Renewable Energy Global Innovations features: Theoretical Analysis for The Centrifugal Effect On Premixed Flame Speed in A Closed Tube

Significance Statement

The effect of centrifugal acceleration on the mixed flame speed has over time been observed to be significantly important in both theoretical research and engineering application. Recently, empirical investigations on the novel inter-turbine burner engine and the Ramgen engine have shown that they possess significant benefits on performance, since they apply the concept of combustion in high centrifugal fields. Previous studies on centrifugal forces have revealed that high centrifugal acceleration possess significant strengthening effect on combustion. On the contrary, little exists on the adaptation, derivation and harnessing of this power in written academia.

Researchers led by professor Yong Huang at the Collaborative Innovation Center of Advanced Aero-Engine, National Key Laboratory of Science and Technology, School of Energy and Power Engineering, Beihang University described the effect of centrifugal acceleration, specifically high centrifugal acceleration of more than 200 times the gravitational acceleration, on the premixed flame speed in a rotating closed tube. Their main objective was to derive a theoretical predicted correlation which would describe the laminar premixed flame speed in a centrifugal field with the aid of directly solving simplified governing equations on 1-D steady adiabatic flame by theoretical analysis. Their research work is now published in International Journal of Hydrogen Energy.

The research team begun by employing the 1-D steady adiabatic flame model which was fixed. The team then obtained the premixed flame speed in a rotating closed tube after considering the amplification effect of the closed tube on the laminar premixed flame speed. The researchers then, using the predicted correlation, obtained the physical mechanisms of the premixed flame speed in a rotating closed tube.

The authors observed that the flame speed accelerated by the centrifugal force was nearly proportional to the square root of the centrifugal acceleration in the rotating closed tube. The team also noted that the theoretical prediction was also able to revealed that the flame speed in a rotating closed tube was determined by the initial temperature, the critical ignition temperature, the adiabatic flame temperature and the thicknesses of reaction zone. Eventually, the premixed flame speed in a rotating closed tube was seen to increase nearly linearly with the increasing of the initial temperature or square root of the thicknesses of reaction zone, or with decreasing of the critical ignition temperature or the adiabatic flame temperature.

Herein, a theoretical analysis to study the effect of centrifugal acceleration, especially high centrifugal acceleration, that is, more than 200 times the gravitational acceleration of earth, on the premixed flame speed has been successfully presented. More importantly, a theoretical predicted correlation has been proposed to describe the premixed flame speed in a rotating closed tube. The results of the theoretical prediction have been seen to agree well with the empirical data obtained by Lewis & Smith. The result of the study verifies that the flame speed accelerated by the centrifugal force is nearly proportional to the square root of the centrifugal acceleration.

About The Author

Dr. Yong Huang is the chief professor in the Department of thermal power engineering, School of Energy and Power Engineering, Beihang University, Beijing, China. He was granted Bachelor Degree from Tsinghua University in 1985. Then, he obtained Master Degree and Doctoral Degree in Beihang University. He did postdoctoral research in Hong Kong University of Science and Technology.

He is one of the top experts in the field of gas turbine combustion in China. In the past years, he has won the second prize of science & technology improvement by Ministry of Aviation Industry of PRC(1993), the third prize of science & technology improvement by Ministry of Aviation Industry of PRC(1993), the second prize of science & technology improvement by Ministry of National Defence(2004).

His main research interests include the mechanism and prediction of ignition and lean blowout in gas turbine combustors, mechanism of atomization and design of atomizers, performance prediction of low pollution combustors, flow field analysis in combustors, and multipoint lean direct injection combustors, etc.

He proposed the concept of Flame Volume(FV) model to improve the prediction of lean blowout limit derived by Lefebvre. This is an important breakthrough for gas turbine combustors in recent years. And he proposed the concept of flame mixing time (FMT) to estimate the NOx formation and obtain good agreement with the experimental data done by NASA that was ever wrongly predicted by other methods. Besides, he firstly proposed the concept of loss of rotational kinetic energy in pressure swirl atomizers due to liquid viscosity to predict the spray cone angle of pressure swirl atomizers. His course, combustion and combustor, is one of excellent courses in Beihang University. He has published more than 150 academic papers.

Contact: yhuang@buaa.edu.cn

About The Author

Dr. Lei Sun is a PhD candidate in the Department of thermal power engineering, School of Energy and Power Engineering, Beihang University, Beijing, China. He was granted Bachelor Degree from Beihang University in 2012. He was a visiting researcher in Hokkaido University, Japan in 2016.

He is experienced in mathematical modeling and theoretical analyses for physical phenomena. He has won the first prize of National Mathematics Competition for College Students(2011), the second prize of National Physics Competition for College Students(2010), the third prize in the Zhou Pei-Yuan Mechanics Competition for College Students(2011), etc. His research topics include the mechanism and prediction of lean blowout in gas turbine combustors, multipoint lean direct injection combustors, and mechanism of atomization, etc. He has published 8 academic papers.

Contact: sunlei1988@buaa.edu.cn

About The Author

Ms. Yingyi Ji is an engineer of gas turbine engine in Aero Engine Corporation of China. She was granted Bachelor Degree from Beihang University in 2013. She received her master degree in Aeronautical Engineering from Beihang University in 2016, researching on the centrifugal effect on premixed flame speed and the optimization design on diffuser of lean direct injection combustor.

Her recent research includes heat transfer of perforated plate, Oxygen-deficient Combustion in low speed gas flow.

Contact: jiyingyi0319@sina.com

Reference

Lei Sun, Yong Huang, Yingyi Ji. Theoretical analysis for the centrifugal effect on premixed flame speed in a closed tube. International Journal of Hydrogen Energy, volume 42(2017) pages 18658 – 18667.

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Renewable Energy Global Innovations features: Molecularly Imprinted Polymer Enables High-Efficiency Recognition and Trapping Lithium Polysulfides for Stable Lithium Sulfur Battery

Significance Statement

Molecularly imprinted polymers have in recent times been attracting widespread interest especially arising from their application in the development of tools for organic synthesis as a result of their high specificity, easy availability, stability and low cost. These synthetic polymers are fabricated by polymerizing polymerizable reagents in the presence of a template. More so, these molecularly imprinted polymers have the capability to selectively reorganize and bind target molecules with tailor made molecular recognition binding sites. With such binding capabilities, molecularly imprinted polymers have been widely applied in catalysis, analytical chemistry, water treatment, sensors and biochemistry field.

However, their potential can still be tapped by constructing different binding sites which would in turn yield new applications. Consequently, the mutual demand for clean energy from modern industries inclusive of military power supplies, civil transportation and stationary storage have placed urgent demands on the energy density of the battery. Lithium-sulfur batteries have been considered promising for powering portable electronics because they have an overwhelming advantage in energy density.

Prof. Chenglin Yan and colleagues from Soochow University in China proposed a breakthrough study on the adaptability of molecularly imprinted polymers to enable high efficiency recognition and trapping of lithium polysulfides for the development of stable lithium-sulfur battery. The researchers aimed at exploiting the ability of the molecularly imprinted polymers to recognize and target specific molecules. Their research work is now published in Nano Letters.

The researchers commenced their empirical procedure by preparing molecularly imprinted polymers with Lithium-Sulphur recognition characteristics by polymerization of acrylamide monomer molecular with tetraglyme catholyte as the target template. Polymerization by initiation at 70⁰C with azodiisobutyronitrile as the initiator was then effected. Eventually, the removal of template molecule by anhydrous dimethylformamide washing and cyclic voltammetry scans, that left featured binding sites in the polymer matrix was done.

The research team observed that the approached they used, permitted them achieve a high capacity retention of over 82% after just 400 cycles at one coulomb. They also noted that the UV/vis spectroscopy revealed low concentrations of tetraglyme catholyte in the electrolyte indicating that the molecularly imprinted polymers matrix has excellent ionic sieving ability to tetraglyme catholyte during electrochemical cycle. More so, the visual characterization gave direct evidence on the affinity and absorbability of molecularly imprinted polymers to tetraglyme catholyte, which was theoretically confirmed by density functional theory calculations.

Herein, a new strategy of using molecularly imprinted polymers as recognition sites for polysulfides in Lithium-Sulphur battery system so as to trap long chain polysulfides, has been brought forward. Acrylamide and tetraglyme catholyte molecule have been employed as functional monomer and template, respectively, for the construction of molecularly imprinted polymers material, which can constraint tetraglyme catholyte in the molecularly imprinted polymers matrix by rebinding the target molecules. Undoubtedly, the original design demonstrated here opens a new direction of the electrochemical application of molecularly imprinted polymers materials in Lithium−Sulphur batteries.

About The Author

Chenglin Yan is a full professor at Soochow University and executive director of key laboratory of advanced carbon materials and wearable energy technology in Suzhou, China. He received his PhD from Dalian University of Technology in 2008. In 2011, he became a staff scientist and a group leader at the Institute for Integrative Nanoscience at the Leibniz Institute in Dresden. In 2013, the IFW-Dresden awarded Dr Chenglin Yan the IIN Research Prize 2013 for his group’s research work. He received the Thousand Young Talents Award from the Chinese Thousand Talents Program in 2014.

Reference

Jie Liu, Tao Qian, Mengfan Wang, Xuejun Liu, Na Xu, Yizhou You, and Chenglin Yan. Molecularly Imprinted Polymer Enables High-Efficiency Recognition and Trapping Lithium Polysulfides for Stable Lithium Sulfur Battery. Nano letters 2017, volume 17, pages 5064−5070.

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Renewable Energy Global Innovations features: Cloud Energy Storage for Residential and Small Commercial Consumers: A Business Case Study

Significance Statement

Both industry and academia have with time come to recognize the significance and potential of energy storage as a prospective resource that can help create a balance between generation and load in power systems. Presently, the world is migrating towards renewable resources with variable renewable energy sources such as wind and photovoltaics. Maintaining the stability of a power system requires real-time balancing of the energy that is consumed and produced. Recent trends are focusing on utilizing distributed energy storage systems by both small residential and commercial users so as to integrate variable renewable energy and reduce electricity bill. Cost, policy, and control efficiency limit the profitability of distributed energy systems and hinders the incentive of both small residential and commercial consumers to purchase the distributed energy storage systems. Among recent power grid and internet technological advances, resource sharing make possible a better utilization of distributed energy systems resources.

Tsinghua University and University of Washington researchers developed a novel way of using energy storage – cloud energy storage – a grid-based storage service that enables ubiquitous and on-demand access to a shared pool of grid-scale energy storage resources. The team aimed at describing how this state of the art technology would be realized and how it is capable of providing energy storage services at substantially lower cost. They also described the cloud energy storage enabling technique that supports both the needs of residential distributed energy systems and the optimal operation of storage resources. Their research work is now published in Applied Energy.

Chongqing Kang and colleagues commenced by conducting empirical works where by, firstly, they proposed the concept of cloud energy storage which utilized central energy storage facilities to provide distributed storage services to residential and small commercial users. They then developed and described the architecture, enabling technologies and operation mechanisms that would facilitate the cloud energy storage. The team then designed the business model of cloud energy storage and demonstrated its profitability using real life residential load and electricity data.

The authors observed that cloud energy storage users can use their cloud batteries just like real energy storage devices. Based on the case study on actual residence load data and electricity price, the team noted that social benefits including, the minimal influence on the percentages of social welfare improved by cloud energy storage due to lower unit price as a result of energy storage. In totality, it was seen that cloud energy storage was more economical than distributed energy systems since the economies of scale has a significant influence on the economy of cloud energy storage.

Chongqing Kang and colleagues successfully described novel concept-cloud energy storage. This new service has the potential to provide the same services as the presently used distributed energy system does, but now at a lower social cost. Its future is so great in that it has the potential to, one day, gather fragments of energy storage resources such as electric vehicles, uninterrupted power supplies and residential distributed batteries. More so, the cloud energy storage business model can presently be merged into some current business models as value-added services.

About The Author

Jingkun Liu is currently a public official in the government of Shuyang Town, Xianghe County, Hebei Province, China. He received his Bachelor’s degrees of Electrical Engineering and Economics from Tsinghua University in 2012 and Peking University in 2013, respectively. He received his Ph.D of Electrical Engineering from Tsinghua University in 2017. He was a visiting student in the University of Washington, Seattle from Sep. 2015 to Sep. 2016.

 His research interests focus on energy storage in power system and power system reliability.

About The Author

Ning Zhang is an associate professor in the Department of Electrical Engineering, Tsinghua University. He got his B.Sc. degree from Tsinghua University, Beijing, China in 2007. He got his Ph.D in electrical engineering with Excellent Doctoral Thesis Award and Excellent Graduate Student Award from Tsinghua University in 2012. After he completed two-year research as a post doctor, he started working in Tsinghua University as a Lecturer in 2014. He was a research associate in The University of Manchester from Oct. 2010 to Jul. 2011 and a research assistant in Harvard University from Dec. 2013 to Mar 2014. He was awarded Yong Elite Scientists Sponsorship Program by Chinese Association of Science and Technology in 2016. His paper is awarded one hundred most influential papers and top articles in outstanding S&T journal of China.

 His research interests include multiple energy system, power system planning and operation with renewable energy (wind power photovoltaic, concentrated solar power).

About The Author

Chongqing Kang is a full professor and the Chairman of Executive Committee of Department of Electrical Engineering. He holds Bachelor’s degrees of both Electrical Power Engineering and Environmental Engineering in 1993, and a Ph.D in Electrical Power Engineering from Tsinghua University in 1997. He has been appointed Professor of Electrical Engineering Department of Tsinghua University since 2005. From 2011 to 2014 he was the Director of Centre for Teaching Excellence, Tsinghua Univ.

He is the recipient of the National Science Fund for Distinguished Young Scholars. He is Fellow of IEEE and IET. He is the senior member of CSEE. He has been on the editorial board of 5 international journals including IEEE Transactions on Power Systems and Electric Power Systems Research and 6 Chinese journals indexed by EI. He won the second prize of National Teaching Achievement Award in 2014. He and his team was granted the Institute Prize in Global Energy Forecasting Competition in 2014. He was granted one gold award and one silver award in the 44th International Exhibition of Inventions in Geneva in 2016.

 His research interests include power system planning, power system operation, renewable energy, low carbon electricity technology, load forecasting and electric market.

About The Author

Daniel S. Kirschen was appointed Close Professor of Electrical Engineering in 2011. From 1994 to 2010, he was Professor of Electrical Energy Systems and Head of the Electrical Energy and Power Systems research group at the University of Manchester in the UK. Prior to joining the academic world, he worked for Control Data Corporation and Siemens-Empros on the development of advanced application software for electric utilities.

His research interests include Integration of renewable energy sources in the grid, power system operation, power system economics, and resilience of the grid to natural disasters.

About The Author

Qing Xia is now a professor at Tsinghua University, Beijing, China. He received his Ph.D. degree from the Department of Electrical Engineering at Tsinghua University in 1989.

 His research interests are mainly power economics, power markets, power system expansion planning, power system reliability, power system load forecasting, and smart grids.

Reference

Jingkun Liu, Ning Zhang, Chongqing Kang, Daniel Kirschen, Qing Xia. Cloud energy storage for residential and small commercial consumers: A business case study. Applied Energy volume 188 (2017) pages 226–236

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Renewable Energy Global Innovations features: Copper nanowire/multi-walled carbon nanotube composites as all-nanowire flexible electrode for fast-charging/discharging lithium-ion battery

Significance Statement

With the rapid evolution of autonomous vehicles, electric vehicles are anticipated to continue to grow rapidly. The electric vehicles offer many benefits such as zero emissions, less noise and vibrations, and are operated by simple electric motors with energy conversion in the range of 80-90%. Electric vehicles also have superior energy resilience since they can be charged using a number of energy sources such as renewable energy, conventional power-plant energy, and regenerative braking energy.

Unfortunately, the electric vehicles suffer some limitations such as cost, safety, mileage, limited lifespan, long charging time, and lack of grid for charging. These problems have led to the development of power systems with Lithium-ion batteries. In a bid to fix cost and mileage issues, the energy density of lithium-ion batteries must be increased, and the only way to improve the energy density would be to come up with new active materials with high theoretical capacity for anodes and cathodes.

Although high capacity materials can be applied to the Li-ion batteries, Li-ion batteries would still take long time to charge owing to their low power densities. Unfortunately, even the recently developed fast chargers with pulse power cannot overcome energy-density fading in the course of high-current charge/discharge reference to the limitation in the energy-conversion reaction of Li-ion batteries.

Researchers led by Professor Youn Sang Kim at Seoul National University, Republic of Korea, proposed a novel all-nanowire electrode structure for fast-charging-discharging Li-ion batteries implementing copper nanowires and multi-walled carbon nanotubes without binders or even conductive agents. Theoretically, the multi-walled carbon nanotubes as the representative one-dimensional carbon-based nanostructure provided fast channels for the effective transport of both electrons as well as ions for Li-ion batteries owing to their unique features that had high aspect ratio as well as large surface area. However, the large voltage range between charging and discharging is normally limited the multi-walled carbon nanotubes to be used for active materials in full cells, due to their morphology and resistivity. The authors firstly overcame this limitation of multi-walled carbon nanotubes, and their work is published in peer-reviewed journal, Nano Research.

The authors fabricated a lightweight 3-dimensional composite anode for a fast charging-discharging Li-ion battery implementing two of 1-dimensional nanomaterials, which were copper nanowires and multi-walled carbon nanotubes. Reference to superior electrical conductivity, large surface areas, and high aspect ratio of these materials, the copper nanowire-multi walled carbon nanotubes composite with 3-dimensional structure provided several advantages concerning transport channels of ions and electrons.

The copper nanowires applied as the current collector and multi-walled carbon nanotubes applied as the active materials provided a number of benefits for enhancing the Li-ion battery performances. These included efficient ion diffusion, thick electrode formation, fast electron transport, and flexible cell design. As an advanced binder-free anode, the proposed composite film with tunable thickness indicated a significant low sheet resistance and internal cell resistance. The copper nanowires network with 3-dimensional structure functioned as a rigid framework connected to the multi-walled carbon nanotubes. They prevented the shrinkage and expansion of the multi-walled carbon nanotubes owing to swelling and aggregation, and minimized the effects of volume change of the carbon nanotubes during the charging-discharging process.

Both the full and half-cells of the Li-ion batteries with 3D-composite film anode indicated high specific capacities and Coulombic efficiencies even at high currents. The authors were able to overcome, for the first time, the limitations of carbon nanotubes as anode materials for fast charging and discharging Li-ion batteries by implementing copper nanowires, and the proposed anode can be used in flexible Li-ion batteries. This new development could result in the development of ultrafast chargeable Li-ion batteries for electric vehicles.

About The Author

Zhenxing Yin completed his Bachelor’s studies at Changchun University of Technologies (China) in 2012. Then, he received his Master’s degree at Seoul National University (Republic of Korea) in 2014, and is currently a Ph.D. candidate at Graduate School of Convergence Science and Technology, Seoul National University. His research interests mainly focus on copper nanowire synthesis and applications.

About The Author

Prof. Jeeyoung Yoo is the research professor in Graduate School of Convergence Science and Technology, Seoul National University at Seoul, Korea. A graduate of Chung-Ang University, she holds a Bachelor of Chemical Engineering, Master of Chemical Engineering, and PhD in Chemical Engineering, specializing in electrochemical engineering. And she is an expert in energy storage materials and device-related research and development.

About The Author

Prof. Youn Sang Kim is the Professor in Graduate School of Convergence Science and Technology, Seoul National University at Seoul, Korea. He received Ph.D. in the Department of Chemical Engineering from Seoul National University at Seoul, Korea in 2002 and then worked for two years as a postdoctoral fellow in Massachusetts Institute of Technology, USA. His current research interests are concentrated on interface engineering for novel devices such as energy harvesting devices, oxide or hybrid TFTs, oxide diodes and printing electronics.

Reference

Zhenxing Yin, Sanghun Cho, Duck-Jae You, Yong-keon Ahn, Jeeyoung Yoo, and Youn Sang Kim. Copper nanowire/multi-walled carbon nanotube composites as all-nanowire flexible electrode for fast-charging/discharging lithium-ion battery. Nano Res. 2017, DOI: 10.1007/s12274-017-1686-0.

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Renewable Energy Global Innovations features: CH3NH3PbI3 Converted from Reactive Magnetron Sputtered PbO for Large Area Perovskite Solar Cells

Significance Statement

Exponential growth in both interest and attention paid to the organic-inorganic metal halide perovskites materials have spiked undeniable concern of late. The outstanding properties possessed by these materials carry all the credit. These properties, including: long exciton diffusion length, strong absorption coefficients, low cost, ease of Synthesis and environmental-friendliness have led to great advancement in perovskite solar cells such as improving the power conversion efficiency from around ten percent in the early years of this decade to about twenty percent at present. Recent studies have shown that the quality and morphology of the perovskite films are crucial to its photoelectric properties and that they directly influence the performance of the resultant perovskite solar cells. Even though several deposition techniques have been proposed for synthesis of the perovskite light-absorption layers, great difficulties are still being encountered in the bid to fabricate perovskite films with both satisfactory coverage and uniformity over a large area.

Researchers led by Professor Meicheng Li at the State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources in North China Electric Power University developed a novel process route based on direct current reactive magnetron sputtering in the preparation of the CH₃NH₃PbI₃ film. They aimed at presenting a complete approach for the fabrication of large area perovskites solar cells with the advantages of easy control, economical and requiring less use of toxic reagents but with diverse potential applications. Their research work is now published in Solar Energy Materials & Solar Cells.

The research team began by fabricating the lead oxide film on an FTO-glass substrate coated with a nanocrystalline rutile titania by using a pure metallic lead target in an argon-oxygen mixture. They then converted the prepared lead oxide film to CH₃NH₃PbI₃ through the sequential reactions setup in isopropanol solution of CH₃NH₃I. Eventually, the research team fabricated solar cells of a complex structure that employed nanocrystalline rutile titania as the contact layer of the photovoltaic devices.

The authors were able to observe that the as-prepared perovskite film exhibited a surface morphology of high uniformity and excellent coverage over a large scale. Also the crystal grains were seen to reach the size of up to 600 nm, which is beneficial to extract photo-generated electrons more effectively and prepare the perovskites solar cells at low temperature.

The new approach employed in their study is technically spin-coating-free for the formation of large area CH₃NH₃PbI₃ film and exhibits advantages ranging from easy process control, economical all the way to less use of toxic reagents. Of crucial importance, it is expected that this novel technique will be applied for the synthesis of perovskites solar cells or other thin-film devices and thus entails potential applications and practical significance.

The schematic illustration of CH3NH3PbI3 formation (on NRT-coated FTO glass substrate) through the sputtered PbO.

The top-view SEM of CH3NH3PbI3 converted from the sputtered PbO, where the insertions are the corresponding one with high magnification.

About The Author

Zhirong Zhang is a Ph.D candidate, who studied at the State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources in North China Electric Power University, under the supervision of Prof. Meicheng Li. He received his B.S. degree majored in Radio Physics, from Lanzhou University, in 2008. His research interests include development of thin film solar cells and the design & application of photovoltaic system. He has been working on perovskite solar cells since the year of 2013.

About The Author

Prof. Meicheng Li is the Director of New Energy Materials and PV Technology Center, and the Vice Dean of the School of Renewable Energy, North China Electric Power University. He obtained his PhD at Harbin Institute of Technology in 2001. He worked in University of Cambridge as Research Fellow from 2004 to 2006. He won the Excellent Talents in the New Century by the ministry of education in 2006. His current research topic is the New Energy Materials and Devices, such as perovskite solar cells, lithium ion battery system. Till now, he contributed more than 200 journal articles and performed the review services for about 80 SCI journals. He got almost more than 10 items of awards for the science and technology success. He served more than 20 academic conferences as the chair, track co-chair or session chair. He is an executive fellow of the China Energy Society, fellow of Chinese Society for Optical Engineering.

Website , Research Gate.

Reference

Zhirong Zhang, Meicheng Li, Wenjian Liu, Xiaopeng Yue, Peng Cui, Dong Wei. CH₃NH₃PbI₃ converted from reactive magnetron sputtered lead oxide (PbO) for large area perovskite solar cells. Solar Energy Materials & Solar Cells, volume 163 (2017) pages 250–254.

 

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Renewable Energy Global Innovations features: Titanium Oxide Nanofibers Decorated Nickel-Rich Cathodes as High Performance Electrodes in Lithium Ion Batteries

Significance Statement

Layered cathode active materials partially-substituted cobalt with transition metals and spinel active materials have been received more attention due to their cost effectiveness as compared to lithium cobaltate. Scholars have realized with time that the spinel cathode active materials are safe with limited specific capacities while layered cathode active materials possess high specific capacity with safety issues. Presently, layered cathode active materials are more preferred as cathode materials for lithium ion batteries, where nickel-rich layered cathode active materials are front runners except for safety issues, due to their high capacity. To overcome the safety issue challenge, measures, such as the substitution of the transition metal ions with other metal counter ions and the modification of the surface by means of coating with metal oxides, have been put in place.

Nanoparticle coatings on layered cathode active materials have been known to suppress the thermal reaction between the electrode and electrolyte. It has thus been seen necessary to coat or decorate the surface of the cathode since probable exothermic reaction starts from the cathode surface when the electrolyte is decomposed. Extensive studies have been performed on coating materials that inhibit this reaction but little exists about nanofibers-based metal oxides decorated on lithium nickel cobalt aluminum oxide cathode active materials.

Professor Chang Woo Lee and colleagues from the Department of Chemical Engineering, College of Engineering, Kyung Hee University, Yongin, Gyeonggi, South Korea, proposed a study to modify the surface of lithium nickel cobalt aluminum oxide particles by decorating them with titania nanofibers. They aimed at comparatively studying, with the novel lithium nickel cobalt aluminum oxide, the various quantities of titania nanofibers decorated over lithium nickel cobalt aluminum oxide (LNCA). Their research work is now published in the peer-reviewed journal, Journal of Industrial and Engineering Chemistry.

The researchers commenced their empirical procedure by obtaining titania nanofibers precursor through electrospinning a sol-gel polymeric solution. They then obtained the LNCA precursor. The titania nanofibers precursors were split at 0.5 wt%, 1 wt% and 1.5 wt% before addition of the LNCA precursor powders. The precursor powder mixture was then sintered at 465^oC for three hours and then calcined at 850^oC for five hours in air. The team then conducted an X-ray photoelectron spectroscopic analysis to investigate the chemical composition of the cycled electrode surface. The team eventually obtained cathode samples and used them to conduct differential scanning calorimetry scans.

The authors also observed that the increase of titania nanofibers decoration over 1wt% ratio showed negative effect during the electrochemical process, as observed using electrochemical impedance spectra for the 1.5wt% titania nanofibers-decorated LNCA. Hence usage of titania nanofibers more than 1wt% was excluded from detailed investigation. The surface modification of LNCA electrodes by 1wt% titania nanofibers decoration greatly increased the cycleability, capacity, and thermal stability of lithium ion batteries at room temperature as well as at elevated temperature. Among titania nanofibers decorated LNCAs, the 1wt% titania nanofibers -decorated LNCA cathode had shown better capacity retention of 89.2% and 81.9% at room and elevated temperature, respectively.

The results of their study second the suggestion of the applicability of titania nanofibers as surface modifiers in order to enhance the electrochemical and thermal properties of lithium ion batteries. Moreover, it has been seen that the capability of the titania nanofibers-decorated LNCA was enhanced compared to that of the pristine LNCA. The onset temperature of thermal decomposition is also shifted towards higher temperature for titania nanofibers-decorated LNCA electrodes than pristine LNCA electrodes.

About The Author

Professor Chang Woo Lee is currently serving in the Department of Chemical Engineering and also Director of Center for the SMART Energy Platform at Kyung Hee University, S. Korea. He joined Kyung Hee University in 2006, having received B.S. and M.S. degrees in 1994 and 1996, respectively, at Kyung Hee University, S. Korea and a Ph.D. at the Illinois Institute of Technology, USA in 2003, both in the field of Chemical Engineering. Prof. Lee has also worked as a Senior Researcher at Korea Electrotechnology Research Institute (KERI) since he obtained Ph.D. degree. He was appointed as a Visiting Scholar in the Materials Department, College of Engineering and Applied Science, at the University of Wisconsin-Milwaukee, for the 2012-2015 academic year.

Prof. Lee’s research is focused on electrochemical energy storage & conversion and seek to synthesize energy materials in metallic micro- and/or nanostructures for the purpose of improving electrochemical properties in the area of batteries, supercapacitors, and fuel cells.

About The Author

Mr. Kijae Kim is currently a Ph.D. candidate at the Department of Chemical System Engineering in The University of Tokyo, Japan. He received his B.S. and M.S. degrees in the Department of Chemical Engineering at Kyung Hee University, S. Korea. He has studied synthesis and analysis of electrode materials for energy storage devices for the M.S. under the supervision of Prof. Chang Woo Lee. He has published several scientific papers and received the Best Poster Award from Korean Battery Society and bachelor graduation with honors.

About The Author

Dr. K. Prasanna obtained his B.S. and M.S. degrees from Bharathidasan University and Anna University in India, respectively. He then joined as assistant professor in the Department of Biotechnology at Vinayaka Missions University, Salem. He joined as a Ph.D. student under Professor Chang Woo Lee in the Department of Chemical Engineering at Kyung Hee University, S. Korea in September, 2011 and received his Ph.D. degree in Aug, 2015. He then continued his career as a postdoctoral fellow at Electrochemical Energy Storage and Conversion Laboratory, Kyung Hee University for two years. Currently he is working as a postdoctoral fellow in Technical University of Denmark, under the H.C. Ørsted Postdoc programme, co-funded by Marie Skłodowska-Curie Actions. His recent research interests include supercapacitors, Li-ion batteries, Mg-ion batteries, and Metal-air batteries.

About The Author

Dr. T. Subburaj received his Ph.D. at Kyung Hee University, South Korea in 2015 under the supervision of Prof. Chang Woo Lee in the Department of Chemical Engineering and he received his M.S. degree from the Department of Chemical Engineering, Anna University, Chennai, India in 2010. Currently, he works with Prof. Chung-Hsin Lu as a MoST Postdoctoral Scholar at National Taiwan University, Taiwan. His research interests focus on synthesis and applications of nanostructured and hybrid materials for electrochemical energy storage and conversion, including rechargeable batteries, electrochemical capacitors, and solar cells.

About The Author

Dr. Yong Nam Jo received his M.S. and Ph.D. degrees in Department of Chemical Engineering from Kyung Hee University, S. Korea in 2013 and 2017, respectively, under the supervision of Prof. Chang Woo Lee. He received Best Thesis Award for the Ph.D. from the President of Kyung Hee University and also several Best Poster and Outstanding Paper Awards from domestic and international conferences. He is currently working as a postdoctoral fellow at the Center for SMART Energy Platform at Kyung Hee University. His current research is focused on enhancement of materials for energy storage and conversion with Li-ion batteries and metal-air batteries.

Reference

Subburaj, Yong Nam Jo, K. Prasanna, Ki Jae Kim, Chang Woo Lee. Titanium oxide nanofibers decorated nickel-rich cathodes as high performance electrodes in lithium ion batteries. Journal of Industrial and Engineering Chemistry, volume 51 (2017) pages 223–228.

 

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Renewable Energy Global Innovations features: Future European biogas: Animal manure, straw and grass potentials for a sustainable European biogas production

Significance Statement

In a bid to meet the European Union political target for energy and climate, biogas production will play a critical role owing to its flexibility and storability as an energy carrier, a wide range of biological sources that can be implemented for its synthesis, and its established implementation in an array of applications. The implementation of anaerobic digestion for biogas production is still widespread as a critical bioenergy production path reference to its robustness in design arrangements.

Anaerobic digestion serves several applications. It offers a treatment pathway for minimizing huge amounts of complex organic matter, converting a good number of these molecules into monomers, for example, carbon dioxide and methane, which can be used in the energy sector. Above all, the nutrient-rich digestate produced from the anaerobic processes can be recycled on farmlands as organic fertilizers as alternatives to chemical fertilizers that cause eutrophication of fresh water bodies.

The choice of substrates used in the production of biogas has been discussed extensively, particularly, in relation to the use of energy crops. Negative economic and environmental issues related to the use of cultivated energy crops for bioenergy production has been reported in literature. Therefore, these substrates will definitely fall out favor as primary feedstock considered for biogas anaerobic digestion process, and thus alternative sources are required.

Agricultural production residues can be incorporated with the EU directive on the use of energy from renewable sources sustainability criteria. In contrast to the existing literature on the topic, researchers led by Professor Jens Bo Holm-Nielsen at Aalborg University in Denmark focused on the biomass and biogas energy potential from a collection of particular agricultural residues that have been documented to enhance in biogas yield when co-digested in biogas production. Their research work is published in Biomass and Bioenergy.

The main aim of their study was to forecast and map the biogas and biomass energy potential from particular potentially sustainable agricultural residues that have been documented to enhance in biogas yields when co-digested in the production of biogas for the EU28 in the year 2030. The authors considered residual types including, animal manure, excess grass from permanent and rotational meadows and grasslands, and straw byproducts from cereal production.

The research team projected energy potential from grass, manure and straw to be in the range of 1.2×10³-2.3×10³PJ/y for the European Union in 2030. The United Kingdom and Germany were identified to have the highest energy potential. The outcomes of the study indicate that there is a huge base for agricultural residues well suited for co-digestion all over Europe that are perfect substitutes to energy crops.

The study found that co-digestion of animal manure incorporating straw and grass is a potential that will enhance the efficiency and economic feasibility of the European Union biogas production in 2030. More technological development and implementation may be necessary if the biomass resources are to be used efficiently. Acquisition and processing of the selected biomasses are challenges that must be addressed before realizing a full potential. However, production of energy based on these residues is a more sustainable and economically viable method for developing the EU biogas industry keeping in mind the potential issues in relation to sustainability.

About The Author

Name: Jens Bo Holm-Nielsen

Date and place of birth: 31th of March, 1954, Fanoe Island, Denmark Nationality: Danish
Civil Status: Married – Lis Ingemann & 3 Children; Sara, Thomas and Anne
Contact details: e-mail: jhn@et.aau.dk; cell: +45 2166 2511.

1st University Degree 1980. M.Sc.: Agricultural Systems, Crops & Soil Science, from KVL, Royal Veterinary & Agricultural University, Copenhagen, Denmark.

2nd University Degree 2008. Ph.D. degree from Aalborg University – Esbjerg Institute of Technology. Process Analytical Technologies for Biogas Systems. Esbjerg, Denmark.

Languages: Danish and Scandinavian languages, English, (German, French – partial proficiency)

Professional career:

1980-85: Riber Kjærgaard Agricultural College, Lecturer

1985-93: Ribe, Bramming, Esbjerg Farmers Organisation, Farming Advisor

1993-95: University Center South Jutland, Esbjerg; Senior Project Manager

1995-00: University Center South Jutland, Esbj.; Head of Bioenergy Section

2000-08: University of Southern Denmark, Esbj. Head of Bioenergy Depart.

2002-08: University of Aalborg, Esbjerg: Senior lecturer & Ph.D. researcher

2008-2010: University of Aalborg, Esbjerg: Assistent Professor & Head of Center for Bioenergy and Green Engineering.

2010 – …..: Aalborg University – Esbjerg Campus: Associate Professor & Head of Energy Section – Department of energy technology & & Head of Center for Bioenergy and Green Engineering.

Years of experience in the field of Biorefinery concepts and Biogas production – Anaerobic Digestion. Implementation projects of Bioenergy Systems. Experience of a variety of EU and UN projects. Organiser of international conferences, workshops and training programmes in Europe, Central Asia and China.

Awards, honors

2000: Honorary Bioenergy Center, SDU, Denmark and partners – Best National Renewable Energy Partnership. Awarded by DG TREN – EU Commission

2010: D.L. Massart Award in Chemometrics. Awarded by the Belgian Chemometrics Society for the best world-wide Ph.D. thesis in the research field during the period of 2008-2010.

Field of research, teaching & supervising:

Research: Managing research, development and demonstration programmes in integrated agriculture, environment and energy systems solutions.

Fulfilled biomass and bioenergy R & D projects. Main focus in biofuels, biogas and biomass resources. New focus since 2008 – Biomass pre-treatment platforms for 2. and 3. generation biorefinery production

Lecturing and graduate supervision: Courses and project supervising in fermentation processes, anaerobic digestion processes and systems. Biogas purification, Nutrient management and balances and upgrading technologies. Agricultural and environmental projects. Biomass resource studies. Optimal utilization of biomass resources and conversion technologies. Bioenergy and Renewable energy system integration.

Training programmes: International courses, training programmes and supervision for academic staff, governmental bodies and experts in bioenergy systems and integrated solutions. Core competences in bioenergy technologies and biomass ressourse conversion to biogas or biofuels.

www.energy.aau.dk; www.vbn.dk; (Search JBHN)

Center for Bioenergy and Green Engineering, AAUE

Established at SUC 1995, transferred to SDU 2000, and as a joint group at SDU/AAUE from 2002-2008. Centre for Bioenergy and Green Engineering established at AAUE 2009. Biomass resource studies. Specific research on anaerobic digestion systems. Biomass and organic waste system analysis and optimisation. Ongoing several Liquid Biofuels projects and Biorefienery studies.

Selected Publications:

1. Holm-Nielsen et al.; Joint biogas plant – agricultural advantages, circulation of N, P and K. Report made for the Danish Energy Agency, Ministry of Energy, 1.th.Edition 1993, 2.nd. Edition 1997. Downloads from www.sdu.dk/bio;
2. Holm-Nielsen; participated in UN-China conference with the lecture; Rapid Commercialisation of Renewable Energy Systems. Danish and European experience of Biogas Systems. Workshop and strategy planning for biogas technology in China. UNDP/GEF Project, Beijing, China 2-7.04.2000
3. Holm-Nielsen J.B., al Seadi T.: Manure-based biogas systems – Danish Experience. Chapt. 17; p 377-394 in Resource Recovery and Reuse in Organic Solid Waste Management. IWA Publishing, 2004. ISBN 1 84339 054 X
4. Holm-Nielsen J.B., Dahl C.K., Esbensen K.H.: Representative sampling for process analytical characterisation of heterogeneous bioslurry systems – a reference study of sampling issues in PAT. Chemometrics and intelligent laboratory systems vol. 83, 114 – 126 (2006) ScienceDirect, Elsevier. DOI: 10.1016/j.chemolab.2006.02.002
5. Holm-Nielsen J.B., Andree H., Lindorfer H., Esbensen K.H.: Transflexive embedded near infrared monitoring for key process intermediates in anaerobic digestion/biogas production. Journal of Near Infrared Spectroscopy vol. 15, 123-135 (2007) ISSN 0967-0335. DOI: 10.1255/jnirs.719
6. Holm-Nielsen J.B., Lomborg C.J., Oleskowicz-Popiel P., Esbensen K.H.: On-line Near Infrared monitoring of glycerol-boosted anaerobic digestion processes – evaluation of Process Analytical Technologies. Biotechnology and Bioengeneering, Vol. 99, No.2, 302 – 313, (2008), Wiley Periodicals inc. – InterScience. DOI: 10.1002/bit21571
7. Holm-Nielsen J.B., Madsen M., Oleskowicz-Popiel P.: Predicted Energy Crop Potentials for Bioenergy Worldwide and for EU-25. Proceedings World Bioenergy 2006, Conference on Biomass for Energy, Jönköping, Sweden, 30. May – 1.June 2006.
8. Holm-Nielsen J.B., Oleskowicz-Popiel P., al Seadi T.: Energy Crop Potentials for Bioenergy in EU-27. Proceedings 15.th European Biomass conference, Berlin, Germany 7-11 May 2007. ISBN 3-936338-21-3.
9. Holm-Nielsen J.B. and Oleskowicz-Popiel P. 2007: The Future of Biogas in Europe: Visions and targets until 2020; Proceedings: European Biogas Workshop – Intelligent Energy Europe, 14- 16 June 2007, Esbjerg, Denmark.
10. Holm-Nielsen J.B.: Process Analytical Technologies for Anaerobic Digestion Systems. – Robust Biomass Characterisation, Process Analytical Chemometrics, and Process Optimisation. Ph.D. Thesis. ACABS-Research Group, Esbjerg Institute of Technology, Aalborg University, August 2008, ISBN 978-87-7606-030-5
11. Holm-Nielsen et al.: Biogas technologies and further treatments steps of co-digestion of animal manure. International Workshop – OECD & USDA; Livestock Waste Treatment Systems of The Future: A challenge to environmental quality, food safety, and sustainability. April 2008, USA, Bioresource Technology 100 (2009) 5478 – 5484. Doi: 10.1016/j.biotech.2008.12.046
12. Holm-Nielsen: Key Note Speaker. Renewable Energy and Climate Change Policies in Denmark and Europe. Bioenergy and Biogas as case examples. Conference: Growing the Margins – Green Energy and Economy, March 10-11, 2010, London, Ontario, Canada.

Full Bibliography and publication list since 2004 can be found at:

www.vbn.dk; – search; Jens Bo Holm-Nielsen.

Earlier bibliography and publication list can be achieved by mailing to: jhn@et.aau.dk;

Contact details:

Jens Bo Holm-Nielsen, M.Sc., Ph.D.

Head of Esbjerg Energy Section
Department of Energy Technology,

Head of Center for Bioenergy and Green Engineering

Aalborg University – Esbjerg Campus
Niels Bohrsvej 8, DK-6700 Esbjerg, Denmark. www.et.aau.dk
Phone: +45 21 66 25 11,  e-mail:  jhn@et.aau.dk

About The Author

A.Katharina P. Meyer, PhD, M.Sc.
paarupmeyer@gmail.com
Education
2012-2015: PhD. Sustainable Biomasses. Department of Energy Technology, AAU Esbjerg.
2009-2011: M.Sc. in Environmental and Resource Management, AAU & SDU Esbjerg
2006-2009: B.Sc. in Environmental and Resource Management, AAU & SDU Esbjerg
Employment:
2017 – now: Danish Energy Agency, EUDP
2015-2017: Postdoc, Department of Energy Technology, AAU Esbjerg.
2012-2015: PhD student, Department of Energy Technology, AAU Esbjerg.
2011-2012: Esbjerg Kommune. Department of Climate and Sustainability.
Research​ ​projects​ ​and​ ​key​ ​tasks
2016-2017: Large Scale Bioenergy Lab. EU funded Interreg5A Project.
Project coordination and management.
2015-2016: Demonstration af AD Booster systemet for øget biogasproduktion (AD Booster).
EUDP project.
Representative sampling of liquid and solid manure samples on biogas plant.
Characterization of manure samples in lab
Analysis of mass flow and efficiency for screw press
BMP tests of samples
2012-2015: Large Scale Bioenergy Lab. EU funded Interreg4A Project
Screening of sustainable resources for biogas in the regions.
Spatial analyses of availability and growth yields of biomass resources
Analysis of energy balances when utilising new biomass substrates for biogas in the project
region
Research​ ​competences
Biomethane potential tests (BMP), Spatial analyses, Data management and visiualisation
Characterization of biomasses, Representative sampling (TOS), Multivariate dataanalysis
Energy balances (Net Energy Gains and Energy Returns on Invested Energy)
Publications
– Future European biogas : Animal manure, straw and grass potentials for a sustainable
European biogas production. / Meyer, A. K.P.; Ehimen, E. A.; Holm-Nielsen, J. B. In: Biomass
and Bioenergy, 06.2017. Journal article
– The potential of surplus grass production as co-substrate for anaerobic digestion : A case study
in the Region of Southern Denmark. T/ Meyer, A. K. P.; Schleier, C.; Piorr, H. P.; Holm-Nielsen,
J. B. In: Renewable Agriculture and Food Systems (Print), Vol. 31, No. 4, 08.2016, p. 330-349.
Journal article
– The energy balance of utilising meadow grass in Danish biogas production. / Meyer, A. K. P.;
Raju, C. Sangaraju; Kucheryavskiy, S. V.; Holm-Nielsen, J. B.. In: Resources, Conservation and
Recycling, Vol. 104, No. Part A, 11.2015, p. 265–275. Journal article
– Bioenergy production from roadside grass : A case study of the feasibility of using roadside
grass for biogas production in Denmark. / Meyer, A. K. P.; Ehimen, E. A.; Holm-Nielsen, J. B.
In: Resources, Conservation and Recycling, Vol. 93, 2014, p. 124-133. Journal article
– Sustainable Biomass Resources for Biogas Production : Mapping and Analysis of the Potential
for Sustainable Biomass Utilization in Denmark and Europe. / Meyer, A. K. P. Department of
Energy Technology, Aalborg University, 2015. 89 p. Ph.D. thesis.

Reference

A.K.P. Meyer, E.A. Ehimen b, J.B. Holm-Nielsen. Future European biogas: Animal manure, straw and grass potentials for a sustainable European biogas production. Biomass and Bioenergy, Available online 1 June 2017.

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Renewable Energy Global Innovations features: Cellulose Biorefinery Based on a Combined Catalytic and Biotechnological Approach for Production of 5-HMF and Ethanol

Significance Statement

The need for development of sustainable technology that employs locally available sources of energy feedstocks for the production of motor fuels and valuable chemicals is on the rise. This can be attributed to the instability in the global energy and hydrocarbon feedstock markets. Sustainability, low power consumption and minimal carbon gas emission are among the contributing qualities towards this move. Lignocellulosic feedstock sources for biorefineries include energy crops, forestry and agricultural waste and residues which are made up of complex biopolymers such as cellulose, lignin and hemicellulose. Amongst, cellulose is relatively easy to process. Conversely, a flaw in its processing demands the need for the catalyst to be separated from the products and regenerated after the reaction which, however, can be averted by using carbon-based solid-acid catalysts to hydrolyze the cellulose.

Ksenia Sorokina and colleagues at the Boreskov Institute of Catalysis, in Russia, proposed a study to explore the potential of combining catalytic and biotechnological methods in a cellulose biorefinery. They aimed at examining the combination of one pot catalytic cellulose conversion into 5-hydroxymethylfurfura and glucose using a solid-acid catalyst and biotechnological glucose fermentation into ethanol with thermotolerant yeasts. Their goal was to produce 5-hydroxymethylfurfural and Ethanol. Their work is now published in the peer-reviewed journal, ChemSusChem.

The researchers commenced their empirical procedure by hydrolyzing the mechanically activated microcrystalline cellulose in the presence of a solid carbon-based catalyst that had been preliminarily oxidized with wet air. They then recovered the 5-hydroxymethylfurfural by isobutanol extraction from the mixture and the remaining sugar mixture was neutralized and concentrated for subsequent fermentation. The research team then selected the most effective ethanol producers by screening of the isolated thermotolerant yeast strains that were able to grow at 40⁰C.

The authors of this paper observed that hydrolytic dehydration of the mechanically activated microcrystalline cellulose over the carbon-based mesoporous Sibunt-4 catalyst resulted in moderate yields of glucose and 5-hydroxymethylfurfural. The 5-hydroxymethylfurfural was extracted from the resulting mixture with isobutanol and subjected to ethanol fermentation. The team also noted that among the isolated yeast strains, some exhibited high thermotolerance and resistance to inhibitors found in the hydrolysates.

Herein, a comprehensive study on the potential of combining catalytic and biotechnological techniques in cellulose biorefinery with an aim of producing 5-hydroxymethylfurfural and Ethanol has been presented. It has been shown that the use of the strains K. marxianus and O. polymorpha for the fermentation of processed catalytic cellulose hydrolysate has a relatively high efficiency since the strains are resistant to fermentation inhibitors. Therefore, the proposed combination of the catalytic processing of mechanically activated cellulose for the production of 5-hydroxymethylfurfural and subsequent fermentation of the extracted hydrolysate with thermotolerant yeasts is a promising alternative technique for ethanol production by fermentation and can be used to produce other valuable substances, such as bio-acids or bio-alcohols.

About The Author

Professor Valentin N. PARMON is an academician of the Russian Academy of Sciences (RAS), Dr.Sci. in chemistry, scientific director of the Boreskov Institute of Catalysis (Novosibirsk), Chairman of the Russian Scientific Council on Catalysis of the Russian Academy of Sciences, Chairman of the National Catalysis Society of Russia, the Russian National representative to the European Federation of Catalysis Societies (EFCATS) and International Association of Catalysis Societies (IACS). He is an expert in catalysis, photocatalysis, chemical kinetics in condensed phases, chemical radiospectroscopy, chemical methods of energy conversion, non-traditional and renewable energy sources, thermodynamics of non-equilibrium processes. Author and co-author of more than 800 papers in refereed journals, 9 monographs, 7 textbooks for universities, more than 100 patents. Editor-in-Chief of journals “Chemistry in Russia” (the Russian Chemical Society), “Catalysis in Industry” (Kalvis, Russia), “Catalysis Bulletin” of the National Catalysis Society of Russia, a Member of Editorial Boards of the “Russian Chemical Journal” (Russia), ), “Russian Chemical Review”, “Russian Journal of Physical Chemistry”, “Chemistry of Solid Fuels” and of the international journals “Chemistry for Sustainable Development” (SB RAS), “Catalysis Today” (Elsevier), “Catalysis Letters” (Springer), “Topics in Catalysis” (Springer), “Catalysis Reviews – Science & Engineering” (Baltzer), “Research on Chemical Intermediates” (VSP), “Chemistry & Technology of Water” (Ukraine), “Material Research Innovations”. Full Professor of the Novosibirsk State University (Chair of Physical Chemistry), Professor of the Tomsk State University and the Kazan State University.

About The Author

Ksenia Sorokina is a senior research scientist in biotechnology at the Boreskov Institute of Catalysis, Laboratory of Catalytic Methods of Solar Energy Conversion, Novosibirsk, Russia. Ksenia graduated from the Faculty of Natural Sciences of Novosibirsk State University, Russia in 2004, and defended her PhD in 2006.

Her primary research interests include the development biotechnological processes for enzymes and chemicals production from renewable biomass based on genetically engineered microorganisms.

About The Author

Professor Oxana P. Taran is Leading Researcher at the Boreskov Institute of Catalysis Siberian Branch Russian Academy of Science (BIC SB RAS) and Full Professor for Analytical Chemistry at the Novosibirsk State Technical University. She studied chemistry at the Novosibirsk State Technical University and completed her PhD with Prof. Valentin N. Parmon at the BIC SB RAS in 1999. She worked as visiting scientist at the Brookhaven National Laboratory (USA) with Dr. Sergei Lymar in 1998-1999 and at the IRCELYON (France) with Profs. Michele Besson and Pierre Gallezot in 2005. She is Professor of Russian Academy of Science since 2016. Her research focused on the development of catalysts and catalytic processes occurring in the aqueous solutions including: carbohydrates processing, wastewaters treatment, artificial photosynthesis and biomass catalytic treatment to produce fuels and chemicals.

Reference

Ksenia N. Sorokina, Oxana P. Taran, Tatiana B. Medvedeva, Yuliya V. Samoylova, Alexandr V. Piligaev, and Valentin N. Par. Cellulose Biorefinery Based on a Combined Catalytic and Biotechnological Approach for Production of 5-HMF and Ethanol. ChemSusChem 2017, volume 10, pages 562 – 574.

 

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Renewable Energy Global Innovations features: General Equations of Lumped Parameter Ladder Circuits and a Special Approach to Analyzing Electrical Line Transient States

Significance Statement

The Telegrapher’s equations, two linear partial differential equations, one for voltages and the other for currents, describe the behavior of voltages and currents in each moment and at any point along an electrical line. They can only be integrated in special cases e. g. if the voltage is sinusoidal function of time and the obtained solution is well-known as the General Line Equations. However, these equations are limited in that they are only convenient for analysis of the transmission lines operating in steady state regimes. Also, these equations are not sufficiently accurate in the case of a lumped parameter ladder circuit that is formed in practice by transmission line ground wires and the belonging tower footing electrodes, especially in the cases when the number of the considered spans is small.

Furthermore, the Telegrapher’s equations can be integrated in the transient regime only using operational calculus, i.e. the Laplas Transformation. However, on the basis of such solution   the finally obtained analytical expressions are not convenient for the interpretation and analysis of resonant phenomena, as well as for determination of transient over-voltages in transmission lines.

Conversely, knowledge exists that lumped parameter ladder circuits represent universal physical and mathematical models of systems having distributed parameters and as such can also be used for analyses of electrical lines. However, these circuits were without the adequate general solutions, i.e. without the equations analogous to the General Line Equations.

Dr. Ljubivoje Popovic at J.P. Elekdrodistribucija-Beograd in Serbia has managed to develop an alternative analytical procedure for obtaining the well-known General Line Equations. Also, on the basis of the same procedure he has obtained the, so far unknown equations and named them “General Equations of Lumped Parameter Ladder Circuits”. These equations enable correct determination of ground fault current distribution for a fault at any point along an HV transmission line. Moreover, these equations enable the analysis of electrical quantities along any actual (with distributed parameters) line in steady state by applying relatively simple mathematical operations and with a desired degree of accuracy.

However, the most important research result is the developed analytical procedure itself, because it opens possibilities for a new approach in analyzing resonant phenomena and transient states in electric-power lines.  The author began by representing an electrical line through its lumped parameter model as a base and then applied the principle of superposition and a summation of the especially formed finite and infinite geometric series. The researcher was able to make observations such as: the developed analytical procedure resulted in relatively simple analytical expressions for the relationship between currents and voltages at different points of transmission lines in transient state conditions. Secondly, the developed analytical procedure was performed to follow, one-by-one, all the phases of the actual physical process occurring during transient states in electrical lines. Eventually, the researcher applied his analytical procedure in a numerical example concerning determination of switching over-voltages in transmission lines and show that this problem can be solved without specially developed computer programs. His research work is now published in the peer-reviewed journal, Electrical Power and Energy Systems.

About The Author

Ljubivoje M. Popović was born in Markovac (at Mladenovac), Serbia, in 1944, graduated (1969) and received Master (1983) and Doctor (1991) degrees, all at the School of Electrical Engineering, University of Belgrade.

In 1969 joined the Electric Power Distribution Company of Belgrade, where he stayed until retirement in 2007.  In 1999 he was elected an associated professor at the School of Electrical Engineering, University of Belgrade and in 2010 he was elected an IEEE R8 Industry Lecturer (Industry Continuing Education Program).

At the beginning of his professional carrier he worked on design of different power installations, including the first 110/10 kV substations in the power distribution network of Belgrade. At the end of the seventies, he moved to the Development and Research Department of the same company.

His research work has been mainly focused on the following  topics:

– Grounding systems of HV substations located in urban areas,
– Ground fault current distribution along the overhead and cable feeding lines,
– Fault locator algorithms,
– Resonant phenomena in the transmission lines and transformer windings,
– Influence of metal installations surrounding the feeding line on the ground fault current distribution,
– Influence of electric-power lines on surrounding metal installations,
– Influence of surrounding metal installations on the transfer characteristics of distribution lines.

In addition to realization of the numerous studies and projects, in the area of power delivery he published: over 50 research papers in international journals and proceedings of international conferences, 2 chapters in two international scientific books and one scientific book, Actual Parameters of Power Lines Passing through Urban Areas.

Some of his papers and research results have had an impact on the following IEC publications: Technical Report IEC 60909-2, Ed 1(1992-09) and IEC standard 60909-3, Ed 2 (2003-09)), and was specially highlighted by: ”Vertical News”, ”High-beam Research”, ”High-beam Business”, ”Goliath Business News” and ”News-edge”. Two of his papers published in 2014 have been selected by ”Renewably Energy Global Innovations” as the key scientific articles.

He was elected a member of the IEC Technical Committee – IEC/TC73- Short Circuit Currents from 2004. A member of IEEE since 1987, he became Senior Member in 1991 and was the Chair of IEEE PES Serbia and Montenegro Chapter from 2002 until 2009.

He received: national ”Nikola Tesla” Award in 2006, IEEE PES Chapter Outstanding Engineer Award, and Certificate of Appreciation for Notable Services and Contributions towards advancement if IEEE and Engineering Professions.

Reference

Ljubivoje M. Popovic. General equations of lumped parameter ladder circuits and a special approach to analyzing electrical line transient states. Electrical Power and Energy Systems, volume 95 (2018) pages 568–576.

 

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Renewable Energy Global Innovations features: Hybrid photovoltaic-thermal solar systems for combined heating, cooling and power provision in urban environment

Significance Statement

The use of renewable energy resources offers a secure and sustainable solution to the energy problem, which encompasses complex and multifaceted aspects such as an increasing global energy demand notwithstanding stagnating oil production capacities and price volatility, concerns relating to energy independence and security, and the detrimental effects to human health and the environment that arise from the continued consumption of fossil fuels. Renewable energy resources currently supply only up to 14% of the world’s total energy, so there is considerable scope to develop and implement new renewable energy technologies.

Solar energy is a particularly promising renewable and sustainable source of energy, which can be tapped to address the energy problem simultaneously from environmental, health and economic perspectives. Nevertheless, the widespread delivery of affordable solar energy through suitable technologies remains an engineering grand challenge that continues to attract a strong interest from academia, industry, government, and beyond. In particular, solar energy systems based on hybrid photovoltaic-thermal (or, PV-T) collectors have been recently receiving an increased interest due to their higher overall efficiencies compared to conventional PV panels. These hybrid panels can reach overall efficiencies (electrical plus thermal) of over 70%, with electrical efficiencies reaching 15-20% and thermal efficiencies of over 50%.

In a PV-T panel, PV cells convert sunlight directly to electricity and thermal energy is removed from the cells via a contacting coolant fluid (liquid or gas); the heated fluid flow is then used downstream for hot water provision or space heating (and/or cooling if necessary), with the added benefit of actively cooling the PV cells and increasing their electrical efficiency. In most applications, the electrical output of a hybrid PV-T system is the main priority. Hence, the contacting fluid is kept at low temperature in order to maximize the system’s electrical performance. However, this imposes a limit on its posterior use and a design conflict arises between the electrical and thermal performance of hybrid PV-T systems.

When optimising the overall output of PV-T systems for combined electricity and heating/cooling provision, this solution can cover about 60% of the heating and between 50-100% (depending on the location) of the cooling demands of households in the urban environment, based on typical household demands and available roof space. To achieve this, PV-T systems can be coupled to vapour-compression heat pumps or absorption refrigeration units.

Researchers in the Clean Energy Processes (CEP) Laboratory at Imperial College London considered the techno-economic advantages and shortcomings of a range of such systems, while aiming at a low cost per kWh of combined energy generation (co- or tri-generation) in the housing sector. They studied the technical feasibility, performance and affordability of proposed systems in ten different geographical locations covering all European climates, with local weather profiles using monthly and annually averaged solar-irradiance and energy-demand data relating to houses with a 100-m² total floor area and 50-m²-rooftop area. The results of this research have been published in Energy Conversion and Management.

Amongst the locations studied, Seville, Rome, Bucharest and Madrid were the most promising for the proposed hybrid PV-T systems. The authors found that the most effective system arrangement entailed the coupling of PV-T panels to water-to-water heat pumps. The electrical output of the panels was used to run the heat pump or an air conditioning system, while the thermal output was used to maintain the source-side temperature of the heat pump at around 15 °C year round. This practice maximizes the heat pump and/or air-conditioning coefficient of performance (COP) and enables a reduction in their electricity consumption. The authors found that the temporal resolution of the simulations affects strongly the predicted system performance. Detailed high-resolution hourly simulations indicated that such PV-T systems are capable of covering 60% of the combined heating demands and almost 100% of the cooling demands of the examined households in middle and low European-latitude regions.

Moreover, the authors estimated the cost of solar thermal, PV and PV-T systems. For PV-T systems, the levelized cost of energy (LCOE), i.e., the total net present value of the system per unit total energy over the system’s lifetime, was found to be mainly influenced by the system size, which will be larger at higher latitudes (lower irradiance). Nevertheless, the calculated LCOE for the PV-T systems varied between 0.06 and 0.12 €/kW h, which is 30-40% lower than the LCOE of small-scale PV-only installations in Europe.

Finally, the authors identify important barriers for the market adoption of PV-T technology, which at present act to limit the PV-T market size, including high initial costs, and uncertainties caused by poor knowledge of the technology due to its limited penetration. They suggest that demonstration projects exploring the potential of PV-T co-generation or tri-generation systems should be encouraged, supported and advertised to the public, to increase the awareness of this technology and to accelerate the adoption rates of these much-promising systems.

Schematic diagram of the proposed PV-T system for solar heating and cooling provision.

Selected locations and global horizontal irradiation in Europe. (b) Space heating, DHW and cooling demands and global irradiance profiles for Seville and Vienna.

About The Author

Dr Alba Ramos Cabal is an Aeronautical Engineer who holds a Masters and a Doctorate degree in Photovoltaic Solar Energy from the Technical University of Madrid (Spain). Currently, she is a Postdoctoral Research Associate in the Clean Energy Processes (CEP) Laboratory at Imperial College London.

Her research involves the modelling, design, fabrication and testing of novel hybrid solar PV-thermal (PV-T) collector technology, as part of wider solar-energy heat, power and cooling (tri-generation) systems. Her previous experience includes the theoretical modelling of physical and chemical vapour deposition (CVD) processes, as well as experimental research with CVD reactor prototypes in the laboratory and at industrial scales. She was also involved in the modelling, design, fabrication and testing of a novel thermal energy storage (TES) system that utilizes high-temperature phase change materials (PCMs) and thermo-photovoltaic (TPV) cells. In addition, during her PhD she was involved with the Solar Energy Institute, a Spanish R&D centre, worked at the Institute for Energy Technology (IFE) in Norway, and undertook postdoctoral research stays at the Cyprus University of Technology (CUT) for the purpose of outdoor solar PV-T collector testing and characterization.

Contact: a.ramos-cabal@imperial.ac.uk 

About The Author

Ms Maria Anna Chatzopoulou is a PhD student in the Clean Energy Processes (CEP) Laboratory at the Department of Chemical Engineering of Imperial College London, working under the supervision of Dr Christos Markides. Her research focuses on the design of low-carbon cogeneration technologies with applications in buildings. She is interested in the design and optimization of novel technologies, such as the organic Rankine cycle (ORC) and absorption refrigeration systems, which are not currently widely adopted in the built environment.

Her research is co-funded by the Imperial College President’s PhD Scholarship scheme, and the Climate-KIC and European Institute of Innovation and Technology. She holds an MEng degree in Mechanical Engineering (Distinction) and an MSc in Environmental Engineering and Business Management (Distinction). Prior to her PhD, she worked as a design engineer in an international engineering consultancy in London. Her main responsibilities involved the design of HVAC systems for critical facilities, such as data centres, aiming to reduce their energy consumption and carbon emissions by considering novel cooling technologies.

Contact: maria-anna.chatzopoulou@imperial.ac.uk

About The Author

Dr Ilaria Guarracino holds a PhD in Chemical Engineering from Imperial College London. She completed her PhD at the Clean Energy Processes (CEP) Laboratory under the supervision of Dr Christos Markides and Dr Ned Ekins-Daukes who led the Quantum Photovoltaics group in the Blackett Laboratory at Imperial College. Her research focused on the design of hybrid solar PV-thermal (PV-T) systems for electricity, hot water and cooling, for which she developed a flexible computer tool for the evaluation of the performance of solar thermal and PV-T collectors and wider systems. The tool was validated against outdoor experimental data generated during a research visit to the Cyprus University of Technology (CUT) where she worked under the supervision of Professor Soteris Kalogirou.

Prior to the PhD, she completed a double Masters degree in Mechanical Engineering at the Royal Institute of Technology (KTH, Stockholm) and at the Universitat Politecnica de Catalunya (UPC, Barcelona) focusing on solar energy systems. She also worked as a summer intern at the Fraunhofer Institute for Solar Energy (ISE) working in a project conducting research into the thermodynamics of molten salts in steam generators for concentrated solar power systems.

Contact: ilaria.guarracino12@imperial.ac.uk

About The Author

Dr James Freeman is a Postdoctoral Research Associate in the Clean Energy Processes (CEP) Laboratory at the Department of Chemical Engineering, Imperial College London. He completed his PhD in solar thermal combined energy systems for distributed applications in 2017. His previous work has included the design, testing and modelling of a small-scale organic Rankine cycle (ORC) engine for use with non-concentrating solar collectors. He has also worked within the CEP Laboratory to develop methods for the testing and modelling of solar thermal and hybrid solar PV-thermal (PV-T) collectors and systems.

His current research focuses on a small-scale modular solar-cooling system for rural cold-chain applications based on a diffusion-absorption refrigeration cycle. He recently participated in an ongoing project to field-test the system in India, which runs until 2018.

Contact: j.freeman12@imperial.ac.uk

About The Author

Dr Christos N. Markides is a Reader in Clean Energy Processes at the Department of Chemical Engineering, Imperial College London, where he heads the Clean Energy Processes (CEP) Laboratory, and leads the Department of Chemical Engineering Energy Research Theme and the cross-faculty Energy Efficiency Network. After graduating with a PhD in Energy Technologies from the University of Cambridge, he co-founded a Cambridge University spin-out company to develop and commercialize a novel thermally-powered device without moving parts capable of converting low-temperature waste heat or solar energy into fluid pumping. He acted as its Technical Director until his appointment at Imperial in 2008.

His research expertise lies in the application of fundamental aspects of thermodynamics, fluid flow, heat and mass transfer, both computationally and experimentally, to novel processes, components, technologies and systems for the recovery, utilization, conversion and storage of thermal energy. He has a particular interest in high-efficiency energy systems, renewable energy technologies, and the efficient utilization of solar and waste heat for cooling, heating and power. He has written over 200 scientific articles in these areas. He is an Executive Editor of Applied Thermal Engineering and is a Subject Editor of Renewable Energy, is on the Editorial Board of Energy (Elsevier) and Frontiers in Solar Energy (EPFL), and is also a member of the UK National Heat Transfer Committee and Scientific Board of the UK Energy Storage SUPERGEN Hub.

Contact: c.markides@imperial.ac.uk

The Clean Energy Processes (CEP) Laboratory, headed by Dr Christos Markides, is based in the Department of Chemical Engineering at Imperial College London. Currently, approximately 35 members (research fellows, postdoctoral and doctoral researchers, and postgraduate students) are at the core of this research laboratory. Its mission is to conduct high-impact research in applied thermodynamics, fluid flow, heat and mass transfer, as applied to technologies for high-performance power generation, heat and/or cooling provision. The CEP Laboratory fosters close interactions with industry and actively collaborates with international research centres and universities. The CEP solar-energy team focuses on innovation, research and development aimed at high-performance solar thermal and hybrid PV-thermal technologies for heating, cooling and power generation.

Reference

Alba Ramos, Maria Anna Chatzopoulou, Ilaria Guarracino, James Freeman, Christos N. Markides. Hybrid photovoltaic-thermal solar systems for combined heating, cooling and power provision in the urban environment. Energy Conversion and Management, Vol. 150, 838-850 (2017)

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