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

Significance Statement

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

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

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

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

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

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

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

About The Author

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

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

Journal References

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

Show Affiliations

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

Go To ACS Nano 

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

 

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

Significance Statement

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

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

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

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

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

About The Author

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

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

Journal Reference

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

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

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

Significance Statement

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

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

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

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

About The Author

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

About The Author

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

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

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

Reference

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

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

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

Significance Statement

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

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

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

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

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

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

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

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

About The Author

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

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

About The Author

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

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

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

Journal Reference

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

Show Affiliations

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

 

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

Significance Statement

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

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

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

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

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

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

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

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

About The Author

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

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

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

Reference

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

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

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

Significance Statement

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

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

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

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

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

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

About The Author

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

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

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

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

About The Author

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

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

About The Author

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

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

Journal Reference

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

Show Affiliations

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

 

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

Significance Statement

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

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

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

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

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

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

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

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

About The Author

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

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

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

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

Journal References

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

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

Show Affiliations

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

 

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