REWAS 2022: Energy Technologies and CO2 Management: Renewable Energy and Combustion Technologies
Sponsored by: TMS Extraction and Processing Division, TMS Light Metals Division, TMS: Energy Committee
Program Organizers: Fiseha Tesfaye, Metso Metals Oy, Åbo Akademi University; Lei Zhang, University of Alaska Fairbanks; Donna Guillen, Idaho National Laboratory; Ziqi Sun, Queensland University of Technology; Alafara Baba, University of Ilorin; Neale Neelameggham, IND LLC; Mingming Zhang, Baowu Ouyeel Co. Ltd; Dirk Verhulst, Consultant, Extractive Metallurgy and Energy Efficiency; Shafiq Alam, University of Saskatchewan; Mertol Gokelma, Izmir Institute of Technology; Camille Fleuriault, Eramet Norway; Chukwunwike Iloeje, Argonne National Laboratory; Kaka Ma, Colorado State University

Monday 8:30 AM
February 28, 2022
Room: 212A
Location: Anaheim Convention Center

Session Chair: Camille Fleuriault, Eramet Norway

8:30 AM Introductory Comments

8:35 AM
Design of a Molten Salt Metal-air Battery with High-energy Density: Mahya Shahabi¹; Nicholas Masse¹; Hongyi Sun¹; Lucien Wallace¹; Adam Powell¹; Yu Zhong¹; ¹Worcester Polytechnic Institute
    Decarbonization of long-haul transportation i.e. ships and trains is among the toughest challenges toward eliminating greenhouse emissions, but metal-air batteries have extraordinary potential to meet this challenge. More specifically, Mg-air batteries have the potential for 30-40 times the energy of lithium-ion batteries at very high efficiency, and their Mg anode and molten salt materials are abundant in seawater. The two main criteria for these batteries are stability of the cathode material and removal of MgO product from the electrolyte through directional solidification. This talk will present experimental and modeling results for a novel molten salt magnesium-air battery with an MgCl₂-NaCl-KCl-MgO electrolyte operating at 420-620°C. O²⁻ dissolves at the cathodes and Mg²⁺ at anodes. Experimental results show 1.9V open-circuit voltage, which is the highest to date for an Mg-air battery. Modeling shows up to 1.17 W/cm² at 73% efficiency and 2.89 W/cm² at 36% efficiency. This work illustrates the proof of concept of Mg-air batteries and discusses the requirements for larger-scale cells.

8:55 AM
Silicon-production from SiO-gas via Gas-phase Reactions: Halvor Dalaker¹; ¹Sintef
    The substitution of solid carbon in silicon production is challenging. As an example, the reaction between SiO₂ and H₂ to Si is thermodynamically unfavourable below 4500 °C . However, the partial reduction to SiO gas is possible. In the Siemens process for high purity polysilicon production, the input is gas-based Si-species like SiH₄ or SiHCl₃. Today, these species are produced from metallic silicon, but if they could be produced from SiO-gas and Cl₂ directly, there would be no need to produce metallic Si, and no need for the final, challenging reducing step from SiO to Si. In other words, it would be possible to eliminate the need for solid carbon as a reductant, and the associated CO₂-emissions, in this part of the silicon market. The present work explores these possibilities and identifies the bottlenecks in a potential process. The work is based on thermodynamical calculations using FactSage.

9:15 AM
Macroscopic Modeling and Phase Field Modeling of Solar Grade Silicon by Molten Salt Electrolysis: Aditya Moudgal¹; Mohammad Asadikiya¹; Douglas Moore¹; Gabriel Espinosa¹; Lucien Wallace¹; Alexander Wadsworth¹; Alexander Alonzo¹; Peter Catalino¹; Andrew Charlebois¹; Evan Costa¹; Tyler Melo¹; Adam Powell¹; Yu Zhong¹; Uday Pal²; ¹Worcester Polytechnic Institute; ²Boston University
    Conventional production of solar silicon by the Siemens Process is energy intensive, has inherent safety challenges and is expensive due to multiple operations. Therefore, there have been concentrated efforts since the 1970’s to produce silicon electrochemically. Toward this end, a new molten salt electrolyte was engineered at Boston University which improves properties such as SiF4 volatility, low electrolyte bath conductivity and high viscosity, low silica solubility by and order of magnitude or better. This talk builds on this work by modeling an electrochemical cell and solving conservation equations of mass, momentum, charge and heat and diffusion to understand transport in the molten salt bath. The phase field model will model electrodeposition and give insights into interface stability by solving the Cahn-Hilliard equation. The talk will also correlate these models to lab scale experiments.

9:35 AM
Design of Phase Change Material Composites for Efficient and Rapid Storage of Thermal Energy: Patrick Shamberger¹; Alison Hoe¹; Achutha Tamraparni¹; Chen Zhang¹; Alaa Elwany¹; Jonathan Felts¹; ¹Texas A&M University
    While phase change material (PCM) heatsinks and energy storage modules have been shown to act as highly efficient transient energy storage components, they have traditionally been limited by the rate at which heat is absorbed into the PCM. This limits the ability to effectively recover waste heat or to manage environmental climate control in building settings at sufficiently high rates of energy storage. Composite thermal energy storage (TES) materials, consisting of highly thermally conductive elements and PCMs can overcome some of the challenges presented by the slow rate of heat absorption in PCMs. However, the application of these components is limited by a lack of coherent design guidelines. Here, we present an experimentally and numerically validated design framework based around the concept of PCM composites, where the effective thermal properties of a composite are dictated by constitutive relationships relating the composite structure to its transport properties.