Quest for Materials for Renewable Energy Applications Stefan Stefanoski, Ph.D. Department of Electrical and Renewable Energy Engineering Oregon Institute of Technology, Wilsonville, OR TECH Talks 2016 May 6, 2016

Background St. Cyril and Methodius University Natural Sciences and Mathematics Skopje, Macedonia BS in Applied Physics (2005) University of South Florida Department of Physics Tampa, FL, USA MS (2010) and PhD (2012) in Applied Physics Oregon Institute of Technology Department of EREE, Wilsonville, OR, USA MS in REE (2017) Adjunct Professor Max Planck Institute Institute for Chemical Physics of Solids Dresden, Germany Visiting Scientist (2011) Carnegie Institution for Science Geophysical Laboratory Washington, D.C. USA Postdoctoral Fellow (2013-2015) Quest for Materials for Renewable Energy Applications S. Stefanoski

Why Are Materials Important? Mars Exploration Rover: solar panels providing 600 W Wind turbine-blades: made of GRP = carbon or glass-fiber reinforced thermosetting plastic (glass fibers are 1/10 of the prices of carbon fibers www.inhabitat.com Quest for Materials for Renewable Energy Applications S. Stefanoski

New Allotrope of Silicon, Si24 1000 ton Multianvil Press D. Y Kim, S. Stefanoski et al. Nature Materials, 14, 169-173, (2015) Temperature: 800 0C Pressure: 8 GPa Zr2O3 insulation Ta heater and capsule MgO Mixture of Na-Si in 1:6 ratio inside Ta capsule Quest for Materials for Renewable Energy Applications S. Stefanoski

New Allotrope of Silicon, Si24 5 m 400 K RT = 1.3 eV AM1.5 radiative limit Radiative limit with potential fluctuations D. Y Kim, S. Stefanoski et al. Nature Materials, 14, 169-173, (2015) Quest for Materials for Renewable Energy Applications S. Stefanoski

Thermoelectric Effect - Thermoelectricity + - + Quest for Materials for Renewable Energy Applications S. Stefanoski

Thermoelectric Generator Seebeck Effect Peltier Effect S = Seebeck coefficient (V/T)  = electrical conductivity  = thermal conductivity (lattice + electrons) High S  generate the largest V for a given T (S = V/T); High   device carries the largest current possible for a given V; Low   heat is not conducted through the legs, and T is easily maintained. Quest for Materials for Renewable Energy Applications S. Stefanoski

Thermoelectric Materials for Automotive Applications www.GM.com Automotive Energy Flow Diagram Quest for Materials for Renewable Energy Applications S. Stefanoski

Radioisotope Thermoelectric Generator (RTG) Voyager Cassini Quest for Materials for Renewable Energy Applications S. Stefanoski

Thermoelectric Materials Skutterudites Half-Heuslers Alloys Te Pb Clathrates Yb14MnSb11 Chalcogenides Quest for Materials for Renewable Energy Applications S. Stefanoski

Synthesis and Properties of Clathrates X (Na-content) [1] S. Stefanoski et al. Chem. Matter. 23, 1491, (2011) [2] S. Stefanoski et al. in The Physics and Chemistry of Inorganic Clathrates, ed. G. S. Nolas, (2014) Quest for Materials for Renewable Energy Applications S. Stefanoski

Summary, Projections, Recommendations Materials relevant for Renewable Energy applications are in the focus of scientific R&D: heavy funding of Universities and National Labs; multiple openings for MS/PhD positions are available. “Frontiers in Crystalline Matter: From Discovery to Technology”, National Academies Press, 2009: “ The U.S. has an urgent need for increased research and discovery and crystal growth of materials” Every technologically-relevant application starts with the synthesis and characterization (crystal structure, electrical, thermal, optical, and other properties) of materials. Global Solar Forecast Global solar installations will grow to 64.7 GW in 2016. The top countries are China, U.S. and Japan. IF materials with higher solar-absorption potential are available, industry will grow even further. Si24 is a promising candidate to replace conventional silicon for PV applications. Scaling-up is needed before commercialization. Quest for Materials for Renewable Energy Applications S. Stefanoski

Thank you! Quest for Materials for Renewable Energy Applications S. Stefanoski