Improving Energy Storage using Various Materials By: Jamison Chang, Carlos Hernandez, Lianne Monterroso, Jeanene Tomecek Overview  Attaining and storing energy can be done in various ways. Each method has its pros and cons, but engineers are constantly finding ways to make those methods more efficient and inexpensive.  Effect of technologies future based on lowered cost, efficiency, and the transfer from nonrenewable processes to greener processes that are better for the environment.  -Solar Cells  -Biosolar Cell -Dye-Sensitized Solar Cells -Thermal Batteries What is a Solar Cell?  Use semiconductors like silicon to absorb light  Impurities are added to allow the charged particles to move around – Hence, electrical conduction  N-type impurities: extra electrons in the material  P-type impurities: extra protons in the material How does a solar cell work? http://science.howstuffworks.com/environmental/energy/solar-cell.htm  When the p-type and n-type are put together the electrons move toward the p-n boundary and form an electrical field  When light hits the cell, electrons begin to move from the p to the n side and create an electrical current Efficiency of Solar Cell -Can only absorb 15 to 25% of solar energy -Why? -Not all light rays are strong enough to bump an electron -Silicon is a semiconductor so it is not very efficient at conducting electrons compared to a conductor Dye-sensitized solar cell One design type  Made from inorganic material called titania with organic dye on the surface  Dye absorbs light and generates electrons  The titania then moves the electrons to the electrode  Another Design Type  Inorganic material made from alumina nanoparticles with perovskite(organic/inorganic) instead of organic dye  Perovskite does same job as dye  BUT it also does what the titania does in the other type of cell DyeSensitized Solar Cell -The efficiency of the first design is about 12.3% -The efficiency of the perovskite: about 10.9% -Both efficiences small compared to photovoltaic solar cell -Efficiency is offset by cost. Relatively inexpensive dye solar cells. Biosolar Energy from Plants • A new breakthrough in “green” energy from Dr. Barry Bruce and researchers from MIT: • Photosystem – I ( or PS-I: a key component of photosythesis) is extracted from blue-green algae • The complex is engineered to react with a semi-conductor, creating a “green” solar cell. • Energy is produced with sunlight exposure What does this solar cell consist of ? • Non-biological materials • Small tubes of zinc oxide • Tubes attract PS-I • Biological components • PS-I • When both materials are combined and illuminated, electrons are transferred to the ZnO to produce an electrical current. Illustration of the Biosolar cell Source: http://www.nature.com/srep/2012/120202/srep00234/full/srep00234.html Benefits of Biosolar Energy • • • • Potential to make “green” energy significantly cheaper Requires significantly less natural resources than most biofuels Does not release toxic chemicals during production as opposed to photovoltaic solar power systems Uses completely renewable resources (algae) Future Improvements • Possible optimizations for the current technology: • Can better orient PS-I to semi- conductor • More biofriendly electrolytes can be matched with photoanode substances • The long-term performance of the biophotovoltaic system can be measured. • Why? • 90% of energy generation is consumed or wasted thermally • Significant role in heating and cooling, solar energy harvesting, etc. • Problem: Finding efficient and cost-effective ways to store thermal energy • Two groups of materials for thermal batteries: thermophysical and thermochemical Thermal Batteries http://micro.magnet.fsu.edu/electromag/electricity/batteries/thermal.html Potential Impacts • Solar power plants can generate electricity 24 hours a day • Increase energy output of nuclear plants • Improve performance of electric vehicles • Decrease fossil-fuel based electricity use https://en.wikipedia.org/wiki/Sustainable_development  Energy storage relies on Thermophysical Materials http://community.controlglobal.com/content/power-scavenging-strikes-again changes in physical state of material  Achieved through sensible heat and/or latent heat  Stores heat in an object to use later  Need to insulate system to minimize heat losses  Ex: Solar thermal power plants store solar energy by heating molten salts Thermochemical Methods • Chemical reactions reversibly store energy • Do not require insulation • Low energy density: requires large volume • Ex: ZnO + heat -> Zn + ½ O2; Zn + H2O -> ZnO + H2 http://www.pre.ethz.ch/research/projects/?id=solarhydroviaredox Limitations  Thermophysical: materials have high volumetric energy density but low gravimetric energy density  Thermochemical: materials have high gravimetric density but low volumetric energy density  Mechanical compression…  Current thermal energy storage materials performance  Lithium-ion battery: energy density ~ 5000 MJ/m3 and specific energy ~ 1.3 MJ/kg  Performance needs to improve to become competitive with current technology Searching for a Better Thermal Battery. Ilan Gur et al. Science 335, 1454 (2012). Recent Developments  ARPA-E High Energy Advanced Thermal Storage program  Goal: “develop revolutionary, cost effective ways to store thermal energy”  High-temperature solar thermal energy storage  Create synthetic fuel from sunlight by converting sunlight to heat  Improve the driving range of electric vehicles and enable thermal management of thermal combustion engine vehicles  MIT: Efficient Heat Storage Materials  University of Florida: Solar Thermochemical Fuel Production  UT-Thermal Batteries for Electric Vehicles MIT: Efficient Heat Storage Materials Traditional salt encapsulated for thermal storage Source: http://www1.eere.energy.gov/solar/sunshot/csp_newsletter. html  Need efficient thermal storage to maximize capacity of solar and nuclear plants. Current solar power plants only run at 25% capacity because there is no generation at night  Goal is to find materials with a large latent heat, able to store >1 MJ/kg. Hope to reduce cost of thermal energy storage by 75%  Considering metallic alloys instead of traditional salts University of Florida: Solar Thermochemical Fuel Production • • Klausner et al. University of Florida. Solar Fuel: Pathway to a Sustainable Energy Future. http://www.floridaenergysummit.com/pdfs/presentations 2012/klausner.pdf • Store solar energy through a thermochemical conversion of carbon dioxide and water to fuel Reactor converts solar energy to syngas, which can be used to produce gasoline Goal: lower cost of production of syngas UT-Thermal Batteries for Electric Vehicles • • http://www.tmi.utexas.edu/facultyresearch-spotlight/dr-li-shi/ • Batteries based on silicide materials for waste heat recovery Currently, inefficient heating and cooling of EVs increase load on the battery Thermal storage system can take the waste heat and convert it to electrical power and can increase driving range Renewable Cathode Materials from Biopolymer/Conjugated Polymer Interpenetrating Networks  What are they?  Renewable and cheap materials in electrodes that can store charge and create a renewable energy system when enough charge density is acquired. http://www.intechopen.com/books/composites-and-theirproperties/c-li2mnsio4-nanocomposite-cathode-material-for-li-ionbatteries Advantages Electroactive materialChanges shape as charge is passed through it http://www.electricfoxy.com/2010/03/exploring-the-potential-of-electro-active-polymers/  Conjugated polymers with added quinone groups give improved charge storage  The combined redox processes of polymer and redox anion contribute to charge capacity in materials.  It is desirable to use the quinone redox function in electroactive materials to enhance chargestorage capacity. Limitations  Does it work with all types of polymers?  No, renewable energy systems based on intermittent sources require methods for power balancing over time, and thus some means of storage.  Organic polymers do not provide enough charge density to work in secondary batteries and super.  Inorganic insertion electrodes are much better at charge storage. Inorganic Electrodes http://www.gizmag.com/ibm-lithium-air-battery/22310/ Methods  Redox Functions (Redox processes of polymer & Redox anion)  Conjugated polymers with added quinone groups  Electrochemical polymerization (to generate solids with extremely high conductance) Andreas Mershin, Kazuya Matsumoto, Liselotte Kaiser, Daoyong Yu, Michael Vaughn, Md. K. Nazeeruddin, Barry D. Bruce, Michael Graetzel, Shuguang Zhang. Self-assembled photosystem-I biophotovoltaics on nanostructured TiO2 and ZnO. Scientific Reports, 2012 Cyclic Voltammetry • Cyclic voltammetry, a type of potentiodynamic electrochemical measurement, of polypyrrole shows the two redox waves that correspond to the reaction involved. Fig. 1CV of the Ppy(Lig) composite electrode. (A) Voltammograms recorded between 0.1 and 0.4 V. (B) Voltammograms recorded between 0.1 and 0.75 V versus Ag/AgCl, scan rates 5 to 25 mV s−1 (inner to outer). (C) Dependence of the redox peak currents on scan rate. Film thickness, 0.5 Andreas Mershin, Kazuya Matsumoto, Liselotte Kaiser, Daoyong Yu, Michael Vaughn, Md. K. Nazeeruddin, Barry D. Bruce, Michael Graetzel, Shuguang Zhang. Self-assembled photosystem-I biophotovoltaics on nanostructured TiO2 and ZnO. Scientific Reports, 2012 Galvanostatic discharge curves for (A) thinner (0.5 μm) and (B) thicker (1.9 μm) Ppy(Lig) composite film. Two regions are visible, assigned to electrochemical activity of Ppy and lignin-derived quinones, along with linear regression lines used for capacitance analysis. For clarity, in (A) the regression lines are shown for the highest discharge current only; the other ones nearly overlap with each other. rent redox potentials Andreas Mershin, Kazuya Matsumoto, Liselotte Kaiser, Daoyong Yu, Michael Vaughn, Md. K. Nazeeruddin, Barry D. Bruce, Michael Graetzel, Shuguang Zhang. Self-assembled photosystem-I biophotovoltaics on nanostructured TiO2 and ZnO. Scientific Reports, 2012 Discharge under galvanostatic conditions • The galvanostic discharge curves for polypyrrole and quinone show that the charge capacity for polypyrrole is about 30-35 mAh(milliamp-hour) /g and about 40 mAh/g for quinone. The Implications of Using Inorganic Biopolymers for charge storage • • • Low-cost Safer and non-toxic operation in water Can be further improved through research to get greater charge and energy storage. References  Getting Moore from Solar Cells. David J. Norris and Eray S. Aydil. Science 2 November 2012: 338 (6107), 625-626.  Renewable Cathode Materials from Biopolymer/Conjugated Polymer Interpenetrating Networks. Grzegorz Milczarek and Olle Inganäs. Science 23 March 2012: 335 (6075), 1468-1471.  Searching for a Better Thermal Battery. Ilan Gur, Karma Sawyer, and Ravi Prasher. Science 23 March 2012: 335 (6075), 1454-1455  Andreas Mershin, Kazuya Matsumoto, Liselotte Kaiser, Daoyong Yu, Michael Vaughn, Md. K. Nazeeruddin, Barry D. Bruce, Michael Graetzel, Shuguang Zhang. Self-assembled photosystem-I biophotovoltaics on nanostructured TiO2 and ZnO. Scientific Reports, 2012