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Processes
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Sustainable Biorefinery Processes
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Sustainable Biorefinery Processes

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Environmental and Green Processes".

Deadline for manuscript submissions: closed (30 June 2019) | Viewed by 20409

Special Issue Editors

Dr. Julia A. Valla

E-Mail Website
Guest Editor
Chemical and Biomolecular Engineering, University of Connecticut, Storrs, CT 06269-3222, USA
Interests: fuel processing; sulfur removal; zeolites; refinery operations; biomass conversion to fuels
Special Issues, Collections and Topics in MDPI journals
Dr. Matthew Stuber

E-Mail Website
Guest Editor
Chemical & Biomolecular Engineering, University of Connecticut, Storrs, CT 06269-3222, USA
Interests: deterministic global optimization; robust design; process systems; computational mathematics; concentrating solar energy; water treatment; agriculture

Special Issue Information

Dear Colleagues,

Analogous to the traditional refinery process that utilizes petroleum resources, biorefineries integrate various processes to produce fuels, power, heat, and value-added chemicals from biomass resources. However, the advantage of a biorefinery over the traditional petrochemical refinery is the processing of a renewable resource, namely biomass, to produce a variety of sustainable, green bio-products. Therefore, the produced liquid biofuels can be used for transportation purposes, the generated bio-energy can be used for power and heat, while high-value biochemicals can be used as feedstocks in pharmaceutical or other chemical processes. Although the concept of a biorefinery appears very attractive and promising from an environmental standpoint, there are still many challenges to be addressed before it is fully realized. Biomass feedstock availability, cost and diversity (energy crops, agricultural and forestry residues and waste, industrial and municipal waste, algae, triglycerides, sugar and starch, lignocellulosic feedstocks), process intensification and integration (thermochemical, biochemical, biological conversion of biomass along with upgrading and heat/power production processes), lifecycle analysis, market and economic viability, and even compatibility with current refinery infrastructure are all research areas that will play critical roles in the further development and feasibility of the biorefinery concept.

This Special Issue on “Sustainable Biorefinery Processes” invites articles focused on research regarding the development of the biorefinery concept. Experimental, theoretical, and computational research on the biorefinery concept are all encouraged.

Topics include, but are not limited to:

  • Type of biomass feedstock utilization
  • Innovations in biomass conversion and upgrading or retrofitting existing processes for bio-products (fuels, chemicals, power, and heat)
  • Process integration and intensification
  • Technoeconomic and lifecycle analysis
  • Novel modeling and simulation approaches

Dr. Julia Valla
Dr. Matthew Stuber
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Processes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • biorefinery concept
  • biomass feedstock
  • thermochemical and biological conversion
  • biofuels
  • bio-energy
  • sustainability

Published Papers (5 papers)

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Research

15 pages, 2335 KiB  
Article
A Feasibility Study of Cellulosic Isobutanol Production—Process Simulation and Economic Analysis
by Avraam Roussos, Nikiforos Misailidis, Alexandros Koulouris, Francesco Zimbardi and Demetri Petrides
Processes 2019, 7(10), 667; https://doi.org/10.3390/pr7100667 - 27 Sep 2019
Cited by 23 | Viewed by 4958
Abstract
Renewable liquid biofuels for transportation have recently attracted enormous global attention due to their potential to provide a sustainable alternative to fossil fuels. In recent years, the attention has shifted from first-generation bioethanol to the production of higher molecular weight alcohols, such as [...] Read more.
Renewable liquid biofuels for transportation have recently attracted enormous global attention due to their potential to provide a sustainable alternative to fossil fuels. In recent years, the attention has shifted from first-generation bioethanol to the production of higher molecular weight alcohols, such as biobutanol, from cellulosic feedstocks. The economic feasibility of such processes depends on several parameters such as the cost of raw materials, the fermentation performance and the energy demand for the pretreatment of biomass and downstream processing. In this work, two conceptual process scenarios for isobutanol production, one with and one without integrated product removal from the fermentor by vacuum stripping, were developed and evaluated using SuperPro Designer®. In agreement with previous publications, it was concluded that the fermentation titer is a crucial parameter for the economic competitiveness of the process as it is closely related to the energy requirements for product purification. In the first scenario where the product titer was 22 g/L, the energy demand for downstream processing was 15.8 MJ/L isobutanol and the unit production cost of isobutanol was $2.24/L. The integrated product removal by vacuum stripping implemented in the second scenario was assumed to improve the isobutanol titer to 50 g/L. In this case, the energy demand for the product removal (electricity) and downstream processing were 1.8 MJ/L isobutanol and 10 MJ/L isobutanol, respectively, and the unit production cost was reduced to $1.42/L. The uncertainty associated with the choice of modeling and economic parameters was investigated by Monte Carlo simulation sensitivity analysis. Full article
(This article belongs to the Special Issue Sustainable Biorefinery Processes)
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25 pages, 992 KiB  
Article
Integrating Genome-Scale and Superstructure Optimization Models in Techno-Economic Studies of Biorefineries
by Amir Akbari and Paul I. Barton
Processes 2019, 7(5), 286; https://doi.org/10.3390/pr7050286 - 15 May 2019
Cited by 2 | Viewed by 4094
Abstract
Genome-scale models have become indispensable tools for the study of cellular growth. These models have been progressively improving over the past two decades, enabling accurate predictions of metabolic fluxes and key phenotypes under a variety of growth conditions. In this work, an efficient [...] Read more.
Genome-scale models have become indispensable tools for the study of cellular growth. These models have been progressively improving over the past two decades, enabling accurate predictions of metabolic fluxes and key phenotypes under a variety of growth conditions. In this work, an efficient computational method is proposed to incorporate genome-scale models into superstructure optimization settings, introducing them as viable growth models to simulate the cultivation section of biorefinaries. We perform techno-economic and life-cycle analyses of an algal biorefinery with five processing sections to determine optimal processing pathways and technologies. Formulation of this problem results in a mixed-integer nonlinear program, in which the net present value is maximized with respect to mass flowrates and design parameters. We use a genome-scale metabolic model of Chlamydomonas reinhardtii to predict growth rates in the cultivation section. We study algae cultivation in open ponds, in which exchange fluxes of biomass and carbon dioxide are directly determined by the metabolic model. This formulation enables the coupling of flowrates and design parameters, leading to more accurate cultivation productivity estimates with respect to substrate concentration and light intensity. Full article
(This article belongs to the Special Issue Sustainable Biorefinery Processes)
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11 pages, 2452 KiB  
Article
The Potential for a Pellet Plant to Become a Biorefinery
by Stefan Frodeson, Jonas Berghel, Magnus Ståhl, Karin Granström, Carl Romlin and Alexander Thelander
Processes 2019, 7(4), 233; https://doi.org/10.3390/pr7040233 - 24 Apr 2019
Cited by 7 | Viewed by 3746
Abstract
The use of bioenergy has increased globally in recent years, as has the utilization of biomaterials for various new product solutions through various biorefinery concepts. In this study, we introduce the concept of using a mechanical dewatering press in combination with thermal drying [...] Read more.
The use of bioenergy has increased globally in recent years, as has the utilization of biomaterials for various new product solutions through various biorefinery concepts. In this study, we introduce the concept of using a mechanical dewatering press in combination with thermal drying in a pellet plant. The purpose of the study is to increase the understanding of the effects a mechanical dewatering press has in a pellet production chain and investigate whether a pellet plant could thus become a biorefinery. The evaluations in this study are based on industrial data and initial tests at the university. The results show that the concept of using the mechanical dewatering press together with a packed moving bed dryer reduces energy use by 50%, compared to using only a packed moving bed dryer. The press water could be used as a raw material for biogas, bioplastics, and biohydrogen. Hence, this study points out the possibilities of a pellet plant increasing the efficiency of the drying step, while moving towards becoming a biorefinery. Full article
(This article belongs to the Special Issue Sustainable Biorefinery Processes)
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12 pages, 2380 KiB  
Article
Study on Mass Transfer Kinetics of Sugar Extraction from Sweet Sorghum Biomass via Diffusion Process and Ethanol Yield Using SSF
by Nana Baah Appiah-Nkansah, Jun Li, Ke Zhang, Meng Zhang and Donghai Wang
Processes 2019, 7(3), 137; https://doi.org/10.3390/pr7030137 - 05 Mar 2019
Cited by 8 | Viewed by 3259
Abstract
Sweet sorghum juice, a potential bioethanol feedstock, can be incorporated into the dry-grind ethanol process to improve sugar utilization efficiency, thereby enhancing ethanol yields. The juice is normally obtained by pressing the stalk through roller mills in tandem. Juice extraction by this process [...] Read more.
Sweet sorghum juice, a potential bioethanol feedstock, can be incorporated into the dry-grind ethanol process to improve sugar utilization efficiency, thereby enhancing ethanol yields. The juice is normally obtained by pressing the stalk through roller mills in tandem. Juice extraction by this process is known to be labor intensive, less efficient, and susceptible to considerable fermentable sugar loss due to microbial activities when stored at room temperature. Sweet sorghum juice extraction via diffusion has recently been proposed to improve sugar recovery efficiency. In this study, extraction kinetics based on the optimized diffusion parameters (8% grain loading, 85 °C, and 120 min) were determined to describe the mass transfer of sugars in sweet sorghum biomass during the diffusion process. Diffusion parameters obtained from previous studies were used to extract free sugars and convert them into ethanol using granular starch hydrolyzing enzymes (GSHE) and traditional enzymes. Ethanol yields at 72 h of fermentation mashes treated with GSHE and those with traditional enzymes were comparable (14.49–14.56%, v/v). Ethanol fermentation efficiencies also ranged from 88.92–92.02%. Full article
(This article belongs to the Special Issue Sustainable Biorefinery Processes)
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20 pages, 821 KiB  
Article
Integrated Hydrolysis of Mixed Agro-Waste for a Second Generation Biorefinery Using Nepenthes mirabilis Pod Digestive Fluids
by Nkosikho Dlangamandla, Seteno Karabo Obed Ntwampe, Justine Oma Angadam, Elie Fereche Itoba-Tombo, Boredi Silas Chidi and Lukhanyo Mekuto
Processes 2019, 7(2), 64; https://doi.org/10.3390/pr7020064 - 28 Jan 2019
Cited by 6 | Viewed by 3520
Abstract
To sustainably operate a biorefinery with a low cost input in a commercial setting, the hydrolysis of lignocellulosic biomass must be undertaken in a manner which will impart environmental tolerance while reducing fermenter inhibitors from the delignification process. The challenge lies with the [...] Read more.
To sustainably operate a biorefinery with a low cost input in a commercial setting, the hydrolysis of lignocellulosic biomass must be undertaken in a manner which will impart environmental tolerance while reducing fermenter inhibitors from the delignification process. The challenge lies with the highly recalcitrant lignin structure, which limits the conversion of the holocelluloses to fermentable total reducing sugars (TRS). Due to these challenges, sustainable and innovative methods to pre-treat biomass must be developed for delignocellulolytic operations. Herein, Nepenthes mirabilis digestive fluids shown to have ligninolytic, cellulolytic and xylanolytic activities were used as an enzyme cocktail to hydrolyse mixed agro-waste constituted by Citrus sinensis (orange), Malus domestica (apple) peels, cobs from Zea mays (maize) and Quercus robur (oak) yard waste. The digestive fluids contained carboxylesterases (529.41 ± 30.50 U/L), β-glucosidases (251.94 ± 11.48 U/L) and xylanases (36.09 ± 18.04 U/L), constituting an enzymatic cocktail with significant potential for the reduction in total residual phenolic compounds (TRPCs), while being appropriate for holocellulose hydrolysis. Furthermore, the maximum TRS obtainable was 310 ± 5.19 mg/L within 168 h, while the TRPCs were reduced from 6.25 ± 0.18 to 4.26 ± 0.09 mg/L, which was lower than that observed when conventional methods were used. Overall, N. mirabilis digestive fluids demonstrated an ability to support biocatalytic processes with minimised cellulases hydrolysis interference. Therefore, the digestive enzymes in N. mirabilis pods can be used in an integrated system for feedstock hydrolysis in a second generation biorefinery. Full article
(This article belongs to the Special Issue Sustainable Biorefinery Processes)
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