Renewable Energy Global Innovations features: Structural dynamics of innovation networks funded by the European Union in the context of systemic innovation of the renewable energy sector

Significance Statement

In a recent article of Kang and Hwang (2016) which was published in Energy Policy, examined whether related innovation activities transforms into a systemic direction when considering the European Union funded international networks while also checking whether the European Union has contributed to establishing an effective ecosystem for systemic renewable energy innovation.

Several structural properties as indicators were used to evaluate the systemic innovation conditions of a network due to its dual dimensions as appropriate measurement were suggested. Two network properties; the structural closure and structural holes diagnosed the overall network structure with respect to market exploitation and technology exploration, measuring the overall degree of connectivity.

The other indication applied two properties namely; the hierarchy and disassortativity in order to evaluate interoperability between technology exploration and market exploitation. The use of the hierarchy with a core-periphery structure reveals the heterogeneity in relations of capable organization across the network. The disassortativity property showed the tendency of the nodes in the network to connect one another with those who exhibit dissimilar degrees.

For effective combination of openness strategies for network positioning, the authors regarded the country boundary as a condition for judging organization openness to external partnerships provided that renewable energy innovation depends on geographical factors, market readiness and institutional schemes. A two-step approach was also implemented to determine whether an organization has more relationship with foreign or domestic firms and later measured by use of an external-internal index and secondly, correlation between external-internal index while checking whether the actors are in line with systematic innovation in the network based on their openness strategies.

The authors also employed framework programs and Intelligent Energy Europe sub-program for studying correlation between technology exploration and market exploitation.

When observing the overall network structures, both actual and random networks in period I (2003-2007) and period II (2008-2013) were similar in average path lengths indicating small-world tendencies but a larger overall clustering coefficient in actual networks was found. Higher constraint were also found in actual networks in both periods compared to random networks depicting a major relational redundancies of the renewable energy innovation networks while structural holes were missing.

The renewable energy innovation network under the European Union which follows the small-world model direction had a diminished structural hole assembly as overall connectivity increases which is characterized by a high centralization and segmentation.

The hierarchy in both actual and random network was significant with cohesiveness of core organizations but the degree distribution in actual network was stronger compared to random network. A greater degree of correlations between that of focal length and its direct neighbors was more positive for actual networks compared to random networks which confirms presence of an assortative structure.

The core-periphery model when compared to the random models can be likened to a systemic renewable energy innovation under the European Union’s program. The core and periphery structures are dense and assortative but less segmented. This means that the core and peripheries are not effectively combined which can be related to the dissociation between the explorative and exploitation phase for systemic renewable energy innovation.

This study shows an increasing number of organizations have appropriate openness strategies based on their network positions which proposes its capability for systemic renewable energy innovation after a period of time.

  

About The Author

Dr. Jongwoon Hwang
Head of Smart Convergence Group, KIST Europe 

Dr. Jongwoon Hwang is Head of Smart convergence group of KIST Europe. He joined KIST Europe in 2000 and is in charge of international cooperation especially between the EU and Korea.

He has involved in many national and international projects such as FP7 KESTCAP, FP7 KORRIDOR, FP7 KONNECT, Development of smart energy monitoring system etc. He also leaded studies such as Sustainable Waste Management Strategy for Green Printing Industry Business of FP7 ECO-INNOVERA and strategic global regulation compliance for Samsung.

He got his doctoral degree in information and communication management system at Technical University of Berlin in Germany with the topic ‘Architecture model for the SOA-based IT-services in the power supply industry’ and has relevant and interdisciplinary experiences in Science and Technology Cooperation.  

 

About The Author

Ms Moon Jung Kung
PhD candidate, TU Berlin, Innovation Economics

Moon Jung Kang holds a Diplom degree in Environmental Science from Leuphana University Lueneburg, Germany. Since 2011, she has been doing the Ph.D. study on “International Networks for Promoting the Eco-innovation in the Era of Climate Change” at Technical University of Berlin, Chair of Innovation Economics in Germany. She has published several SCI papers as well as many academic articles based on data from OECD, Eurostat, Clean Development Mechanisms, EU’s R&I programs (FP, IEE, and Horizon2020), and EU’s Community Innovation Survey on eco-innovation.

Moon Jung Kang was a research scientist at Smart Convergence Group, Korea Institute of Science and Technology (KIST) Europe located in Saarbruecken, Germany where she worked from 2007 to 2016. At KIST Europe, she participated in a number of European and Korean projects on strategy & policy developments in the fields of eco-innovation as well as international S&T cooperation between the EU and Korea.  

Journal Reference

Moon Jung Kang^1, 2, Jongwoon Hwang². Structural dynamics of innovation networks funded by the European Union in the context of systemic innovation of the renewable energy sector, Energy Policy 96 (2016) 471-490.

Show Affiliations

1. Chair of Innovation Economics, Technical University of Berlin, Müller-Breslau-Straße 15, 10623 Berlin, Germany.
2. Industry and Technology Strategy Department, Korea Institute of Science and Technology Europe, Campue E 71 Uni des Saarlandes, 66123 Saarbruecken, Germany.

 

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Renewable Energy Global Innovations features: Enhanced Oil Recovery (EOR) Using Nanoparticle Dispersions: Underlying Mechanism and Imbibition Experiments

Significance Statement

Nanofluids have become attractive agents for EOR recently. Higher ultimate oil recovery has been reported previously by using nanofluids. The two major mechanisms reported in literature in achieving this feature include: The reduction of interfacial tension between the aqueous phase and oil phase, and the rock wettability alteration. Despite recently widely conducted research using a nanofluid for EOR, the underlying operating mechanism of recovery by a nanofluid is still not well understood.

A new approach which makes use of nanofluids for displacement of oil from solid substrate by nanoparticle structuring leads to structural disjoining pressure which separates oil from the solid substrate. Other factors such as combination of nanoparticle formulation, contact angle and capillary pressure are also known to influence the separation of oil from substrate.

Researchers from Illinois Institute of Technology at Chicago presented results of imbibition experiments using a silica nanofluid and an Illinois Institute of Technology (IIT) nanofluid that displaces crude oil from Berea sandstone and single-glass capillaries. The researchers developed a nanoparticle formulation in view of surviving at a high-salinity environment containing calcium and magnesium ions accompanied with study of structural disjoining pressure mechanism for crude oil displacement. The work was published in peer-reviewed journal, Energy & Fuels.

Through imbibition test, 55% of the crude oil was recovered using the silica nanofluid, compared to only 2% recovered with the pH 9.7 DI water after 15 days. At an increased temperature of 55 ^oC, the IIT nanofluid displaced crude oil approximately 50% from Berea sandstone compared with 17% by the brine solution.

For the mechanistic study, the researchers observed rapid shrinkage of contact region after introduction of brine and the position of contact region didn’t change with time after wedge region was formed, hence oil drop was not detached. However, for the nanofluid case, a new contact line (inner contact line) appears and spreads due to nanoparticles ordering in the oil/solid/aqueous three phase contact region after the wedge film formed. This confirms the structural disjoining pressure mechanism. It is the first time that this mechanism of crude oil displacement from a solid substrate is demonstrated experimentally.

The authors finally conducted model studies of crude oil displacement using single glass capillaries to directly visualize the crude oil displacement process from inside the pore. Around 60% crude oil was displaced by IIT nanofluid compared to 3% in the brine. Moreover, the authors were able to show from their results that the IIT nanofluid thrives in harsh saline environment where silica nanoparticles cannot.

 

About The Author

Hua Zhang is a Ph.D. Student in the Chemical and Biological Department at Illinois Institute since 2011. He received his B.S. and M.S. degrees in Chemical Engineering from Beijing University of Chemical Technology, China in 2008 and 2011 respectively.

His research area lies in wetting and spreading of nanofluids on solid substrate; dynamics of liquids in the capillary; surface cleaning and enhanced oil recovery using nanofluids.  

Journal Reference

Hua Zhang, Alex Nikolov, Darsh Wasan.  Enhanced Oil Recovery (EOR) Using Nanoparticle Dispersions: Underlying Mechanism and Imbibition Experiments, Energy Fuels 28 (2014) 3002-3009.

Department of Chemical and Biological Engineering, Illinois Institute of Technology, Chicago, Illinois 60616, United States.

 

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Renewable Energy Global Innovations features: Effect of PEO molecular weight on sunlight induced photocatalytic activity of ZnO/PEO composites

Significance Statement

Markovic and colleagues (2016) have used the method of heterogeneous photocatalysis, as an efficient method for degradation and mineralization of pollutants present in water bodies and did some modifications. The materials used to initiate photocatalysis are the semiconductor oxides like TiO₂ and ZnO. Researchers modified these semiconductor oxides so that they can become suitable for visible light photocatalysis as these oxides (TiO₂ and ZnO) can absorb only UV light from the sunlight which is present in very minute percentage (~3-5%). So, they used Microwave processing (MW) method to introduce lattice defects to modify the absorption properties and visible photocatalytic activity.

The study investigated the influence of PEO molecular weight on the photocatalytic activity of ZnO/PEO nano-structured composites. ZnO nanoparticles of wurtzite structure were synthesized using MW method which generated fast crystallization of spheroidal nano-structured particles with high density of intrinsic crystal defects (oxygen vacancies and zinc interstitials). These defects helped in the absorption of visible light and enhanced the photocatalytic efficiency under direct sunlight irradiation. Further, ZnO nanoparticles composites with polyethylene oxide (PEO,  –[CH2CH2O]_n–) were prepared, thus creating oxygen interstitials at the composite’s (ZnO/PEO) surface that enhanced the photocatalytic activity of MW processed ZnO.

Researchers used the PEO with molecular weight of 200,000, 600,000 and 900,000 g/mol respectively, to study its influence on photolytic efficiency of ZnO/PEO nano-composites by using the method of de-colorization of methylene blue, under direct sunlight irradiation. They found ZnO/PEO 600,000 was the most efficient composite to enhance the photolytic efficiency because by further increase in the molecular weight particles would get gelled in water suspension.

Further, the researchers investigated the phase purity and crystal structure of the composites by X-ray diffraction and Raman spectroscopy. They also studied the composite’s particles morphology and size distributions by FE-SEM and laser diffraction particle size analyzer, respectively. The optical properties were also analyzed by using UV–Vis diffuse reflectance and photoluminescence spectroscopy. They found that the ZnO and ZnO/PEO composites absorb about 50% of the incident light intensity in the wavelength range 550–800 nm. They also determine the red-shift of band gap energy (0.12–0.15 eV) compared to bulk ZnO.

Calculations based on density functional theory were performed, in order to confirm and further clarify their results. The researchers calculations confirmed that the visible light photolytic efficiency can be enhanced due to the presence of intrinsic defects that caused the band gap narrowing.

 

About The Author

Dr. Smilja Markovic: senior research associate at Institute of Technical Sciences of SASA, Belgrade, Serbia (smilja.markovic@itn.sanu.ac.rs)  

Smilja Markovic joined Institute of Technical Sciences of SASA, Belgrade, Serbia in 2001. She received PhD in material science from Faculty of Physical Chemistry, University of Belgrade, Serbia in 2008. For more than 15 years she developed research activity on the BaTi_1-xSn_xO₃ functionally graded materials. Her current research interest is focused on correlation of point defects in the crystal structure of oxide ceramics such are perovskites (BaTi_1-xSn_xO₃ and CaCu₃Ti_4-xRu_xO₁₂) and zinc oxide based materials (ZnO, ZnO substituted with 3d ions) with their electrical and optical properties.

Markovic is interested in testing of a biomass as a sorbent for wastewater treatment (S. Markovic, et al., Application of raw peach shell particles for removal of methylene blue, Journal of Environmental Chemical Engineering 3 (2015) 716-724). She is a highly skilled in materials characterization techniques including XRD, FTIR and Raman spectroscopy, impedance spectroscopy, particle size distribution based on laser diffraction, and DTA/DSC/TG-MS.

S. Markovic has published over 50 papers in peer-reviewed ISI journals, with citation over 460 and h-index 13, also, presented more than 100 papers at conferences. She is co-inventor of one patent registered in the Register of the Intellectual Property Office of the Republic of Serbia. 

About The Author

Prof. Dr. Dragan Uskokovic was born on April 3, 1944, in Cetinje, Montenegro. He finished his studies at the Faculty of Technology and Metallurgy in 1967 in Belgrade, and in 1974 his doctoral dissertation named Study of Basic Processes Occurring during Sintering of Crystalline Materials. He started his research work at the Institute for Nuclear Sciences Vinca in 1968. In July of 1974, just before finishing his doctoral dissertation, he transferred to the Institute of Technical Sciences of the SASA. He was elected in all scientific and university titles.

He was the director of the Institute between 2001 and 2011. He is a President of Materials Research Society of Serbia (previously then 2007 known as Yugoslav Materials Research Society), which held 18 Conferences in Herceg Novi, between 1995 and 2016.

He published more than 250 articles in international periodicals, many of which in high-ranking journals, held more than 100 lectures worldwide, out of which 50 Plenary Lectures at different international conferences or world-leading research centers. Under his guidance more than 20 Master theses and the same number of Ph.D. dissertations were done. According to Scopus, his articles published in ISI publications were cited about 3300 times (h-index = 29).

About The Author

Dr. Ana Stankovic, Research associate at Institute of Technical Sciences of SASA, Belgrade, Serbia (ana.stankovic@itn.sanu.ac.rs)  

Ana Stankovic joined Institute of Technical Sciences of SASA, Belgrade, Serbia in 2005. She received PhD in material science from Faculty of Physical Chemistry, University of Belgrade, Serbia in 2014.

Her research interests are: ZnO nanostructures, materials chemistry, biomaterials, biotechnology, drug delivery and physical chemistry.

 

 

Journal Reference

Smilja Marković¹ , Vladimir Rajić¹, Ana Stanković¹, Ljiljana Veselinović¹, Jelena Belošević-Čavor², Katarina Batalović², Nadica Abazović², Srečo Davor Škapin³, Dragan Uskoković¹. Effect of PEO molecular weight on sunlight induced photocatalytic activity of ZnO/PEO composites.  Solar Energy, Volume 127, 2016, Pages 124–135.

Show Affiliations

1.  Institute of Technical Sciences of SASA, Knez Mihailova 35/IV, 11000 Belgrade, Serbia
2.  The Vinča Institute of Nuclear Sciences, University of Belgrade, 11001 Belgrade, Serbia
3.  Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia

 

 

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Renewable Energy Global Innovations features: Drivers and inhibitors of renewable energy: A qualitative and quantitative study of the Caribbean

Significance Statement

Many countries seek to exploit renewable energy resources for a sustainable economy and environment. However, they face challenges such as high upfront costs of developing renewable energy and lack of necessary funding.

Researchers from the Haskayne School of Business at University of Calgary in Canada made findings on the factors affecting development of renewable energy in the Caribbean and recommendations were provided on how best to make use of the factors identified. Their study appeared in Energy Policy.

A lot of researchers have related the degree of development of renewable energy technologies to institutional factors or environmental innovation. However, despite all the previous research, it remains unclear the extent to which these institutional factors influence the development of renewable energy technologies.

According to background reviews and research in the Caribbean, factors such as level of legislative and regulatory sophistication and differences in ownership structure of electricity utilities play major roles in the development of renewable energy industries both in the Caribbean and in the wider international context.

The Caribbean is made up of small island states in an area where the development of renewable energy technology is favourable, due to its vulnerability to the impacts of climatic change, availability of renewable energy resources and dependence on imported fossil fuels, that makes them susceptible to price volatility and geopolitics associated with these fuels. At the same time the unique and isolated ecosystem of the Caribbean can serve as a natural laboratory for study by bio-geographers and ecologists.

Ince et al. (2016) study partially replicates and extends previous research of Shirley and Kammen, Energy Policy, 2013. by replicating and extending personal interview-based case studies to the previously unstudied political jurisdictions in the Caribbean.

Ince et al. (2016) research explored in detail number of cases in selected political jurisdictions of  the Caribbean and a questionnaire survey-based was conducted on 34 out of the 36 political jurisdictions in the Caribbean.

For this study, grid-tied renewable energy technologies such as wind, solar and geothermal were explored and a two-phase methodology study was implemented; the first involving comparative case analysis through in-depth face-to-face interviews in 12 political jurisdictions in Caribbean and the second involving quantitative testing of emergent determinants and their interactions in questionnaire survey-based study in 34 out of 36 political jurisdictions in the  Caribbean.

The survey- based questionnaire  was designed to test the model developed in the qualitative phase that included 75 interviews in  12 jurisdictions in the Caribbean. The questions were tested to ensure external validity.

The second phase of the study, the quantitative analysis, included a survey of Caribbean energy stakeholders in order to determine the extent to which the relationships uncovered in the qualitative phase held in the wider 36 political jurisdictions in the Caribbean. Quantitative data collection was hosted online by CVENT Company that provides software for survey administration and event planning.

Based on coding results, the authors developed theoretical models for renewable energy development in Caribbean which proposed five major factors that influenced renewable energy industry development. These include local entrepreneurial attitudes, role of local champions, informal institutions, influence of incumbent electricity utility and influence of international agencies.

From these five factors explored in the qualitative study, Ince et al. (2016) suggested that the extent of entrepreneurial attitude in political jurisdiction, influence of local champions and pressure exerted by informal institutions in a political jurisdiction correlated positively with effectiveness of policies that promote renewable energy development within a political jurisdiction. The level of incumbent utility influence could potentially be positively or negatively correlated with the extent of renewable energy development.

The quantitative study indicated that the level of incumbent utility influence correlated negatively with the level of effectiveness of policies that promote renewable energy developments within a political jurisdiction. Meanwhile the level of informal institutions present correlates with the level of effectiveness of policies that promote renewable energy development.

Results of the quantitative analysis of phase II showed no statistically significant difference and no significant single informant bias when two responses from the same political jurisdiction were compared. Each possible pair of responses were compared if there were more responses from the same jurisdiction.

Results from multiple regression mode confirmed the researchers findings that the weaker the influence of an incumbent electric utility and the stronger the presence of informal institutions, the stronger the level of renewable energy development.

Journal Reference

David Ince, Harrie Vredenburg, Xiaoyu Liu. Drivers and Inhibitors of Renewable energy: A Qualitative and Quantitative study of The Caribbean.  Energy Policy, Volume 98, November 2016, Pages 700–712.

Haskayne School of Business, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada.

 

 

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Renewable Energy Global Innovations features: Accurate estimation model for small and micro hydropower plants costs in hybrid energy systems modelling

Significance Statement

Due to high need of available and reliable energy, renewable sources have aided the increasing diffusion of small plants and distributed generation, allowing the use of low-density distributed renewable sources and provision of self-sufficient energy for small communities in order to reduce transmission loss and grid congestion problems.

Various models used in analyzing energy systems despite their accuracy and complexity, focused less on model input data such as investment cost. There arises some situation in cases of hybrid energy system technology such as small hydropower plants as simplified models cannot accurately estimate investment costs.

Researchers from Department of Industrial Engineering, at University of Padova in Italy proposed a new approach for the estimation of cost of electro-mechanical equipment, where the final cost was decomposed in three terms, two of which represents the cost of mechanical equipment and one the cost of electrical equipment. The work is published in journal, Energy.

Cavazzini et al. (2016) proposed methodology decomposes cost of electro-mechanical equipment which includes ex-works market prices of turbine, automatic valve, regulation elements and alternator in three terms depending on net head, design flow rate and design power. The great diversity in the topology of turbines was taken into account by defining them for each type of turbine separately as regards to correlation constants. The constants were evaluated by applying a recent modified version of the Particle Swarm Optimization ASD-PSD algorithm.

When optimization procedure to determine correlation coefficients was applied to a data set of 13 small hydropower plants located in Italy and equipped with Pelton turbines, it was seen that correlation simulated with good agreement of the real costs of power plants with an average error equal to 6.4% and standard deviation of 6.5%.

For data set of 12 small hydropower plants located in Italy and in Guatemala equipped with Francis turbine, correlation also simulated with good agreement of the real costs of power plants with an average error equal to 10.6% and standard deviation of 4.4%. For Kaplan turbines, resulting correlation simulates with good agreement the real costs of power plants with an average error equal to 8.1% and a standard deviation of 8.8%.

In comparison with the most popular and accurate literature correlations, the proposed approach reached obtained mean errors of 9.2% for Pelton turbine, 9.8% for Francis turbine and 18.2% for Kaplan turbine which were all smaller than all the literature correlations and in particular than those of Ogayar and Vidal’s widely adopted method (10.2% for Pelton turbines, 11.5% for Francis turbine and 25.0% for Kaplan turbines).

It can be deduced that the researchers approach is capable of reaching good values of accuracy with a mean error smaller than all the literature correlations.

The proposed correlation structure with a direct dependency not only on power and net head, but also on design flow rates seems to generate a better approximation of the real cost trend of the electro-mechanical equipment of small hydropower plants.

 

 

About The Author

Giovanna Cavazzini, associate professor, received her Master’s degree with honour in Mechanical Engineering in 2003 from the University of Padova and her doctorate with European Label in Energetics in 2007 from the University of Padova.

She spent in 2005 a research period at the Ecole Nationale Superieure Arts et Métiers ParisTech de Lille with emphasis to the study of unsteady turbulent phenomena developing in turbomachines.

In 2009 she received the qualification of Maitre de Conference from the Ministère de l’Enseignement Supérieur et de la Recherche in France and since 2016 she is Associate Professor of Fluid Machines and Energy Systems at the University of Padova.

Her main research interests include analysis and modeling of renewable energy systems, techno-economical optimization of hydropower plants and design optimization of fluid machines with particular emphasis on hydraulic turbines and pump-turbines. She is author of about 80 scientific publications, the most part of which published in International Journals with Impact Factor and in Proceedings of International Conferences.  She is Deputy Chair of the joint sub-program of the European Energy Research Alliance (EERA) on “Mechanical Energy Storage”.  

About The Author

Alberto Santolin, received his master’s degree in Mechanical Engineering in 2005 and his Ph.D. in Design of Small Hydroelectric Turbine in 2008, both at the University of Padua. He has worked in the field of hydroelectric since 2005 as design consultant of hydraulic turbines for companies all over the world with more than 50 turbines designed and in operation.

Since 2016 he is CEO and founder of 45 Engineering a company that develops research projects in the field of mechanical engineering with particular focus on hydraulic machines like pumps, turbines and valves. In 2015 he created a web-app named hpp-design.com to help developers of hydropower plant to find the main parameters for their hydro power plant.

He is a mechanical key expert for consultancy services for undertaking feasibility study and preparation of tender documents for developing small hydropower station in Africa and central America with more than 40 technical and economical due diligences of hydroelectric plants in Italy already built and in operation. He is author of various scientific publications, most of them published in International Journals with Impact Factor and in Proceedings of International Conferences. 

 

About The Author

Giorgio Pavesi, currently serves as  President of Energy Engineering. He received his MS in Mechanical Engineering with honour from the University of Padova and  his Ph.D. in Mechanical Engineering in 1989 on ” Small gas turbine for cogeneration plants “. In 2002, Giorgio Pavesi accepted the professorship in Energy Conversion Systems and Machines at the Department of Mechanical Engineering, University of Padova.

He is  Member of ETC (EuroTurbo Committee) and of IEC (International Electromechanical Commission).

He was working since 1987 in the field of Turbomachinery and Energy Conversion Systems, with special attention to hydraulic turbomachinery: Blade Design Optimisation; Improvement of Pump Design Criteria; Improvement of Hydraulic Design Criteria; Dynamic  Behaviour of Reversible Pump Turbines; Off Design Instabilities.  

About The Author

Guido Ardizzon, full professor, graduated with honours in Mechanical Engineering in 1982 at the University of Padova and from 1984 to 1992 was Research Fellow at the University of Padova. In 1992 he became Associate Professor and held the courses of Design of Energy Conversion Machine at the University of Parma and since 1993 of Energy Conversion Systems and Machines at the University of Padova. In the period 1998-2002 he was member of the U.N.I. Technical Commission for Pumps and Small Hydraulic Turbines and since 2001 he is Full Professor of Energy Conversion Systems and Machines at the University of Padova.

He carried out research activities with several Companies. From 2009 to 2011 he was Head of the Department of Mechanical Engineering at the University of Padova.

He is author of more than 110 publications in the hydraulic machine field, the most part of which published in International Journals and in Proceedings of International Conferences.  

 

Journal Reference

Giovanna Cavazzini , Alberto Santolin , Giorgio Pavesi , Guido Ardizzon. Accurate estimation model for small and micro hydropower plants costs in hybrid energy systems modelling, Energy, Volume 103, 2016, Pages 746–757.

Department of Industrial Engineering, University of Padova, Via Venezia 1, 35131, Padova, Italy

 

 

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Renewable Energy Global Innovations features: A reduced low-temperature electro-thermal coupled model for lithium-ion batteries

Significance Statement

Despite various advantages lithium-ion battery LIB offers as a favorable candidate for electric vehicles, they however face certain challenges due to dramatic increase of impedance at low temperature and lithium deposition which overall affects battery performance. Internal or external heating of lithium-ion batteries before charging or discharging is usually done in cold weather until it reaches the effective operating temperature.

Internal heating however is preferred due to uniform temperature distribution coupled with higher efficiency when compared to external heating strategy. In order to ensure high efficiency and less damage to battery lifetime when using internal heating strategy, it is essential to build a high-fidelity electro-thermal coupled model for voltage estimation and prediction of temperature evolution of lithium-ion battery.

In a recent article of Jiang et al. (2016) which was published in journal, Applied Energy, a low-temperature electro-thermal coupled model was investigated based on electrochemical mechanism which was developed to accurately capture both electrical and thermal behaviors of batteries.

Several modelling strategies such as black box, electrochemical model and equivalent electrical circuit (RQ, Warburg and RC elements) model in predicting voltage performance of LIBs have been studied but equivalent electrical circuit has more advantage over others in terms of good compromise between computation time, parameterization effort and simulation accuracy.

However, at low temperature, a general equivalent electrical circuit has lower accuracy. Further, sluggish charge-transfer kinetics, decreased solid-state lithium-ion diffusivity, reduced electrolyte conductivity and strong existence of mutual coupling between various influencing factors are founded in the battery at low temperature, resulting in highly non-linear characteristic of model parameters. Hence, most models developed to describe low-temperature performance of LIBs are complicated and highly sensitive to temperature.

The authors proposed a low-temperature electro-thermal coupled model, reduced electro-thermal coupled model based on frequency-dependent FD equation where it was experimentally validated under different temperature, current frequency and current amplitude conditions with simulation results implemented to show good agreement with the experimental data.

In their experiments, three different kinds of batteries consisting of graphite anode and cathode materials; LiNi_1/3Co_1/3Mn_1/3O₂ (NCM), LiFePO₄ (LFP) battery and LiCoC₂ (LCO) battery were used. Electrochemical impedance spectroscopy were conducted using electrochemical workstation over a temperature range of -15°C to 6°C with intervals of 3°C at 50% state of charge SOC. Verification experiments for voltage performance were done using sinusoidal alternating current with various sets of frequencies, temperature and amplitude, and using dynamic varying current profile such as urban dynamometer driving schedule UDDS for NCM batteries while verification experiments for thermal behavior was carried out under sinusoidal alternating current conditions including constant frequency constant current CFCC and constant frequency variable current CFVC.

For electro-thermal coupled model, various resistance and capacitance RC elements was used to describe the kinetic process of charge transfer on cathode and anode surface, lithium-ion diffusivity in solid state and representation of lithium ion migration through passive film, and resistance and inductance elements indicates response at high frequency.

When checking the effectiveness of model reduction, influence of frequency on polarization voltage showed that different electrochemical process can be controlled by varying the sinusoidal alternating current frequency while irreversible heat within the battery can be controlled by varying the frequency. It was discovered that resistance increases and capacitance decreases with decrease in environmental temperature when observing frequency dependence of resistance and capacitance.

Results shown when considering verification at different frequencies and comparing mean value of absolute error between measured and simulated voltage showed two models, electro-thermal coupled and reduced electro-thermal coupled having similar distribution of voltage deviations. However, simulation errors of the electro-thermal coupled model are smaller than the reduced electro-thermal coupled model. But mean errors of 13.8mV and 15.6mV respectively and maximum relative errors of less than 1.76% and 1.77% of electro-thermal and reduced electro-thermal coupled model were observed indicating that present model can accurately emulate voltage behavior of lithium-ion batteries despite slight difference at various frequency.

Comparison between experimental data and simulation results at four different temperatures with battery subjected to sinusoidal alternating current excitation of 10A and 500Hz for 1361s showed that mean errors and maximum relative errors of presented model gradually increase with decrease in temperature indicating nonlinearity at lower temperature. Mean errors of electro-thermal and reduced electro-thermal coupled models are less than 16.15mV and 26.7mV respectively and maximum relative error less than 1.88% and 2.12% at four different temperatures.

Battery subjected to different sinusoidal alternating current excitation with CFCC consisting of 50 Hz-5A and 50 kHz-10A showed temperature errors less than 1.5°C and 1.58°C respectively which confirms accurate thermal behavior of LIBs predicted by models under various conditions.

Simulation results and measurements with maximum sinusoidal alternating current amplitude showed good agreement observed for a variety of current rates at -15°C where mean errors and maximum relative errors were less than 1.62mV and 18.4mV, 1.76% and 1.85% for electro-thermal and reduced electro-thermal coupled respectively.

With battery subjected to sinusoidal alternating current excitation of 500Hz and 5 kHz, electro-thermal and reduced electro-thermal coupled models gave maximum error of 1.32°C and 1.79°C at CFVC conditions. Temperature trend are nicely consistent with measured ones indicating that the proposed models exhibit high accuracy in evaluating battery temperature under various conditions.

Comparing with the equivalent electrical circuit model, Thevenin model and exponential function, the reduced equivalent electrical circuit model, based on the FD equation, cannot only accurately describe electrochemical characteristic within the battery, but also precisely predict the impedance in wide frequency ranges with a lower computational effort. Furthermore, the effectiveness and adaptability of the proposed methodology for model reduction is verified based on the highly consistent results between simulation and experiments using batteries with three different cathode materials from different manufacturers. It is also concluded that there is superior adaptability of the new FD equation.

The model verification when considering UDDS profile gave mean voltage error and maximum relative voltage error at 24.25mV and 2.65% respectively indicating good agreement between simulation results and experimental data.

This study proposed reduced electro-thermal coupled model with maximum relative voltage error and temperature error of 2.65% and 1.79°C respectively fulfils requirement of engineering applications. It also offers lower computational effort, lower complexity under various conditions and its characterization of state of health for LIBs which can be used in application of on-board battery management system.

About The Author

Jiuchun Jiang (M’10-SM’14) was born in Jilin Province, China. He received his B.S. degree in Electrical Engineering from Northern Jiaotong University in Beijing, China, in 1993, and the Ph.D. degree in Power System Automation at the same university in 1999.

He is currently a professor with the School of Electrical Engineering, Beijing Jiaotong University, Beijing. His main interests are related to battery application technology for electric vehicles and high speed trains, electric vehicles charging stations and micro-grid technology. He has undertaken more than 60 projects and published 150 papers, 19 patents and 5 books.

He received the Ministry of Education technology invention 1st Award for his work on EV battery management system, the National Science and Technology Progress 2nd Award for his work on EV Bus system, and the Beijing Science and Technology Progress 2nd Award for his work on EV charging system. 

About The Author

Haijun Ruan is currently pursuing his Ph.D. degree in Electrical Engineering in the National Active Distribution Network Technology Research Center, Beijing Jiaotong University (BJTU), under the supervision of Prof. Jiuchun Jiang.

His current research interests lie in the electrochemical impedance spectroscopy, low-temperature modeling and simulation, low-temperature internal heating strategy, thermal characteristic and the state evaluation for lithium-ion batteries, and design of power electronic equipment for generating sinusoidal alternating current. He was awarded as Outstanding College Graduates in Beijing in 2014 and Municipal-level Merit Student in Beijing.

He has obtained National Scholarship for three times, National Motivational Scholarship for three times, and ‘Siyuan’ scholarship, which is the highest scholarship for undergraduate student in BJTU. He won about 20 academic competition and technology design contest awards, more than 5 awards of which were municipal level or above. 

About The Author

Bingxiang Sun，was born in Jilin province, China, in 1979. She received her doctorate degree in electrical engineering at the Institute of Electrical Engineering, Chinese academy of sciences. In 2009, she joined the National Active Distribution Network Technology Research Center, Beijing Jiaotong University，as a post doctoral fellow, and in 2011 became a lecturer. Since 2015, she was promoted to be an associate professor.

From 2006, she focused on the application technique research of Li-ion batteries, including modeling and simulation, thermal characteristic and low-temperature internal heating strategy, performance evaluation and design of battery management system strategies, economic analysis of electric vehicle operation, etc. She has undertaken some projects from the Ministry of Science and Technology (MOST), State Grid Company and ABB Company etc. She has published 30 papers, 5 patents and 2 books.

She is an expert in Beijing electric vehicles experts’ database and achieved the University ‘Excellent teacher’ award in 2016. She has participated as a core member to assist the dean with a lot of fundamental work at the first development stage of Hanergy School of Renewable Energy (HASRE), an international school. 

 

Journal Reference

Jiuchun Jiang^1,2,Haijun Ruan^1,2, Bingxiang Sun^1,2, , , Weige Zhang^1,2, Wenzhong Gao³, Le Yi Wang⁴, Linjing Zhang^1,2. A Reduced Low-Temperature Electro-Thermal Coupled Model for Lithium-ion Batteries.  Applied Energy, Volume 177, 2016, Pages 804–816.

Show Affiliations

1. National Active Distribution Network Technology Research Center (NANTEC), Beijing Jiaotong University, Beijing 100044, China
2. Collaborative Innovation Center of Electric Vehicles in Beijing, Beijing Jiaotong University, Beijing 100044, China
3. Department of Electrical and Computer Engineering, University of Denver, Denver, CO 80208, USA
4. Department of Electrical and Computer Engineering, Wayne State University, Detroit, MI 48202, USA

 

 

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Renewable Energy Global Innovations features: Catalytic adsorptive desulfurization of model diesel fuel using TiO2/SBA-15 under mild conditions

Significance Statement

Removing trace amount of refractory sulfur compounds from diesel under mild conditions has been a great challenge in refinery. Recently, Xiao’s lab from South China University of Technology proposed an effective and economic desulfurization approach (catalytic adsorptive desulfurization, CADS) for ultra-clean fuel production under mild conditions.

A coupling oxidation-adsorption process was developed for selective desulfurization. Plausibly, such CADS approach shows superior desulfurization uptake at low sulfur concentration range, fast adsorption kinetics, excellent regenrability, operation at mild conditions, and facile and low-cost adsorbent synthesis. CADS may provide a promising path for ultra-deep desulfurization to achieve ultra-clean diesel. For more details, read X. Ren et al. / Fuel 174(2016) 118-125. 

About The Author

Prof. J. Xiao received her BS in applied chemistry and MS in Chemical Engineering from South China University of Technology, and her PhD majoring in fuel science from the Pennsylvania State University in 2012. Then, she joined the School of Chemistry and Chemical Engineering at South China University of Technology. Her research interests include adsorption for clean energy and environmental pollution control, i.e. fuel desulfurization and denitrogenation and CO₂ capture, new adsorbent materials, and environmental catalysis, etc. 

Journal Reference

Fuel, Volume 174,  2016, Pages 118–125.

Xiaoling Ren, Guang Miao, Zhiyong Xiao, Feiyan Ye, Zhong Li, Haihui Wang, Jing Xiao^, 

School of Chemistry and Chemical Engineering and Key Laboratory of Enhanced Heat Transfer and Energy Conservation, South China University of Technology, Guangzhou 510640, China.

Abstract

This study investigates catalytic adsorptive desulfurization (CADS) of model diesel fuel using TiO₂/SBA-15 under mild conditions. The TiO₂/SBA-15 was prepared by a facile incipient wetness impregnation method and characterized by N₂ adsorption and X-ray diffraction. The CADS referred to ADS performance were evaluated in a batch reactor.

High desulfurization uptake of 12.7 mg/g was achieved at low sulfur concentration of 15 ppmw-S by TiO₂/SBA-15 under CADS, which was two-magnitude higher than that under ADS without the in-situ catalytic oxidation of dibenzothiophene. Kinetic results suggested that the CADS equilibrium over TiO₂/SBA-15 was reached fast in 0.5 h. In the CADS–TiO₂/SBA-15 system, the TiO₂ loading, cumene hydroperoxide/dibenzothiophene ratio and CADS temperature were optimized to be 10 wt%, 2, and 35 °C, respectively.

Furthermore, desulfurization tests in 5 consecutive CADS-regeneration cycles suggested that the bi-functional TiO₂/SBA-15 can be regenerated by acetonitrile washing followed with oxidative air treatment. The CADS–TiO₂/SBA-15 mechanism went through the oxidation of DBT to oxidized DBTO₂ over TiO₂/SBA-15 by cumene hydroperoxide, which was followed by the adsorption of the oxidized DBTO₂ over TiO₂/SBA-15.

The superior desulfurization uptake at low sulfur concentration range, fast adsorption kinetics, excellent regenerability, operation at mild conditions, and facile and low-cost adsorbent synthesis make the CADS–TiO₂/SBA-15 system an effective and economic desulfurization approach for ultra-clean fuel production.

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Renewable Energy Global Innovations features: Central versus localized optimization-based approaches to power management in distribution networks with residential battery storage

Significance Statement

Different approaches have been proposed previously for scheduling demand-side battery storage, usually with one of two objectives; alleviating the need for distribution grid reinforcement by managing bi-directional power flows or reducing electricity bills for customers. However, without careful coordination, the potentials of demand-side approaches might not be fulfilled.

Dr. Elizabeth Ratnam from the University of California Berkeley (formerly of the University of Newcastle, Australia) and Professors Steven Weller and Christopher Kellett from the University of Newcastle in Australia investigated two optimization-based algorithms to balance an increase in the operational savings that accrue to residential customers with combined photovoltaic (PV) battery storage systems against management of distribution grid power flows to alleviate voltage rise and other local conditions that necessitate grid reinforcement. The article was published in the International Journal of Electrical Power and Energy Systems.

The two optimization-based approaches used are a centralized quadratic program energy-shifting, where selected customers implement a distributor-specified day-ahead battery schedule and a second approach, referred to as local quadratic program energy-shifting, where distributor-specified weights are incorporated into a quadratic program-based algorithm implemented directly by customers to obtain an individual day-ahead battery charge and discharge schedule. The algorithms were applied to load and generation data from 145 Australian residential customers to investigate the customer-distributor benefits of coordinated residential battery scheduling.

The researchers introduced a modeling framework consisting of a dynamical model of a residential energy system and a distribution region described by a directed graph. Residential customers were identified in a specified region and considered ways to coordinate their day-ahead battery schedules under the assumption of a financial policy of net metering.

The two different optimization-based approaches require load and generation forecasts at different locations in the network.  Forecasting is performed by the distributor in the centralized QP case, while in the local QP case the forecasting is done at each residence.  The authors described an approach to emulate imperfect forecasts using historical data.

As a particular application of the techniques presented, the authors investigated the case where the distributor identifies its “weakest link” (via a power flow analysis), which then provides the distribution region of interest and places constraints on the optimization problems.

When assessing the benefits of residential battery scheduling with reference to a 52-week period, the baseline profile exceeded the upper limit for the edge of interest at subgraph forecast constraints of 300KW on 9 days in a year and falls below the lower limit of -150KW on 5 days in the year. It can be said that on most days, subgraph members received a reliable supply of electricity when they do not use or have a battery.

When assessing operational savings accrued to a single subgraph member (i.e., each residence) over a period of 52 weeks denoted by annual savings in $/year, it was seen that local quadratic program energy-shifting may disproportionately penalize some customers when implementing a local quadratic program-based battery schedule.  In fact, using such a localized approach resulted in a few customers seeing additional annual costs.

By contrast, the authors demonstrated that, in terms of customer benefit, the centralized quadratic program-based approach was preferable in that all customers received the same annual savings, so that no customers were penalized for utilizing battery storage.

About The Author

Elizabeth L. Ratnam received the B.E. (Hons I) degree in Electrical Engineering in 2006, and the Ph.D. degree in Electrical Engineering in 2016, both from the University of Newcastle, Australia. She subsequently held a research position with the Center for Energy Research at the University of California, San Diego. During 2001?2012 she gained engineering experience at Ausgrid, one of the largest electricity distribution networks in Australia.

Since 2016, Elizabeth has held a research position with the Berkeley Energy and Climate Institute at the University of California, Berkeley. Her research interests lie in areas that facilitate the integration of renewable energy into power systems. 

About The Author

Steven R. Weller received the B.E. (Hons.I.) degree in Computer Engineering in 1988, the M.E. degree in Electrical Engineering in 1992, and the Ph.D. degree in electrical engineering in 1994, all from the University of Newcastle, Australia. During 1994?1997, he was a Lecturer in the Department of Electrical and Electronic Engineering, University of Melbourne, Australia. In 1997, he joined the University of Newcastle, where he is currently an Associate Professor.

He served as Head of School of Electrical Engineering and Computer Science (2007-2009), and since 2013 has served as Deputy Head of the Faculty of Engineering and Built Environment. He is the recipient of an IET Control Theory and Applications Premium Award. His research interests lie in the areas of control theory and its application to energy systems and climate. 

About The Author

Christopher M. Kellett received the B.Sc. in Electrical Engineering and Mathematics from the University of California, Riverside in 1997 and the M.Sc. and Ph.D. in Electrical and Computer Engineering from the University of California, Santa Barbara in 2000 and 2002, respectively.  He subsequently held research positions with the Centre Automatique et Systemes at Ecole des Mines de Paris (France), the Department of Electrical and Electronic Engineering at the University of Melbourne (Australia), and the Hamilton Institute at the National University of Ireland, Maynooth.

Since 2006, Chris has been with the School of Electrical Engineering and Computer Science at the University of Newcastle, Australia, where he is currently an Associate Professor.

A/Prof. Kellett is an Associate Editor for IEEE Transactions on Automatic Control, the European Journal on Control, and Mathematics of Control, Signals and Systems, as well as a member of the IEEE Control Systems Society Conference Editorial Board.  He has been the recipient of an Australian Research Council Future Fellowship (2011-2015), an Alexander von Humboldt Research Fellowship (2012-2013), and the 2012 IET Control Theory and its Applications Premium Award.

His research interests are broadly in the area of systems and control, with specific emphases on stability and robustness properties for nonlinear systems, high speed model predictive control, applications in electricity distribution networks, and applications in social systems such as carbon pricing and opinion dynamics.

 

 

Journal Reference

Elizabeth L. Ratnam¹, Steven R. Weller², Christopher M. Kellett ². Central versus localized optimization-based approaches to power management in distribution networks with residential battery storage, International Journal of Electrical Power and Energy Systems 80 (2016) 396-406.

Show Affiliations

1. Center for Energy Research, Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0411, USA.
2. School of Electrical Engineering and Computer Science, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.

 

 

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Renewable Energy Global Innovations features: Experimental investigation on emission and stability of dual feed biogas swirl combustor

Journal Reference

Journal of Renewable and Sustainable Energy , volume 8, Issue 2 ,  2016.

Marija Živković¹ , Aleksandar Milivojević², and Miroljub Adžić²

Show Affiliations

1. Faculty of Mining and Geology,University of Belgrade Djusina 7, 11000 Belgrade, Serbia
2. Faculty of Mechanical Engineering,University of Belgrade, Kraljice Marije 16, 11000 Belgrade, Serbia

Abstract

Biomass is a renewable energy source with the highest potential to contribute in meeting energy needs and providing a secure and sustainable energy supply. For combustion of biogas (low calorific gas), an efficient technology is needed. It should provide stable combustion with low emission of pollutants such as CO and NOx over a wide operating range.

This paper presents the experimental investigation on emission and stability of a premixed dual feed biogas swirl combustor with a pilot burner. For the experimental investigation, swirlers with swirl numbers 1.13 for the main burner and 1.98 for the pilot burner were used. The tests were performed at atmospheric conditions. The effects of carbon dioxide content, nominal thermal power, and equivalence ratio were analyzed and briefly discussed.

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