(Invited) Applications of Novel Electrochemical Technologies for Sustainable Fuel/Chemical Production and Resources Recovery

Abstract

Electrochemical processes offer R&D opportunities toward decarbonization and resource recovery for circular economics. Innovate material produced by advancing manufacture techniques further widens its applications. In this presentation, we will discuss electrochemical process designs and material innovation to address technical and economic challenges of separations in biochemical/ biofuel production, resources recovery, CO2 utilization and impaired water treatment. In separations, the electrically driven force enabling selective capture of charged species and/or in-situ aqueous pH manipulation provides high energy efficiency, low capital footprint and cost for industrial applications compared to other separation technologies, e.g., separations by pressure-driven, thermally driven and biological-related. The common practices known are electrodialysis (ED), electrodeionization (EDI), capacitive deionization (CDI), cation intercalation desalination (CID), and ion concentration polarization (ICP). In these techniques, concentrated ions are separated from the liquid energy use is correlated with the quantity of ions removed. Therefore, the selective target capture provides “fit-for-purpose” separations. Pressure-driven processes cannot tune salinity for fit-for-purpose quality desalination but are effective at organic and biological species removal that electrochemical processes are not able to do. Thermal-driven processes cannot tune salinity for fit-for-purpose quality but are effective at organic and biological species removal. Biological-related processes typically apply bioelectrochemical reactions via microbes and bacteria to drive the removal of ions from the solution. In biological processes, ions are removed from the water solution. The ability to produce fit-for-purpose water has not been explored with biological processes, but they can treat targeted organics and biologicals. Compared to the pressure-driven membrane separation technologies used most in industrial separations, applications of selective separations have increased in recent years and becomes important to address the challenges of technology adaptation to climate change. For examples, the production of biofuel and bio-products to reduce green-house gas emission from fossil fuel and the non-conventional water supply for water-energy nexus have required high energy efficient and cost effective separation technologies. Innovative electrochemical separations can provide transformational impacts in advancing selective separations for highly energy efficient, small capital footprints and low processing cost. It, thus, enables the paradigm-shift of using alternative fuels and water supplies for industrial applications. We will discuss the key process performance metrics, energy consumption and processing rate, of various electrochemical technologies applied in biorefinery, waste to energy and water energy nexus to separate charges species from “dilute” aqueous phase. The ions separation performance demonstrated from various aqueous streams include 1) Inorganic and organic salts removal/capture in lignin valorization. and from bioprocessing streams in biofuel production; 2) volatile fatty acid removal/capture as well as biogas purification from solid waste anaerobic digester for waste to energy; 3) selective desalination of hardness, alkalinity, silica, and ammonia from impaired water for cooling water supply; 4)Capture and delivery for CO2 utilization. Critical issues in process design and material property to achieve electrochemical separation rate and energy efficiency for economic viability will be discussed.