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SALT: Solar and Alternative Technologies Research Experience

What is SALT?

The Solar and Alternative Technologies (SALT) research experience is a 10-week summer research program providing undergraduate students with the opportunity to research and develop exciting alternative energy technologies such as fuel, catalysts, power, energy reservoirs, clean water and plastics from renewable sources or using renewable energy, thereby reducing the world’s dependence on fossil fuels. Students working on SALT projects will learn analytical techniques, responsible conduct and environmental ethics, as well as communication and social media skills through oral and written reports. SALT research will include fascinating technologies such as microalgal biofuel, biocatalysts and nanoellipsoids.

As SALT researchers, students will get a taste of graduate level research, acquire important skills under the mentorship of experienced TU Faculty, see alternative energies in action during field trips and contribute to building a better world through renewable energy.  Please look at the bottom of the page for a description of each research project.  Room, a subsistence stipend for food, and a $500/week traineeship are included.

Field Trips

SALT students will experience alternative energy in action on six local and two one-day field trips to fascinating locations like the Pensacola Dam, Covanta Energy-from-Waste, FRE Renewable Solutions, the Gathering Place, Gilcrease Museum and Redbud Valley Nature Preserve. These trips will include discussion of the challenges those industries face in achieving more widespread use of their technologies.

Faculty Research Mentors

SALT participants will collaborate with experienced faculty research mentors to guide them through the research project. These mentors include:

Timeline

Application deadline: Thursday, March 21
Notification of acceptance into the program:  Thursday, March 28
2019 dates to be on site at the University of Tulsa:  May 26 – Aug. 3

Contact Information

For more information on the SALT research experience, contact Dr. Laura Ford at laura-ford@utulsa.edu, or by using the contact form below.

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Funded through the National Science Foundation Grant No. 1852477 and 1852351

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

An Integrated Renewable Energy System (Mentor Dr. Ashenayi)

The traditional approach to providing electrical energy is to burn fossil fuel to rotate a shaft which then generates electricity. Transmission lines are used to deliver electricity to load centers. This approach is both expensive and inefficient and could cause environmental harm [5]. In addition, this approach wastes energy while it is being transmitted. In this project we will introduce the students to the concept of maximizing efficiency of the energy generation system [6] – [7] by both matching energy resource with the load as well as improving the efficiency of each individual energy conversion system. An example application is photovoltaic (PV) power. The low efficiency of PV
cells [8] increases the cost and requires a significantly larger footprint, which also increases the cost and eliminates the possibility of installing the PV cells close to load centers. This means we need to use transmission lines to transmit energy. We will introduce and study the concept of “Max Power Point Tracking” [9] for a PV cell and identify how we can control the cell’s output to maintain its maximum output. We will also study how to evaluate each resource and how to obtain the load
information. We will be using software tools such as PowerWorld, SUNREL, and HOMER to study load flow, energy available from resources and impact of adding local generation. The hypothesis is that using correlation between different renewable resources, in addition to resource and need matching, will increase the system conversion efficiency to the point that we will be able to use smaller foot print to create a micro-grid to meet local needs; which will eliminate the need for long and expensive transmission lines.
Experimental and Analytical Goals for this Project: The students will develop and simulate an Integrated Renewable Energy System with these specific objectives:
1. Evaluate energy available from each resource (solar, wind, hydro, etc.)
2. Identify and quantify energy needs (low/high grade heat, electricity, rotating shaft, etc.)
3. Evaluate impact of transmission lines in overall efficiency.
4. Match resource best suited to each load classification.
5. Maximize energy output of each individual energy conversion device (PV, wind turbine, burners, etc.) by controlling parameters such as direction and angle that PV or the wind turbine is facing.
6. Apply different types of energy storage.

[5] A. Chauhan and R. P. Saini, “A review on Integrated Renewable Energy System Based Power Generagion for Stand-Alone Applications: Configurations, Storage Options, Sizing Methodologies and Control,” Renewable and Sustainable Energy Reviews, vol. 38, pp. 99 – 120, 2014.
[6] K. Ashenayi and R. Ramakumar, “IRES a Program to Design Integrated Renewable Energy Systems,” Energy, vol. 15, pp. 1143 – 1152, 1990.
[7] A. B. Kanese-Patil, R. P. Saini and M. P. Sharma, “Integrated Renewable Energy Systems for Off Grid Rural Electrification of Remote Area,” Renewable Energy, vol. 35, pp. 1342 – 1349, 2010.
[8] M. A. Green, K. Emery, Y. Hishikawa, W. Warta and E. D. Dunlop, “Solar Cell Efficiency Tables (Version 48),” Progress in Photovoltaics: Research and Applications, vol. 24, pp. 905 – 913, 2016`.
[9] J. P. Ram, T. S. Babu and N. Rajasekar, “A Comprehensive Review on Solar PV Maximum Power Point Tracking Techniques,” Renewable and Sustainable Energy Reviews, vol. 67, pp. 826 – 847, 2017.
Numerical Transport Phenomena in Energy Production (Mentor Dr. Crunkleton)

The University of Tulsa has a long history in energy-related research, including both traditional and alternative energy.  In this REU research area, undergraduate students will have the opportunity to conduct research in model-assisted energy decision making, especially as they pertain to solar energy and biofuel production.  Specifically, we hypothesize that computational fluid dynamics (CFD) simulations will capture fluid and nutrient flows in various solar and biofuel production techniques in a way that will guide future experimental studies.  For solar energy, an insolation model of energy availability will be coupled with a fluid flow and heat transfer algorithm for predicting energy production in various solar configurations.  For biofuels research, CFD techniques are coupled with optimization routines to find the best combination of design and operating conditions that will yield the most economical production of biofuels, especially those that are algae-derived.

 

Hydrate Technology for Desalination Process (Mentor Dr. Daraboina)

Several million gallons of water are treated daily for fracturing, injection, disposal and reuse operations during oil and gas production.  The use of fresh water sources for fracturing operations is discouraged.  Fortunately, over the past decade, the oil and gas industry is making an enormous effort to recycle and re-use produced water from onshore and offshore operations and to use alternate water sources for well operations.  Produced water can contain 500-180,000 mg/L of dissolved solids concentration compared to fresh water (<500 mg/L).  Therefore, it is often times necessary to reduce salinity of these waters prior to reuse or recycle.

 

Current desalination technologies are divided mainly into two categories: thermal and membrane techniques.  The traditional desalination plants based on the multi-stage flash (MSF) distillation and reverse osmosis (RO) processes are reliable and established processes [10] – [11], but they are energy intensive. The energy cost of supplying the projected global water need with present technologies is high – especially in a carbon-constrained world. Overall, there are still opportunities to develop water treatment technologies to process produced water at a large scale with a focus on minimizing energy costs and maximizing water recovery. Recently, hydrate-based desalination (HBD) has been proposed for seawater desalination. The advantage of HBD process is that it is less energy intensive as it operates at temperatures well above the normal freezing point of water [12]. The limitation of slow kinetics can be overcome through the prudent choice of favorable guest gas/liquid, promotor addition, and improved reactor designs. The hypothesis is that the chemistry of promotors is the important factor in increasing the kinetic rate of hydrate formation and decomposition.

 

Objectives:

  • to operate hydrate reactor, differential scanning calorimeter and high temperature gas chromatography
  • to analyze thermodynamic and kinetic data for hydrate process
    S. A. Kalogirou, “Seawater desalination using renewable-energy-sources,” Progress in Energy and Combustion Science, vol. 31, pp. 242 – 281, 2005.
    A. D. Khawaji, I. K. Kutubkhanah and J.-M. Wie, “Advances in seawater desalination technologies,” Desalination, vol. 221, pp. 47 – 69, 2008.
    A. J. Barduhn, H. E. Towlson and Y. C. Hu, “The properties of some new gas hydrates and their use in demineralizing sea water,” AIChE Journal, vol. 8, no. 2, pp. 176 – 183, 1962.
Selenium-based Thin Film Solar Cell Fabrication (Dr. Hari)

Traditionally, photovoltaic (PV) cells are tuned to air mass 1.5 spectrum from the sun. Indoor light can also be used for power in wireless and sensing applications, as well as facilitating algae growth using light emitting diodes, to name a few. The wavelength of the indoor light spectrum maximizes at 1.9 eV, which coincides perfectly with the band gap of selenium. Selenium-based solar cells have been stuck on 5% conversion efficiency for the past four decades [13].

There are two fundamental issues for improving the conversion efficiency of selenium-based PV cells beyond 5%. The first issue is to determine the optimum thickness of the absorption p-layer made of selenium for maximum efficiency. If the thickness is large, it will enable higher absorption [14]. However, the drift-based carriers collected at the back side will be reduced for a thick layer. The diffusion length must be optimized to improve the collection of drift current and efficiency of the PV cell. Secondly, selenium at normal deposition conditions predominantly consists of an amorphous structure, which leads to a high recombination rate and a reduction in efficiency. The degree of amorphous component in selenium must be reduced to improve collection efficiency. The basic hypothesis is that by controlling the thickness and amorphous content of the selenium layer in a Se-ZnO heterojunction solar cell, we can attain conversion efficiency of 30% or above [15].

M. A. Mayer, D. T. Speaks, K. M. Yu, S. S. Mao, E. E. Haller and W. Walukiewicz, “Band structure engineering of ZnO(1-x)Se(x) alloys,” Applied Physics Letters, vol. 97, p. 220104, 2010.
A. Kaphle and P. Hari, “Enhancement in Power Conversion Efficiency of Silicon Solar Cells,” Thin Solid Films, vol. 657, pp. 76 – 87, 2018.
A. Kaphle, M. Borunda and P. Hari, “Influence of cobalt doping on residual stress in ZnO nanorods,” Materials in Semiconductor Processing, vol. 84, pp. 131 – 137, 2018.
Solar Charging System and Optimization Using Low Power Microcontrollers (Mentor Dr. Hutchins)

Current small systems solar chargers being deployed are being developed as a static system, where placement of the cells is optimized only by the user. The introduction of low power microcontrollers is allowing the development of very low power systems, which is perfect for quick optimization task on small deployment photovoltaic cell systems. This system will be designed to use modern low power microprocessors to optimize the position in relation to the sun of PV cell arrays to increase the reliability and maximum out put of the solar system. The microprocessor should be extremely low power and optimized for minimal loss. The charging circuit being developed should operate at maximum efficiency over the range of output of the PV cells and be configurable to charge a range of different energy storage devices, such as, Lithium-Ion, Lithium-Polymer, and nickel-based batteries. The final design should be a portable PV array with a position optimizing microcontroller which can be used to power/charge small portable systems.

Development Goals Include:

  1. Evaluate PV cells for range of energy transfer.
  2. Select and test a microcontroller for optimized power constraints.
  3. Selection of a low power actuator for PV array positioning.
  4. Design charging circuit based around the range of energy transfer of the PV cells.
  5. Evaluation of the power system, including the supply of the PV cells, load of the controllers, and loading issues of the charging circuit and energy storage devices.
  6. Work with DC-DC converters for providing the power needed for the microprocessor and any onboard sensors.
Integration of Biosynthetic Pathways into Microalgae for Biofuels Production (Mentor Dr. Johannes)

A new approach for assembling and integrating multi-gene pathways into the nuclear genome of microalgae using CRISPR-Cas9 [16] is the focus of this project, which will study the assembly and integration of complex multi-gene biosynthetic pathways into the nuclear genome of the microalgae species Chlamydomonas reinhardtii.  The potential of algae-based biofuels [17] and protein therapeutics [18] is well documented, but in order to achieve its full potential, genetic engineering is needed to increase the production of target metabolites to desirable levels. Although recombinant protein expression in the microalgae has recently become more robust, the assembly and expression of complex multi-gene biosynthetic pathways in microalgae has yet to be fully accomplished and is a significant step in our ability to engineer microalgae metabolite production for the production of commercially important products [19], [20]. Thus we hypothesize that based on the successful development of similar methods in other species, an efficient nuclear multi-gene assembly and integration method can be developed co C. reinhardtii.  Biosynthetic pathways consisting of one to four genes will be assembled using homologous recombination in the yeast strain Saccharomyces cerevisiae and integrated into the C. reinhardtii nuclear genome using CRISPR-Cas9.  Multi-gene biosynthetic pathways of increasing complexity will be studied systematically. Pathways to be assembled include well studied selection markers and reporter genes and the biosynthetic pathway for the bioplastic polyhydroxybutyrate (PHB) [21]. Once integrated into the nucleus, the genetically engineered strains will be tested using a variety of methods to determine the levels of gene expression and the production level of PHB. The proposed project will provide important insights into the assembly and expression of biosynthetic pathways in microalgae and result in the development of an important tool for genetically modifying the nuclear genome of C. reinhardtii. These insights and the resulting methodology will aid current efforts to produce biofuels from microalgae, enhance our ability to produce therapeutic proteins in microalgae, and be an effective new tool for genetically engineering higher plants and other strains of microalgae.

[16] M. Jinek, K. Chylinski, I. Fonfara, M. Hauer, J. A. Doudna and E. Charpentier, “A programmabel dual-RNA-guided DNA endonuclease in adaptive bacterial immunity,” Science, vol. 337, pp. 816-821, 2012.
[17] M. K. Lam and K. T. Lee, “Microalgae biofuels: A critical review of issues, problems and the way forward,” Biotechnology Advances, vol. 30, pp. 673-690, 2012.
[18] B. A. Rasala, M. Muto , P. A. Lee, M. Jager, R. M. F. Cardoso, C. A. Behnke, P. Kirk, C. A. Hokanson, R. Crea, M. Mendez and S. P. Mayfield, “Production of therapeutic proteins in algae, analysis of expression of seven human proteins in the chloroplast of Chlamydomonas reinhardtii,” Plant Biotechnology, vol. 8, pp. 719-733, 2010.
[19] S. Noor-Mohammadi, A. Pourmir and T. Johannes, “Method for assembling and expressing multiple genes in the nucleus of microalgae,” Biotechnology Letters, vol. 36, pp. 561-566, 2014.
[20] S. Noor-Mohammadi, A. Pourmir and T. W. Johannes, “Methods to assemble and integrate biochemical pathways into the chloloplast genome of Chlamydomonas reinhardtii,” Biotechnology and Bioengineering, vol. 109, pp. 2896-2903, 2012.
[21] W. Chaogang, H. Zhangli, L. Anping and J. Baohui, “Biosynthesis of poly-3-hydroxybutrate (PHB) in the transgenic green alga Chlamydomonas reinhardtii,” Journal of Phycology, vol. 46, pp. 396-402, 2010.
Electrochemical Purification of Silicon from Abundant Silica Sources (Mentor Dr. LeBlanc)

While many new material systems are currently being explored for photovoltaic modules, silicon has long been the most widely adopted photovoltaic technology. Silicon has several advantages over newer material systems that have been the focus of much photovoltaics research. Beyond the well-established market performance of silicon based modules, the inherent advantages of abundance, ruggedness, and safety (over the operating life) position silicon based systems to remain a critical commercial photovoltaic technology for the foreseeable future. The process for generating solar grade silicon (99.9999% purity) requires several energy intensive and hazardous procedures, making the polysilicon material a significant contributor to the overall cost and energy payback time of the photovoltaic [16]. In this project we will explore a new electrochemical strategy to purify silicon from abundant silica sources using ionic liquids and liquid metal electrodes.

 

Figure 1. Schematic of the electrochemical liquid-liquid-solid growth method [17].

Recently, researchers have described an electrochemical liquid-liquid-solid (ec-LLS) growth method in which crystalline silicon was deposited and subsequently purified through the saturation of the product in a liquid-metal electrode [17]. This strategy takes advantage of the unique property of liquid gallium to partially solubilize silicon. This property means that the electrochemically deposited silicon undergoes a purification process akin to recrystallization. However, the current process cannot be used with a silica starting material due to solvent limitations. As a part of this project we will explore how the electrochemistry of gallium is affected by environment of an ionic liquid. The hypothesis of this work is that thermodynamically stable materials such as silica can be suspended in task-specific ionic liquid solvents based on electrostatic interactions while maintaining the necessary electrochemical stability to be processed using ec-LLS. By coupling the recent finding that ionic liquids can be used to solubilize SiO2 starting materials with the established ec-LLS growth method, we will demonstrate how high purity silicon can be produced at low costs, ultimately reducing the overall costs of silicon based photovoltaics.

[16] M. Jinek, K. Chylinski, I. Fonfara, M. Hauer, J. A. Doudna and E. Charpentier, “A programmabel dual-RNA-guided DNA endonuclease in adaptive bacterial immunity,” Science, vol. 337, pp. 816-821, 2012.
[17] M. K. Lam and K. T. Lee, “Microalgae biofuels: A critical review of issues, problems and the way forward,” Biotechnology Advances, vol. 30, pp. 673-690, 2012.
Biochar-based Carbon-encapsulated Iron Nanoparticles (CEINPs) as Adsorbents for Contaminants in Wastewater (Mentor Dr. Ramsurn)

Carbon-based materials are preferred as a metal catalyst support, since they offer higher chemical and thermal stability as well as biocompatibility when compared to polymer or silica coatings [34].  The advantages of using carbon-materials as catalyst support also include lower cost than alumina or silica supports and resistance to the presence of oxygenated functional groups which may enhance metal adsorption and catalyst dispersion [35]. The economic value of biomass relies on the revenue of the products. Biochar is a carbon-rich solid product obtained after carbonization of biomass in hydrothermal media [36].  Research shows biochar obtained from different feedstocks was used for soil amendment to mitigate greenhouse gas emissions, as contaminant adsorbents and for the generation of heat and energy [37], [38]. The Ramsurn lab has successfully synthesized carbon-encapsulated iron nanoparticles (CEINPs) by carbonizing and impregnating biomass model compounds (cellulose, hemicellulose and lignin) [39]. Herein, we aim to test these CEINPs for their adsorption features and their ease of separation due to their magnetic properties. The objectives of this work will be to

  1. Identify the most common heavy metals (Cr, Ar, Cu) present in wastewater in the literature.
  2. Prepare solutions of the identified metals and generate calibration curves for the analytical instrument (UV-Vis and ICP-MS: it is proposed to compare the two methods).
  3. Test biomass derived activated carbon (without Fe) as a baseline.
  4. Repeat Objective 3 with the CEINPs. A number of parameters may be investigated: type of CEINPs [derived from lignin, cellulose or hemicellulose], amount of CEINPs, change in contaminant concentration, reaction time etc.

The hypothesis is that these CEINPs have a higher adsorption efficiency due to the graphitic layers formed around the Fe and they should easily come out of solution using a strong enough magnet.

[34] A. Taylor, Y. Krupskaya, S. Costa, S. Oswald, K. Kramer, S. Fussel, R. Klingeler, B. Buchner, E. Borowiak-Palen and M. P. Wirth, “Functionalization of carbon-encapsulated iron nanoparticles,” Journal of Nanoparticle Research, vol. 12, pp. 513-519, 2010.
[35] E. Lam and J. H. Luong, “Carbon materials as catalyst supports and catalysts in the transformation of biomass to fuels and chemicals,” ACS Catalysis, vol. 4, pp. 3393-3410, 2014.
[36] H. Ramsurn, S. Kumar and R. B. Gupta, “Enhancement of biochar gasification in alkali hydrothermal medium by passivation of inorganic components using Ca (OH) 2,” Energy & Fuels, vol. 2011, pp. 2389-2398, 2011.
[37] F. R. Amin, Y. Huang, Y. He, R. Zhang, G. Liu and C. Chen, “Biochar applications and modern techniques for characterization,” Clean Technologies and Environmental Policy, vol. 18, pp. 1457-1473, 2016.
[38] D. A. Laird, R. C. Brown, J. E. Amonette and J. Lehmann, “A review of the pyrolysis platform for coproducing bio-oil and biochar,” Biofuels, Bioproducts and Biorefining, vol. 3, pp. 547-562, 2009.
[39] S. T. Neeli and H. Ramsurn, “Synthesis and formation mechanism of iron nanoparticles in graphitized carbon matrix using biochar from biomass model compounds as a support,” Carbon, vol. 134, pp. 480-490, 2018.
Bulk Synthesis of Monodisperse Nanoellipsoids (Mentor Dr. Weston)

Thin coatings are used for corrosion, friction, self-cleaning surfaces, and aesthetics. These coatings must uniformly cover the surface, and surfactants are often used to improve wetting. Surfactants, however, can result in new complications. Surfactants remain at the film/surface interface after the film has dried, which can lower the film’s adhesion to the surface. The surfactants also destabilize the complex dispersion of polymers, filler particles, and pigments. Thus, the presence of surfactants limits the options for coating formulations. Improving coating uniformity without surfactants would greatly expand the material choices for coatings. Increasing interfacial viscosity by adding ellipsoidal nanoparticles shows such improvements, but they cannot currently be manufactured at industrial scales [40, 41]. We hypothesize that by combining a controlled shear field with a photopolymerization reaction ellipsoidal nanoparticles with narrow size and aspect ratio distributions could be manufactured in a scalable manner.

Ellipsoidal particles are useful because they experience strong interparticle capillary forces when adsorbed at fluid-fluid interfaces [42 – 44], causing them to aggregate into complex networks that greatly increase interfacial viscosity. Network formation limits the coffee-ring effect and improves coating uniformity [45, 46]. Industry-level use of this effect would require a way to predictably generate bulk quantities of particles with controlled aspect ratios. Currently, the most common methods to generate similar particles are solute precipitation and film-stretching. Precipitation can produce bulk quantities of particles, but control of particle size and aspect ratio is poor, making it much more difficult to model and understand, mechanistically, how these particles form networks that affect interfacial rheology. Oppositely, film stretching methods provide excellent control of particle size and aspect ratio but are not efficiently scalable.

In this project, the student will formulate microemulsions with a UV-curable monomer (styrene) and cross-linker (divinyl benzene) as the dispersed droplet phase.  The droplets will then be deformed via shear in a UV-transparent Couette cell, where the degree of droplet deformation is controlled by altering the droplet’s capillary number [47]. UV light will photopolymerize the deformed droplets to create anisotropic polymer particles. This method allows independent control of the size and aspect ratios of the particles. If the project proceeds successfully, the student will pursue two long-term goals: 1) Adapting the process to operate steadily by adding inlet/outlet streams to the Couette cell and controlling droplet residence time; 2) Altering the mechanical properties of the polymer particles by varying polymer molecular weight and degree of cross-linking to investigate how this affects interfacial rheology.

[40] P. Yunker, T. Still, M. Lohr and A. Yodh, “Suppression of the coffee-ring effect by shape-dependent capillary interactions,” Nature, vol. 476, pp. 308-311, 2011.
[41] C. Seo, D. Jang, J. Chae and S. Shin, “Altering the coffee-ring effect by adding a surfactant-like viscous polymer solution,” Scientific Reports, vol. 500, 2017.
[42] J. Loudet, A. Alsayed, J. Zhang and A. Yodh, “Capillary interaction between anisotropic colloidal particles,” Physical Review Letters, vol. 94, p. 18301, 2005.
[43] L. Botto, E. Lewandowski, M. Cavallaro Jr. and K. Stebe, “Capillary interactions between anisotropic particles,” Soft Matter, vol. 8, pp. 9957-9971, 2012.
[44] S. Coertjens, P. Moldenaers, J. Vermant and L. Isa, “Contact Angles of Microellipsoids at Fluid Interfaces,” Langmuir, vol. 30, pp. 4289-4300, 2014.
[45] B. Madivala, J. Fransaer and J. Vermant, “Self-assembly and rheology of ellipsoidal particles at interfaces,” Langmuir, vol. 25, pp. 2718-2728, 2009.
[46] B. Madivala, S. Vandebril, J. Fransaer and J. Vermant, “Exploiting particle shape in solid stabilized emulsions,” Soft Matter, vol. 5, pp. 1717-1727, 2009.
[47] M. Thompson, J. Pearson and M. Mackley, “The effect of droplet extension on the rheology of emulsions of water in alkyd resin,” Journal of Rheology, vol. 45, pp. 1341-1358, 2001.