Process design and simulation-based life cycle inventory modeling for chemical manufacturing
Excerpts reprinted with permission from Parvatker, A. G.; Eckelman, M. J. Comparative Evaluation of Chemical Life Cycle Inventory Generation Methods and Implications for Life Cycle Assessment Results. ACS Sustain. Chem. Eng. 2019, 7 (1). Copyright 2019 American Chemical Society. Excerpts reprinted with permission from Parvatker, A. G.; Tunceroglu, H.; Sherman, J. D.; Coish, P.; Anastas, P.; Zimmerman, J. B.; Eckelman, M. J. Cradle-to-Gate Greenhouse Gas Emissions for Twenty Anesthetic Active Pharmaceutical Ingredients Based on Process Scale-Up and Process Design Calculations. ACS Sustain. Chem. Eng. 2019, 7 (7), 6580-6591. Copyright 2019 American Chemical Society. Excerpts reprinted with permission from Parvatker, A. G.; Eckelman, M. J. Simulation-Based Estimates of Life Cycle Inventory Gate-to-Gate Process Energy Use for 151 Organic Chemical Syntheses. ACS Sustain. Chem. Eng. 2020, 8 (23), 8519-8536. Copyright 2019 American Chemical Society. Synthetic chemicals are ubiquitous and are an integral part of almost every value chain in the industrialized world. Hence, comprehensive assessment of health and environmental impacts over the chemicals life cycle is critical in the pursuit of sustainable development, using quantitative modeling tools such as life-cycle assessment (LCA). However, lack of primary production data, and time- or resource-intensive design calculations often forces LCA practitioners to rely on simplistic methods for estimating chemical process data. Use of such "shortcut" methods for calculating chemical life cycle inventory (LCI) data introduces uncertainties and inaccuracies in environmental sustainability analysis. Research in this doctoral dissertation focuses on developing and implementing novel methods to reduce the time and resources required in chemical LCI data generation. An analysis of eight alternative methods to account for missing chemical LCI data was conducted to identify their strengths and drawbacks. Out of the four methods with whichfull LCIs can be generated, the advanced process-based methods give the most accurate life cycle GHG emission results compared to plant data for the case studies of styrene and its downstream product, acrylonitrile-butadiene-styrene (ABS). Stoichiometric calculations, which are the most commonly used approach, underestimate the actual global warming results by 35-50%.1 Among the 18 impact categories of the ReCiPe LCIA method, results for the estimated LCI data were within 10% of the actual plant results for only 4-5 categories. These techniques were then used in conjunction with a novel process scale-up and design method to estimate LCIs and cradle-to-gate greenhouse gas emissions for twenty common active pharmaceutical ingredients (API) used as injectable anesthetics and 130 intermediate pharma compounds. The cradle-to-gate GHG emissions of the 20 anesthetic drugs range from 11 kg CO2 eq. for succinylcholine to 3,000 kg CO2 eq. for dexmedetomidine. The LCI methods and data generated in this work greatly expand the available environmental data on APIs and can serve as a guide for LCA practitioners in future analysis of other pharmaceutical drugs. Process energy is a key input in a chemical LCI and has significant impact on LCA results. A streamlined process simulation-based methodology was developed to estimate energy consumption in chemical manufacturing. The methodology is applied to 151 different chemical processes using Aspen Plus to estimate their gate-to-gate process energy use, representing the largest such simulation-based LCI data set to date.3 The results from process simulations were then used to develop predictive models for heating and cooling requirements in chemical production. The multiple linear regression (MLR) and artificial neural network (ANN) models with R2 of 0.63 to 0.73 with measured error of less than 50% are robust alternatives for rapid estimations and screening analysis compared to the current methods used in LCI databases. The series of methods presented in this work can be used with varying availability of chemical synthesis data for life cycle inventory modeling. This research not only introduces and demonstrates novel methods for chemical LCI data estimation but also adds a significant number of new LCI data sets to the literature.--Author's abstract
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