Documents published in Scipedia

• Marginal abatement cost curve for wind power in China: a provincial-level analysis

  W. Xiong, Y. Yang, Y. Wang, X. Zhang

  Energy Science & Engineering (2017).

  
  

  Abstract

  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 (CO2) 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 CO2 emission mitigation at an average abatement cost of 75 RMB/t of CO2 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.

  Abstract
  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 [...]

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• Design of photovoltaics for modules with 50% efficiency

  E. Warmann, C. Flowers, J. Lloyd, C. Eisler, M. Escarra, H. Atwater

  Energy Science & Engineering (2017).

  
  

  Abstract

  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.

  Abstract
  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 [...]

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• Energy production advantage of independent subcell connection for multijunction photovoltaics

  E. Warmann, H. Atwater

  Energy Science & Engineering (2017).

  
  

  Abstract

  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.

  Abstract
  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 [...]

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• Status and future strategies for Concentrating Solar Power in China

  J. Wang, S. Yang, C. Jiang, Y. Zhang, P. Lund

  Energy Science & Engineering (2017).

  
  

  Abstract

  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 Chinas 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 Chinas CSP development is elaborated based on Chinas 13th 5-year program, but also on Chinas 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.

  Abstract
  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 Chinas possible role [...]

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• Tracing the energy footprints of Indonesian manufacturing industry

  Y. Vivadinar, W. Purwanto, A. Saputra

  Energy Science & Engineering (2017).

  
  

  Abstract

  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.

  Abstract
  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 [...]

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• Lock-in thermography as a tool for quality control of photovoltaic modules

  A. Vetter, F. Fecher, J. Adams, R. Schaeffler, J. Theisen, C. Brabec, C. Buerhop

  Energy Science & Engineering (2017).

  
  

  Abstract

  In this short communication, we present a method which utilizes contactless ILIT (illuminated lock-in thermography) measurement of a photovoltaic (PV) module and image postprocessing in order to calculate the peak power Pmpp of the module and to study the influence of local defects on the module performance. In total, 103 Copper-Indium-Gallium-Diselenide (CIGS) modules were investigated and the results showed a good correlation (mean error less than 6%) between the calculated IR-signal and the measured Pmpp. We performed our study on CIGS modules but the presented approach is not restricted to CIGS modules. The method provides a valuable tool for PV quality control.

  Abstract
  In this short communication, we present a method which utilizes contactless ILIT (illuminated lock-in thermography) measurement of a photovoltaic (PV) module and image postprocessing [...]

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• Reactivity of CaO with CO2 in molten CaF2–NaF: formation and decomposition of carbonates

  V. Tomkute, A. Solheim, S. Sakirzanovas, E. Olsen

  Energy Science & Engineering (2017).

  
  

  Abstract

  The characteristics of CO2 reacting with CaO in a molten eutectic mixture of CaF2 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 CO2 absorption or desorption were employed to identify the phases present in the melt. Efficient CO2 absorption from a simulated flue gas was observed, due to a combined reaction where CaO initially reacts with CO2 and forms CaCO3. Subsequently, Na2CO3 is formed by an ion exchange reaction between CaCO3 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 CO2 reactivity efficiency, probably because of precipitation and agglomeration of the sorbent. The total carbonation conversion was independent of the CO2 concentration in the inlet gas, and the sorbent carrying capacity was in the range 0.722–0.743 g CO2/g CaO corresponding to 0.037–0.144 g CO2/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 CO2 concentration in the outlet gas exhibited a rapid desorption step followed by a slow step.

  Abstract
  The characteristics of CO2 reacting with CaO in a molten eutectic mixture of CaF2 and NaF has been investigated. Calculations of the Gibbs free energy, temperature analysis [...]

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• Cover Image

  A. Tolbert, A. Ragauskas

  Energy Science & Engineering (2017).

  
  

  Abstract

  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.

  Abstract
  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 [...]

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• Advances in understanding the surface chemistry of lignocellulosic biomass via time-of-flight secondary ion mass spectrometry

  A. Tolbert, A. Ragauskas

  Energy Science & Engineering (2017).

  
  

  Abstract

  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.

  Abstract
  Overcoming the natural recalcitrance of lignocellulosic biomass is necessary in order to efficiently convert biomass into biofuels or biomaterials and many times this requires [...]

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• In situ synchrotron-based X-ray powder diffraction and micro-Raman study of biomass and residue model compounds at hydrothermal conditions

  M. Thomas, I. Butler, J. Kozinski

  Energy Science & Engineering (2017).

  
  

  Abstract

  The applications of synchrotron X-ray powder diffraction (XRPD) and laser micro-Raman techniques in an examination of the dissolution, transformation, and gasification of pure cellulose and models for biomass residue under hydrothermal conditions in a diamond-anvil cell are reported. The results contribute to the measurement of in situ time-resolved profiles of biomass reactions, catalyst stability, and residue formation that occur in aqueous fluids at near- and supercritical conditions.

  Abstract
  The applications of synchrotron X-ray powder diffraction (XRPD) and laser micro-Raman techniques in an examination of the dissolution, transformation, and gasification of [...]

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