An emissions analysis for environmentally sustainable freight transportation modes: distance and capacity

Transportation is one of the largest air pollutants as well as the Greenhouse Gas (GHGs) contributors. The inclusion of air pollutants in optimisation studies is less established than the use of CO2 and/or GHGs which are often used as an indicator of environmental sustainability. This study aims to assess environmentally sustainable alternatives for freight transportation by considering both GHG and air pollutants. A case study identifying air emissions of different freight transport modes for moving goods from Rotterdam is presented. The assessed freight transports include articulated lorry, container ship, bulk carrier, and rail operated by diesel. The environmentally sustainable freight transport of the studied route based on the common practice (GHGs only) and the inclusion of air pollutants are discussed. Evaluation of the results shows that transport with lower GHG emissions does not result on PM and SOx as well. A possibility of inappropriate decision making has been consequently highlighted. The impact of loaded capacity in moving the goods on the emission is assessed from the perspective of logistics service provider. A further comprehensive study which includes the entire life cycle is needed as this study only considers the tank to wheel emissions

Review on the characteristic and feasibility of leachate for biogas production by anaerobic digestion

The sound handling of municipal solid waste (MSW) is of high priority to minimise environmental degradation and pollution. MSW can be treated via various technologies including landfilling, incineration, composting, anaerobic digestion (AD) and more. Landfill without landfill gas capturing serves as an enclosed bioreactor to store and stabilise waste. Other technologies such as incineration, composting and AD allow substantial volume reduction and generate value-added products. The treatment for MSW is commonly focusing on the solid part. Organic waste contains high moisture content of 70 - 90 %. The pressing of the water content before entering treatment unit, the release of water during and after the treatment, can generate high strength wastewater, known as leachate. Leachate is rich in organic matter, organic pollutants, pathogens, heavy metals and more, which can lead to severe secondary environmental pollution if not properly treated. Leachate from different treatment units showed certain unique characteristics, such as high Na, high Ca, different species and availability of heavy metals. This review summarised some of the important characteristics of different leachates and the suitability of AD as a mean of treatment. The efficiency of AD to treat leachate was presented in terms of the removal efficiency of chemical oxygen demand (COD) and biogas production. The COD removal efficiency was between 60 - 98 %, following the treatment of different leachates under different reactors and operational parameters. Among the different stream of leachates, the leachate from landfill is most commonly studied as a co-digestion substrate for AD, as compared to leachate from the composting facility

Exergy Footprint Assessment of Cotton Textile Recycling to Polyethylene

Circular economy implementations tend to decrease the human pressure on the environment, but not all produce footprint reductions. That observation brings the need for tools for the evaluation of recycling processes. Based on the Exergy Footprint concept, the presented work formulates a procedure for its application to industrial chemical recycling processes. It illustrates its application in the example of cotton waste recycling. This includes the evaluation of the entire process chain of polyethylene synthesis by recycling cotton waste. The chemical recycling stages are identified and used to construct the entire flowsheet that eliminates the cotton waste and its footprints at the expense of additional exergy input. The exergy performance of the process is evaluated. The identified exergy assets and liabilities are 138 MJ/kg ethylene and 153 MJ/kg ethylene, reducing the Exergy Footprint by 75% and the greenhouse gas footprint by 43% compared to the linear pattern of polyethylene production. The exergy requirements for producing raw cotton constitute a large fraction of the liabilities, while the polyethylene degradation provides the main asset in the reduction of the Exergy Footprint

Temperature disturbance management in a heat exchanger network for maximum energy recovery considering economic analysis

The design of heat exchanger networks (HEN) in the process industry has largely focused on minimisation of operating and capital costs using techniques such as pinch analysis or mathematical modelling. Aspects of operability and flexibility, including issues of disturbances affecting downstream processes during the operation of highly integrated HEN, still need development. This work presents a methodology to manage temperature disturbances in a HEN design to achieve maximum heat recovery, considering the impact of supply temperature fluctuations on utility consumption, heat exchanger sizing, bypass placement and economic performance. Key observations have been made and new heuristics are proposed to guide heat exchanger sizing to consider disturbances and bypass placement for cases above and below the HEN pinch point. Application of the methodology on two case studies shows that the impact of supply temperature fluctuations on downstream heat exchangers can be reduced through instant propagation of the disturbances to heaters or coolers. Where possible, the disturbances have been capitalised upon for additional heat recovery using the pinch analysis plus-minus principle as a guide. Results of the case study show that the HEN with maximum HE area yields economic savings of up to 15% per year relative to the HEN with a nominal HE area

Journal of Cleaner Production

The Journal of Cleaner Production is an international, transdisciplinary journal focusing on Cleaner Production, Environmental, and Sustainability research and practice. Through our published articles, we aim at helping societies become more sustainable.'Cleaner Production' is a concept that aims at preventing the production of waste, while increasing efficiencies in the uses of energy, water, resources, and human capital.The Journal of Cleaner Production serves as a platform for addressing and discussing theoretical and practical cleaner production, encompassing environmental, and sustainability issues in corporations, governments, education institutions, regions, and societies.Subject areas include, but are not limited to:- Cleaner production and technical processes- Sustainable Development and Sustainability- Sustainable Consumption- Environmental and sustainability assessment- Sustainable Products and Services- Corporate sustainability and Corporate Social Responsibility- Education for Sustainable Development- Governance, legislation, and policy for sustainability1565p.;21x28c

Water footprints and virtual water flows embodied in the power supply chain

Water use within power supply chains has been frequently investigated. A unified framework to quantify the water use of power supply chains deserves more development. This article provides an overview of the water footprint and virtual water incorporated into power supply chains. A water-use mapping model of the power supply chain is proposed in order to map the analysed research works according to the considered aspects. The distribution of water footprint per power generation technology per region is illustrated, in which Asia is characterised by the largest variation of the water footprint in hydro-, solar, and wind power. A broader consensus on the system boundary for the water footprint evaluation is needed. The review also concludes that the water footprint of power estimated by a top-down approach is usually higher and more accurate. A consistent virtual water accounting framework for power supply chains is still lacking. Water scarcity risks could increase through domestic and global power trade. This review provides policymakers with insights on integrating water and energy resources in order to achieve sustainable development for power supply chains. For future work, it is essential to identify the responsibilities of both the supply and demand sides to alleviate the water stress

A numerical analysis for total site sensitivity

Total Site Heat Integration (TSHI) is an established method for analysis and mapping of heat sources and sinks of multiple processes linked via a centralised utility system. The TSHI method is very beneficial for analysing a total site's sensitivity to plant maintenance shutdown and production changes that affect integrated heat sources and sinks. This paper presents the Total Site Sensitivity Table (TSST) as a systematic approach for exploring the effects of plant shutdown or production changes. TSST can be used hand in hand with TSHI graphical approaches (Grand Composite Curve, Total Site Profile and Site Composite Curve) or numerical approach (Total Site Problem Table Algorithm). The graphical approach provides better insights while the numerical approach provides faster, easier and accurate calculations. Both approaches have its advantages and disadvantages and it is up to the engineers which approach they prefer or complement. The use of TSST allows a design engineer to clearly see the sensitivity of Total Site (TS) towards operational changes. The best setting for different operation condition in total site context can be selected by exploiting this tool. The worst case scenario can also be explored for the integrated TS system through the use of TSST. This information is useful for exploring the individual plant operational flexibility. Decision for having a backup heat exchanger network according to TSST would increase the energy saving for various TS operating conditions. TSST can be used to consider various 'what if' scenarios. They allow the determination of the optimum size of utility generation system and backup piping needed to be designed, external utilities that need to be bought and stored. Application of this technique on a case study demonstrates with the assistance of TS-PTA, TSST clearly pinpoint the effects of plant shutdown or production changes on heat distribution and utility generation systems of a Total Site

A numerical tool for integrating renewable energy into total sites with variable supply and demand

Total Site Heat Integration (TSHI) of multiple plants on a total site has recently been extended to include variable supply and demand of renewable energy. A graphics- based targeting procedure based on Time Slices (TSLs) was proposed recently to handle this variability. It has been based on the construction of Composite Curves (CCs), Grand Composite Curve (GCC) and the Total Site Profiles for each time interval. However, a dedicated numerical algorithm can offer more useful features. This paper introduces a numerical algorithm to efficiently address large-scale TSHI problems involving variable supply and demand. The tool is an extension of the Total Site Problem Table Algorithm (TS-PTA) published recently. Due to its numerical nature, it locates the stream origins conceptually and precisely and it can be embedded into larger algorithms. TS-PTA allows rapid and precise determination of the Total Site targets utilities and heat storage, while still preserving the ability to show the curves used by the graphical methodology (e.g. GCC and Site CC, which are better for visualisation). Heat storage facilities are used in solving variable supply and demand problem. Total Site Heat Storage Cascade (TS-HSC) is introduced in this work for analysing heat excess in certain TSL that can be cascaded to the next TSL during start-up and operation. This novel tool also could be used for estimating the heat storage capacity required. The procedure is illustrated on a previously published case study, confirming the advantages of TS-PTA to the graphics-based targeting methodology