Advances and emerging techniques for energy recovery during absorptive CO2 capture: a review of process and non-process integration-based strategies

Absorptive CO2 Capture (ACC) is widely embraced as a mature technology to mitigate CO2 emission, but it is energy-intensive and expensive to implement on a commercial scale. It is envisaged that energy recovery could be achieved during ACC by synthesizing and integrating a complex network of flexible heat exchangers to transfer as much energy as possible from a set of hot flows to cold flows. This review provides information on the progress made in the development of process and non-process integration-based techniques alongside their benefits for effective energy recovery during ACC. An exposition on the integration of flexible Heat Exchanger Networks (HENs), its synthesis methodologies, and developments for improving energy recovery during ACC is presented. Furthermore, this review highlights the current state of knowledge creation in process integration and ACC, as well as its underpinning principles, challenges, and opportunities to provide a summary and important discussion on current practices in process integration-based strategies for energy recovery. Current opinions on the integration of flexible HENs for energy recovery during ACC are highlighted. The review also presents a proposed roadmap for large-scale energy recovery during ACC, and suggestions on the improvement opportunities for future research and development were provided. Finally, this review revealed that the integration of flexible HENs is a promising technique for energy recovery during ACC. This study will be beneficial to researchers exploring cost-effective methods for designing sustainable energy systems for effective energy recovery.http://www.elsevier.com/locate/rserpm2022Chemical Engineerin

Update on current approaches, challenges, and prospects of modeling and simulation in renewable and sustainable energy systems

Modeling and simulation (M&S) is a well-known scientific tool that could be used to analyze a system or predict its behavior before physical construction. Despite being an established methodical tool in engineering, only a few review articles discussing emerging topics in M&S are available in open literature, especially for renewable and sustainable energy systems. This review critically examines recent advances in modeling and simulation in the energy sector, with few insights on its approaches, challenges, and prospects in selected renewable and sustainable energy systems (RSES). In addition, the concept of model validation in RSES is systematically discussed based on in-sample and out-of-sample approaches, while potential data sources with crucial elements for model validation in RSES are highlighted. Furthermore, three major groups of sustainable energy system models that play important roles in supporting national and international energy policies arepresented, to bring to light how the modeling of energy systems is evolving to meet its challenges in the design, operation, and control of RSES. This review also presents a comprehensive assessment of the current approaches, challenges, and prospects in modeling the behavior and evaluating the performance of RSES. Finally, areas that need further research and development in renewable and sustainable energy system modeling are also highlighted.https://www.elsevier.com/locate/rserpm2022Chemical Engineerin

Microbial cell immobilization in biohydrogen production: a short overview

The high dependence on fossil fuels has escalated the challenges of greenhouse gas emissions and energy security. Biohydrogen is projected as a future alternative energy as a result of its non-polluting characteristics, high energy content (122 kJ/g), and economic feasibility. However, its industrial production has been hampered by several constraints such as low process yields and the formation of biohydrogen-competing reactions. This necessitates the search for other novel strategies to overcome this problem. Cell immobilization technology has been in existence for many decades and is widely used in various processes such as wastewater treatment, food technology, and pharmaceutical industry. In recent years, this technology has caught the attention of many researchers within the biohydrogen production field owing to its merits such as enhanced process yields, reduced microbial contamination, and improved homogeneity. In addition, the use of immobilization in biohydrogen production prevents washout of microbes, stabilizes the pH of the medium, and extends microbial activity during continuous processes. In this short review, an insight into the potential of cell immobilization is presented. A few immobilization techniques such as entrapment, adsorption, encapsulation, and synthetic polymers are discussed. In addition, the effects of process conditions on the performance of immobilized microbial cells during biohydrogen production are discussed. Finally, the review concludes with suggestions on improvement of cell immobilization technologies in biohydrogen production

Revising the dark fermentative H2 research and development scenario – An overview of the recent advances and emerging technological approaches

The indiscriminate use of fossil fuels has led to several challenges such as greenhouse gas emissions, environmental degradation, and energy security. Establishment of clean fuels is at the forefront of science and innovation in today’s society to curb these problems. Dark fermentation (DF) is widely regarded as the most promising clean energy technology of the 21st century due to its desirable properties such as high energy content, its non-polluting features, its ability to use a broad spectrum of feedstocks and inoculum sources, as well as its ability to use mild fermentation conditions. In developing nations, this technology could be instrumental in establishing effective waste disposal systems while boosting the production of clean fuels. However, DF is still hindered by the low yields which stagnate its commercialization. This paper reviews the recent and emerging technologies that are gaining prominence in DF based on information that has been gathered from recent scientific publications. Herein, novel enhancement methods such as cell immobilization, nanotechnology, mathematical optimization tools, and technologies for biogas upgrading using renewable H2 are comprehensively discussed. Furthermore, a section which discusses the potential of bioenergy in Sub-Saharan Africa including South Africa is included. Finally, scientific areas that need further research and development in DF process are also presented

The Potential of CO2 Capture and Storage Technology in South Africa’s Coal-Fired Thermal Power Plants

The global atmospheric concentration of anthropogenic gases, such as carbon dioxide, has increased substantially over the past few decades due to the high level of industrialization and urbanization that is occurring in developing countries, like South Africa. This has escalated the challenges of global warming. In South Africa, carbon capture and storage (CCS) from coal-fired power plants is attracting increasing attention as an alternative approach towards the mitigation of carbon dioxide emission. Therefore, innovative strategies and process optimization of CCS systems is essential in order to improve the process efficiency of this technology in South Africa. This review assesses the potential of CCS as an alternative approach to reducing the amount CO2 emitted from the South African coal-fired power plants. It examines the various CCS processes that could be used for capturing the emitted CO2. Finally, it proposes the use of new adsorbents that could be incorporated towards the improvement of CCS technology

Batch Fermentative Biohydrogen Production Process Using Immobilized Anaerobic Sludge from Organic Solid Waste

This study examined the potential of organic solid waste for biohydrogen production using immobilized anaerobic sludge. Biohydrogen was produced under batch mode at process conditions of 7.9, 30.3 °C and 90 h for pH, temperature and fermentation time, respectively. A maximum biohydrogen fraction of 48.67%, which corresponded to a biohydrogen yield of 215.39 mL H2/g Total Volatile Solids (TVS), was achieved. Therefore, the utilization of immobilized cells could pave the way for a large-scale biohydrogen production process

Energy and Material Minimization During CO2 Capture Using a Combined Heat and Mass Integration Technique

Heat and mass exchange occur concurrently during CO2 capture. Therefore, the application of a combined heat and mass exchanger network (CHAMEN) could be a very good option to reduce energy and material consumption simultaneously during CO2 capture. In this study, a systematic technique for the synthesis of combined heat and mass exchanger networks (CHAMENs) was introduced to concurrently minimize the use of external utilities and mass separating agents (MSA) during adsorptive CO2 capture. The method proposed in this study is based on an innovative approach that integrates a mathematical programming technique for the heat exchanger networks (HENs) synthesis and a sequentially-based composition interval technique for mass exchanger networks (MENs) synthesis with regeneration. A combined optimization approach was used to minimize the total annualized cost of the synthesized CHAMEN. An example was solved to test the efficacy of the proposed method. The cost of mass separating agents, as well as hot and cold utilities which form the total annualized costs (TAC) for the combined heat and mass exchangers, was minimized. The total annualized cost (TAC) of the synthesized CHAMEN obtained in this study (TAC=$199800/yr) showed significant improvement over the TAC reported in the literature using other synthesis techniques. Results obtained in this study confirmed that the integration of a combined heat and mass exchanger with regeneration network is an effective way to minimize heat and mass during adsorptive CO2 capture. The combined heat and mass exchanger networks adequately satisfied the heat and mass balance of the process with a lower total annualized costpublishedVersio

Lignocellulosic Biomass-Derived Nanocellulose Crystals as Fillers in Membranes for Water and Wastewater Treatment: A Review

The improvement of membrane applications for wastewater treatment has been a focal point of research in recent times, with a wide variety of efforts being made to enhance the performance, integrity and environmental friendliness of the existing membrane materials. Cellulose nanocrystals (CNCs) are sustainable nanomaterials derived from microorganisms and plants with promising potential in wastewater treatment. Cellulose nanomaterials offer a satisfactory alternative to other environmentally harmful nanomaterials. However, only a few review articles on this important field are available in the open literature, especially in membrane applications for wastewater treatment. This review briefly highlights the circular economy of waste lignocellulosic biomass and the isolation of CNCs from waste lignocellulosic biomass for membrane applications. The surface chemical functionalization technique for the preparation of CNC-based materials with the desired functional groups and properties is outlined. Recent uses of CNC-based materials in membrane applications for wastewater treatment are presented. In addition, the assessment of the environmental impacts of CNCs, cellulose extraction, the production techniques of cellulose products, cellulose product utilization, and their end-of-life disposal are briefly discussed. Furthermore, the challenges and prospects for the development of CNC from waste biomass for application in wastewater treatment are discussed extensively. Finally, this review unraveled some important perceptions on the prospects of CNC-based materials, especially in membrane applications for the treatment of wastewater

Energy and Material Minimization During CO2 Capture Using a Combined Heat and Mass Integration Technique

Heat and mass exchange occur concurrently during CO2 capture. Therefore, the application of a combined heat and mass exchanger network (CHAMEN) could be a very good option to reduce energy and material consumption simultaneously during CO2 capture. In this study, a systematic technique for the synthesis of combined heat and mass exchanger networks (CHAMENs) was introduced to concurrently minimize the use of external utilities and mass separating agents (MSA) during adsorptive CO2 capture. The method proposed in this study is based on an innovative approach that integrates a mathematical programming technique for the heat exchanger networks (HENs) synthesis and a sequentially-based composition interval technique for mass exchanger networks (MENs) synthesis with regeneration. A combined optimization approach was used to minimize the total annualized cost of the synthesized CHAMEN. An example was solved to test the efficacy of the proposed method. The cost of mass separating agents, as well as hot and cold utilities which form the total annualized costs (TAC) for the combined heat and mass exchangers, was minimized. The total annualized cost (TAC) of the synthesized CHAMEN obtained in this study (TAC=$199800/yr) showed significant improvement over the TAC reported in the literature using other synthesis techniques. Results obtained in this study confirmed that the integration of a combined heat and mass exchanger with regeneration network is an effective way to minimize heat and mass during adsorptive CO2 capture. The combined heat and mass exchanger networks adequately satisfied the heat and mass balance of the process with a lower total annualized cos

A review on heat and mass integration techniques for energy and material minimization during CO2 capture

Abstract One major challenge confronting absorptive CO2 capture is its high energy requirement, especially during stripping and sorbent regeneration. To proffer solution to this challenge, heat and mass integration which has been identified as a propitious method to minimize energy and material consumption in many industrial applications has been proposed for application during CO2 capture. However, only a few review articles on this important field are available in open literature especially for carbon capture, storage and utilization studies. In this article, a review of recent progress on heat and mass integration for energy and material minimization during CO2 capture which brings to light what has been accomplished till date and the future outlook from an industrial point of view is presented. The review elucidates the potential of heat and mass exchanger networks for energy and resource minimization in CO2 capture tasks. Furthermore, recent developments in research on the use of heat and mass exchanger networks for energy and material minimization are highlighted. Finally, a critical assessment of the current status of research in this area is presented and future research topics are suggested. Information provided in this review could be beneficial to researchers and stakeholders working in the field of energy exploration and exploitation, environmental engineering and resource utilization processes as well as those doing a process synthesis-inclined research