantial and multifaceted. This article describes and assesses a proposal for using waste heat from a large-scale research facility to enable industrial scale intensive food production. The article shows that the sustainability benefits would be substantial, as the proposed heat recycling model would be generally applicable in industry in cool climates and, if broadly implemented, would significantly decrease the fossil fuel dependency of food production and broaden the variety and deepen the robustness of production, enhancing security of food supply.

Beschreibung: This study investigates the performance of dye-sensitized solar cells constructed with a Fe-Cu metastable material as the mesoporous layer on which a natural organic dye is applied. The synthesis of the Fe-Cu material is done via a high throughput process that produces nanosized particles from elemental metallic powders. Xanthophyll is singled out as the organic natural dye of choice among other dyes that were extracted, as it exhibited wider spectral absorptivity in terms of wavelength range and magnitude. Two compact solar cells were constructed and tested; one is a reference cell with a TiO 2 working electrode and the other with a Fe-Cu working electrode. The results show a better power conversion efficiency for the Fe-Cu-based solar cell 0.943% compared to 0.638% for the TiO 2 , and the number of carriers in the former is found to be orders of magnitude higher than the latter (10 19 vs. 10 32 , respectively). A thorough optical, electrical, and thermal analysis of the Fe-Cu material is conducted and used to explain the obtained results. This study presents the unique result of the Fe-Cu compound as a semiconducting nanoscale material to replace TiO 2 as a mesoporous layer. Although mechanical alloying is a well-researched method for producing such a system, the novelty of this study is the attractive properties reported in this work.

Beschreibung: The characteristics of CO 2 reacting with CaO in a molten eutectic mixture of CaF 2 and NaF has been investigated. Calculations of the Gibbs free energy, temperature analysis of the decomposition of the formed carbonates, and XRD analyses of quenched samples taken during CO 2 absorption or desorption were employed to identify the phases present in the melt. Efficient CO 2 absorption from a simulated flue gas was observed, due to a combined reaction where CaO initially reacts with CO 2 and forms CaCO 3 . Subsequently, Na 2 CO 3 is formed by an ion exchange reaction between CaCO 3 and NaF. It was found that the CaO activity is highest in the temperature range 826–834°C. Increasing the CaO concentration from 5 to 20 wt% in the molten salt resulted in reduced CO 2 reactivity efficiency, probably because of precipitation and agglomeration of the sorbent. The total carbonation conversion was independent of the CO 2 concentration in the inlet gas, and the sorbent carrying capacity was in the range 0.722–0.743 g CO 2 /g CaO corresponding to 0.037–0.144 g CO 2 /g total liquid. Decarbonation was conducted by raising the temperature. 40% conversion back to CaO was recorded at 1160°C. The recorded curves for the CO 2 concentration in the outlet gas exhibited a rapid desorption step followed by a slow step. Calcium looping by CaO dispersed in a molten salt containing NaF has been studied.

Beschreibung: Solar cells used in building integration of photovoltaic cells (BIPV) are commonly made from crystalline wafer cells. This contribution investigates the challenges and benefits of using bifacial solar cells in vertical installations. We show that those cells get up to 13% more irradiance compared to optimum tilted south facing monofacial modules in Germany. The role of the n-layer in thin amorphous bifacial single-junction cells intended to be used as bifacial cells in BIPV applications is investigated. In contrast to the superstrate cell design, a transparent n-layer and back contact play a key role to achieve high bifaciality. We therefore increased the transparency of the n-layer by adding CO 2 , increasing the PH 3 flow in the deposition gas and tested different thicknesses. With those measures, we reached a bifaciality of 98% for short-circuit current density and 99% for open-circuit voltage. In this contribution, we propose to use bifacial solar cells in vertical installation for BIPV. We demonstrate that a vertical plane, regardless of orientation, gets more irradiance from both sides than a plane from one side in optimum tilt and orientation. We show that the removal of the back reflecting layer and a slight tuning of the n-layer can turn single a-Si:H solar cells into good bifacial cells with a high bifaciality which offer a lot of advantages for BIPV applications.

Beschreibung: During the first half of 2015, for the first time, the zonal electricity price in Sicily decreased below than the national wholesale price in Italy. Showing the unique pattern of electricity consumption in Italy's largest region at different time scales, we identify the effectiveness of the impact of renewable power generation on utility-scale in Sicily upon the whole of Italy's electricity market. Increasing the electrification of the energy end uses, as it is happening despite prolonged reduction in electricity demand, will lead to further benefits for power consumers throughout the whole country. Showing the unique pattern of electricity consumption in Italy's largest region, we identify the effectiveness of the impact of renewable power generation on utility-scale in Sicily upon the whole of Italy's electricity market.

Beschreibung: Shading systems improve building energy performance and occupant comfort by controlling glare, natural lighting, and solar gain. Integrating PV (photovoltaics) in shading systems opens new opportunities for BIPV (building integrated photovoltaics) on façades. A key problem of such systems is mutual shading among PV modules as it can lead to electrical mismatch losses and overheating effects. In this work, we present a new modeling framework, which couples parametric 3D with high-resolution electrical modeling of thin-film PV modules to simulate electric energy yield of geometrically complex PV applications. The developed method is able to predict the shading pattern for individual PV modules with high spatio-temporal resolution, which is of great importance for electrical system design. The methodology is applied to evaluate the performance of different dynamic BIPV shading system configurations, as well as its sensitivity to façade orientation and module arrangement. The analysis shows, that there is a trade-off between tracking performance and mutual shading of modules. Distance between modules is a critical parameter influencing the amount of mutual shading and hence limiting solar irradiation and electricity generation of PV shading systems using solar tracking. Planning of module string configuration, PV cell orientation, and location of bypass diodes according to partial shading conditions, reduces electrical mismatch losses and results in significantly higher electricity generation. The integration of parametric 3D and electrical modeling opens new possibilities for PV system design and dynamic control optimization. Though the analysis focuses on BIPV, the method is useful for the planning and operation of solar tracking systems in general. In this work, we present a new modeling framework, which couples parametric 3D with high-resolution electrical modeling of thin-film photovoltaic modules to simulate electric energy yield of geometrically complex photovoltaic applications. The methodology is applied to evaluate the performance of different dynamic BIPV shading system configurations, as well as its sensitivity to façade orientation and module arrangement.

Beschreibung: South Africa's Renewable Energy Independent Power Producer Procurement Program has run four competitive tenders/auctions since 2011, which have seen US$19 billion in private investment, and electricity prices of wind power falling by 46% and solar PV electricity prices by 71%, in nominal terms. Competitive tenders were introduced after an unsuccessful attempt to implement feed-in tariffs. The tenders incorporated standard, nonnegotiable contract documents, including 20-year Power Purchase Agreements and an Implementation Agreement whereby the Government of South Africa back-stops IPP payments by the national utility, Eskom. All of these projects have reached financial close to date and some are already delivering power to the grid. The financing success has been due in part to the requirements for commercial banks to undertake a thorough due diligence of projects prior to bids being offered. The details of the policy package described may be useful for other policy makers in countries developing policies for renewable energy deployment. Auctions have proven to reduce renewable energy costs in South Africa.

Beschreibung: Solar-to-hydrogen conversion based on photocatalytic water splitting is a promising pathway for sustainable hydrogen production. The photocatalytic process requires highly active, inexpensive, and earth-abundant materials as photocatalysts. As a presentative layer-structured transition metal dichalcogenides, molybdenum disulfide (MoS 2 ) is attracting intensive attention due to its unique electro and photo properties. In this article, we comprehensively review the recent research efforts of exploring MoS 2 as a co-catalyst for photocatalytic hydrogen production from water, with emphasis on its combination with CdS, CdSe, graphene, carbon nitride, TiO 2 , and others. It is shown that MoS 2 –semiconductor composites are promising photocatalysts for hydrogen evolution from water under visible light irradiation. This article comprehensively reviews the recent research efforts of exploring MoS 2 as a co-catalyst for photocatalytic hydrogen production from water.

Beschreibung: In the present work, dual-chamber microbial fuel cell (MFC) was constructed, in which anaerobic sludge was used as the inoculum and potassium ferricyanide as the electron acceptor. We have investigated the untapped potential of carbon microspheres modified graphite anode (CGA) fabricated by hydrothermal and calcinations method in the MFCs operation. The results showed that the CGA could be utilized as a novel and efficient MFC anode. The output power of the MFC involved with CGA is approximately 358 mW·m −2 , which is 3.1 times of the counterpart MFC with graphite anode (GA). Furthermore, this MFC showed a 68% chemical oxygen demand (COD) removal rate of the wastewater. Through further analysis, the CGA could improve the specific surface area and enhance the adsorption of microorganism, which could efficiently favor the electron transfer rate between the microorganism and external circuit, resulting in the increase of the electrochemical activity of MFC. The carbon microspheres modified graphite anode (CGA) was successfully prepared. The output power of the MFC with CGA was improved. The CGA can improve the specific surface area and enhance the adsorption of microorganism. The CGA can favor the electron transfer rate in the MFC operation.

Beschreibung: A novel green reaction system of CO 2 –water–isopropanol has been developed for the production of furfural (FF) from xylose. Initially, a simple CO 2 –water system was investigated, and the results showed that the formation of FF from xylose was greatly enhanced. CO 2 at high pressure could increase the acidity of the reaction system, and thus the FF yield was improved. By raising the reaction temperature, the conversion of xylose was remarkably accelerated in the CO 2 –water–isopropanol system, leading to an acceptable conversion rate (94.41%) and FF yield (55.81%). Addition of an appropriate amount of NaCl further increased the yield to 69.20%. Other carbohydrates (arabinose and xylan) were also tested in the same reaction system and modest results were obtained. A novel green reaction system of CO 2 –water–isopropanol was developed for the production of furfural from carbohydrates. Xylose dehydration was greatly enhanced by CO 2 as an acidic catalyst. The system exhibited satisfactory performance and showed promising opportunities for furfural production from carbohydrates.

Beschreibung: The cover image, by Vladimir Švrček et al., is based on the Research Article Stable ultrathin surfactant free surface-engineered silicon nanocrystal solar cells deposited at room temperature , DOI: 10.1002/ese3.165 .

Beschreibung: Over the past few months, China has published its development plans for the 13th Five Year Plan [FYP] period [2016–2020] for energy, and separately for the electricity sector, renewable energy, hydro, wind, solar, and biomass energy. Here, we review these policies, as well as a number of key supporting policy documents that aim at increased renewable energy use in China. Presuming that China will not overshoot its growth targets for wind and PV, annual additions over the 13th FYP period will average 16 GW for wind and 13.5 GW for PV, well below the growth levels seen in recent years. The key to success in China's continued transition to renewable energy, however, does not lie in such capacity additions alone. At least as important will be the efforts at improving grid interconnectedness, flexibility of generating capacity and the grid, market mechanisms that will reduce and spread electricity demand, and better enable renewables to compete, and efforts at increasing the level of consumption of the renewable power generated. We review China's 13th FYP development plans, and a number of key supporting policy documents for [renewable] energy. Growth targets for installations of wind and PV are well below the growth levels seen in recent years. Policy attention is focused more strongly on improved grid flexibility, market mechanisms that promote renewables, and efforts to reduce curtailment.

Beschreibung: Evaluation of available potential and suitable alternative options for various renewable energy sources (RES) requires the explicit consideration of inter-regional disparities and site-specific conditions (e.g., environmental, socio-economic, and resources features) for a larger scale region or country. This paper presents a novel multiregional analytical framework considering inter-regional suitability difference and inter-RES competitiveness at a given location in order to support efficient and sustainable RES spatial planning strategies. A GIS-based multicriteria evaluation technique was used to identify the geospatial potential/appropriate sites for various RES through combination of satellite-derived information, reanalysis data, ground measurements, and statistical data. The composite index (CI) considering location suitability and sustainability of renewable energy technology was then used to compare different RES options, and as a selection criteria to define suitable strategies for each specific region. A real case study concerning the China's eastern coastal 10 provinces of RES planning issue demonstrates the applicability of the proposed approach. The present results illustrate how to coordinate the competing relationships between inter-regions and inter-RES for a given location in the eastern coastal regions of China. This could provide useful insight into plan the long-term RES developing paths and facilitate the determination of optimal energy mix for the other same type area. A novel multregional analytical framework considering inter-regional suitability difference and inter-RES competitiveness at a given location was present in this paper. GIS-based multicriteria evaluation technique and the composite index (CI) were used to identify the geospatial potential/appropriate sites for various RES.

Beschreibung: Enhancing light absorption within thin film amorphous silicon (a-Si) solar cells should lead to higher efficiency. This improvement is typically done using various light trapping techniques such as utilizing textured back reflectors for pronounced light scattering within the cell thus achieving higher absorption. It is believed that embedding metallic nanoparticles (MNPs) inside the structure could increase light scattering. However, embedding MNPs can also cause significant structure defects and pronounced efficiency drop as well – it has been indicated by many experiments that disproved this belief. In search of ways to improve efficiency, we have investigated the impact of MNP's size, and location within the solar cell, in addition to the effect of defects, and doping levels on the overall efficiency. On the basis of our 3D multiphysics (optical-electric) modeling, we developed a design guideline for embedding these MNPs and reducing the impact of defects created in the embedding process. The results of simulations were compared to relevant measured data, and it showed a good agreement. Subsequently, models were used to predict performance, and over 30% improvement in solar cell efficiency (~13% is predicted); which is beyond the state of the art. This was predicted by optimizing the size and location of the MNPs and tailoring the doping levels to have better forward light trapping and absorption. In this research, we did improve the efficiency of thin film amorphous silicon solar cells (~30%) based on applying metallic nanoparticles as plasmon surface in different layers. We discussed the problems like defects and optical loss could happen during fabrication. We achieved a good agreement between the simulation result and measured data.

Beschreibung: The material quality degradation of silicon wafers by metal impurities, various crystal defects as well as light and thermally induced mechanisms is very important for the solar cell performance and has been investigated by various groups. In this paper, the material degradation during epitaxial deposition at high temperatures above 1100°C will be discussed. Annealing experiments in hydrogen atmosphere are done with the laboratory rapid thermal chemical vapor deposition reactor to mimic the thermal process conditions for epitaxial growth of silicon from the gas phase. A general investigation of crystallographic and electronic properties of n- and p-type silicon wafers has been done between 950°C and 1150°C. A detailed sensitivity analysis of process parameters like cooling ramp, peak temperature, duration, and ambient gasses has been conducted. The degradation mechanism by metal impurities has been investigated by using silicon wafers with different diffusion barriers. Besides effective minority carrier lifetime, measurements by quasi steady state photo conductance, etch pit density, Raman spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy measurements have been done. The presented results have been used to improve the deposition process of epitaxial thin-film solar cells, the production of silicon foils with a thickness 〈80  μ m, and the fabrication of epitaxial multi junction solar cells with silicon bottom cell. Effective lifetimes for six different silicon wafers processed for 7 min and 35 min, respectively, at three different temperatures.

Beschreibung: This article introduces a new technology about a rod pumping in the offshore platform according to the demand of offshore heavy oil thermal recovery and the production of stripper well, analyzes the research status of hydraulic pumping unit at home and abroad, and designs a new kind of miniature hydraulic pumping unit with long-stroke, low pumping speed and compact structure to resolve the problem of space limitation. The article also describes the whole structure and the working principle of this pumping unit, determines the choice of stroke and rate of the pumping unit, and establishes mathematical models based on the polished rod loads. A new composite hydraulic cylinder with a special structure was designed by combining the hydraulic cylinder with the energy accumulator. This composite hydraulic cylinder is applied on land, and the model prototype runs smoothly, which indicates that the whole structure design of the pumping unit is reasonable and the control strategy is correct. This article introduces a new technology about rod pumping in offshore platform according to the demand of offshore heavy oil thermal recovery and the production of stripper well, analyzes the research status of hydraulic pumping unit at home and abroad, and designs a new kind of miniature hydraulic pumping unit with long-stroke, low pumping speed and compact structure to resolve the problem of space limitation.

Beschreibung: Spectral response measurements of germanium-based triple-junction solar cells were performed under a variety of light and voltage bias conditions. Two of the three junctions exhibited voltage and light bias-dependent artifacts in their measured responses, complicating the true spectral response of these junctions. To obtain more insight into the observed phenomena, a set of current-voltage measurement combinations were also performed on the solar cells under identical illumination conditions, and the data were used in the context of a diode-based analytical model to calculate and predict the spectral response behavior of each junction as a function of voltage. The analysis revealed that both low shunt resistance and low breakdown voltages in two of the three junctions influenced the measured quantum efficiency of all three junctions. The data and the modeling suggest that combination of current-voltage measurements under various light bias sources can reveal important information about the spectral response behavior in multijunction solar cells. This paper discusses quantum efficiency measurements of a triple junction solar cell where severe measurement artifacts related to low shunt resistance and low breakdown voltage for two of the junctions complicate the behavior of the entire stack. A combination of I–V measurements under three sets of LED lights and modeling the results within the context of a diode-based equivalent circuit model predicts the voltage bias and light bias dependence of the quantum efficiency data relatively well.

Beschreibung: It is well known that the performance of solar cells may significantly suffer from local electric defects. Accordingly, infrared thermography (i.p. lock-in thermography) has been intensely applied to identify such defects as hot spots. As an imaging method, this is a fast way of module characterization. However, imaging leads to a huge amount of data, which needs to be investigated. An automatized image analysis would be a very beneficial tool but has not been suggested so far for lock-in thermography images. In this manuscript, we describe such an automatized analysis of solar cells. We first established a robust algorithm for segmentation (or recognition) for both, the PV-module and the defects (hot spots). With this information, we then calculated a parameter from the IR-images, which could be well correlated with the maximal power ( P mpp ) of the modules. The proposed automatized method serves as a very useful foundation for faster and more thorough analyses of IR-images and stimulates the further development of quality control on solar modules. In this manuscript, we describe an automatized analysis of infrared images of solar cells. We first established a robust algorithm for segmentation (or recognition) for both, the PV-module and the defects (hot spots). With this information, we then calculated a parameter from the IR-images, which could be well correlated with the maximal power ( P mpp ) of the modules.

Beschreibung: We present a scalable technology at room temperature for the fabrication of ultrathin films based on surfactant-free surface-engineered silicon nanocrystals (SiNCs). Environmentally friendly pulsed fsec laser induced surface engineering of SiNCs and vacuum low-angle spray deposition is used to produce ultrathin films. Surface engineering of SiNCs improved stability and dispersibility of SiNCs by allowing thin (30 nm thickness) and exceptionally smooth (mean square roughness corresponds to 0.32 nm) film deposition at room temperature. The quality of the SiNC thin films is confirmed by ultrafast photoluminescence measurements and by applying such films for solar cells. We demonstrate that films produced with this approach yield good and stable devices. The methodology developed here is highly relevant for a very wide range of applications where the formation of high-quality ultrathin films of quantum dots with controllable thickness and smoothness is required. Environmentally friendly pulsed fsec laser induced surface engineering of silicon nanocrystals and vacuum low-angle spray deposition is used to produce stable ultrathin film solar cells.

Beschreibung: Improvement of solar cell efficiency beyond the Shockley–Queisser limit requires introduction of new physical concepts. One such concept is hot carrier solar cell, proposed more than three decades ago and still not impressively demonstrated in experiment. Here we show that hot carrier solar cell may be considered as thermoelectric device based on Seebeck effect. This enables one to describe the operation of hot carrier solar cell in a simple way. We fabricated a prototype of the hot carrier solar cell showing open circuit voltage at room temperature larger than the band gap in the absorber material. Extrapolation of open circuit voltage to absolute zero temperature results in barrier height depending on light intensity, interpreted by splitting of quasi-Fermi levels between the regions of different carrier temperature. Properties of the prototype solar cell may be described by kinetic transport theory as well as from the point of view of the thermoelectric theory. We show that hot carrier solar cell may be considered as thermoelectric device based on Seebeck effect. We fabricated a prototype of the hot carrier solar cell showing open circuit voltage at room temperature larger than the band gap in the absorber material. Properties of the prototype solar cell may be described by kinetic transport theory as well as from the point of view of the thermoelectric theory.

Beschreibung: A power balancing method of distributed generation (DG) and electric vehicle charging is presented for minimizing operation costs of distribution systems with uncertainties, which includes the uncertainties in output power of DG and the randomness of charging power of electric vehicles (EV). A probability model is established for the uncertain characteristics of DG and electric vehicle charging. A multi-state optimization coordination method for DG of renewable energy systems and electric vehicle charging in distribution systems based on quadratic rotation cone programming is presented to minimize the expected generation cost of generators in the main power grid, the expected operation cost of DG systems in distribution systems, and the expected social outage loss. An objective function maximizing the operation efficiency of distribution systems with DGs and EVs is proposed. Using quadratic rotated conic programming, the nonlinear objective function and constraint functions are transformed into a linear form. An IEEE 14-node distribution system is used as a study example to illustrate adaptability of the proposed model and the feasibility of the proposed method. The simulation results show that the proposed method simplifies the original problem of the optimization problem and makes its solution faster, more stable, and better. A power balancing method of distributed generation (DG) and electric vehicle charging is presented for minimizing operation cost of distribution systems with the uncertainties in output power of DG and the randomness of charging power of electric vehicles. A multi-state optimization coordination method for DG of renewable energy systems and electric vehicle charging in distribution systems based on quadratic rotation cone programming is presented to minimize the expected generation cost of generators in the main power grid, the expected operation cost of DG systems in distribution systems, and the expected social outage loss.

Beschreibung: This article describes the method of deriving Global Horizontal Irradiance (GHI) from combining power measurements with static meta data (tilt, orientation, brand/type) of rooftop photovoltaic (PV)-systems. This inverse PV model implements a forward yield model that is based on a modified Orgill and Hollands decomposition model and the Perez transposition model for irradiance. The forward as well as the inverse PV model were validated with DC power measurements of four different mono- and polycrystalline modules combined with weather station data (2 minute resolution data over a period ranging from the 11th of June through the 24th of August 2014). The bias-corrected forward PV model shows a best (r)RMSE of 16.0 W (15.1%) with a (r)MBE of −1.67 W (−1.57%) for one of the polycrystalline modules. The bias-corrected inverse PV model shows a best (r)RMSE of 65.6 Wm −2 15.1% with a (r)MBE of 0.994 Wm −2 (0.229%) for one of the polycrystalline modules. Similar results were obtained for the three other modules. We use modified, inverted versions of existing decomposition and transposition models for determining the global horizontal irradiance (GHI) from measured photovoltaic (PV) power measurements. This enables the use of a network of PV systems as a de facto GHI sensor network.

Beschreibung: This paper focuses on tar conversion on solid oxide fuel cell (SOFC) anodes and its consequences for operation performance and degradation issues. Based on an extensive literature review it discusses the chemical behavior of tar species in typical gas environments/operation conditions at the Nickel anode and describes an experimental investigation methodology. A numerical 1-D discretized cell model is developed that represents global tar conversion kinetics on SOFC anodes based on an Arrhenius power law approach. This permits the determination of the apparent kinetic rate constants based on simple OCV measurements at cells operated on tar-laden gases. The approach is applied and verified with measurement data from literature. Resulting conversion rate constants varied with the investigated tar species (naphthalene, toluene) and the operation temperature (800–900°C) in the range 0.1–1.04 mol/sec/m 2 /bar. The results showed good consistency within varying tar concentration levels and with FID measurement in the off gas of the SOFC anodes. This paper focuses on tar conversion on solid oxide fuel cell (SOFC) anodes and its consequences for operation performance and degradation issues. A numerical 1-D discretized cell model is developed, that permits the determination of the apparent kinetic rate constants of tar conversion based on simple OCV measurements at cells operated on tar-laden gases.

Beschreibung: Solar energy is a clean energy resource, so the large-scale deployment of photovoltaic (PV) power generation is of great significance for achieving carbon emission reductions in the electric power industry. This paper proposes models and methods for evaluation of the low-carbon benefits of grid-connected PV power generation projects. The carbon emission (or emission reduction) characteristics and the economic benefits of PV generation are analyzed using the following four metrics: generation capacity revenue, PV cost, loss efficiency improvement, and reserve capacity cost. The corresponding low-carbon benefit models and economic benefit models are then established. By combining the low-carbon and economic characteristics of photovoltaic power generation, a model is proposed for evaluating the low-carbon comprehensive benefits (LCBs) of photovoltaic power generation and the concept of a carbon emission payback period (CPP) is put forward. Examples with typical operating data from real-world applications are used to verify the validity of the models and methods proposed in this paper. The analysis results show that photovoltaic power generation has great potential in terms of low-carbon comprehensive benefits compared with conventional power generation. This paper proposes the models and methods on evaluation of low-carbon benefits of grid-connected photovoltaic power generation project during its life cycle. It can answer the puzzles of power distribution network engineers in utilities presently that whether developing PV generation is worthy of its cost, and it may be beneficial to boost the PV accessing development into power systems in China.

Beschreibung: A novel integrated liquid absorbent-based CO 2 capture and desalination process is proposed. It is based on the use of a forward osmosis operation replacing the trim cooler in the capture process. This cooler controls the absorption liquid inlet temperature to the absorber. In the forward osmosis operation water is transferred from a saline solution to the absorption liquid. It can be recovered in two ways: via the overhead condenser of the desorber or via an intercooling operation by flashing the absorption liquid under vacuum, followed by condensation of the water vapor produced. In both cases the energy requirement for the water production process is considered negligible as it is part of the energy requirement of the capture process. The amount of produced water and its quality is such that it can be used as makeup for flue gas desulphurization and/or cooling tower makeup. Thus, it can provide a resolution for the increase in specific cooling water requirement as a result of a CO 2 capture retrofit to an existing coal-fired power station. Monoethanolamine and sodium glycinate solutions were evaluated as absorption liquids in this study. Amino acid salt solutions are preferred because of the high osmotic pressure and low vapor pressure, providing the best option for high water quality. Inclusion of a forward osmosis in an amine-based postcombustion CO 2 capture plant integrated in a power plant is able to produce significant amounts of freshwater from seawater. Process modeling and laboratory-based evaluation of commercially available membranes indicate that it can provide a resolution for the increase in specific cooling water requirement as a result of a CO 2 capture retrofit to an existing coal-fired power station.

Beschreibung: We explore degradation pathways within encapsulated CH 3 NH 3 PbI 3- x Cl x perovskite devices based on the inverted architecture: ITO/PEDOT:PSS/CH 3 NH 3 PbI 3- x Cl x /PC 70 BM/LiF/Al. Devices were subjected to more than 670 h of continuous illumination approximating AM1.5, with a Ts80 lifetime of (280 ± 20) hours determined. Devices stored in the dark underwent a similar drop in efficiency over the same time-period. Using external quantum efficiency, time-resolved photoluminescence, X-ray diffraction, scanning electron microscopy and laser beam induced current mapping, we attribute the primary cause of degradation to reactions with residual moisture trapped in the device, resulting in the decomposition of the perovskite. In the following article, we explore degradation pathways of the CH3NH3PbI3-xClx mixed-halide perovskite. By measuring devices stored under either continuous illumination or complete darkness, we are able to attribute the primary cause of degradation to be trapped moisture within the devices.

Beschreibung: As transport sector takes a big share of the whole energy consumption in China, it is crucial to predict its energy demand. To forecast China's transport energy demand, group method of data handling (GMDH) was introduced. The model can help policymakers’ select influential variables and build prediction models automatically. Furthermore, it can reduce the negative impact of the noise in the Chinese statistical data. To produce comparable results, four of the six data sets used in this paper contain the same variables as in previously published research. Artificial neural networks (ANN), GMDH, multiple linear regression (MLR), and support vector machine (SVM) models were trained using fivefold cross-validation. The performance of these models was measured in terms of coefficient of determination and root mean square error. Results showed that GMDH achieved better performance than the other models. Finally, projections were made with two scenarios. Both of the projected results showed that the energy demands peak in certain years and then decrease gradually. This study suggests that GDP is not the essential variable, while urbanization rate is an important variable to forecast the transport energy demand in China. It also suggests that Chinese government needs to prepare for the development and deployment of transport energy. To forecast China's transport energy demand, group method of data handling (GMDH) was introduced. Projections were made with two scenarios. Both of the projected results showed that the energy demands peak in certain years and then decrease gradually.

Beschreibung: An inherent characteristic of high concentrator photovoltaics (HCPV) modules is a tight mechanical tolerance caused by the narrow angular transmission of the optical system, typically below or close to 1°. Misalignments in the modules caused during the assembly process in the production line will degrade not only the electrical but also the angular performance of the module. Moreover, dispersion in the electrical characteristics of the elementary units comprising a module would lead also to power loss. Quality control and data analysis on the production line is of great significance for adjusting the production line and preserving the angular tolerance and the electrical performance. This is particularly critical during the set-up and tuning of an automated production line. This paper presents the results of a pilot production line for HCPV modules carried out within the European funded ECOSOLE project. Several quality controls were established, which are the binning of the photovoltaic receivers, the measurement of misalignments among the elementary units within every module, and the indoor electrical characterization of the modules. Collected experimental data during the tuning phase of the pilot line were used to validate a module performance model based on production parameters. Monte Carlo method is lately applied to the model to assess the influence of production defects of diverse nature and the adequacy of quality controls, in several manufacturing scenarios beyond the specific constrains of the ECOSOLE experience. Collected experimental data during the quality control (e.g., the binning of the photovoltaic receivers, the measurement of misalignments among the elementary units within every module, and the indoor electrical characterization of the modules) of a production line for high concentrator photovoltaics (CPV) were used to validate a developed module performance model based on production parameters. Monte Carlo method is lately applied to the model to assess the influence of production defects of diverse nature, in several manufacturing scenarios.

Beschreibung: Reservoir modeling and simulation have become important elements of reservoir management. However, high computational cost associated with the use of numerical simulators make them cumbersome, especially with large-scale simulation models and complex oil recovery processes like steam-assisted gravity drainage (SAGD). A data-driven proxy model can be an alternative to predict SAGD recovery performance in real heterogeneous reservoirs, however, computationally efficient proxy model which can handle large number of input variables while providing accurate results requires further attention. In this work, a proxy model based on polynomial chaos expansion (PCE) is developed to predict the production parameters of SAGD reservoir. Karhunen–Loeve (KL) expansion is used to parameterize input variables in terms of random variables using which PCE further calculates production data for the given reservoir. To calculate coefficients of PCE, probabilistic collocation method is used. To demonstrate the functionality of the proposed approach, case study of a SAGD reservoir located in northern Alberta, Canada is shown in this paper. Various production parameters predicted from the PCE proxy model are compared with the actual simulation results and other proxy models based on radial basis functions (RBF) and artificial neural networks (ANN). From the results, it can be said that PCE proxy model demonstrates good agreement with full-physics simulation results and outperforms other proxy methods in terms of training data required and accuracy of predictions. In addition, since proposed PCE proxy model greatly reduces the computing cost, it potentially paves the way for expedited and frequent execution of uncertainty quantification, assisted history matching, and optimization workflows, resulting into efficient reservoir management and significant monetary benefits. Polynomial Chaos theory-based proxy model is proposed for heterogeneous SAGD reservoirs. The application of the proposed model is explored using real-field SAGD case study. Computational requirement for the development of the proxy model is emphasized. Results demonstrated a significant reduction in computational time and cost. Proposed model outperformed artificial intelligence-based data-driven proxy models.

Beschreibung: In this review, an attempt has been made to analyze passive solar heating and cooling concepts along with their effects on performance of a building's thermal management. The concepts of Trombe wall, solarium, evaporative cooling, ventilation, radiative cooling, wind tower, earth air heat exchanger, roof pond, solar shading for buildings, and building-integrated photovoltaic thermal (BiPVT) systems are extensively covered in this review. Comparison of results by various heating and cooling concepts has been made. It has been observed that direct heating through double-glazed window saves maximum conventional fuel for thermal heating during winter months. Further, an evaporative cooling is one of the best cooling concepts which is economical too in summer period. Review of various passive heating concepts, passive cooling concepts, and passive heating and cooling concepts along with their impact on thermal comfort of the occupants.

Beschreibung: Cone-shaped semiconductor silicon nanowires (CS-Si-NWs) grown in vapor liquid solid mode are promising for the fabrication of low-cost high-performance solar cells because of their low processing cost and lower use of Si materials, as compared to planar devices. In this article, the effect of injected charge carriers on the refractive indices and extinction coefficient values in a cone-shaped pin Si NW (CS-pin-Si NW) were considered. Then, the influence of top diameters and periods on the optical absorption was investigated using a finite difference time-domain (FDTD) modeling method. The absorption increased when we decreased the period from 300 to 150 nm for a light wave with a wavelength of 700 nm. However, in the case of incident light at a wavelength of 500 nm, the absorption significantly increased by up to 100% and was found to be independent of the period. On the other hand, we varied the period and the top diameter of the NWs with a fixed bottom diameter. In this case, we found that the period did not significantly affect the absorption value. A high value of the short circuit current density of 19.5 mA/cm 2 was found in the case of NWs with a top diameter of 110 nm and a period of 150 nm. Combined with the analysis of the ultimate photocurrents, an optimum geometric structure with a top diameter of 70 nm and a period of 150 nm for a CS-pin-Si NW-based top cell for tandem solar cell applications was proposed. A cone-shaped pin Si nanowire solar cell is modeled using a finite difference time-domain modeling method. An optimum geometric structure with a top diameter of 70 nm and a period of 150 nm for a CS-pin-Si NW based top cell for tandem solar cell applications was proposed.

Beschreibung: The energy group of SCI (Society of Chemical Industry) was host for an event on 28th March 2017 at SCI Headquarters in London (UK) with a meeting on the important topic of the energy trilemma (sustainable, affordable and secure supply of energy). Alexandra Carrick gives an overview of the event.

Beschreibung: We describe a spectrum splitting solar module design approach using ensembles of 2–20 subcells with bandgaps optimized for the AM1.5D spectrum. Device physics calculations and experimental data determine radiative efficiency parameters for III-V compound semiconductor subcells and enable modification of conventional detailed balance calculations to predict module efficiency while retaining computational speed for a wide search of the design space. Accounting for nonideal absorption and recombination rates due to realistic material imperfections allows us to identify the minimum subcell quantity, quality, electrical connection configuration, and concentration required for 50% module efficiency with realistic optical losses and modeled contact resistance losses. We predict a module efficiency of 50% or greater will be possible with 7–10 electrically independent subcells in a spectral splitting optic at 300–500 suns concentration, assuming a 90% optical efficiency and 98% electrical efficiency, provided the subcells can achieve an average external radiative efficiency of 3–5% and a short circuit current that is at least 90% of the ideal. In examining spectrum splitting solar cells with both series-connected and electrically independent subcells, we identify a new design trade-off independent of the challenges of fabricating optimal bandgap combinations. Series-connected ensembles, having a single set of electrical contacts, are less sensitive to lumped series resistance losses than ensembles where each subcells are contacted independently. By contrast, ensembles with electrically independent subcells can achieve lower radiative losses when the subcells are designed for good optical confinement. Distributing electrically independent subcells in a concentrating receiver module allows flexibility in subcell selection and fabrication, and can achieve ultra-high efficiency with conventional III-V cell technology. Spectrum splitting can enable ultra-high-efficiency photovoltaic modules with realistic cell quality, optical and electrical losses. This analysis identifies minimum requirements for number of subcells and cell quality, electrical configuration and concentration to achieve 50% efficiency.

Beschreibung: China is the world leader in several areas of clean energy, but not in Concentrating Solar Power (CSP). Our analysis provides an interesting viewpoint to China's possible role in helping with the market breakthrough of CSP. We present a short overview of the state-of-the-art of CSP including the status in China. A blueprint for China's CSP development is elaborated based on China's 13th 5-year program, but also on China's previous success factors in PV and wind power. The results of this study suggest that China could play a more prominent global role in CSP, but this would require stronger efforts in several areas ranging from innovation to policies. Concentrating Solar Power is a potential clean energy option for China. CSP is still an underused technology in China. China may play a role in the global breakthrough of CSP.

Beschreibung: The cover image, by Allison Tolbert and Arthur J. Ragauskas, is based on the Review Advances in understanding the surface chemistry of lignocellulosic biomass via time-of-flight secondary ion mass spectrometry , DOI: 10.1002/ese3.144 . The authors would like to acknowledge the following image contributors: Robert Davies (Renewable Bioproducts Institute, Georgia Tech) greatly assisted with the image formatting, Wellington Muchero and Jay Chen (Oak Ridge National Laboratory) and Bruce Arey (Environmental Molecular Science Laboratory) provided the Helium Ion Microscope image of Populus cell walls, and Chang Geun Yoo (Oak Ridge National Laboratory) assisted with the creative design.

Beschreibung: N-type silicon-based solar cells are currently being used for achieving high efficiency. However, most of the photovoltaic modules already constructed are based on p-type silicon solar cells, and there are few studies on potential induced degradation (PID) in n-type solar cells. In this study, we investigated PID in n-type silicon solar cells with a front p+ emitter. Further, the PID characteristics of n-type solar cells are compared with those of p-type solar cells. The electrical properties of PID in solar cells are observed with the light I-V, quantum efficiency (QE), and electroluminescence (EL). The possible causes for the change in the external quantum efficiency (EQE) after PID are interpreted using PC1D and are discussed by comparing the experimental results with the simulation results. The electrical properties of the PID of n-type silicon solar cells with a front p+ emitter are studied. Also, the possible causes for the PID are discussed, comparing simulated data with experimental result.

Beschreibung: An Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFC) system fed by not conventional fuels such as biogas can produce electric energy with high conversion efficiency and thermal energy. Inside the energy system, the methane in the biogas is mixed with steam, and then it is converted into carbon monoxide, hydrogen and carbon dioxide through steam reforming and water gas shift chemical reactions in an indirect internal reformer (IIR) mostly and in the SOFC anode minimally. The chemical energy of the electro-oxidation of hydrogen and carbon monoxide produced is directly converted into electric energy in the fuel cell anode. A part of the anode exhaust gas can be recirculated at the IIR inlet and the percentage of this recirculated anode exhaust gas together to the fuel utilization factor influence the performances (electric and thermal powers and efficiencies, primary energy saving and first law efficiency) of the SOFC system in a cogenerative arrangement. Through the simulation model of an IT-SOFC system fed by biogas in cogenerative arrangement, which was formulated ad hoc and implemented in a Matlab environment, the influence of the above-mentioned variables on the IT-SOFC system performances was evaluated. The verification of carbon formation at the anode was made. Intermediate Temperature IIR-Solid Oxide Fuel Cell (IT IIR-SOFC) fed by biogas is modeled. IT IIR-SOFC system fed by biogas in cogenerative arrangement is analyzed. Biogas conversion to H 2 is in Indirect Internal Reformer mostly and in anode minimally.

Beschreibung: Conceptual design using multi-bed series reactors consisting of catalysts and adsorbent beds was performed for a new SF 6 abatement and utilization technology free of toxic chemicals to reduce SF 6 emissions and produce valuable products like CaF 2 and CaSO 4 simultaneously. With process simulation studies using Aspen HYSYS ® , comparative studies for a single-bed reactor (SR-1), a two-bed series reactor (SR-2), and a three-bed series reactor (SR-3) revealed that more CaF 2 and CaSO 4 were produced in multi-bed series reactors compared to a SR-1 (SR-3 〉 SR-2 〉 SR-1) possibly due to sorption-enhanced hydrolysis. In addition, lower operating temperatures were observed in multi-bed series reactors (T SR 1  〉 T SR 2  〉 T SR 3 ) showing the positive effect of using multi-bed series reactors for a simultaneous SF 6 abatement and utilization technology. Conceptual design using multi-bed series reactors consisting of catalysts and adsorbent beds was performed for a new SF 6 abatement and utilization technology free of toxic chemicals to reduce SF 6 emissions and produce valuable products like CaF 2 and CaSO 4 simultaneously using Aspen HYSYS ® .

Beschreibung: Cassava residue is the solid waste generated from the production of tapioca starch and has considerable reuse value. In this study, cassava residue was examined as a hydrolysate for ethanol production, and the effects of different liquid phase oxygen transfer coefficients ( k L α ) on the production of ethanol from cassava residue hydrolysates were studied. Based on analyses of dissolved oxygen and a set of optimal experimental schemes, dynamic models of cell growth and product synthesis were optimized, using MATLAB. When k L α was 85, fermentation was optimal; the ethanol titer reached 23.14 g L −1 at 72 h and cell growth reached 6.23 g L −1 at 96 h. Additionally, experiments were performed according to the dissolved oxygen curve obtained under these conditions. The resulting ethanol titer was 24.43 g L −1 (72 h) and the cell mass was 6.45 g L −1 (96 h). This paper considered the liquid vapor oxygen transfer coefficient and dissolved oxygen to simulate and empirically estimate ethanol production, and the fermentation kinetics was performed.

Beschreibung: A novel method is developed to realize a III-V/Si dual-junction photovoltaic cell by combining epitaxial lift-off (ELO) and print-transfer-assisted bonding methods. The adoption of ELO enables III-V wafers to be recycled and reused, which can further lower the cost of III-V/Si photovoltaic panels. For demonstration, high crystal quality, micrometer-thick, GaAs/AlGaAs/GaAs films are lifted off, transferred, and directly bonded onto Si wafer without the use of any adhesive or bonding agents. The bonding interface is optically transparent and conductive both thermally and electrically. Prototype AlGaAs/Si dual-junction tandem solar cells have been fabricated and exhibit decent performance. A novel method is developed to realize an III-V/Si multijunction photovoltaic device by combining the epitaxial lift-off (ELO) and print-transfer-assisted bonding methods. The adoption of ELO enables III-V wafers to be recycled and reused, which is promising to further lower the cost of III-V/Si photovoltaic panels.

Beschreibung: The All India Survey of Photovoltaic Module Reliability 2014 is an enhanced version of the survey conducted in the previous year, with detailed characterization of PV modules including current-voltage, infrared and electroluminescence imaging, visual inspection, insulation resistance test and interconnect breakage test. More than a thousand modules were inspected in the field and the main results of the survey are presented in this paper. The average P max degradation rate for the so-called ‘good’ modules (Group X) is 1.33%/year which is higher than that commonly projected by manufacturers, and widely employed in financial calculations. Modules falling in the ‘not-so-good’ category (Group Y) show even higher degradation rates, and it is at least partly due to higher number of micro-cracks in the modules, and increased degradation of the packaging materials like encapsulant, backsheet, etc. Modules in ‘Hot’ climates degrade faster than modules in the ‘Non-Hot’ climates. Degradation in fill factor is the primary cause for performance degradation in the young modules (ages 〈5 years), whereas short-circuit current degradation is the main contributor to power degradation in the older modules. Small installations (〈100 kW p capacity) show higher degradation than large systems, which may be partly due to lack of proper due diligence by the owner at the time of procurement and installation. All India Survey of Photovoltaic Module Reliability was conducted in 2014, with detailed characterization of PV modules. The average degradation rate for modules from good sites is the highest in the warm and humid zone, closely followed by the hot and dry zone and the composite zone, while it is lowest in the cold and sunny zone. The results which have emerged from this survey of module reliability provide useful indicators for future deployment in India.

Beschreibung: Due to numerous hazardous chemicals to handle, the process plant industry has a higher risk of fire, explosion, and toxic release than other industries. Reviewing the accidents at process plants in the past, it is clear that fire accidents occur with the highest frequency, leading this study to consider accidental fire scenarios at process plants. For the scenario of an incident, a jet fire involving a massive amount of hydrogen gas to be processed or delivered at the process plant has been selected. The analysis of incident outcome resulting from the hydrogen jet fire has been implemented through the computational fluid dynamics simulation methodology Kameleon FireEx. Based on the outcome of this simulation, the consequences of a jet fire with high temperature and heat radiation are analyzed and evaluated. In addition, the results from Phast ver. 7.11 simulation for the same scenario are presented for comparison and further validation. A new approach for accidental large-scale jet fire is described in the paper. For process plants dealing with hydrogen, the hazard from jet fire is critical to prevent second accident. Using CFD, more accurate predictions are performed for heat radiations out of the process with high pressure hydrogen.

Beschreibung: The low energy efficiency is the source of the large energy consumption issue and the rapid growth of energy demand in the manufacturing industry sector in Indonesia. The driving forces behind the low energy efficiency situation in this sector are both economic and efficiency factors. The objective of this study is to generate the map of the energy flow in the manufacturing industry sector to investigate the energy utilization in the industrial process. The data sample that represents 80% of energy consumption in the manufacturing sector is used to generate this map. The generated map shows the heating system is the largest energy consumer among all energy equipment and as the primary source of the energy losses. Additionally, we found the industry groups such as sugar, cement, pulp and paper, and textile use enormous amounts of energy as their source for the heating system; meanwhile, the industries such as basic chemical, metal, and textile are the largest electricity consumers for their motor-driven machinery. The energy flow analysis together with the comparison of the Specific Energy Consumption shows the areas that should be the focus for further energy conservation measures. Recommended measures are also discussed. The objective of this study is to generate the map of the energy flow in the manufacturing industry sector to investigate the impact of the energy utilization on the energy efficiency factor in the industrial process. The generated maps show most of the energy used by the industrial heating system, while the main source of energy losses comes from the heating process and the on-site power generation. We established that the industry groups labeled as sugar, cement, pulp and paper, and textile use enormous amounts of energy as their source for heating; meanwhile, the industries labeled as basic chemical, metal, and textile are the largest electricity consumers to start their motor-driven machinery. The energy flow analysis together with the comparison of Specific Energy Consumption shows that the above-mentioned areas should be the focus for further energy conservation measures.

Beschreibung: Overcoming the natural recalcitrance of lignocellulosic biomass is necessary in order to efficiently convert biomass into biofuels or biomaterials and many times this requires some type of chemical pretreatment and/or biological treatment. While bulk chemical analysis is the traditional method of determining the impact a treatment has on biomass, the chemistry on the surface of the sample can differ from the bulk chemistry. Specifically, enzymes and microorganisms bind to the surface of the biomass and their efficiency could be greatly impacted by the chemistry of the surface. Therefore, it is important to study and understand the chemistry of the biomass at the surface. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a powerful tool that can spectrally and spatially analyze the surface chemistry of a sample. This review discusses the advances in understanding lignocellulosic biomass surface chemistry using the ToF-SIMS by addressing the instrument parameters, biomass sample preparation, and characteristic lignocellulosic ion fragmentation peaks along with their typical location in the plant cell wall. The use of the ToF-SIMS in detecting chemical changes due to chemical pretreatments, microbial treatments, and physical or genetic modifications is discussed along with possible future applications of the instrument in lignocellulosic biomass studies. Understanding the surface chemistry of lignocellulosic biomass through ToF-SIMS spectra and images. Summary of chemical, biological, and genetic modified biomass surface chemistry. Overview of different sample preparation techniques and how to analyze ToF-SIMS spectra in relation to key lignocellulosic biopolymers.

Beschreibung: Sequestrating CO 2 in deep saline aquifers is maybe the most effective option to mitigate CO 2 emission. The storage capacity of CO 2 is the key factor for site selection before a project is carried out. Most of the existing methods are for assessment of CO 2 sequestered by stratigraphic and structural trapping, as well as residual trapping and solubility trapping. In this study, we used a new method that considers CO 2 consumption through geochemical reactions with minerals of reservoir rocks, mainly sandstones. Contribution of storage capacity from carbonate mineral mainly refers to calcite is excluded. That is because lifetime of calcite (the whole time from reaction starting to calcite running out) is very short contrast with geological time-scale or it is a temporary trapping. The geochemical reactions between CO 2 and feldspar minerals with thousand-year lifetime are regarded as the permanent methods for trapping CO 2 . CO 2 consumptions by K-feldspar, albite, and anorthite are assessed with volume method based on corresponding geochemical reactions. Storage efficiency factor is also considered as one of the most important parameters in the reaction formula and it depends on specific surface area of minerals contacting with formation water and kinetics of precipitation and dissolution of minerals. We assessed the CO 2 storage capacity of mineral trapping in Baokang sedimentary system, south Songliao Basin through the detailed analysis of geological data in this area. The calculated results show the total CO 2 storage capacity of mineral trapping of the study area is 457.5–5114.5 Mt and the corresponding storage efficiency factor is 1%. The CO 2 consumed by albite makes up more than 60% of the total storage capacity and it is about 30% for anorthite. A new method is proposed which considers CO 2 consumption through geochemical reactions per unit of reservoir rock minerals and it mainly refers to sandstone reservoir. Contribution of storage capacity from carbonate minerals, including calcite and dolomite are excluded because lifetime of calcite is short compared with the geological timeframe and it is temporary trapping.

Beschreibung: The world conference (Conference of the Parties (COP23)) under the UN Framework Convention on Climate Change took place in Bonn (Germany) from 6 to 17 November. Speakers at the meeting stressed the severity of the threat from global warming and the urgent need to act but what commitments came out of the COP23 meeting? Alexandra Carrick gives a short summary of the meeting and some of the energy outcomes of the conference.

Beschreibung: This paper presents the main experiences gained and conclusions drawn from the demonstration of a first-of-its-kind wood-based biomethane production plant (20-MW capacity, 150 dry tonnes of biomass/day) and 10 years of operation of the 2–4-MW (10–20 dry tonnes of biomass/day) research gasifier at Chalmers University of Technology in Sweden. Based on the experience gained, an elaborated outline for commercialization of the technology for a wide spectrum of applications and end products is defined. The main findings are related to the use of biomass ash constituents as a catalyst for the process and the application of coated heat exchangers, such that regular fluidized bed boilers can be retrofitted to become biomass gasifiers. Among the recirculation of the ash streams within the process, presence of the alkali salt in the system is identified as highly important for control of the tar species. Combined with new insights on fuel feeding and reactor design, these two major findings form the basis for a comprehensive process layout that can support a gradual transformation of existing boilers in district heating networks and in pulp, paper and saw mills, and it facilitates the exploitation of existing oil refineries and petrochemical plants for large-scale production of renewable fuels, chemicals, and materials from biomass and wastes. The potential for electrification of those process layouts are also discussed. The commercialization route represents an example of how biomass conversion develops and integrates with existing industrial and energy infrastructures to form highly effective systems that deliver a wide range of end products. Illustrating the potential, the existing fluidized bed boilers in Sweden alone represent a jet fuel production capacity that corresponds to 10% of current global consumption. The article presents a summary of experiences and conclusions drawn from comprehensive work on a first-of-its-kind wood-based biomethane production plant and 10 years of operation of the 2–4-MW research gasifier at Chalmers University of Technology in Sweden. We highlight key issues and breakthroughs that led to the successful operation of the gasification-based plant of GoBiGas. Based on this valuable and unique experience, we give an outline for the commercialization of the technology for a wide range of applications and end-products.

Beschreibung: A new model for predicting the specific chemical exergy of municipal solid waste (MSW) is presented; the model is based on the content of carbon, hydrogen, oxygen, nitrogen, sulfur, and chlorine on a dry ash-free basis (daf). The proposed model was obtained from estimations of the higher heating value (HHV) and standard entropy of MSW using statistical analysis. The ultimate analysis of 56 different parts of MSW was used for the derivation of the HHV expression. In addition, 30 extra parts were used for validation. One hundred and seventeen relevant organic substances that represented the main constituents in MSW were used for derivation of the standard entropy of solid waste. The substances were divided into different waste fractions, and the standard entropies of each waste fraction and for the complete mixture were calculated. The specific chemical exergy of inorganic matter in the waste was also investigated by considering the inorganic compounds in the ash. However, as a result of the extremely low value calculated, the exergy of inorganic matter was ignored. The results obtained from the HHV model show a good correlation with the measured values and are comparable with other recent and previous models. The correlation of the standard entropy of the complete waste mixture is less accurate than the correlations of each individual waste fraction. However, the correlations give similar results for the specific chemical exergy, indicating that HHV has a greater impact when estimating the specific exergy of solid waste than entropy. A model containing C, H, O, N, S, and Cl from the elemental compositions of waste for predicting the specific chemical exergy of municipal solid waste (MSW) on a dry ash-free basis is developed. The proposed model was obtained from estimations of the higher heating value and standard entropy of MSW using statistical analysis. The results obtained demonstrate that the specific chemical exergy is always slightly higher than the highest heating value, indicating the validity and accuracy of the model.

Beschreibung: In order to effectively utilize the steam superheat of ultra-supercritical power plants, a regenerative turbine (RT) system was proposed. In the RT system, a portion of the high-pressure turbine exhaust steam is sent to an extra turbine termed as RT, and the extracted steam of several regenerative heaters (RHs) would be extracted from the RT instead of the intermediate-pressure turbine. The superheat degree of related extracted steam would decrease and the exergy destruction of the heat transfer process in RHs would be reduced. Thermodynamic and economic analyses of the RT system in a typical 1000 MW power plant were carried out. The results showed that the heat consumption rate would be reduced as compared to the conventional configuration. When the RT isentropic efficiency is set to 85%, the heat consumption rate of the RT system could decrease by 46.9 kJ/kWh as compared to that of the reference system without RT under design condition. The heat consumption rate decrement will be greater with higher RT isentropic efficiency. Meanwhile, thermodynamic analysis of the RT system under off-design condition showed that the energy saving effect of the RT system would be decreased when the design conditions are no longer met. The exergy analysis showed that the total exergy destruction decrement of related RHs in the RT system decreases as the load drops down. Moreover, the economic analysis revealed that the net economic benefit of the RT system could reach 0.57 M$ per year, and would perform economically within a wide range fluctuations of power market conditions. A regenerative turbine (RT) system was proposed to use steam superheat. The RT system exhibited a more preferable performance as the power load increased. The RT system was economic in a wide range fluctuations of power market conditions.

Beschreibung: The cement production process is energy intensive both in terms of the thermal energy (firing the kiln, drying and De carbonation) and electrical energy for driving the numerous drives within the process line. The average specific power consumption of the case study plant was 111 kWh/ton of cement with an average peak demand of 9.7 MW. The high cost of electric power at 0.14 USD/kWh results in very high cost of production that significantly lowers the company's profit margin and limits its competitive advantage. The generation of electrical power from waste heat recovery would reduce the electricity power bill through partially substituting the power procured from the national grid. This research evaluated the potential that the plant has for generating electrical power from the hot waste gases vented into the atmosphere and it was found that the plant has the potential to generate 3.4 MWh of electrical power. This results to a net potential to generate 2.89 MWh of electrical power after factoring in the auxiliary power consumption by Waste heat recovery plant system at 15%. This ultimately gave a reduction of 33% in the electricity power bill of the case study plant. The paper recommends the installation of a steam rankine cycle for the power generating plant. In this work the authors designed the steam boilers for the waste heat recovery plant for conversion of thermal energy to electrical energy, selected a commercial steam turbine and evaluated its economic feasibility and established that the designed plant would have a simple payback period of 2.7 years. Cement production is an energy intensive process in terms of electrical and thermal energy. However, nearly half of the energy input is lost as waste gases into the atmosphere and this research work sought to recover this wasted thermal energy through conversion into electrical energy and utilize it in running the plant. This has the potential to reduce the electrical power bill by 33% which is key in enhancing the competitive advantage of the case study plant.

Beschreibung: In this paper, a tower solar collector-aided coal-fired power generation (TSCACPG) system is proposed and studied in order to save the fossil energy and protect the environment. The integration scheme of tower solar collector and conventional coal-fired power plant is proposed. Based on the simulation platform TRNSYS, the TSCACPG system model is established and the dynamic performance of the TSCACPG system with the operating mode of coal saving is studied. The TSCACPG system performances of 1 day and 1 year are all discussed by using the DNI data of typical year in Chinese typical city of Dunhuang. Then, the sensitivity analysis of the TSCACPG system is carried out by changing the heliostat field scale (the size of the molten salt tower also changes accordingly). The annual performance of the TSCACPG system is also acquired. In consideration of the economic costs, the heliostat field area with the maximum annual solar-to-electric efficiency is selected as the optimal value. The results show that, for the case studied, the optimal heliostat field area is 101,400 m 2 , and the maximum annual solar-to-electric efficiency is 16.74%. And under the optimal situation, the standard coal consumption rate of the original coal-fired power plant is reduced from 301.5 g/kWh to 294.5 g/kWh. In this paper, a tower solar collector-aided coal-fired power generation (TSCACPG) system is proposed and studied in order to save the fossil energy and protect the environment. The integration scheme of tower solar collector and conventional coal-fired power plant is proposed. The TSCACPG system performances of 1 day and 1 year are all discussed by using the DNI data of typical year in Chinese typical city of Dunhuang.

Beschreibung: The main influencing parameter on the efficiency of adsorptive thermochemical energy storage is the efficiency of the desorption process, which is influenced by the process conditions, for example, desorption time and desorption temperature, and the working pair (adsorbent–adsorbate). Due to constrained process requirements, for example, hours of sun shine and low desorption temperatures available from a flat plate solar collector (333–373 K), the only possibility to increase the efficiency is to change the working pair. The reference working pair water–zeolite 13X needs high desorption temperatures of 500 K and high heat inputs per mass adsorbent (1080 kJ kg −1 ) in the desorption process to reach the maximum efficiency of 79 % and maximum energy density of 844 kJ kg −1 . Therefore, the goal is to reach efficiencies in the same range as the maximum efficiency of water–zeolite 13X for desorption temperatures lower than 500 K with the usage of different adsorbates. Four systems of alcohol as adsorbate on activated carbon are compared with the reference working pair. The usage of alcohols on activated carbon allows for highly efficient adsorptive storage even at low desorption temperatures between 360 and 450 K. The maximum efficiency is shifted to higher desorption temperatures with increasing carbon chain length of the alcohol. At low desorption temperatures, the energy density and efficiency of methanol, ethanol, and propanol are higher than the energy density of the reference system. Hence, the alcohol systems on activated carbon are viable alternative approaches for regulating these process parameters. A systematic way to achieve high efficiencies in thermochemical energy storage by adsorption at different charging conditions is presented. This is done by changing the chain length of the homologous series of alcohols. With rising chain length of the alcohol, the ideal charging temperature rises to higher temperatures.