Renewable Energy Global Innovations features: Direct Conversion of Cellulose and Hemicellulose to Fermentable Sugars by a Microbially-Driven Fenton Reaction

Significance Statement

Lignocellulose is recalcitrant to enzymatic degradation due to the crystalline structure of the cellulose polymers and strong bonding to lignin, and the main components of lignocellulose include complex carbohydrate and aromatic polymers. Microbial degradation of lignocellulose is conventionally initiated by enzymes produced by lignocellulolytic fungi or bacteria.

A team of researchers led by Professor Thomas J. DiChristina from the Georgia Institute of Technology developed a microbially-driven Fenton reaction that fragments cellulose and hemicellulose, degrades cellodextrins and xylodextrins, and produces short-chain oligosaccharides and monomeric sugars in a single bioreactor. The research work is now published in Bioresource Technology.

According to the authors, the microbially-driven Fenton reaction was introduced to generate extracellular HO radicals that fragmented cellulose and hemicellulose, degraded cellodextrins and xylodextrins, and produced short-chain oligosaccharides and monomeric sugars in a single bioreactor system that operated at neutral pH conditions. Instead of the conventional lignocellulose-degrading enzymes, cellulose and xylan were fragmented and degraded by a microbially-driven Fenton reaction in a single bioreactor.

They confirmed the ability of the microbially-driven Fenton reaction to degrade carboxymethyl cellulose CMC and xylan in Fe(III)-amended liquid batch cultures exposed to nine alternating aerobic and anaerobic phases. The initial 78 h time period shows that the total number of carboxymethyl cellulose and xylan reducing ends increased sharply, indicating that shorter oligosaccharides were produced through degradation of the partially fragmented carboxymethyl cellulose and xylan polymers. The total number of xylan-reducing ends exposed during xylan fragmentation was 2-fold greater than the number of carboxymethyl cellulose reducing ends exposed during CMC fragmentation. The authors found that the rates of microbially-catalyzed Fe(III) reduction and O₂-catalyzed Fe(II) oxidation were not affected by the presence of carboxymethyl cellulose or xylan.

The newly developed microbially-driven Fenton reaction reported in this study was able to produce a suite of short-chain oligosaccharides and fermentable sugars that were subsequently transformed enzymatically to the more readily degradable bioplastic polyhydroxybutyrate (PHB; published in Applied and Environmental Microbiology). Their research thus laid the foundation for development of consolidated bioprocesses for lignocellulose degradation that may be linked to downstream production of a myriad of useful bioproducts, such as ethanol, butanol, biodiesel, bioplastic, and lactic acid.

Microbially-driven Fenton degradation of cellulose and xylan

About The Author

Dr. Thomas J. DiChristina received his BS in Chemical Engineering from the University of Rochester (Rochester, NY), MS in Physical Chemistry from the University of Bordeaux (Bordeaux, France), and PhD in Environmental Engineering Science from Caltech (Pasadena, CA). He was awarded a National Science Foundation Postdoctoral Fellowship to carry out postdoctoral research at the Woods Hole Oceanographic Institution (Woods Hole, MA). He currently holds the title of Full Professor in the School of Biological Sciences at Georgia Tech (Atlanta, GA) where he has been a faculty member for 24 years.

His areas of research expertise include the molecular mechanism of microbial metal respiration, bioremediation of hazardous organic and inorganic contaminants, and novel techniques for production of biofuel and biorefinery products from renewable lignocellulosic biomass.

About The Author

Dr. Ramanan Sekar received his B. Tech in Chemical Engineering from Anna University (Chennai, India), MS degree in Chemical Engineering from SUNY Buffalo (NY), and PhD in Biology from Georgia Tech.

His areas of research expertise include bioremediation of hazardous organic contaminants, and novel techniques for biofuel and biorefinery products from renewable lignocellulosic biomass. He recently joined Intel Corporation (Hillsboro, OR) as a Process Engineer in lithography.

About The Author

Dr. Hyun-Dong Shin received his PhD in Genetic Engineering from Kyungpook National University (Daegu, South Korea) and is currently a Research Scientist in the School of Biological Sciences at Georgia Institute of Technology (Atlanta, GA). He is author of approximately 130 scientific papers.

His areas of research expertise include enzyme and metabolic engineering for production of biofuel and biorefinery products from renewable lignocellulosic biomass and bioremediation of radionuclides by anaerobic metal-reducing microorganisms.

References

Ramanan Sekar, Hyun Dong Shin, Thomas J. DiChristina, Direct Conversion of Cellulose and Hemicellulose to Fermentable Sugars by a Microbially-Driven Fenton Reaction, Bioresource Technology 218 (2016) 1133–1139.

Sekar, R., H-D. Shin, and T. DiChristina. 2016. Activation of an otherwise silent xylose metabolic pathway in Shewanella oneidensis.  Applied and Environmental Microbiology, 82:3996-4005.

School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, United States.

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Renewable Energy Global Innovations features: Reproducing Statistical Property of Short-term Fluctuation in Wind Power Profiles

Significance Statement

Wind power generation which serves as a source of renewable energy faces certain challenges due to short-term fluctuations in power output. This led to the addition of a battery system in order to reduce these pitfalls and as a result, the effect of the short-term fluctuations in relation to the battery system needs to be evaluated. One means of evaluating this effect is the use of a power flow simulation.

A group of researchers from , Waseda University in Japan, proposed an innovative method whereby synthetic wind power profiles with high temporal resolutions for power flow simulation can be generated by reproducing plausible statistical behavior of a realistic short-term fluctuation. The work is now published in journal, Energy Procedia.

In order to achieve a realistic short-term fluctuation which occurs in wind power generation, the power flow simulation observes the time-series statistical behaviors. The methods used in achieving the realistic short-term fluctuation include; the previously used autoregressive mean average approach and the block bootstrap approach.

The authors further compared the statistical property of the short-term fluctuations generated from three different approaches; naive bootstrap, autoregressive mean average bootstrap approach and the block bootstrap coupled with evaluations made by finding the autocorrelation functions of the detrended sequence which stands for the typical short-term fluctuation in wind power generation.

Following the generation of ten plausible short-term fluctuations for each approach from a dataset of a case study in Japan, the lowest root mean square error of the autocorrelation functions was observed in the block bootstrap approach. This shows that the block bootstrap approach gave the highest accuracy amongst the three. It improved 26.5% from the autoregressive mean average approach.

The lowest root mean square error for variance sequences was also observed with the block bootstrap approach, which indicates that the generated short-term fluctuations possess realistic volatility.

The block bootstrap approach which exhibited plausible volatility and accuracy of the detrended sequence indicated an imaginative time-series statistical property of the real-world fluctuation in wind power generation which would be of relevance in determining the effects of the short-term fluctuations on battery systems of future wind energy technologies.

About The Author

Seigo Furuya received his B.Eng and M.Eng degree in electrical engineering and bioscience from Waseda University, Japan, in 2014 and 2016, respectively. His research interests are generating synthetic wind power generation profiles by statistical approach.

About The Author

Yu Fujimoto received his Ph.D. in engineering from Waseda University, Tokyo, Japan, in 2007. He is an Associate Professor at the Advanced Collaborative Research Organization for Smart Society (ACROSS), Waseda University.

His primary areas of interest are machine learning and statistical data analysis. His current research interests include data mining in energy domains especially for operating and controlling devices in smart grids, and statistical prediction of the power fluctuation under the large introduction of renewable energy sources. He is a Member of Information Processing Society of Japan.

About The Author

Noboru Murata received the B. Eng, M. Eng, and Dr. Eng degrees in mathematical engineering and
information physics from the University of Tokyo in 1987, 1989, and 1992, respectively. After working at the University of Tokyo, GMD FIRST in Germany, and RIKEN in Japan, since April 2000, he joined Waseda University in Japan where he is currently a professor.

His research interest includes the theoretical aspects of learning machines such as neural networks, focusing on the dynamics and statistical properties of learning.

About The Author

Yasuhiro Hayashi received his B. Eng., M. Eng., and D. Eng. degrees from Waseda University, Japan, in 1989, 1991, and 1994, respectively. In 1994, he became a Research Associate with Ibaraki University, Mito, Japan. In 2000, he became an Associate Professor with the Department of Electrical and Electronics Engineering, Fukui University, Fukui, Japan. He has been with Waseda University as a Professor of the Department of Electrical Engineering and Bioscience since 2009; and as a Director of the Research Institute of Advanced Network Technology since 2010. Since 2014, he has been a Dean of the Advanced Collaborative Research Organization for Smart Society at Waseda University.

His current research interests include optimization of distribution system operation and forecasting, operation, planning, and control concerned with renewable energy sources and demand response. Prof. Hayashi is a Member of the Institute of Electrical Engineers of Japan and the International Council on Large Electric Systems.

Reference

Furuya, S., Fujimoto, Y., Murata, N., Hayashi, Y. Reproducing Statistical Property of Short-term Fluctuation in Wind Power Profiles, Energy Procedia 99 ( 2016 ) 130 – 136.

Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.

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Renewable Energy Global Innovations features: W(Nb)Ox-based efficient flexible perovskite solar cells

Significance Statement

Perovskite solar cells are emerging photovoltaics that have attracted significant attention in industrial applications. Based on the superior attributes of the perovskite semiconductors, significant progress has been made. With planar and mesoporous architectures, high power conversion efficiency have been recorded in perovskite solar cells.

Electron selective layer is crucial to the photovoltaic performance of solar cells. High temperature treatment of the electron selective layer is imperative to achieve highly condensed and crystallized films for efficient perovskite solar cells. This extreme process increases the production cost and energy payback time. It also limits the application of perovskite solar cells in gadgets fabricated on plastic substrate. For this reason, it is indispensable to explore low-temperature substitutes.

A number of feasible approaches have been adopted to fabricate electron selective layers on plastic conductive substrates. Most of these methods implement planar configurations and do not employ mesoporous scaffold layer, which is normally synthesized at high temperature. Therefore, Dalian University of Technology researchers in China prepared amorphous niobium-modified tungsten oxide as an electron selective layer for flexible perovskite solar cells. The authors proved that WOx as a building block for electron selective layer could be fabricated at low temperature. Their work has been published in peer-reviewed journal, Nano Energy.

The authors prepared the electron selective layers from a mixture of tungsten ethoxide, ethanol and niobium ethoxide. The obtained precursor mixture was coated on the polyethylene naphthalate substrate and heated below 150 ^oC to achieve a smooth layer. They mixed 4-tert-butyl pyridine with lead chloride and N,N-dimethylformamide in a bid to optimize the crystallization process of perovskite layer. Silver was then evaporated on the samples’ surface to give the back contact.

The results from the x-ray diffraction spectroscopy indicated that the obtained electron selective layers were amorphous. Moreover, x-ray photoelectron spectroscopy results indicated that the predominant valence state of the layers was W⁶⁺ in addition to small amounts of W⁵⁺. The compound was therefore named WO_X.

The authors prepared for the first time amorphous WO_X though the solution approach. They found that this was a promising building block for low-temperature preparation of flexible perovskite solar cells. They developed an approach to modify optoelectronic behavior of electron selective layer using NbOx, which resulted in enhanced conductivity and donor density, suppressed charge combination and reduced surface traps states.

Using niobium-modified tungsten oxide as electron selective layer, high power conversion efficiencies up to 15.65% have been attained by flexible perovskite solar cells. The cells with electron selective layers prepared at room temperature also recorded a power conversion efficiency of 13.14%. The authors assessed the effect of the layer thickness on hysteresis characteristics of the cells. They suggested that a capacitance existed across the layer in the perovskite structure. The suggestion explained the effect of the layer thickness on the hysteresis attributes. The proposed approach will facilitate the development of novel and functional materials.

About The Author

Kai Wang received his bachelor degree in 2012 at Dalian University of Technology, China. And now he is a Ph.D candidate under supervisions of Professor Tingli Ma and Yantao Shi at the same university. His research interests focus on developing novel low temperature functional material as photo-anode for dye-sensitized solar and perovskite solar cells.

About The Author

Yantao Shi graduated from Lanzhou University in 2005 with a Bachelor’s degree, then studied at Tsinghua University for his Master’s degree and Ph.D from 2005 to 2010. As a visiting scholar, he worked at the Department of Physics, Hong Kong University of Science and Technology (HKUST) in the following two years. In 2012, he joined Dalian University of Technology as a lecture. Currently, he is a full professor in the Department of Chemistry at the same university.

His research interests focus on the third generation thin film solar cells, e.g. dye-sensitized solar cells and perovskite solar cells. His contributions include synthesizing novel photoelectric materials, revealing the effects of nanostructures on cell performance, improving long-term durability, and so on. He has published around 60 papers with more than 800 citations by other researchers.

About The Author

Tingli Ma graduated from Kyushu University with a Ph.D degree. In 2007, she was employed as a professor in state key laboratory of fine chemicals of Dalian University of Technology. In 2014, she joined the School Petroleum and Chemical Engineering of Dalian University of Technology in Panjin Campus, China. At the same time, she worked at the Graduate School of Life Science and Systems Engineering of Kyushu Institute of Technology, Japan.

She mainly studied on the third generation thin film solar cells including the dye-sensitized solar cells, quantum dot sensitized solar cells, and perovskite solar cells. Her contributions include developing novel electrode material, optimizing the device architecture, revealing the charge kinetic process, improving long-term durability, and so on.

Reference

Kai Wang¹, Yantao Shi¹, Liguo Gao², Rihan Chi¹, Kun Shi¹, Bingyi Guo¹, Liang Zhao¹, Tingli Ma^2,3. W(Nb)Ox-based efficient flexible perovskite solar cells: From material optimization to working principle. Nano Energy, volume 31 (2017), pages 424–431.

Show Affiliations

1. State Key laboratory of Fine Chemicals, School of Chemistry, Dalian University of Technology, Dalian 116024, China
2. School Petroleum and Chemical Engineering, Dalian University of Technology, Panjin Campus, Panjin 124221, China
3. Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2–4 Hibikino, Wakamatsu, Kitakyushu, Fukuoka 808-0196, Japan

 

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Renewable Energy Global Innovations features: Co-Combustion Characteristics of Hydrothermally Treated Municipal Solid Waste with Coal in a Fluidized Bed

Significance Statement

Co-combustion of municipal solid biomass wastes and coal at high efficiency has been a challenge in recent time due to the hazardous nature of the waste gases generated in the process. Utilization of bubbling fluidized beds reactors, that use coal, has been called into question due these pollution effects. Measures have been taken to try and solve this problem that originates from the use of coal. In this paper, numerical and experimental models have been adopted for the simulation of the combustion process, within a bubbling fluidized bed reactor, so as to determine temperatures at which coal could be substituted with hydrothermally treated municipal solid waste.

A research team led by Professor Kunio Yoshikawa from Tokyo Institute of Technology and Associate Professor Tamer Ismail from Suez Canal University in Egypt, with Dr. Liang, Dr. Abd El-Salam and Prof. Yuqi Jin investigated the co-combustion characteristics of hydrothermally treated municipal solid waste with coal in a fluidized bed reactor. Their aim was to present models that use composite fuel (coal and municipal solid wastes) at least reactor modification. Their work is now published in the peer-reviewed journal Fuel Processing Technology.

Foremost, experiments had to be conducted using reliable CFD in order to predict crucial results and critical requirements for curbing and ensuring efficiency. The three approaches that were available for numerical simulations were: Euler-Lagrange approach, Euler-Euler approach and Discrete Element Method. Euler-Euler approach was adopted where ratios of 10, 20, 30 and 50% of the hydrothermally treated municipal solid waste were chosen to be tested at 700°C, 800 °C and 900 °C so as to determine the temperatures at which coal could be replaced with the hydrothermally treated municipal solid waste.

The research team had to determine the right temperature and mixture of the system that had the least emissions and yet could be operated at the least cost. They observed that for mixing ratios of 10 and 20% of the HT MSW there was a significant reduction in the CO outflow emission during the co-combustion with coal. Additional mixing of coal with the HT MSW lead to a further decrease in SO₂ emission from the combustion. Low levels of HCL were recorded for all the mixtures displaying a positive effect of the mixture. Nitrogen levels were also kept to a minimal as the blending mixing ratios of the HT MSW were increased.  Initially, high levels of NO were recorded due to increase in temperature but with the mixing of the HT MSW to 30% level, a significant drop was observed for all temperatures.

This research paper shows that with accurate simulation, trends for co-combustion can be predicted for various emitted gas species in the bed. This research sheds light into a promising way to simulate the combustion of solid waste in bubbling fluidized beds when using minimal coal. This study also reveals the features of a detailed structure for the combustion process inside the solid bed. Finally, it indicates the possibility of accepting the mixing ratio of the hydrothermally treated municipal solid waste, co-combusted with coal up to 30% without major modification of the coal-fired bubbling fluidized beds reactor.

About The Author

Dr. Tamer M. Ismail is an associate professor of Department of Energy and Fuel Science, Suez Canal University, Egypt. He obtained PhD in 2010, in Mathematical Modelling of MSW Incineration. He is one of the expert in the field of CFD of solid combustion and gasification having several research in this field. He is considered the pioneer in this field in Suez Canal University. He has a patent for CFD simulation code called, COMMENT- Code. Also, in the field of waste to energy he has several special work in designing many reactors, such as, fluidized bed, chemical looping combustor and bioreactor fermentor.

His major research areas are energy conversion, thermal engineering, combustion, gasification, waste treatment technologies, and he wrote many papers in this field. He works as research associate in Harbin Institute of Technology, Tokyo Institute of Technology and nstituto Politécnico de Portalegre, Universidade de Trás-os-Montes e Alto for combustion and gasification technologies.

About The Author

Dr. Kunio Yoshikawa is a professor of Department of Environmental Science and Technology, Tokyo Institute of Technology, Japan. He graduated from Tokyo Institute of Technology and obtained PhD in 1986. After graduation from Tokyo Institute of Technology, Prof. Yoshikawa worked for Mitsubishi Heavy Industries for one year, and then went back to his home university to become a research associate, associate professor and professor.

His major research areas are energy conversion, thermal engineering, combustion, gasification, waste treatment technologies and atmospheric environmental engineering, and he wrote more than 200 papers. He is an associate editor of Applied Energy. His main awards are AIAA (American Institute of Aeronautics and Astronautics) Best Paper Award in 1999, ASME (American Society of Mechanical Engineers) James Harry Potter Gold Medal in 2001, JSME (Japan Society of Mechanical Engineers) Environmental Technology Achievement Award in 2006, Fellow of JSME in 2008 and Best Educator Award of Tokyo Institute of Technology in 2014.

Reference

Liang Lu¹, T.M. Ismail², Yuqi Jin³, M. Abd El-Salam⁴, Kunio Yoshikawa¹. Numerical and experimental investigation on co-combustion characteristics of hydrothermally treated municipal solid waste with coal in a fluidized bed.  Fuel Processing Technology volume 154 (2016) pages 52–65.

Show Affiliations

1. Department of Environmental Science and Technology, Tokyo Institute of Technology, G5-8, 4259 Nagatsuta, Midori-Ku, Yokohama 226-8502, Japan
2. Department of Mechanical Engineering, Suez Canal University, Ismailia, Egypt
3. State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China
4. Department of Basic Science, Cairo University, Giza, Egypt

 

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Renewable Energy Global Innovations features: Hysteresis-Suppressed High-Efficiency Flexible Perovskite Solar Cells Using Solid-State Ionic-Liquids for Effective Electron Transport

Significance Statement

Metallic oxides used as electron transport material in perovskite solar cells normally undergo high temperature process to attain their desired structural characteristics. However, the recent incorporation of friendly, low-temperature electron transport material also faces positive demanding situations due to the high cost of production and resultant low electron mobility.

In order to improve this technology, new research must be conducted in view of producing high electron mobility electron transport material, well-suited to a low-temperature process technology coupled with a low-cost production approach.

Researchers led by Professor Shengzhong (Frank) Liu from Shaanxi Normal University in China investigated a solid-state ionic-liquid as an electron transport material with the use of low-temperature processing to attain high efficiency flexible perovskite solar cells with good reproducibility. The research work is now published in the journal, Advanced Materials.

The authors discovered a reduction  in work function of indium-tin-oxide cathode whilst coated with 1-benzyl-3-methylimidazolium chloride solid-state ionic-liquid, enabling electron collection as a result of decreased interface barrier between the cathode and the perovskite absorber. The addition of the solid-state ionic-liquid also led to enhanced short-circuit current density and fill factor in the perovskite solar cells due to their wider bandgap.

The solid-state ionic-liquid coated with flexible poly(ethylene terephthalate)/indium-tin-oxide PET/ITO had a higher transparency and average transmittance approximately 88% in region of 400-450 nm and 400-800 nm respectively compared to the bare samples thereby showing its anti-reflective properties.

The authors were able to provide an appropriate solid-state ionic-liquid layer thickness of flexible perovskite solar cells because of their major role in output performance. A layer thickness of 10nm for the solid-state ionic-liquid was chosen.

Results from current density-voltage curves also showed a higher power conversion efficiency PCE of value 16.09% for perovskite solar cells based on (HC(NH₂)₂PbI₃)_0.85(CH₃NH₃PbBr₃)_0.15 with the solid-state ionic-liquid as an electron transport material compared with the absent electron transport material. Incident photon-to-current conversion efficiency, short-circuit current density, fill factor and energy levels were also confirmed with higher values.

The authors also discovered a heavily suppressed hysteresis in the current density-voltage. This was attributed to the increase in higher electron mobility as a result of the solid-state ionic-liquid as an electron transport material.

Results from dark current-voltage analysis showed a significant decrease of electron trap density in perovskite films deposited on substrates of the solid-state ionic-liquid coated with indium-tin-oxide which results in a large short-circuit current density.

With these attributes, the solid-state ionic-liquid used in this study as an electron transport material meets the requirement of a low-temperature processing and low-cost manufacturing process favors the technology involved in high efficiency flexible perovskite solar cells.

Reference

Yang, D.¹, Yang, R.², Ren, X.¹, Zhu, X.¹, Yang, Z.¹, Li, C.², Liu, S.^1,2 Hysteresis-Suppressed High-Efficiency Flexible Perovskite Solar Cells Using Solid-State Ionic-Liquids for Effective Electron Transport, Advanced Material 28 (2016) 5206-5213.

Show Affiliations

1. Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an, 710119, P. R. China.
2. Dalian National Laboratory for Clean Energy, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023, P. R. China.

 

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Renewable Energy Global Innovations features: High-Efficiency Nanowire Solar Cells with Omnidirectionally Enhanced Absorption Due to Self-Aligned Indium-Tin-Oxide Mie Scatters

Significance Statement

Photovoltaic cells implementing high-index planar materials suffer from reflection losses. Micro-sized scattering particles as well as antireflection coatings have been applied to lessen this reflection. Nanoimprinted dielectric materials have been used to enhance the in-coupling of light in planar materials. The enhanced coupling can be discussed in terms of Mie resonances that scatter the light in the forward direction.

Nanowire solar panels are an important field owing to intrinsic benefits over the planar solar devices, leading to higher photocurrent and photovoltage. However, the size and shape of the nanowire are necessary for attaining high absorption efficiency and the highest photocurrent of the III-V nanowire solar cell has been below that of the optimum planar cells fabricated with the same materials.

Dutch scientists led by professor Jos Haverkort at the Eindhoven University of Technology developed a InP nanowire solar cell where the indium-tin-oxide reflection loss was reduced significantly and the nanowire absorption enhanced with respect to a planar contact by applying Mie scattering of the nanostructured transparent contact layer. Their work is published in peer-reviewed journal, ACS Nano.

In a bid to produce the cells, n-and p-doped InP layers were fabricated on an InP substrate. An etching mask was made of a silicon nitride layer was realized by nanoimprint lithography. The nanowires were then etched in a plasma etching chamber. The side walls were then etched by surface oxidation. Chemical etching followed to scrap the oxide. The nanowires were covered with silicon oxide and the spaces between them filled with benzocyclobutene. Finally, an indium-tin-oxide layer was deposited as a conductive layer. The full cell was exposed to light. Photocurrent density was then calculated.

The authors fabricated solar cells based on InP nanowires, which were then covered with silicon oxide to enhance adhesion with the material surrounding the layer. Benzocyclobutene layer was applied for insulation and planarization. It was then etched back to expose the ends of the nanowires. Benzocyclobutene was selected owing to its electrical insulation properties and transparency in the visible infrared. The indium-tin-oxide formed spherical particles because the deposited material stuck better on the InP than on the benzocyclobutene surface. The current-voltage of the nanowire solar cell was measured independently.

This paper shows that appropriately designed hemispherical nano-particles on top of the transparent top contact of the nanowire solar cell can enhance the absorption efficiency for the full wavelength and incident angle gap. Calculations as well as simulations indicated that forward Mie scattering was the approach behind this improvement. The absorption improvement that is wavelength averaged at normal incidence makes the self-aligned indium-tin-oxide hemispheres elementary design building blocks for solar cells based on nanowires. In this approach, the authors demonstrated a nanowire solar cell that was 17.8% efficient with a short-circuit current of 29.3 mA/cm2 measured at 1 sun incident light. This record efficiency is among the highest of III-V solar cells.

“Nanowire solar cells show enhanced light incoupling due to forward Mie scattering of the hemispherical ITO nanoparticles, but they also fundamentally outperform planar solar cells due to an enhanced light outcoupling in comparison with a planar solar cell. At V=Voc, a solar cell is not generating any current, implying that in a lossless cell, all absorbed light should be emitted externally”. Said Dr. Jos Haverkort.

About The Author

Dr. Jos E.M. Haverkort is a lecturer at the Eindhoven University of Technology. He currently specializes on III/V semiconductor nanowires for photovoltaic applications and in the optical study of hexagonal crystal phase group IV and III/V nanowires. Under his guidance, an 11.1% efficiency InP nanowire array solar cell was reported in 2013.

He has shown in a recent Nano Letter paper that a nanowire solar cell fundamentally outperforms a planar solar cell, which resulted in a top-down etched InP nanowire solar cell with 17.8% efficiency.

Journal References

Dick van Dam† , Niels J. J. van Hoof†‡, Yingchao Cui†, Peter J. van Veldhoven†, Erik P. A. M. Bakkers†§ , Jaime Gómez Rivas†‡, and Jos E. M. Haverkort*†. High-efficiency nanowire solar cells with omnidirectionally enhanced absorption due to self-aligned indium-tin-oxide mie scatters. ACS Nano, volume 10 (2016), pages 11414-11419.

Show Affiliations

† Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
‡ Dutch Institute for Fundamental Energy Research DIFFER, P.O. Box 6336, 5600 HH Eindhoven, The Netherlands
§ Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands  

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Y. Cui, D. van Dam, S.A. Mann, N.J.J. van Hoof, P.J. van Veldhoven, E.C. Garnett, E.P.A.M. Bakkers, J.E.M. Haverkort, Boosting solar cell photovoltage via nanophotonic engineering, Nano Lett 16, 6467-6471 (2016).

 

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Renewable Energy Global Innovations features: Fe-Based Metal-Organic Framework and Its Derivatives for Reversible Lithium Storage

Significance Statement

Researchers led by Professor Cai Shen from Ningbo Institute of Materials Technology and Engineering in China used iron-based metal organic framework as an anode for the first time in lithium ion battery applications. The research work is now published in Journal of Materials Science & Technology.

They synthesized MIL-88B_(Fe) as the iron-based metal organic framework followed by production of Fe₂O₃ and Fe₃O₄/C  composites via thermal treatment. In current density of 200mAg^-1, the columbic efficiency increases up to 100% of the 100th cycle with an increase in discharge and charge capacity. After 200 cycles, the cyclic performance of the metal organic framework was up to 700mA hg^-1 and reduced to an approximate value of 680mA hg^-1 after 500 cycles, showing a high cyclic stability. An increase in current density up to 2.0Ag^-1 maintained a capacity as high as 475mA hg^-1, indicating a high cyclic performance despite reduction in discharge capacity of the metal organic framework.

Following the successful preparation of Fe₂O₃ and Fe₃O₄/C composites, They found that the metal oxide of Fe₂O₃ had a discharge capacity of 460mA hg^-1 at a current density of 0.5C which remained after 100th cycle with a columbic efficiency of 100%. The discharge capacity was 180mA hg^-1 at a current density of 5C, but attained a discharge capacity of 700mA hg^-1 when current density was reversed to 0.2C, indicating high cycling stability.

For composites of Fe₃O₄/C, discharge capacity was approximately 800mA hg^-1 in the 100th cycle and attained a value of 928mA hg^-1 when the number of cycles was 200. As current density increases to 5C, a steady discharge capacity was attained, showing high cycling stability.

The iron-based metal organic framework MIL-88B(Fe) coupled with metal oxides of Fe₂O₃  and Fe₃O₄/C  composites both demonstrated high capacity and excellent cycling stability.

About The Author

Dr. Cai Shen received his Ph. D. in Chemistry from the University of St Andrews at UK in 2008. Before joining Ningbo institute of Materials Technology and Engineering, Chinese Academy of Science as an Associate Professor, he worked as a postdoc fellow in the University of Maryland (USA) and Aarhus University (Denmark).

His current research area involves lithium-ion batteries and the application of scanning probe microscopy techniques (in-situ electrochemical STM, AFM) to investigate the surface chemistry of nano materials.

Journal Reference

Jin, Y., Zhao, C., Lin, Y., Wang, D., Chen, L., Shen, C. Fe-Based Metal-Organic Framework and Its Derivatives for Reversible Lithium Storage, Journal of Materials Science & Technology (2016), doi: 10.1016/j.jmst.2016.11.021.

Chinese Academy of Sciences, Ningbo Institute of Materials Technology & Engineering, Ningbo 315201, China.

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Renewable Energy Global Innovations features: Design and optimization of spectral beamsplitter for hybrid thermoelectric-photovoltaic concentrated solar energy devices

Significance Statement

Spectrally selective beam splitting or filtering of radiation can be applied in various types of systems that convert solar energy into electricity. In thermophotovoltaics it was proposed to apply a filter between a heat source and a long-wavelength solar cell transmitting only thermal radiation in a narrow spectral window with high conversion efficiency in the solar cell. Multilayer interference structures for spectrally selective beam splitting are of interest for increasing the conversion efficiency of systems combining a number of solar cells, being efficient at various wavelengths.

A type of system of special interest in which spectrally selective beam splitting is utilized is in a hybrid system consisting of a beamsplitter, a PV cell (solar cell), and a thermoelectric (TE) generator. Here the basic idea is to spectrally split the sunlight incident on the beamsplitter, such that the short wavelengths are reflected onto the solar cell. The longer wavelengths that cannot be converted in the solar cell are instead transmitted onto the TE generator, and in this way the efficiency of the hybrid system can exceed that of a single solar cell. Previous work on this type of beam splitting system assumed an ideal beamsplitter that reflects all the short wavelengths onto the solar cell and transmits all the long wavelengths onto the TE generator with a perfectly sharp cutoff and no losses. Under this assumption, theoretical studies have shown a potential for increasing the efficiency of the hybrid system beyond that of a single solar cell. The optimal cut-off wavelength has been studied in order to maximize the total efficiency, but the question of how to actually construct the beamsplitter has not been addressed, nor has the study of how close it is possible to get to the ideal beamsplitter using a constructed beamsplitter.

Therefore Associate professor Thomas Søndergaard and his master student Enok Skjølstrup from Aalborg University in Denmark have now examined how to actually construct a beamsplitter in practice. It is designed for maximizing the output of the hybrid system taking into account the spectral efficiency of realistic solar cells based on amorphous (a-Si) or microcrystalline (mc-Si) silicon, efficiencies of the TE generator of either 4% or 8%, and the AM1.5 solar spectrum. They have constructed the beamsplitter using thin-film layers of silicon nitride (Si₃N₄) and silicon dioxide (SiO₂) deposited on N-BK7 glass. As an initial design, the beamsplitter consists of different blocks, where each block consists of a certain number of unit cells serving as a layered bandgap structure with large reflection in a certain wavelength interval. When combining several blocks appropriately the structure reflects almost 100% within a much larger wavelength interval than a single block would. For a given TE generator and solar cell, and a given solar radiation spectrum, the conversion efficiency of the hybrid system is a function of all the layer thicknesses of the beamsplitter, which here can vary from app. 20 to 200. Thus the authors have optimized a function of a large number of variables, where the initial block structure is used as the initial guess in the optimization procedure.

The beamsplitter is optimized for both the a-Si and mc-Si solar cells, and in both cases the efficiency of the hybrid system is found to remarkably exceed that of a single solar cell, and the number of layers required to construct a useful beamsplitter is determined. The efficiency of the hybrid system is found to scale approximately linear with the TE efficiency, and the relative improvement compared to a single solar cell is found to be 21.4% for the a-Si solar cell. The beamsplitter is optimized for an incident angle of 45^o but the efficiency as a function of incident angle is found to be relative insensitive to the angle of light incidence from 35-55^o. Furthermore, due to higher order band gaps it was found impossible to construct a useful beamsplitter for the reverse configuration with the TE generator and solar cell interchanged.

About The Author

Enok Johannes Haahr Skjølstrup is a Ph.d student at the Department of Physics and Nanotechnology at Aalborg University, Denmark. In his Master Thesis, which he wrote during the spring 2016, he worked with the design and optimization of a beamsplitter to be implemented in a hybrid system consisting of a solar cell and a thermoelectric generator in order for the efficiency of the hybrid system to exceed that of a single solar cell. Co-author Thomas Søndergaard was Enoks supervisor, and the present paper is Enoks first publication. Enok got his Master degree in June 2016 and during the autumn 2016 he was employed as a research assistant, where he amongst other things studied the optics of multiple ultrasharp grooves in metal. He started as a Ph.d student in January 2017, where he is now theoretically studying the interaction between light and matter on nanoscale. The interaction involves field enhancement in and near plasmonic structures due to nonlocal and quantum effects, why surface plasmons is one of his research interests.

About The Author

Thomas Søndergaard is associate professor within the area of nano optics at the Department of Physics and Nanotechnology, Aalborg University, Denmark. He received the M.Sc. and the Ph.D. in Electrical Engineering from the Technical University of Denmark, respectively in 1999 and 2002. He was then employed in the company Micro Managed Photons A/S for three years working with modeling and design of optical components based on a combination of surface plasmon polaritons and photonic crystals. He obtained a grant from the Danish Agency for Science, Technology, and Innovation for a three-year Post. Doc. at Aalborg University working with plasmonic nanostructures for bio-molecular spectroscopy and microscopy. This was followed by his present position. He received the Danish Independent Research Councils’ Young Researcher’s Award in 2006, and the Danish Optical Society Award in 2008.

His research interests are centered around theoretical modeling of electromagnetic fields in nanostructures, which includes for example work on increasing the efficiency of thin-film silicon solar cells by utilizing surface micro- and nanostructures and embedding of nanoparticles, multilayer coatings for solar power concentrator systems, development of Greens function integral equation methods and other methods for theoretical studies, and basic research within nano-plasmonics. He is presently also interested in antennas and lenses for THz radiation.

He is the author of 84 peer-reviewed journal papers (35 first-authored), and a co-author of the book Numerical Methods in Photonics, CRC Press, 2015. Web-of-science h-index: 27. A detailed list of publications is available . He has won both silver (2006) and bronze (2007) in the Danish national marathon running championships.

Reference

Enok J.H. Skjølstrup and Thomas Søndergaard. Design and optimization of spectral beam-splitter for hybrid thermoelectric-photovoltaic concentrated solar energy devices. Solar Energy, volume 139 (2016), pages 149-156.

Department of Physics and Nanotechnology, Aalborg University, Skjernvej 4A, DK-9220 Aalborg East, Denmark.

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Renewable Energy Global Innovations features: Cultivation of Chlorella sp. with livestock waste compost for lipid production

Significance Statement

Microalgae have received significant attention as a biodiesel feedstock. This is in response to energy shortage, climate change and global warming. Microalgae offer many advantages for use in biodiesel production. They have high photosynthetic efficiency, which translates to high growth rate. Moreover, most algal species have high lipid content. Furthermore, it is possible to launch algal biorefinery facilities in lands with low economic value, such as saline and arid lands therefore microalgae cultivation does not compete with food production for farmlands.

Liandong Zhu and colleagues from University of Vaasa in Finland developed a method to determine algal biomass accumulation for biodiesel production when algal cultivation with livestock waste compost was combined. In their work, an optimal concentration level for algal cultivation was found, and the productivities of biomass and lipids was specified. The work is published in peer-reviewed journal, Bioresource Technology.

Chlorella sp. microalgae were used in this study. It was isolated from local fresh-water habits by Utex and grown in a BG11 medium. Livestock waste compost from a local collection point was used. Windrow composting technology was applied to compost cattle waste. The compost was immersed in water, and stirred with a magnetic stirrer. The mixture was then filtered to eliminate non-soluble particulate solids.

Livestock waste compost medium was diluted using fresh water to four varying concentrations (200, 1500, 1000 and 500 mg L^-1 COD). The undiluted media and four diluted media were applied as cultures for microalgal cultivation for 10 days. For comparison, BG11 media (control group) were also used to grow algae. The livestock waste compost with the variable chemical oxygen demand concentrations were introduced into 0.4L flasks.  The optical density of Chlorella sp. was measured every day using spectrophotometer.

The authors determined the lipid contents of chlorella sp. in five cultures with varying nutrient concentration. The culture with the initial chemical oxygen demand concentration at 500 mg L^-1 experienced the highest algal lipid accumulation (44.30% of dry weight). They attributed this to the fact that low biomass concentration in the culture could make more algal cells access and receive more light that triggered and benefited lipid storage. As the initial chemical oxygen demand concentration increased from 500 mg L^-1 to 2680 mg L^-1 the lipid content decreased from 44.30% to 33.90%.

The authors also found that about one third to one fourth of lipids would be converted into fatty acid methyl esters; efficient biodiesel ingredients. This is because some lipids such as phospholipid, chlorophyll and glycolipid are not efficient ingredients for biodiesel production.

This study successfully found the optimal concentration level for algal cultivation and productivities of biomass. The authors concluded the following parameters: specific growth rate of Chlorella sp. grown in the five cultures ranged from 0.275 to 0.375 day^-1. Initial nutrient concentration affected lipid accumulation, and the lipid content ranged from 33.90% to 44.30%. The 2000 mg L^-1 chemical oxygen demand culture was found to be the optimum medium for algal cultivation, since the highest biomass and lipid productivities were realized.

This study was possible with partial funding from TranAlgae. A network of relevant stakeholders within the algae industry in the Botnia-Atlantica region with the aim of implementing innovative solutions for the production of micro- and macroalgae biomass from waste streams at industrial scale.

About The Author

Professor Zhaohua Li is the Dean of the School of Resources and Environmental Science. He was born in 1964 at Hubei Province in China, educated at China, the U.K. and Germany. His research spans including plant ecology, aquatic ecology, and environmental ecology.

Professor Li is of broad members of Chinese Geographical Association and Chinese Association of Agricultural Resources and Zonning. He received an Honorary of National Advanced Workers from Chinese government and more than 10 awards from Chinese ministries and Hubei Province. He has published 22 research works and 176 papers.

About The Author

Dr. Liandong Zhu is an assistant professor at the Faculty of Technology of the University of Vaasa and Vaasa Energy Institute, Finland. Through Talent Program, he has also been selected as a professor in several leading Chinese universities. In January 2014 he graduated from the University of Vaasa as a doctor in the area of biofuels. He is also the recipient of the Åbo Akademi Award and Chinese Government Award for Outstanding Self-financed Student Abroad. His background is environmental engineering and his doctoral and current research resides in biodiesel production by integration of microalgae cultivation with wastewater treatment.

Until now, he has published more than 50 papers in many esteemed peer-reviewed scientific journals, such as Water Research, Renewable and Sustainable Energy Reviews, Energy, Bioresource Technology, Applied Energy, Biofuels, Bioproducts and Biorefining (Biofpr) and Ecological Engineering. In total, the current impact factor (IF) of his papers has reached up to 101 points. According to Google Scholar, his papers have been well cited and the current H-index reaches 13. According to the Web of Science (ESI), three of his papers were marked as highly cited papers. In addition, Dr. Zhu serves as the Lead Guest Editor of the BioMed Research International, Associate Editor of the JSM Environmental Science & Ecology and the reviewer for more than 40 journals including Environmental Science & Technology, Water Research, Energy, Applied Energy, etc.

Currently Dr. Zhu is working on TransAlgae project, receiving funding from EU’s Botnia-Atlantica Programme. Dr. Zhu’s previous research has also been well reported by two local Finnish newspapers (Pohjalainen and Ilkka) on their cover pages. Dr. Zhu’s research interests fall into the scopes of wastewater treatment, biofuels, waste recycling, and sustainable development. Dr. Zhu welcomes all kinds of cooperation in research, project application, publications and academic exchange or visits.

Journal Reference

L.-D. Zhu^1,2,5, Z.-H. Li¹, D.-B. Guo³, F. Huang⁴, Y. Nugroho², and K. Xia². Cultivation of Chlorella sp. with livestock waste compost for lipid production. Bioresource Technology, volume 223 (2017), pages 296–300.

Show Affiliations

1. Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, and Faculty of Resources and Environmental Science, Hubei University, Wuhan 430062, China
2. Department of Energy Technology, Faculty of Technology, University of Vaasa, Vaasa 65101, Finland
3. School of Environmental Science & Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
4. Laboratory of Tropical Agro-Environment, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China
5. Renewable Energy Research Group, Vaasa Energy Institute, Vaasa 65101, Finland

 

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Renewable Energy Global Innovations features: Catalytic Combustion of Hydrogen for Residential Heat Supply Application

Significance Statement

Various means of deriving energy from hydrogen has been effectively studied as it serves as an important source of renewable energy. One of the means which involves catalytic combustion of hydrogen offers several advantages such as low temperature combustion and favorable heat supply.

Incorporation of a platinum catalyst in catalytic combustion of hydrogen achieves a low temperature process which is far more preferable for domestic heat supply uses. Despite this, there requires more knowledge on provision of a basic design of a catalytic hydrogen burner and an effective heat supply system at low temperatures.

Researchers at China Jiliang University designed an industrial-scale heat acquisition system based on hydrogen catalytic combustion with the aim of obtaining an improved combustion and heat efficiency coupled with a reduced effect of hydrogen combustion in air. The research work is now published in International Journal of Energy Research.

The authors synthesized 1wt% platinum catalyst in glass fiber felts via a wet impregnation process before installing them into a catalytic hydrogen burner of a stainless steel reactor with heat capacity of 1KW. The authors further fabricated a prototype heat supply based on the hydrogen catalytic combustion.

A stable heat supply by the simple regulation of hydrogen-to-air ratio became founding. The catalytic hydrogen burner was also capable of attaining a hydrogen conversion rate of 100% at different hydrogen-to-air ratio with respect to time.

Following authors’ fabrication of the prototype heat supply system, a heating efficiency of 82% found at the stable phase. This obtained efficiency was higher than that of the previously reported ones involving the catalytic hydrogen combustion process. The result also shows that an adequate heat supply could be gotten from the proposed catalytic hydrogen burner which would be of relevance to residential heat supply applications.

In addition to the required features attained, inhibition of catalytic hydrogen combustor which occurs at very low temperature as a result of presence of platinum catalyst could also be resolved during the cooling process of the burner.

Schematic diagram of the prototype heat supply system based on hydrogen catalytic combustion (1-air compressor; 2-hydrogen supply unit based on metal hydride storage pack; 3-flow rate controller; 4-pre-mixed chamber; 5-catalytic burner; 6-Pt loaded glass fiber felt catalyst; 7-aluminum clapboard; 8- thermocouples; 9-heat exchanger; 10-water tank; 11-system controller)

About The Author

Dr. Yuexiang Huang is currently a professor at China Jiliang University. He received his BSc degree in 1987 from Zhejiang University, and his PhD in 1998 from University of Aveiro, Portugal. He carried out postdoctoral research in Shanghai Institute of Metallurgy, Chinese Academy of Sciences, from 1999 to 2001. Since 2001, he then worked as a general manager in Tianjin Highland Energy Technology Development Co. Ltd, mainly responsible for the development of hydrogen storage alloys and its systems for fuel cells. In November 2007, he joined China Jiliang University.

He has received several awards, including the Elite returned postdoctor by Shanghai Personnel Bureau (2000), the K.C. Wong Education Foundation of Hong Kong (2000), the special-subsidized specialist by the State Council (2004), and the Third Prize for Progress in Science & Technology of Tianjin (2010) and the Third Prize of Natural Science Award of Zhejiang Province (2016).

His current research interests include the design and synthesis of functional energy materials for energy conversion and storage and environmental treatment, as well as the technological design for hydrogen energy applications.

Reference

Wang, S., Chen, L., Niu, F., Chen, D., Qin, L., Sun, X., Huang, Y. Catalytic combustion of hydrogen for residential heat supply application, International Journal of Energy Research 40 (2016) 1979-1985.

College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018, Zhejiang, China.

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Renewable Energy Global Innovations features: Strategies for Lipid Production Improvement in Microalgae as a Biodiesel Feedstock

Significance Statement

As the transition to cleaner energy grows, researchers have been working endless hours to achieve green energy that is economically feasible. Microalgae accepted as a source of cleaner energy and can replace use of cultivated crops as food feedstock. Moreover, microalgae present a promising alternative source for the production of biodiesel, due to a high lipid content in microalgal cells. During the photosynthesis of microalgae, neutral lipids are accumulated as triacylglycerols in microalgal cells, improving lipid content in microalgal cells would lead to a sustainable development of microalgal biodiesel.

To induce microalgal lipid accumulation, it involves application of feasible strategies. Liandong  Zhu and colleagues wrote a recent review published in BioMed Research International, aimed to bridge the gap and to systematically concentrate on the main lipid induction strategies that can evidently promote microalgal lipid production.

The authors discussed two types of lipids, neutral lipids that serve as the energy reserves and polar lipids that are constituents of organelles and membranes. To improve the lipid production, external cultivation conditions, such as light intensity, temperature, carbon dioxide, nutrient starvation, salinity stress, and metal stress must be considered.

From the researchers’ observation, positive light intensity increases lipid accumulation functions only up to a limit while extremely high light intensity will cause photoinhibition, damaging the microalgal photosystems, and thus reduce lipid accumulation. The effect of the temperature is said to be same as light intensity in that it varies directly with temperature. The salinity stress created inside the cells results in increment in the lipid content, on the other hand nutrient starvation was found to be feasible and environmentally friendly approach for the control of the cell cycle to enhance lipid productivity.

This paper strategized on promoting microalgae lipid production and the authors identified the application of nutrient starvation as the most efficient strategy to work with and optimum lipid production can be achieved by combining strategies together.

The research undertaken is partially funded by TranAlgae. This is a network of relevant stakeholders within the algae industry in the Botnia-Atlantica region with the aim of implementing innovative solutions for the production of micro- and macroalgae biomass from waste streams at industrial scale. This study is said to provide stakeholders, authorities, and practitioners with the foundation for better understanding microalgal lipid induction strategies and their significances in practice.

About The Author

Dr. Liandong Zhu is an assistant professor at the Faculty of Technology of the University of Vaasa and Vaasa Energy Institute, Finland. Through Talent Program, he has also been selected as a professor in several leading Chinese universities. In January 2014 he graduated from the University of Vaasa as a doctor in the area of biofuels. He is also the recipient of the Åbo Akademi Award and Chinese Government Award for Outstanding Self-financed Student Abroad.

His background is environmental engineering and his doctoral and current research resides in biodiesel production by integration of microalgae cultivation with wastewater treatment. Until now, he has published more than 50 papers in many esteemed peer-reviewed scientific journals, such as Water Research, Renewable and Sustainable Energy Reviews, Energy, Bioresource Technology, Applied Energy, Biofuels, Bioproducts and Biorefining (Biofpr) and Ecological Engineering. In total, the current impact factor (IF) of his papers has reached up to 101 points. According to Google Scholar, his papers have been well cited and the current H-index reaches 13. According to the Web of Science (ESI), three of his papers were marked as highly cited papers.

In addition, Dr. Zhu serves as the Lead Guest Editor of the BioMed Research International, Associate Editor of the JSM Environmental Science & Ecology and the reviewer for more than 40 journals including Environmental Science & Technology, Water Research, Energy, Applied Energy, etc.

Currently Dr. Zhu is working on TransAlgae project, receiving funding from EU’s Botnia-Atlantica Programme: http://ift.tt/2oTKlXK. Dr. Zhu’s previous research has also been well reported by two local Finnish newspapers (Pohjalainen and Ilkka) on their cover pages. Dr. Zhu’s research interests fall into the scopes of wastewater treatment, biofuels, waste recycling, and sustainable development. Dr. Zhu welcomes all kinds of cooperation in research, project application, publications and academic exchange or visits.

About The Author

Professor Zhaohua Li is the Dean of the School of Resources and Environmental Science. He was born in 1964 at Hubei Province in China, educated at China, the U.K. and Germany. His research spans including plant ecology, aquatic ecology, and environmental ecology. Professor Li is of broad members of Chinese Geographical Association and Chinese Association of Agricultural Resources and Zonning.

He received an Honorary of National Advanced Workers from Chinese government and more than 10 awards from Chinese ministries and Hubei Province. He has published 22 research works and 176 papers.

About The Author

Erkki Hiltunen is a Professor and Research Director of the Faculty of Technology of the University of Vaasa, Finland. He is also the leader of Renewable Energy Research Group of the Faculty of Technology of the University of Vaasa.

His research interests are renewable energy, environmental protection and sustainable development. He has published more than 80 articles in journals and conference proceedings.

Journal Reference

L.D. Zhu^1,2, Z. H. Li², and E. Hiltunen¹, Strategies for Lipid Production Improvement in Microalgae as a Biodiesel Feedstock, BioMed Research International, Volume 2016 (2016), Article ID 8792548, 8 pages.

Show Affiliations

1. Faculty of Technology, University of Vaasa and Vaasa Energy Institute, P.O. Box 700, 65101 Vaasa, Finland
2. Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources and Faculty of Resources and Environmental Science, Hubei University, Wuhan 430062, China

 

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Renewable Energy Global Innovations features: Biorefinery as a Promising Approach to Promote Microalgae Industry: An Innovative Framework

Significance Statement

Microalgae, which grow in aquatic environments, are widely used as feedstock for traditional applications in cosmetics, pharmacy and nutrition sectors. In response to energy crisis, such as global warming and climatic changes, biofuels a renewable and alternative energy types have become the spotlight of research in an effort to search for sustainable development. Microalgae, which constitute lipids, carbohydrates and proteins in large amounts, have come under increased research interest with regard to the production of biofuels. The microalgae has advantages such as high photosynthetic efficiency, high lipid content, noncompetition for farmlands, and toleration to wastewaters during cultivation, applications appear to be strongly economically convenient only in conjunction with wastewater treatment.

Dr. Liandong Zhu from University of Vaasa in Finland mapped an innovative biorefinery for microalgae industry development in an effort to search for a better understanding of microalgae-based biofuel production scenarios and paths forward for microalgal research and commercialization. The research is now published in Renewable and Sustainable Energy Reviews.

Prior to this research, many studies have been carried out to analyze the economic feasibility of commercializing microalgae production for biofuel use. Commercialization of microalgae production as fuel is feasible from the technical point of view, but from the economical point of view, it is yet to reach an acceptable level. The author pointed out that large scale microalgae cultivation can only be achieved by combining technical breakthroughs and innovative pathways.

To make microalgae production more economical, the microalgae product market sizes and their values needs to be reviewed, that is the cost gap between microalgae biofuels and fossil fuels must be reduced or closed and also cater for the leftovers after high values of microalgae biofuels are produced.

He also suggested multi-production through microalgae biorefinery. The microalgae biorefinery which involve different system integration and engineering technologies will not only produce multiple products but also maximize the value derived from different microalgae components.

To examine the feasibility of this work, two assessments were carried out that is relative net energy ratio and cost-effective assessment. The net energy ratio is calculated from energy lifecycle assessment perspective as the ratio of total energy produced to the energy required for all relative plant construction and operation. And the higher the net energy ratio, the positive the biorefinery chain will be.

This study also mapped out an innovative frame work which includes cultivation technologies developed on the basis of the desired end product, exploring new markets for high values, integration of both traditional microalgal industry and biofuel corporate, and creating of policy beneficial to microalgal biofuel development.

Finally the author concluded in his study that high-value products can help drive the economy through systematic integration and engineering application in microalgae biorefinery.

About The Author

Dr. Liandong Zhu is an assistant professor at the Faculty of Technology of the University of Vaasa and Vaasa Energy Institute, Finland. Through Talent Program, he has also been selected as a professor in several leading Chinese universities. In January 2014 he graduated from the University of Vaasa as a doctor in the area of biofuels. He is also the recipient of the Åbo Akademi Award and Chinese Government Award for Outstanding Self-financed Student Abroad.

His background is environmental engineering and his doctoral and current research resides in biodiesel production by integration of microalgae cultivation with wastewater treatment. Until now, he has published more than 50 papers in many esteemed peer-reviewed scientific journals, such as Water Research, Renewable and Sustainable Energy Reviews, Energy, Bioresource Technology, Applied Energy, Biofuels, Bioproducts and Biorefining (Biofpr) and Ecological Engineering. In total, the current impact factor (IF) of his papers has reached up to 101 points. According to Google Scholar, his papers have been well cited and the current H-index reaches 13. According to the Web of Science (ESI), three of his papers were marked as highly cited papers.

In addition, Dr. Zhu serves as the Lead Guest Editor of the BioMed Research International, Associate Editor of the JSM Environmental Science & Ecology and the reviewer for more than 40 journals including Environmental Science & Technology, Water Research, Energy, Applied Energy, etc.

Currently Dr. Zhu is working on TransAlgae project, receiving funding from EU’s Botnia-Atlantica Programme: http://ift.tt/2oTKlXK. Dr. Zhu’s previous research has also been well reported by two local Finnish newspapers (Pohjalainen and Ilkka) on their cover pages. Dr. Zhu’s research interests fall into the scopes of wastewater treatment, biofuels, waste recycling, and sustainable development. Dr. Zhu welcomes all kinds of cooperation in research, project application, publications and academic exchange or visits.

Journal References

Liandong Zhu^1,2, Biorefinery as a Promising Approach to Promote Microalgae Industry: An Innovative Framework, Renewable and Sustainable Energy Reviews 41 (2015) 1376– 1384.

Zhu, Huo, Shakeel and Li , Algal biorefinery for sustainable development and the challenges. Proceedings of the Institution of Civil Engineers, Energy 169 November 2016 Issue EN4, Pages 179–186.

Show Affiliations

1. Faculty of Technology, University of Vaasa, FI65101 Vaasa, Finland
2. Department of Civil and Environmental Engineering, Aalto University, FI00076 Espoo, Finland

 

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Renewable Energy Global Innovations features: Benchmarking of five typical Meteorological year Datasets dedicated to Concentrated-PV Systems

Significance Statement

Accurate analysis of meteorological and pyranometric data for long-term prediction is the basis of the conception and development, so as decision-making for banks and investors, regarding solar energy conversion systems, either photovoltaic (PV) concentrated solar power (CSP) or concentrated photovoltaic (CPV). This has led to the development of methodologies for the generation of Typical Meteorological Years (TMY). A TMY is a customized weather dataset of one-year of meteorological data that aims at representing climatic conditions judged to be typical over a long-term period. A TMY dataset has 12 calendar months. The most representative block of monthly data for each calendar month is selected based on the smallest Filkenstein-Schafer distance measuring the difference of two cumulative distribution functions.

The “standard” method for solar energy conversion systems was proposed in 1978 by the Sandia Laboratory. In 2012, a new approach was proposed in the framework of the European project FP7 ENDORSE introducing the concept of “driver” time series defined by the user as a function of the pyranometric and meteorological relevant variables to improve the representativeness of the TMY datasets with respect the specific solar energy conversion system of interest.

Ana M. Realpe and colleagues from SOLAÏS, MINES ParisTech and NEOEN, in France benchmarked the classical Sandia method of TMY generation with innovative methods based on the driver concept, in the particular case of a given CPV system in a given site. The research work is now published in Energy Procedia.

According to the team, using 18-year data of the meteorological station Desert Rock (United States), five types of TMY were created using hourly and 1-minute data. The construction of the meteorological year is achieved by comparing the CDF of each block of data at a given month to the CDF of the concatenation of all blocks of data for this month over the long-term. The energy generation output of the concentrated photovoltaic system over the long-term 18-years period was the quantity used for the comparison between the different TMY datasets. The team used a simulation tool for each TMY as input to determine the yield of the concentrated photovoltaic system. Then two analyses were performed: one comparing the long-term average yield with the yield associated to the TMY datasets and another comparing the corresponding CDFs using the Kolmogorov-Smirnov test Integral parameter (KSI), in order to measure the distance between two cumulative distribution functions.

The team found out that the monthly results obtained from the drivers, with hourly and 1-min data, are significantly better than those obtained with the Sandia method. The maximum annual deviations obtained with the Sandia method and with the drivers have no consistent pattern. From the monthly KSI test, the team observed that the maximum monthly deviations from the Sandia method approach exceed twice the deviations obtained by the drivers. Considering the annual KSI, the simplified and filtered drivers provide relative KSI values systematically less than 45 % from 8-year data.

Researchers were able to compare the innovative method which is based on driver concept, by using classical Sandia method as reference point. They found the driver concept to be more promising and efficient than the classical Sandia method.

About The Author

Ana Maria Realpe received her degree in Electrical Engineering from the Simon Bolivar University of Venezuela, in 2009. She carried out her research internship in the Fraunhofer Institute of Solar Energy in Germany, about the development of an encapsulation technique for Compact Concentrated Modules (CCM) used in high concentration photovoltaic (HCPV) systems. In 2011, she received her European Master’s degree in renewable energies (EUREC) from the Ecole MINES ParisTech in France, with a specialisation in hybrid systems at the Kassel University in Germany.

She joined SOLAÏS in 2012 where she has been continuously working in research and development projects with close collaboration with ARMINES / MINES ParisTech on various topics so as material assessment, mechanical structures and aerodynamic studies and solar resource analysis.

She is responsible of the innovation in SOLAÏS and leads the R&D activities related to the glare problematics regarding PV projects that may jeopardize the transportation safety (airports, networks of railways and motorways).

About The Author

Sébastien Pitaval is graduated from Ecole Nationale Supérieure d’Electrotechnique, d’Electronique, d’Informatique, d’Hydraulique et de Télécommunications (2000, Toulouse, France), with specialization in fluid mechanics and energy. He started his career working in the space industry, for Alcatel Space Industries then Thalès Alenia Space (2000-2008), occupying successive management positions for Herschel and Planck satellites: propelling system, Attitude and Orbit Control Systems (AOCS) then system integration.

His interest and convictions regarding renewable energies and his entrepreneurial spirit led him to co-create SOLAÏS in 2008. He developed R&D, Engineering and Export activities while setting up Corporate Social Responsability (CSR) within the company. He is also judicial expert at the Court of Appeal of Aix-en-Provence (France).

About The Author

Christophe Vernay is graduated from Ecole Supélec (1997), a general engineering school in France. He started his career by working in the space industry, for Alcatel Space Industries (1998-2001), as a Research Engineer in Attitude and Orbit Control Systems (AOCS). Then, he worked in the Telecom industry for Nortel Networks then Alcatel-Lucent (2001-2010) on several positions, from the integration to the engineering of 3G and 4G systems. His interest and convictions regarding renewable energies led him to attend photovoltaic and wind-power courses in 2010 at the Conservatoire national des arts et métiers (CNAM), Paris. In 2011, he post-graduated from Ecole Nationale Supérieure d’Arts et Métiers (ENSAM) with a specialized Master’s Degree in renewable energy.

He carried out its professional thesis in SOLAÏS, a French consulting company dedicated to photovoltaic, in collaboration with MINES ParisTech / Armines, about the characterizing of the measurements campaigns of the global irradiation. Since then, he is Technical Director in SOLAÏS, in charge of R&D, engineering, technical due diligence and commissioning.

Linkedin with publications 

About The Author

Prof. Philippe BLANC is graduated from the engineering school Telecom Bretagne (Ecole Nationale Supérieure de Télécommunications de Bretagne) and received his PhD degree from the MINES ParisTech in 1999 in the field of engineering sciences and applied mathematics. He has been working as a research engineer for Thales Alenia Space in signal and image processing and data fusion for Earth Observation systems and various projects where scientific support in signal and image processing, statistics, algorithmic prototyping and applied mathematics is required. He joined ARMINES / MINES ParisTech in 2007. He is working on the modelling of solar radiation and its assessment from in situ measurements or/and satellite images.

He is the head of the research group involved in renewable energy resource assessment within the research center Observation, Impacts, Energy. He has passed in 2015 his professoral habilitation (Habilitation à Diriger des Recherches) and is Professor at MINES ParisTech since then. In addition, he is currently a sub-task Leader of the Task 16 of the International Energy Agency program PVPS and associate editor for the Elsevier journal Solar Energy of the International Solar Energy Society (ISES).

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Reference

Ana M. Realpe¹, Christophe Vernay¹, Sébastien Pitaval¹, Camille Lenoir², Philippe Blanc³, Benchmarking of five typical Meteorological year Datasets dedicated to Concentrated-PV Systems, Energy Procedia 97 ( 2016 ) 108 – 115.

Show Affiliations

1. SOLAÏS, 400 avenue Roumanille, BP 309, F-06906 Sophia Antipolis Cedex, France.
2. NEOEN, 4 rue Euler, 75008 Paris, France.
3. MINES ParisTech, PSL Resear University, O.I.E. – Center of Observation, Impacts, Energy, 1 Rue Claude Daunesse, CS 10207, F-06904 Sophia Antipolis Cedex, France.

 

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