L. Zhu, S. Yin, Q. Yin, H. Wang, S. Wang, S. Myong, J. Park, S. Kwon
Energy Science & Engineering (2017).
Abstract
Biochar (BC), a by-product from the fast pyrolysis of rice husk, was activated by chemical and physical process. The activated biochar (ABC) showed graphite-like morphology and had a large amount of random pores with BET surface area of 1058 m2/g. The biochar properties observed by further characterization revealed its feasibility to be used as a catalyst support. Syngas methanation as a probe reaction was utilized to characterize biochar supported Ru catalyst. The catalytic performance of the Ru/ABC catalyst in methanation was superior or comparable to the conventional activated carbon (AC) supported Ru catalyst. A high CH4 selectivity of 98% and a CO conversion of 100% were obtained under the proper reaction conditions over the Ru/ABC catalyst.
Abstract Biochar (BC), a by-product from the fast pyrolysis of rice husk, was activated by chemical and physical process. The activated biochar (ABC) showed graphite-like morphology [...]
We investigate the stabilized performance of encapsulated hydrogenated amorphous silicon photovoltaic modules depending on the deposition speed. The module products are degraded differently depending on the light-soaking environment. The modules deposited at a high speed demonstrate significant degradation in an outdoor exposure test, despite moderate degradation during indoor light soaking. However, the modules deposited at a low speed show a relatively more stable performance against the outdoor exposure test. Notably, some modules show the trend that a higher initial performance stimulates a higher light-induced degradation, leading to a lower performance in the outdoor environment.
Abstract We investigate the stabilized performance of encapsulated hydrogenated amorphous silicon photovoltaic modules depending on the deposition speed. The module products are degraded [...]
H. Yanti, R. Wikandari, R. Millati, C. Niklasson, M. Taherzadeh
Energy Science & Engineering (2017).
Abstract
Esters are major flavor compounds in fruits, which are produced in high volume. The widespread availability of these compounds in nature attracts interest on their behavior in anaerobic digestion in waste and wastewater treatments. The aim of this work was to study the effects of various esters at different concentrations in anaerobic digestion followed by determination of their minimum inhibitory concentration (MIC), and to study the effect of chain length of functional group and alkyl chain of ester on methane production. Addition of methyl butanoate, ethyl butanoate, ethyl hexanoate, and hexyl acetate at concentration up to 5 g L−1 increased methane production, while their higher concentrations inhibited the digestion process. The MIC values for these esters were between 5 and 20 g L−1. Except hexyl acetate, the esters at concentration 5 g L−1 could act as sole carbon source during digestion. For ethyl esters, increasing number of carbon in functional group decreased methane production. For acetate esters, alkyl chain longer than butyl inhibited methane production. Effect of ester on methane production is concentration-dependent.
Abstract Esters are major flavor compounds in fruits, which are produced in high volume. The widespread availability of these compounds in nature attracts interest on their behavior [...]
Domestic natural gas production has increased markedly in the United States, and now compressed natural gas (CNG) has the potential to become a cleaner and less expensive energy source than diesel fuel for use in the public transportation sector, especially for city bus fleets. This paper provides an economic analysis of possible CNG conversion for Lafayette, IN CityBus Corporation. It uses benefit–cost analysis to compare the total cost of three potential options for bus replacement: standard diesel, hybrid diesel-electric, and CNG. A spreadsheet model was used to estimate the total cost of these three fleet options over a 15-year project horizon. Results suggest that the CNG option has the lowest net present value (NPV) cost, and that cost savings would be larger if the corporation could obtain a grant for the CNG fueling station or if the project life span could expand to 20 years. From the environmental perspective, the CNG option would reduce greenhouse gas and particulate emissions particularly in comparison with the diesel option. Monte Carlo simulation was used to examine the inherent riskiness of the three fleet options. CNG is always lower cost than hybrid diesel-electric. Depending on assumptions regarding the underlying price distributions, the CNG option has a 51–100% chance of being lower cost than the standard diesel option.
Abstract Domestic natural gas production has increased markedly in the United States, and now compressed natural gas (CNG) has the potential to become a cleaner and less expensive [...]
Load forecasts of short lead times ranging from an hour to a day ahead are essential for improving the economic efficiency and reliability of power systems. This paper proposes a hybrid model based on the wavelet transform (WT) and the weighted nearest neighbor (WNN) techniques to predict the day ahead electrical load. The WT is used to decompose the load series into deterministic series and fluctuation series that reflect the changing dynamics of data. The two subseries are then separately forecast using appropriately fitted WNN models. The final forecast is obtained by composing the predicted results of each subseries. The hourly electrical load of California and Spanish energy markets are taken as experimental data and the mean absolute percentage error (MAPE), Weekly MAPE (WMAPE) and Monthly MAPE (MMAPE) are computed to evaluate the forecasting performance of the next-day load forecasts. The forecasting efficiency of the proposed model is evaluated using db2, db4, db5 and bior 3.1 wavelets. The results demonstrate the forecasting accuracy of the proposed hybrid model.
Abstract Load forecasts of short lead times ranging from an hour to a day ahead are essential for improving the economic efficiency and reliability of power systems. This paper proposes [...]
Recent achievements in the proactive turbine control, based on the upwind speed measurements, are described in a unified framework (as an extension of the tutorial [1]), that in turn represents a systematic view of the control activity carried out within the Swedish Wind Power Technology Center (SWPTC). A new turbine control problem statement with constraints on blade loads is reviewed. This problem statement allows the design of a new class of simultaneous speed and pitch control strategies based on the preview measurements and look-ahead calculations. A generation of a piecewise constant desired pitch angle profile which is calculated using the turbine load prediction is reviewed in this article as one of the most promising approaches. This in turn allows the reduction of the pitch actuation and the design of the collective pitch control strategy with the maximum possible actuation rate. Two turbine speed control strategies based on one-mass and two-mass models of the drivetrain are also described in this article. The strategies are compared to the existing drivetrain controller. Moreover, postprocessing technique that can be used for estimation of the turbine parameters with improved performance is also discussed. Postprocessing-based estimation of the turbine inertia moment is given as an example. All the results are illustrated by simulations with a wind speed record from the Hönö turbine, located outside of Gothenburg, Sweden.
Abstract Recent achievements in the proactive turbine control, based on the upwind speed measurements, are described in a unified framework (as an extension of the tutorial [1]), that [...]
Detection of blade root moment sensor failures is an important problem for fault-tolerant individual pitch control, which plays a key role in reduction of uneven blade loads of large wind turbines. A new method for detection of blade root moment sensor failures which is based on variations induced by a vertical wind shear is described in this paper. The detection is associated with monitoring of statistical properties of the difference between amplitudes of the first harmonic of the blade load, which is calculated in two different ways. The first method is based on processing of the load sensor signal, which contains a number of harmonics. The first harmonic is recovered via least squares estimation of the blade load signal with harmonic regressor and strictly diagonally dominant (SDD) information matrix. The second method is a model-based method of estimation of the first harmonic, which relies on the blade load model and upwind speed measurements provided by multibeam Light Detection and Ranging (LIDAR). This is a new application for future LIDAR-enabled wind turbine technologies. Moreover, adaptation of the load model in a uniform wind field is proposed. This adaptation improves accuracy of the load estimation and hence the performance of the blade load sensor failure detection method.
Abstract Detection of blade root moment sensor failures is an important problem for fault-tolerant individual pitch control, which plays a key role in reduction of uneven blade loads [...]
M. Soroush, D. Wessel-Berg, O. Torsaeter, J. Kleppe
Energy Science & Engineering (2017).
Abstract
Two-dimensional glass model experiments are used to investigate the residual trapping mechanism of CO2 stored in saline aquifers. For this purpose, two proxy fluids are chosen to simulate the CO2-brine behavior under reservoir conditions. The first set of experiments is carried out by flooding n-heptane in a mixture of glycerol and water inside a glass bead porous media. Fluids and porous materials are designed so that the dimensionless groups are in the range of real storage sites. Another set of proxy fluid consists of dodecane and a different mixture of glycerol and water, representing the second wettability condition for the system. The size of the glass beads chosen was fine (70–110 μm) in order to investigate residual trapping phenomena. For each set, after complete drainage process, an imbibition process is performed and in each time step, images are taken from the phenomena. The images are processed using a red, green, blue (RGB) color concept using a Matlab code that was developed for this study. By using this process, it is possible to measure the residual trapping of CO2 proxy fluid for each test and to determine the saturation profile in the model. Tests are carried out at various imbibition and drainage rates to study the effect of the rate on the results. Fine-scale numerical simulation models are constructed for comparison with experimental results. Good agreement is obtained between the simulation results and the image processing estimations, as well as the readings from the material balances during the experiments. This study could provide a framework for modeling different reservoir conditions for residual trapping mechanism and the impact of different parameters in future studies.
Abstract Two-dimensional glass model experiments are used to investigate the residual trapping mechanism of CO2 stored in saline aquifers. For this purpose, two proxy fluids are chosen [...]
R. Søndergaard, M. Hösel, N. Espinosa, M. Jørgensen, F. Krebs
Energy Science & Engineering (2017).
Abstract
Here, we present a process based on roll-to-roll (R2R) technology which allows for very fast processing of polymer thermoelectric (TE) devices and we furthermore demonstrate a simplified but more efficient way of serially connecting these devices by means of R2R thin-film processing. The new device architecture makes it possible to use only one TE material (opposed to two materials which are employed in well-known Peltier elements), and a total of 18, 000 serially connected junctions were prepared by flexoprinting of silver electrodes and by rotary screen printing of poly(3, 4-ethylenedioxythiophene) (PEDOT):polystyrene sulfonate (PSS) as the TE material. Testing of devices revealed that the new architecture clearly showed to be functioning as expected, but also pointed toward challenges for thin-film TE development which is the influence of the substrate thickness on the thermal gradient over a device and the currently low performance available. A life-cycle assessment (LCA) was carried out in order to evaluate the sustainability of the new architecture and to estimate the requirements for development of a successful technology.
Abstract Here, we present a process based on roll-to-roll (R2R) technology which allows for very fast processing of polymer thermoelectric (TE) devices and we furthermore demonstrate [...]
One of the main aspects when designing a permanent magnet (PM) generator is to choose suitable PMs, both in terms of achieving the required flux in the generator but also of withstanding high demagnetizing fields, that is, having sufficiently high coercivity. If the coercivity is too low, the magnets are at risk of demagnetizing, fully or partially, at the event of a short circuit and/or an increase in temperature. This study aims to determine the risk of demagnetization for a 12 kW direct driven permanent magnet synchronous generator. Furthermore, as the prices on PMs have increased drastically the last few years the possibility to use smaller and/or cheaper PMs of different grades has been investigated. A new proprietary finite element method (FEM) model has been developed, which is also presented. The study is based on simulations from this FEM model and is focused on NdFeB magnets. Results show that the reference magnet can withstand a two-phase short circuit at both the temperatures tested and in both geometries. The use of cheaper magnets, smaller air gap and in the event of a two-phase short circuit often results in partial irreversible demagnetization. However, magnets with lower coercivity are easier demagnetized.
Abstract One of the main aspects when designing a permanent magnet (PM) generator is to choose suitable PMs, both in terms of achieving the required flux in the generator but also [...]
A simultaneously “nuclear”, permanent, and in-time solution to mankinds energy-related problems would require the relatively rapid manufacture of 10, 000–30, 000 genuinely sustainable, full-sized (~1 GWe) reactors. This “nuclear renaissance” would have to be implemented with breeder reactors because todays commercial nuclear fuel cycle is unsustainable and based upon a fuel (235U) that is intrinsically expensive and politically problematic. The purpose of this paper is to point out why a simple/cheap “minimal reprocessing” implementation of the European Unions (EUs) molten salt fast reactor (MSFR) concept represents the most promising way to implement that technical fix: Its primary drawback is that it would require virtually everyone currently involved with managing, researching, implementing, regulating, or “helping” the USAs nuclear power industry to embrace a massive paradigm shift.
Abstract A simultaneously “nuclear”, permanent, and in-time solution to mankinds energy-related problems would require the relatively rapid manufacture of 10, 000–30, 000 genuinely [...]
Flexible supercapacitors, a state-of-the-art material, have emerged with the potential to enable major advances in for cutting-edge electronic applications. Flexible supercapacitors are governed by the fundamentals standard for the conventional capacitors but provide high flexibility, high charge storage and low resistance of electro active materials to achieve high capacitance performance. Conducting polymers (CPs) are among the most potential pseudocapacitor materials for the foundation of flexible supercapacitors, motivating the existing energy storage devices toward the future advanced flexible electronic applications due to their high redox active-specific capacitance and inherent elastic polymeric nature. This review focuses on different types of CPs-based supercapacitor, the relevant fabrication methods and designing concepts. It describes recent developments and remaining challenges in this field, and its impact on the future direction of flexible supercapacitor materials and relevant device fabrications.
Abstract Flexible supercapacitors, a state-of-the-art material, have emerged with the potential to enable major advances in for cutting-edge electronic applications. Flexible supercapacitors [...]
We examined pilot-scale bioethanol production from rice straw using sodium carbonate pulping as the alkaline pulping method and enzymatic saccharification. The yield of prewashed rice straw after the crushing and prewashing stage decreased with an increase in the input in rice straw. The pulp yield after alkaline cooking was 66–68% at kappa number ranging from 32 to 36, which was comparatively higher than the laboratory-scale study. The yield of enzymatic saccharized glucose was decreased with the increase in washed pulp and its saccharification rate was approximately 20%. We successfully produced approximately 100 liters of 95% ethanol from 1000 Bone-Dry kg (BDkg) rice straw. The results of our pilot-scale study indicated that the relationship between resource input and product yield for each operation exhibited exponential or logarithmic curves, rather than linear decreases or increases, which could suggest a high-cost structure for bioethanol production when the resource input is larger. However, we established an optimum quantity of resource input, approximately 2000–3000 BDkg in our pilot-scale study, for higher efficiencies.
Abstract We examined pilot-scale bioethanol production from rice straw using sodium carbonate pulping as the alkaline pulping method and enzymatic saccharification. The yield of prewashed [...]
Fusion energy, based on the use of broadly available inexhaustible resources as lithium and deuterium and with minimal impact to the environment, aims at a change in the energy supply paradigm: instead of its current dependence on natural resources and environmental impact, energy would become a technology-dependent resource with unlimited adaptive availability and whose unit cost should decrease as technology progresses. This article intends to give a picture of where fusion research stands today and the perspectives: the achievements, the difficulties, the current status, marked by the construction of the ITER experiment which will demonstrate the scientific feasibility of fusion power, and the perspectives toward the first demonstration power plant, DEMO, which, according to the European Roadmap, could start the construction shortly after the full power experiments in ITER (
Abstract Fusion energy, based on the use of broadly available inexhaustible resources as lithium and deuterium and with minimal impact to the environment, aims at a change in the energy [...]
A project has been initiated in South Africa to design, model, build, and evaluate an easy to install solar fueled combined heat and power (micro-CHP) system to supply off-grid rural villages and eco-estate communities. This study describes the design of a model that offers a combined 3 kW peak electrical, 12 kW peak thermal, stand-alone solar power technology solution with microgrid storage to deliver power, and heat when the sun is shining and after sunset (at night time). The CHP demand side management system manages power and heat distribution to individual households in a small rural village based on a proposed smart microgrid technology solution. The solution aims to balance the heat/power demand side requirements based on digital feedback on heat/power utilization patterns and user demand. Aspects of the micro-CHP system microgrid control are discussed while a modular smartgrid solution is selected for smart microgrid applications.
Abstract A project has been initiated in South Africa to design, model, build, and evaluate an easy to install solar fueled combined heat and power (micro-CHP) system to supply off-grid [...]
The purpose of this study was to highlight the technical and economic issues arising in lithium-ion cells for automotive applications, and to indicate some potential solutions to lower the cost. This topic has already been the subject of some studies, but, although of primary importance, the role on cost of a cell design parameter, the electrode coating thickness, has rarely been described. This study intends to explore particularly the influence of this parameter. To do so, the cost of cells with four positive electrode materials (NMC, NCA, LFP, and LMO), and the same negative electrode material are compared at several electrode thickness. The cost of these cells is computed using an innovative model and varies between 230 and 400 $ per kWh. With the assumptions used, it appears that the potential savings resulting from doubling the electrode coating thickness from 50 to 100 μm at a given porosity represent roughly 25% of the cell cost. The electrode coating thickness emerges as an essential parameter for an unbiased cells cost comparison. This article gives a view of the current lithium-ion cells costs, and provides guidelines to lower cells cost.
Abstract The purpose of this study was to highlight the technical and economic issues arising in lithium-ion cells for automotive applications, and to indicate some potential solutions [...]
M. Pagliaro, F. Meneguzzo, F. Zabini, R. Ciriminna
Energy Science & Engineering (2017).
Abstract
We investigate the value of solar photovoltaic (PV) power in the Italian wholesale electricity market (IPEX). A model is developed and applied to simulate and predict the monthly average electricity prices in peak hours, as well as to simulate scenarios without PV generation. The computed merit-order effect of the PV generation in Italy, around −2.9 €/MWh per each additional GWh of PV production, as well as the greater −4.5 €/MWh absolute value evaluated under the hypothesis of stationary electricity demand, are in line with the upper values found in related studies of near mature renewable energy markets. A strong relationship of the value of PV electricity in the IPEX with the electricity demand is clearly evident, leading to important policy implications in terms of possible actions on the granted subsidies, electrification of energy end use, and promotion of specific PV technologies. The anomalous temporal behavior of the IPEX, shown by high off-peak electricity prices that followed the installation of Italys large PV park, partly offsets the beneficial effect of PV generation.
Abstract We investigate the value of solar photovoltaic (PV) power in the Italian wholesale electricity market (IPEX). A model is developed and applied to simulate and predict the [...]
Quebecs large solar power potential markedly contrasts with its poor achievements in using solar energy in this large and wealthy region of the world. Reviewing recent developments and putting discussion in the socioeconomic context, we provide arguments that justify our viewpoint that solar energy will soon be a relevant source of power in this Province of Canada. The rapid fall in price of both main solar power technologies, photovoltaics, and solar thermal, along with significant levels of insolation and the pronounced environmental awareness of Quebecs population support the conclusions of this study.
Abstract Quebecs large solar power potential markedly contrasts with its poor achievements in using solar energy in this large and wealthy region of the world. Reviewing recent developments [...]
The energy supply characteristic of a proton-exchange membrane fuel cell for houses is strongly influenced in a hydrogen supply unit. Therefore, a bioethanol reforming system (FBSR) with a sunlight heat source is developed as a potential fuel supply system for distributed fuel cells. However, the temperature distribution of a catalyst layer in the reactor is not stable under conditions of unstable solar radiation and unstable outside air temperature, as a result, it is thought that the inversion ratio (the percentage of hydrogen obtained from ethanol) of a reforming reaction will decrease. In this paper, heat transmission analysis was used in the catalyst layer of the reformer of FBSR, and the fundamental performance of FBSR was investigated. Fluctuations of the solar insolation over a short period of time affect the hydrogen-generating rate of FBSR. Moreover, the amount of hydrogen production of FBSR was simulated using meteorological data from a day in March and a day in August in a cold region (Sapporo in Japan). In this research, the relation between the collected area of a solar collector and the energy supply to an individual house was obtained.
Abstract The energy supply characteristic of a proton-exchange membrane fuel cell for houses is strongly influenced in a hydrogen supply unit. Therefore, a bioethanol reforming system [...]
In this article, we present performance results and analysis of a novel rotary lobe expander device. This is part of a larger research effort into the analysis and design of a small-scale solar system that would compete with available distributed technologies for heat and electricity generation. To choose an appropriate working fluid and components for a distributed concentrating solar combined heat and power (DCS-CHP) system, we compared many different working fluids, collectors, and expander choices. Of the expanders analyzed, including piston expanders, radial inflow turbines, Tesla turbines, screw expanders, and scroll expanders, the rotary lobe expander shows the greatest promise in small-scale power applications due to its high efficiency in expanding fluids over large pressure ratios and its low cost to manufacture. This article focuses on testing of a prototype small-scale expander that was chosen because, to date, no suitable commercial product of less than 10 kW has been found for this application. Initial testing was completed with air to get results that should be indicative of future testing with steam. The test system consists of a compressed air expander (a prototype designed by Katrix, Inc. of Australia) connected to an induction motor driven by a variable frequency drive (VFD) that enables expander testing at varying shaft speeds. Results of the expander testing are reported isentropic efficiencies of 22–25%, thermomechanical efficiencies of 80–95%, and pressure ratios of 6–11 at the tested speeds. Despite mixed results from this particular expander, future refinements could lead to a new class of expanders with low cost and high performance for use in solar combined heat and power and waste-heat recovery.
Abstract In this article, we present performance results and analysis of a novel rotary lobe expander device. This is part of a larger research effort into the analysis and design [...]
Biochar: a new promising catalyst support using methanation as a probe reaction 
