ABSTRACT: Consumption of fossil fuels along with accelerated deforestation is leading to a significant increase in concentration of greenhouse gases (e.g., CO2) in the atmosphere. Carbon Capture, Utilization and Storage (CCUS) is considered a promising alternative to lower the amount of CO2 emissions. This talk will briefly discuss technical and environmental aspects of three particular cases in the context of CO2 utilization (or/and conversion) and storage processes.
Ex-Situ CO2 Sequestration. CO2 has proven potential for EOR operation in petroleum reservoirs and storage in saline aquifers. However, CO2 can flow upward due to buoyancy effects and leak through thief zones during geological sequestration. To tackle this matter, the ex-situ dissolution (ESD) concept is introduced aiming at full dissolution of CO2 at surface facilities, before it is injected into the underground formations. A mathematical model was developed to formulate the size of the CO2 droplets in terms of process parameters for the ESD technique. The proposed model explicitly accounts for mass transfer and pressure changes along the pipeline length employed in ESD. The introduced model is able to determine the size variation of CO2 droplets and the length of pipeline required for complete dissolution of droplets before injecting CO2 into the porous media (e.g., saline aquifers and depleted reservoirs).
Algae-Based Biofuels. It is well known that organic compounds can be synthesised by algae from CO2, water and sunlight. The resulting biomass has high potential to produce biofuels, as renewable fuels. Biofuels are an apt option to fossil fuels in the near future in terms of source stability, availability and environmental prospective. Algal-based biofuels have received renewed interest in recent years. A quantitative approach is developed for synthesis of microbial consortia as an interesting technique to low cost sustainable production of algae-based fuels and chemicals. The developed mathematical tool is based on dynamic flux balance analysis (DFBA), which is the integration of genome-scale metabolic model and mass conservation law applied to extracellular environment. This study showcases a process system engineering strategy to design, control and optimize synthetic environments for biochemical/biological processes that leads to greater efficiency in terms of technical, environmental and economical prospects.
Urea Synthesis. A large quantity of CO2 is utilized through reaction with ammonia to produce urea as an important fertilizer. A mathematical model and a connectionist technique are proposed for the simulation and optimisation of the urea plant in an industrial petrochemical company. The developed mathematical model consists of complex vapour–liquid equilibria for the mixture system in thermodynamic and reaction frameworks. An acceptable agreement is attained between various deterministic methods. Through implementation of a systematic sensitivity analysis, it was found that a temperature of 191oC, a pressure of 132 atm and a NH3/CO2 ratio of 2.7 are the optimum process conditions for the urea production.
Bio-Sketch: Sohrab Zendehboudi is a postdoctoral research associate at the Massachusetts Institute of Technology (MIT), USA where he is currently focusing on modeling and optimization of various processes in energy and environment sectors. For over 10 years, Sohrab worked/contributed as a process engineer, researcher, consultant, instructor and co-supervisor at several companies/universities in Iran, Australia, Canada and USA. His experience and interests are in the fields of Energy and Environment, Modeling and Optimization, Process Systems Engineering, and Oil and Gas Engineering. He is a recipient of several honors and awards (e.g., NSERC PDF, MIT International Scholar Funding, Academic MITACS Elevate PDF, Top Rank in M.Sc and B.Sc programs). He published over 50 papers in ISI journals and presented many conference papers. He is also contributing to Chemical, Environmental and Petroleum Engineering communities by being a reviewer as well as technical editor of several journals. Sohrab obtained his Ph.D. degree under the supervision of Prof. Ioannis Chatzis in chemical engineering department ,University of Waterloo, Canada, in 2010. He is a member of the Chemical Engineering Society, American Chemical Society, and the Society of Petroleum Engineers (SPE).