11 research outputs found
Proceedings of the 29th EG-ICE International Workshop on Intelligent Computing in Engineering
This publication is the Proceedings of the 29th EG-ICE International Workshop on Intelligent Computing in Engineering from July 6-8, 2022. The EG-ICE International Workshop on Intelligent Computing in Engineering brings together international experts working on the interface between advanced computing and modern engineering challenges. Many engineering tasks require open-world resolution of challenges such as supporting multi-actor collaboration, coping with approximate models, providing effective engineer-computer interaction, search in multi-dimensional solution spaces, accommodating uncertainty, including specialist domain knowledge, performing sensor-data interpretation and dealing with incomplete knowledge. While results from computer science provide much initial support for resolution, adaptation is unavoidable and most importantly, feedback from addressing engineering challenges drives fundamental computer-science research. Competence and knowledge transfer goes both ways.
 
Proceedings of the 29th EG-ICE International Workshop on Intelligent Computing in Engineering
This publication is the Proceedings of the 29th EG-ICE International Workshop on Intelligent Computing in Engineering from July 6-8, 2022. The EG-ICE International Workshop on Intelligent Computing in Engineering brings together international experts working on the interface between advanced computing and modern engineering challenges. Many engineering tasks require open-world resolution of challenges such as supporting multi-actor collaboration, coping with approximate models, providing effective engineer-computer interaction, search in multi-dimensional solution spaces, accommodating uncertainty, including specialist domain knowledge, performing sensor-data interpretation and dealing with incomplete knowledge. While results from computer science provide much initial support for resolution, adaptation is unavoidable and most importantly, feedback from addressing engineering challenges drives fundamental computer-science research. Competence and knowledge transfer goes both ways.
 
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Spatial Modeling of Decentralized Wastewater Infrastructure: The Case for Water Reuse and Nitrogen Recovery
Climate change and increasing patterns of drought throughout the world are challenging the effectiveness of conventional water systems. A growing population in conjunction with more extreme weather events, threatens water supply infrastructure and increases uncertainty about how utilities will meet demand without sacrificing water quality. This issue has recently manifested in California, prompting utilities to invest in alternative water sources as a means of ensuring that water infrastructure is resilient to climate change scenarios.Decentralized wastewater treatment is a promising option for increasing the sustainability of water infrastructure as it spatially merges supply and demand, minimizing large conveyance requirements. Decentralization can also promote nutrient management and recovery as it enables the source separation of the different wastewater sources. Specifically closing the nitrogen loop, by capturing it and reusing it to generate valuable high-end products can potentially improve the efficiency of the system and create revenue streams. However, smaller decentralized water treatment units are potentially more energy intensive and costly than their centralized alternatives per unit of water treated. Due to these efficiency tradeoffs, planning tools and frameworks for holistically assessing decentralized water treatment systems need to be developed to optimally manage the new urban water supply paradigm. Better data management and data-driven decision support tools can provide valuable insight on the benefits and impacts of implementing future water systems.This research assesses the technical performance of emerging decentralized technologies and implementation scenarios for residential uses, by assessing the feasibility of integrating decentralized facilities in cities with existing wastewater infrastructure. This work aims to create algorithmic models that integrate the spatial design of a wastewater treatment and distribution network with a life-cycle assessment to determine the associated environmental impacts. This dissertation utilizes spatial modeling to contextually evaluate the implementation and distribution potential and uses a life-cycle assessment approach to provide an extensive analysis of all the life-cycle impacts. By incorporating environmental indicators and metrics, a planning support framework can be created to help guide the water industry towards smart investments for a less energy-intensive future. Specifically, this work will 1) investigate how spatial terrain variability, demographics and distribution affect the performance of decentralized water treatment systems, 2) analyze the major parameters that affect the energy intensity, cost and greenhouse gas emissions of these systems, 3) quantify the unit processes that mostly impact the prementioned metrics and 4) identify the optimal system scale for decentralized infrastructure implementation under various spatial and demographic conditions.The insights from this dissertation can help wastewater researchers and practitioners understand the complex relationships between the system scale and system performance. By evaluating the potential benefits and tradeoffs, this work can lead to management tools that will help transition away from traditional water management and create a water supply that (1) is resilient to changes in climate, (2) uses local water sources, and (3) leaves more water in natural ecosystems. This dissertation further adds to the growing body of literature on decentralized wastewater treatment assessing optimal scales, reuse potential, resource recovery and sewerage connections to investigate key factors affecting future implementation
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Spatial Modeling of Decentralized Wastewater Infrastructure: The Case for Water Reuse and Nitrogen Recovery
Climate change and increasing patterns of drought throughout the world are challenging the effectiveness of conventional water systems. A growing population in conjunction with more extreme weather events, threatens water supply infrastructure and increases uncertainty about how utilities will meet demand without sacrificing water quality. This issue has recently manifested in California, prompting utilities to invest in alternative water sources as a means of ensuring that water infrastructure is resilient to climate change scenarios.Decentralized wastewater treatment is a promising option for increasing the sustainability of water infrastructure as it spatially merges supply and demand, minimizing large conveyance requirements. Decentralization can also promote nutrient management and recovery as it enables the source separation of the different wastewater sources. Specifically closing the nitrogen loop, by capturing it and reusing it to generate valuable high-end products can potentially improve the efficiency of the system and create revenue streams. However, smaller decentralized water treatment units are potentially more energy intensive and costly than their centralized alternatives per unit of water treated. Due to these efficiency tradeoffs, planning tools and frameworks for holistically assessing decentralized water treatment systems need to be developed to optimally manage the new urban water supply paradigm. Better data management and data-driven decision support tools can provide valuable insight on the benefits and impacts of implementing future water systems.This research assesses the technical performance of emerging decentralized technologies and implementation scenarios for residential uses, by assessing the feasibility of integrating decentralized facilities in cities with existing wastewater infrastructure. This work aims to create algorithmic models that integrate the spatial design of a wastewater treatment and distribution network with a life-cycle assessment to determine the associated environmental impacts. This dissertation utilizes spatial modeling to contextually evaluate the implementation and distribution potential and uses a life-cycle assessment approach to provide an extensive analysis of all the life-cycle impacts. By incorporating environmental indicators and metrics, a planning support framework can be created to help guide the water industry towards smart investments for a less energy-intensive future. Specifically, this work will 1) investigate how spatial terrain variability, demographics and distribution affect the performance of decentralized water treatment systems, 2) analyze the major parameters that affect the energy intensity, cost and greenhouse gas emissions of these systems, 3) quantify the unit processes that mostly impact the prementioned metrics and 4) identify the optimal system scale for decentralized infrastructure implementation under various spatial and demographic conditions.The insights from this dissertation can help wastewater researchers and practitioners understand the complex relationships between the system scale and system performance. By evaluating the potential benefits and tradeoffs, this work can lead to management tools that will help transition away from traditional water management and create a water supply that (1) is resilient to changes in climate, (2) uses local water sources, and (3) leaves more water in natural ecosystems. This dissertation further adds to the growing body of literature on decentralized wastewater treatment assessing optimal scales, reuse potential, resource recovery and sewerage connections to investigate key factors affecting future implementation
Static and seismic deformation fields at models with use of the P.I.V. method
135 σ.Επισυνάπτεται CD με τα πειραματικά αποτελέσματα της εργασίας.Αντικείμενο της παρούσης διπλωματικής εργασίας είναι η παρουσίαση των πειραμάτων που διεξήχθησαν στο Εργαστήριο Γεωτεχνικής Μηχανικής της Σχολής των Αγρονόμων και Τοπογράφων Μηχανικών του Εθνικού Μετσοβίου Πολυτεχνείου με στόχο την φωτογραμμετρική ανάλυση της αστοχίας άοπλων και οπλισμένων πρανών σε στατική και σεισμική φόρτιση. Πρόκειται για μια σειρά πειραμάτων με εδαφικά μοντέλα ξηρά πρανή ύψους 10cm. Τα πειράματα σε στατική φόρτιση περιλάμβαναν δοκίμιο από άμμο το οποίο αντιστηριζόταν από κατακόρυφο τοίχο αντιστήριξης και η αστοχία επερχόταν με τεχνητό τρόπο (με περιστροφή του τοίχου περί τη βάση του). Τα πειράματα με σεισμική φόρτιση περιλάμβαναν άοπλα πρανή με κεκλιμένη επιφάνεια, κατακόρυφα πρανή αντιστηριζόμενα με τοίχο αντιστήριξης και οπλισμένα κεκλιμένα πρανή. Οι σεισμικές φορτίσεις που επιβλήθηκαν σε αυτά τα πρανή ήταν σε ποσοστό επιτάχυνσης της βαρύτητας 0.24g και 0.36g. Συγκεκριμένα στο πρώτο κεφάλαιο της παρούσης εργασίας γίνεται ανάλυση της μεθόδου P.I.V. (Particle Image Velocimetry). Είναι μια μέθοδος μέτρησης μετακινήσεων βασισμένη στην ανάλυση της κίνησης συγκεκριμένων σωματιδίων και στην φωτογραμμετρία κοντινής ανάλυσης που επιτυγχάνει υψηλής ακρίβειας αποτελέσματα στις μετρήσεις των μετακινήσεων. Στο δεύτερο κεφάλαιο της εργασίας παραθέτονται θεωρητικά στοιχεία για την ανάλυση της ευστάθειας των πρανών. Αναλύονται οι σχέσεις κλίμακας μοντέλου – πρωτοτύπου, περιγράφεται η λειτουργία των γεωτεχνικών φυγοκεντριστών, γίνεται η ανάλυση της ευστάθειας πρανών υπό σεισμικές φορτίσεις και τέλος αναφέρονται στοιχεία για την οπλισμένη γη. Στη συνέχεια στο τρίτο κεφάλαιο γίνεται περιγραφή των πειραμάτων που διεξήχθησαν σε στατική και σεισμική φόρτιση και ανάλυση των αποτελεσμάτων που προέκυψαν από την εφαρμογή της μεθόδου P.I.V. σε αυτά. Επίσης γίνεται περιγραφή των σταδίων της μεθόδου ανάλυσης των πειραμάτων. Το τέταρτο κεφάλαιο περιλαμβάνει περιγραφή των μεθόδων ανάλυσης της ευστάθειας των πρανών για ολίσθηση σε επίπεδη και κυκλική επιφάνεια καθώς και τη μέθοδο Bishop, η οποία είναι μία από τις μεθόδους αυτές. Ακόμη γίνεται περιγραφή του προγράμματος ευστάθειας πρανών, Slide, και των δυνατοτήτων που αυτό παρέχει στο χρήστη. Επίσης γίνεται και παραμετρική ανάλυση της επίδρασης διαφόρων χαρακτηριστικών του εδάφους στην ευστάθεια του πρανούς με σεισμική φόρτιση με χρήση του προγράμματος Slide. Τέλος με χρήση του προγράμματος Slide γίνεται μια προσπάθεια μοντελοποίησης του φαινομένου της αστοχίας και υπολογιστική ανάλυση του οπλισμένου πρανούς του πειράματος του κεφαλαίου 3 . Απώτερος στόχος είναι η μελέτη πραγματικού περιστατικού, μέσω της παράθεσης θεωρητικών στοιχείων και της χρήσης εξειδικευμένου λογισμικού ώστε να παρουσιαστεί ο τρόπος με τον οποίο αντιμετωπίζονται τα φαινόμενα αστοχίας των πρανών. Το πέμπτο κεφάλαιο περιλαμβάνει την κοκκομετρική ανάλυση του υλικού που χρησιμοποιήθηκε για τα πειράματα. Περιγράφεται η διαδικασία της κοκκομετρίας και προσδιορίζεται το είδος του υλικού που χρησιμοποιήθηκε. Στο τελευταίο κεφάλαιο της εργασίας παρατίθενται τα συμπεράσματα που προέκυψαν από την πειραματική και υπολογιστική διαδικασία καθώς και τα προβλήματα που προέκυψαν κατά τη διάρκεια του πειραματικού μέρους.The purpose of this study is to present a series of tests that were carried out in the Geotechnical Laboratory of the Rural and Surveying Engineering School of the Technical University of Athens, with main goal the photogrammetric analysis of the deformations of unreinforced and reinforced slopes under static and dynamic conditions. This study is about a series of tests which involve models of dry slopes with a height of 10cm. The static condition test involved a slope model stabilized by a vertical retaining wall and the failure was achieved artificially (by rotation of the wall about its base). The seismic condition tests involved an unreinforced slope, a slope stabilized by a vertical wall and a reinforced slope. The seismic loads that were imposed to them were equal to 0.24g and 0.36g (compared to the acceleration of gravity “g”). The first chapter describes the procedure of the P.I.V. method (Particle Image Velocimetry) which is a method of measuring the deformations based on the analysis of movement of specific particles and close range photo grammetry with high precision results. The second chapter includes the theoretical analysis of the experimental stage. The relationship between the model – prototype scale is analyzed as well as the slope stability under seismic loading. A description of the operation of the geotechnical centrifuge is been done and finally the theoretical analysis of reinforced slopes is mentioned. Then in the third chapter the static and dynamic tests are described and the analysis of the test results using the P.I.V. method. Finally, the analysis stages of the tests are described. The fourth chapter includes the analysis of slope stability and sliding on a flat, circular surface and the Bishop method of, determining the safety of slopes. In addition a description of Slide, a slope stability program is included, and the opportunities the program provides to the user. Finally, the program Slide is used to compute an analysis of the reinforced slope experiment described in Chapter 3 as well as a modelazation of the failure phenomenon. The ultimate goal is to study slope stability using test results and specialised software. The fifth chapter is about the grading analysis of the soil that was used during the experimental stage. The procedure is described and the type of material used is specified. Finally the last chapter provides the conclusions drawn from the experimental and computational process and the problems encountered during the experimentation.Όλγα Μ. Καββαδ
Development of a model for the rainfall-runoff procedure using GIS
171 σ.Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Περιβάλλον και Ανάπτυξη”Τα φυσικά φαινόμενα είναι ιδιαίτερα δύσκολο να μοντελοποιηθούν και να
αναπαρασταθούν με ακρίβεια καθώς δεν μπορεί να θεωρηθεί ότι υπάρχει πλήρης
γνώση των φυσικών νόμων που διέπουν τα φαινόμενα αυτά και τα διαθέσιμα
δεδομένα για την υπάρχουσα κατάσταση είναι ελάχιστα ως ανεπαρκή. Συνεπώς τα
μοντέλα που δημιουργούνται για τις διεργασίες αυτές είναι εννοιολογικά και η
ακρίβεια τους εξαρτάται από τις τιμές των παραμέτρων που ορίζονται.
Στην παρούσα διπλωματική εργασία αναπτύχθηκαν δύο κατανεμημένα εννοιολογικά
μοντέλα αποκλειστικά σε περιβάλλον G.I.S. μέσω του λογισμικού ArcGIS.
Το πρώτο εννοιολογικό μοντέλο βροχής – απορροής προσομοιώνει τα υδρολογικά
γεγονότα που λαμβάνουν χώρα κατά την απορροή και υπολογίζει τους χρόνους που
απαιτούνται από το κάθε σημείο της λεκάνης για να γίνει πλήρης απορροή αυτής.
Επομένως το μοντέλο αυτό, με δεδομένο μόνο το Ψηφιακό Μοντέλο Εδάφους της
περιοχής, μπορεί να υπολογίσει τις ισόχρονες καμπύλες για τη συγκεκριμένη λεκάνη
και να παράγει το αντίστοιχο υδρογράφημα της απορροής το οποίο προκύπτει από
το συνθετικό μοναδιαίο υδρογράφημα της λεκάνης. Κύριος στόχος του μοντέλου είναι
η εκτίμηση της πλημμυρικής αιχμής και κατά δεύτερο λόγο η εκτίμηση του χρόνου
ανόδου (ή χρόνου αιχμής). Το μοντέλο προέκυψε με τροποποίηση υπαρχόντων
μοντέλων βροχής – απορροής, εισάγοντας νέες τεχνικές (νέους εμπειρικούς τύπους)
και εξελίσσοντας την όλη διαδικασία έτσι ώστε να επιφέρει καλύτερα και πιο ακριβή
αποτελέσματα στον ελάχιστο δυνατό χρόνο.
Το δεύτερο μοντέλο που αναπτύχθηκε υπολογίζει την παροχή στην έξοδο της
λεκάνης με δεδομένα τις μετρημένες τιμές του ύψους βροχόπτωσης σε
συγκεκριμένους βροχομετρικούς σταθμούς ή την επιφανειακή κατανομή μιας
βροχόπτωσης. Σκοπός του μοντέλου αυτού είναι η δημιουργία
πλημμυρογραφημάτων για τη δεδομένη λεκάνη απορροής με διαφορετικές συνθήκες
βροχόπτωσης (ένταση, διάρκεια και χωρική κατανομή).
Τα δύο μοντέλα εφαρμόσθηκαν στη λεκάνη απορροής του Σπερχειού ποταμού,
ανάντη της συμβολής του με το Γοργοπόταμο, όπου υπήρχαν διαθέσιμα δεδομένα,
και κατά την εφαρμογή αυτών ελέγχθηκε η επίδραση διαφόρων παραμέτρων. Τα
μοντέλα χρησιμοποιήθηκαν για τη διερεύνηση της επίδρασης της χωρικής κατανομής
της βροχόπτωσης στα παραγόμενα πλημμυρογραφήματα της λεκάνης απορροής
μέσω της εφαρμογής διαφορετικών συνθηκών βροχόπτωσης καθώς και για την
εκτίμηση του πλημμυρογραφήματος σχεδιασμού για περίοδο επαναφοράς 50 ετών.
Το πρώτο κεφάλαιο της εργασίας περιλαμβάνει το θεωρητικό υπόβαθρο των
διαδικασιών που μελετώνται σε όλη την εργασία καθώς και γενικά στοιχεία και
ορισμούς για τα υδρολογικά φαινόμενα και τις λεκάνες απορροής.
Το δεύτερο κεφάλαιο αναφέρεται στα Συστήματα Γεωγραφικών Πληροφοριών
(Σ.Γ.Π.), στη σχέση τους με την υδρολογία και στα εργαλεία που αυτά
περιλαμβάνουν για την αναπαράσταση των υδρολογικών φαινομένων. Επίσης στο
κεφάλαιο αυτό γίνεται αναλυτική περιγραφή, βήμα προς βήμα, των μοντέλων που
δημιουργήθηκαν στην εργασία αυτή με αναλυτική περιγραφή των εργαλείων και των
μεθόδων που χρησιμοποιήθηκαν για να παραχθούν τα απαιτούμενα αποτελέσματα.
Το τρίτο κεφάλαιο της εργασίας περιλαμβάνει τη γεωμορφολογική περιγραφή της
λεκάνης απορροής του Σπερχειού αλλά και συγκεκριμένα του τμήματος αυτής που
επιλέχθηκε ως περιοχή μελέτης.
Το τέταρτο κεφάλαιο αναφέρεται στην εφαρμογή των μοντέλων στη συγκεκριμένη
περιοχή μελέτης. Στο κεφάλαιο αυτό, αναλύονται οι παράμετροι που
χρησιμοποιήθηκαν και παρουσιάζονται τα αποτελέσματα που προέκυψαν. Επίσης,
γίνεται διερεύνηση των παραμέτρων των μοντέλων και περιγραφή της επίδρασης
αυτών στα παραγόμενα αποτελέσματα. Επιπλέον στο κεφάλαιο αυτό γίνεται μελέτη
της επίδρασης της χωρικής κατανομής της βροχόπτωσης στα αποτελέσματα μέσω
της εφαρμογής τεσσάρων πιθανών σεναρίων διαφορετικής βροχόπτωσης και τέλος
εκτιμάται το πλημμυρογράφημα σχεδιασμού της λεκάνης απορροής για περίοδο
επαναφοράς 50 ετών.
Το πέμπτο και τελευταίο κεφάλαιο της εργασίας αναφέρεται στα συμπεράσματα που
προέκυψαν από τη μελέτη, στο σχολιασμό των αποτελεσμάτων και σε πιθανές
προτάσεις για περαιτέρω μελλοντική εργασία πάνω στο θέμα.
Στα παραρτήματα της εργασίας περιλαμβάνονται οι χάρτες που δημιουργήθηκαν
κατά τα στάδια της εργασίας και παρουσιάζονται τα διαγράμματα των μοντέλων που
χρησιμοποιήθηκαν και οι πίνακες με τις εντολές βήμα προς βήμα για την καλύτερη
κατανόηση και επαναδημιουργία των μοντέλων.Natural phenomena are very difficult to be accurately simulated, as our knowledge of
the physical laws that govern these phenomena is not complete and the available
data on the current situation are inadequate. Therefore, the models that are created
for these processes are conceptual and their accuracy depends on the values of the
parameters.
This thesis develops two distributed conceptual models in G.I.S. environment using
the ArcGIS software.
The first model simulates the hydrological phenomena that take place during rainfall -
runoff and calculates the required time for each section of the basin to be fully
drained. The model can calculate the curves representing equal timing conditions for
the runoff of each region, given the Digital Terrain Model, and produces the
corresponding runoff hydrograph resulting from the synthetic unit hydrograph of the
basin. The main objective of the model is to estimate the peak of the flood discharge
and the corresponding time. This model was derived by modifying existing models of
rainfall – runoff, introducing new techniques (new empirical formulas) and updating
the whole process to make the results more accurate in the minimum possible time.
The second model provides estimates of the discharge at the outlet of the basin,
taking as input the measured values of rainfall in specified measuring stations or a
surface distribution of a given rainfall. The purpose of this model is the creation of the
flood hydrographs for a basin with different conditions of rainfall (intensity, duration
and spatial distribution).
These models were applied in the Sperhios river basin, upstream of the junction with
Gorgopotamos river by varying numerous parameters. The models were used to
investigate the spatial distribution of rainfall in the produced flood hydrograph of the
basin by applying different rainfall conditions in the region and to estimate the design
flood hydrograph with 50-year return period. The first chapter of the thesis includes the theoretical background of the processes
considered in the entire thesis and general information and definitions of the
hydrological phenomena and basins.
The second chapter refers to the Geographical Information Systems (G.I.S.) with a
brief reference to their relation with hydrology and the tools which they contain for the
simulation of the hydrological phenomena. This section also includes a detailed step
by step description of the methods used.
The third chapter includes the geomorphological description of the Sperhios river
basin in general and the particular section chosen for this study. It includes the
geometry and altitude characteristics, hydrological network, land cover and geology
of the basin.
The fourth chapter addresses the application of these models in the specified study
area, the description of the parameters used and the presentation of the obtained
results. It includes an investigation of the parameters and a description of their
effects on the output of the models. Furthermore, this chapter includes the study of
the effect of spatial distribution of rainfall in the results through the implementation of
four possible scenarios of different rainfall conditions and the design flood
hydrograph with 50-year return period.
The fifth and final chapter of this thesis gives the conclusions of this study, discussion
of the results and proposal for further research on this topic.
The appendices of this thesis include the maps created throughout the whole
procedure, diagrams of the models used and tables with step by step instructions for
rebuilding the modelsΌλγα Μ. Καββαδ
Organizing debate, debating organization
International audienceControversy analysis is a broad topic where the opinions of different stakeholders are analyzed to identify the various arguments that are stated and classify the positions taken on the subject. Gathering this data can be very time-consuming to do manually and usually is error-prone and not exhaustive. Automated text classification can enhance this process and make it possible to analyze controversial topics by analyzing lists of relevant documents in a short timeframe. In this paper, we propose a 2-step approach to optimize the extraction and classification of arguments in textual data from controversial topics. First, we extract the most relevant paragraphs for the controversy with a retrieval model and then we use an argument mining model to find and classify the relevant arguments. With this method, we are able to successfully characterize long documents and understand the various opinions that are recorded
Life-Cycle Cost and Environmental Assessment of Decentralized Nitrogen Recovery Using Ion Exchange from Source-Separated Urine through Spatial Modeling
Nitrogen standards for discharge
of wastewater effluent into aquatic
bodies are becoming more stringent, requiring some treatment plants
to reduce effluent nitrogen concentrations. This study aimed to assess,
from a life-cycle perspective, an innovative decentralized approach
to nitrogen recovery: ion exchange of source-separated urine. We modeled
an approach in which nitrogen from urine at individual buildings is
sorbed onto resins, then transported by truck to regeneration and
fertilizer production facilities. To provide insight into impacts
from transportation, we enhanced the traditional economic and environmental
assessment approach by combining spatial analysis, system-scale evaluation,
and detailed last-mile logistics modeling using the city of San Francisco
as an illustrative case study. The major contributor to energy intensity
and greenhouse gas (GHG) emissions was the production of sulfuric
acid to regenerate resins, rather than transportation. Energy and
GHG emissions were not significantly sensitive to the number of regeneration
facilities. Cost, however, increased with decentralization as rental
costs per unit area are higher for smaller areas. The metrics assessed
(unit energy, GHG emissions, and cost) were not significantly influenced
by facility location in this high-density urban area. We determined
that this decentralized approach has lower cost, unit energy, and
GHG emissions than centralized nitrogen management via nitrification-denitrification
if fertilizer production offsets are taken into account
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Techno-economic analysis and life-cycle greenhouse gas mitigation cost of five routes to bio-jet fuel blendstocks
Decarbonizing the air transportation sector remains one of the most challenging hurdles to mitigating climate change. Lignocellulosic biomass-derived jet fuel blendstocks can contribute to the shift toward renewable, low-carbon energy sources for aircrafts. Producing these renewable jet fuel molecules from biomass requires advanced pathways with the potential for efficient and affordable conversion routes. This paper presents a detailed techno-economic analysis and sensitivity analysis, including estimated minimum selling price (MSP), and life-cycle greenhouse gas (GHG) mitigation costs for five routes to four potential bio-jet fuel molecules-limonane via limonene, limonane via 1,8-cineole, tetrahydromethylcyclopentadiene dimer (RJ-4), bisabolane, and epi-isozizaane. The simulated biorefineries utilize biomass sorghum and an integrated high-gravity ionic liquid-based biomass deconstruction process. We present results reflecting the current state of the technology and potential future scenarios with improved yields. Among the conversion pathways and the fuel molecules evaluated in this study, limonane, bisabolane, and epi-isozizaane could reach an MSP of 0.91 per L-Jet A (3.45 per gal-Jet A) in optimized future cases, without a hypothetical lignin-derived co-product. RJ-4 requires a more costly upgrading process and catalysts, resulting in a comparatively higher MSP (5.04 per gal-jet A). Based on the GHG footprints of each fuel, the minimum achievable carbon mitigation cost relative to conventional Jet-A is 0.66 per L-Jet A (1.9 per kg. However, the higher energy density of these bio-based blendstocks offers valuable improvements in aircraft efficiency/range; we find that commercial airlines may be willing to pay a 4-14 cent per L premium for these bio-jet fuels. Our results highlight the need for improvements beyond currently-reported yields for the biologically produced intermediates, identification of ideal microbial hosts, selection of metabolic pathways to achieve competitive production costs, and a focus on fuels with attractive properties that increase their value
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Assessing Location and Scale of Urban Nonpotable Water Reuse Systems for Life-Cycle Energy Consumption and Greenhouse Gas Emissions
Nonpotable
water reuse (NPR) is one option for conserving valuable
freshwater resources. Decentralization can improve distribution system
efficiency by locating treatment closer to the consumer; however,
small treatment systems may have higher unit energy and greenhouse-gas
(GHG) emissions. This research explored the trade-off between residential
NPR systems using a life-cycle approach to analyze the energy use
and GHG emissions. Decentralized and centralized NPR options are compared
to identify where decentralized systems achieve environmental advantages
over centralized reuse alternatives, and vice versa, over a range
of scales and spatial and demographic conditions. For high-elevation
areas far from the centralized treatment plant, decentralized NPR
could lower energy use by 29% and GHG emissions by 28%, but in low-elevation
areas close to the centralized treatment plant, decentralized reuse
could be higher by up to 85% (energy) and 49% (GHG emissions) for
the scales assessed (20–2000 m<sup>3</sup>/day). Direct GHG
emissions from the treatment processes were found to be highly uncertain
and variable and were not included in the analysis. The framework
presented can be used as a planning support tool to reveal the environmental
impacts of integrating decentralized NPR with existing centralized
wastewater infrastructure and can be adapted to evaluate different
treatment technology scales for reuse