Optimization of biofuels production via a water–energy–food nexus framework

Biofuels have emerged as an attractive renewable alternative to satisfy the global energy demands. The large-scale production of biofuels requires the installation of biorefining systems that involve strategic decisions for the logistics and operation in the production of biofuels such as location, feedstock type(s), production capacities and interactions with the surrounding environment. This work proposes an optimization framework for the design of a biorefining system while accounting for the interactions with the surrounding watershed using a material flow analysis technique through the design of an efficient supply chain for the production and distribution of feedstocks, grains and biofuels considering the water and land requirements. The proposed model deals with the uncertainty involved in the project (e.g., prices of feedstocks and products, biofuel demands and precipitation in the watershed). A mixed-integer linear programming model is proposed to simultaneously consider the economic and environmental objectives. A case study located in Mexico is solved for a set of scenarios with the purpose of illustrating the capabilities of the proposed optimization approach. The results show strong trade-offs between the considered objectives and the impact of uncertainties.     

Incorporation of process integration into life cycle analysis for the production of biofuels

This article presents a new approach for incorporating process-integration tools into life cycle analysis (LCA) for biofuel production. Process synthesis techniques using mass- and energy-integration tools are employed to generate various scenarios for reducing mass and energy consumption in the process. The global implications of these changes and the associated trade-offs are assessed using the LCA tool: GREET. The developed approach enables the consideration of several levels of process integration while tracking the process economics and the reduction of the net greenhouse gas emissions. Several cases of biofuels with different processing technologies have been considered in this study, and the results show that when the process-integration tools are effectively utilized and combined with LCA, better insights are obtained and the net greenhouse gas emissions decrease drastically for different biofuels.     

Microwave drying characteristics of microalgae (<Emphasis Type="Italic">Chlorella vulgaris</Emphasis>) for biofuel production

Algal biofuels serve as a promising alternative energy source for liquid fuels. However, one of the bottlenecks in the conversion of microalgae to biofuels is the drying process. A moisture content of at most 10 % is desired for algal biomass prior to oil extraction to maximise biofuel yield. Conventional means of drying results to longer drying time and uneven drying of algal biomass. This study investigated the drying characteristics of microwave for microalgae (Chlorella vulgaris). Three microwave intensity levels (300, 600, and 900 W) were considered to dry 10, 20, and 30 of algal mass. Page model gave a better fit on the moisture ratio with time of microwave drying than the exponential model. Furthermore, the specific energy requirement was computed, and a relationship was found between moisture ratio with power and mass. Fourier transform infrared spectroscopy results showed significant reduction of infrared signal intensities of the functional groups present in the algae after drying at higher microwave power level. It was concluded that the 20 W/g microwave drying setting gave a lower specific energy requirement with good quality of remaining high lipid content qualitatively. Furthermore, it was recommended to use gas chromatography mass spectroscopy to further quantify the algal lipids and other functional groups.     

Use of Orthogonal Array Composite Designs to Study Lipid Accumulation in a Cell‐Free System

The development of clean, sustainable alternative energy sources is increasingly important. One promising alternative to depleting fuel reserves is algae‐based biodiesel fuel, which is both non‐toxic and renewable. Despite the tremendous potential of algae‐based biodiesel fuel, it has not yet been profitable because of the high cost per unit area of large cultivation. We present a novel application of Orthogonal Array Composite Designs (OACDs) to optimize lipid production of a cell‐free system for algae. An OACD consists of a two‐level fractional factorial design and a three‐level orthogonal array. We start with an initial screening experiment based on six chemicals using an OACD with 50 runs. Based on this experiment, two chemical compounds were removed and a follow‐up 25‐run OACD with four chemicals was performed. Our analysis shows that only three chemicals – nitrogen, magnesium, and phosphate – are essential for lipid accumulation, and a range of optimum combinations of these three chemicals is identified. The lipid accumulation for these three chemical combinations is substantially higher in comparison to the commercial medium, which contains 16 chemicals and soil water. This leads to a reduced cost of the chemical medium and increased efficiency of biodiesel production from the algal‐based cell‐free system, which can be used to significantly expand the use of biodiesel as a viable alternative to fossil fuels. Copyright © 2015 John Wiley & Sons, Ltd.     

Industrial ecosystem indicators—direct and indirect effects of integrated waste- and by-product management and energy production

In an idealised industrial ecosystem (IE), firms and organisations utilise each other's material and energy flows including wastes and by-products to reduce the system's virgin material and energy input as well as the waste and emission output from the system as a whole, and contribute to sustainable development (SD). IE complements the more conventional individual flow, product, process, organisation, individual actor or sector-focused environmental management approaches and tools with network or systems level approaches. The first research objective of this paper is to construct indicators for IE. The second task is to test the use of these indicators with "what if?" material and energy flow scenarios for the energy and waste system of Satakunta region in Finland including 28 municipalities. Using literature analysis as a source, we arrive at environmental indicators of carbon dioxide (CO₂) equivalents, and at economic indicators of fuel, energy and waste management costs and revenues. The social indicators show the employment effects of the waste management system. The scenarios analyse the current situation (0-scenario) against alternative situations in the future. The future scenarios are developed according to the known and anticipated trends in international and national policy and legislation. The indicator application in the scenarios produces social, environmental and economic effects of waste management in four categories: direct negative, direct positive, indirect negative and indirect positive. Industrial ecosystem theory emphasises the utilisation of wastes as a resource with value alongside the objective of reducing waste. Therefore, the indirect positive effects of waste management are important, as well as the conventional focus of waste management, which has usually been on direct positive effects. The main difficulties in our argument are the system boundary definition, the qualitatively different nature of environmental, economic and social effects and indicators as well as the lack of qualitative or interview data on the preferences and interests of the actors involved.     

Dispatching multi-load AGVs in highly automated seaport container terminals

This paper is concerned with AGV dispatching in seaport container terminals. Special attention is given to multi-load vehicles which can carry more than one container at a time. The characteristics of this complex application environment and the impact on the AGV dispatching problem are analyzed and various solution techniques considered. For practical application within an online logistics control system, a flexible priority rule based approach is developed, making use of an extended concept of the availability of vehicles. For evaluation reasons, this approach is complemented by an alternative MILP formulation. Finally, the performance of the priority rule based approach and the MILP model are analysed for different scenarios with respect to total lateness of the AGVs. The main focus of the numerical investigation is on evaluating the priority rule based approach for single and dual-load vehicles as well as comparing its performance against the MILP modelling approach.     

Safety analysis of manual tasks in automatic production systems--implications for design

A safety procedure for application in the design of automatic production systems is outlined. It involves the specification on safety requirements for a particular system on the basis of general safety requirements and of the results of a safety analysis. During the safety analysis, work tasks inside the danger zone of the system and potential accident scenarios related to these tasks are identified, and safety measures are evaluated. Various checklists have been developed to support each step in the analysis. The method for safety analysis has been tested in field studies of three automatic production systems in operation: two mechanical systems and one process plant. The aim has been to evaluate the method and to collect operational experience concerning accident risks and preventive measures to be considered in design. The main results of the studies are presented, and considerations for the use of the method during the design phases are discussed. It is concluded that the approach that has been selected satisfies the needs of a safety procedure for use in design.     

A Comparative Life Cycle Assessment of Disposable and Reusable Packaging for the Distribution of Italian Fruit and Vegetables

Each year in Italy, millions of tons of fruits and vegetables are harvested, packed and transported to national and foreign retail outlets. Packaging is an essential component of this system, but what is its environmental impact? This study takes into consideration the delivery from the field to the retail outlet of 12 types of fruits and vegetables grown and harvested in Italy and sold in Italy and Europe. The study compares two different packaging and distribution systems: one‐way with corrugated boxes and reusable with plastic containers. A number of different scenarios were generated by combining the most diffused packaging sizes with the most important production and selling locations for each type of fruit and vegetable and by considering the specific route required to perform the transportation with each distribution system. The environmental impact of each system in each scenario has then been analysed using the life cycle assessment methodology. Two algorithms and a number of coefficients were derived to simplify data collection and impact analysis for all scenarios. This provides an easy tool to evaluate the potential environmental burden of the two alternative distribution systems in a specific scenario by taking into consideration only a few variables (such as size of packaging and transportation distance). These algorithms and coefficients are presented in the work, along with the process that led to their generation and with considerations about the main critical environmental aspects for both distribution systems. The work aims to suggest possible design solutions that can make each system more sustainable. Copyright © 2011 John Wiley & Sons, Ltd.     

The rationality of low carbon technologies

Combustion of fossil fuels increases permanently the carbon content of the fast carbon cycle consisting of atmosphere,land and surface ocean.The carbon residence times in these reservoirs are relatively low in the order of some years.Hower,the carbon residence time in the whole fast cycle is in the order of 2,000 years.This means the final storage problem of fossil energy use is in the same order as that of nuclear energy use. There are two other main driving forces for a continuous decarbonisation of the world energy system.The first one is the shortening of raw materials,an the second one is the greenhous gas effect of carbon dioxide with the risk of climate change. Based on the "molecular fingerprints"of various fossil fuels a new quantity.the "energetic carbon efficiency"can be derived.This quantity favours methane(natural gas)more than any other fossil fuel.E.g.,methane is two times more efficient than lignite or hard coaL Therefore,the future role of this energy carrier will be discussed more in detail. Carbon capture and storage(CCS)is not a convincing concept and therefore it cannot be considered as a responsible excuse for new coal fired power stations.A reasonable way out may be the carbon moratorium.This means a thermal splitting of methane into carbon and hydrogen.Only the hydrogen is used as a fuel whereas the carbon is deposited in the earth,because storage of carbon is much safer than storage of carbon dioxide. Very often biofuels are considered as a sustainable option.Critical arguments are presented against the meander of biofuels. Negative climate implications and very low efficiencies are serious arguments against these teehnolgies.Even the fashionable new hope for bioenergy from algea farms has no rational fundament. A long-time sustainable energy system requires not only low carbon but zero carbon technologies.This means solar energy in all kinds of its appearance(water power,wind,solar heat and photovoltaics).However these kinds of energy require new energy storage technologies.Various storage technologies will be discussed with a special focus on electrochemical batteries and electromobility. All of these new energy technologies are not able to remove any carbon from the fast carbon cycle.Therefore,some prominent concepts of climate engineering will be introduced.     

Study of microalgae cultivation systems based on integrated analytic hierarchy process–life cycle optimization

Optimization of sustainable process plant configurations requires the use of systematic assessment methods based on the usage of natural resources, release of pollutants and generation of environmental impact. This paper presents an integrated life cycle optimization framework for the synthesis of microalgae cultivation systems, using a multiple objective linear program formulation; in the model, individual objective functions are aggregated and weighted using the analytic hierarchy process. Four different cultivation alternatives were used as case study to demonstrate the capability of this formulated integrated model. The model takes into account three main environmental criteria in assessing different cultivation alternatives, namely energy, water (direct and indirect water) and carbon footprints. It is determined in the case study that the open pond cultivation system is preferred compared to other alternatives.     

Optimal operation of a distributed energy generation system for a sustainable palm oil-based eco-community

The palm oil industry potentially can be environmentally sustainable through utilizing the vast availability of biomass residues from palm oil mills as renewable energy sources. This work addresses the optimal operation of a combined bioenergy and solar PV distributed energy generation system to meet the electricity and heat demands of an eco-community comprising a palm oil mill and its surrounding residential community. A multiperiod mixed-integer linear programming planning and scheduling model is formulated on an hourly basis that optimally selects the power generation mix from among available biomass, biogas, and solar energy resources with consideration for energy storage and load shifting. A multiscenario approach is employed that considers scenarios in the form of many possible weather conditions and various energy profiles under varying mill operation modes and residential electricity consumption. The proposed approach is demonstrated on a realistic case study for a palm oil mill in the Iskandar Malaysia economic development region. The computational results indicate that biomass-based resource is the preferred renewable energy to be implemented due to the high cost associated with solar PV. As well, load shifting and energy storage can be feasibly deployed for demand peak shaving particularly for solar PV systems.     

A methodology for screening of microalgae as a decision making tool for energy and green chemical process applications

The increasing interest for biotechnological use of microalgae demands a methodology for selection of species suitable to support the development of technologies based on the use of such non-conventional renewable raw material, i.e., green industrial applications. The vast and expanding collection of experimental data on both cell growth and biomass composition available in the literature can be used to reduce the cost of the experimental investigations required to support process engineering and optimization. Selecting the appropriate organism requires extracting useful information from such data, a cumbersome task since various multidisciplinary factors must be considered. This paper presents a computer-aided methodology for selecting appropriate algal species given an energy or green chemical process application employing microalgae as a renewable raw material. The approach is “system oriented”, based on biomass composition and chemical processing of the biomass downstream of the CO₂ biofixation and harvesting operations. Quantitative performance results are supported by professional process simulation. Besides comparison of a set of species performances, the proposed methodology also allows the discrimination among distinct algal compositions resulting from different growth conditions for a given species. Furthermore, three categories of screening metrics are proposed to be maximized by the decision making procedure in order to elicit the relevant information. To demonstrate the potential of the proposed methodology, a databank of both biochemical and elemental compositions of microalgal biomass was used in three green applications: Assessment of biomass heating value; production of syngas by gasification of the biomass; and production of Bio-H₂. Within the accuracy of the databank employed to illustrate the procedure, the methodology selected Botryococcus braunii and Isochrysis galbana as potential promising candidates, for the three examined applications.     

Strategies for Improving the Photocatalytic Hydrogen Evolution Reaction of Carbon Nitride-Based Catalysts

Due to the depletion of fossil fuels and their-related environmental issues, sustainable, clean, and renewable energy is urgently needed to replace fossil fuel as the primary energy resource. Hydrogen is considered as one of the cleanest energies. Among the approaches to hydrogen production, photocatalysis is the most sustainable and renewable solar energy technique. Considering the low cost of fabrication, earth abundance, appropriate bandgap, and high performance, carbon nitride has attracted extensive attention as the catalyst for photocatalytic hydrogen production in the last two decades. In this review, the carbon nitride-based photocatalytic hydrogen production system, including the catalytic mechanism and the strategies for improving the photocatalytic performance is discussed. According to the photocatalytic processes, the strengthened mechanism of carbon nitride-based catalysts is particularly described in terms of boosting the excitation of electrons and holes, suppressing carriers recombination, and enhancing the utilization efficiency of photon-excited electron–hole. Finally, the current trends related to the screening design of superior photocatalytic hydrogen production systems are outlined, and the development direction of carbon nitride for hydrogen production is clarified.     

An analytic-hierarchy-process based simulation model for implementation and analysis of computer-aided systems

The many successful implementations of computer-aided systems (CAx) have created major advantages for most companies in the competitive world market. In particular, some companies have implemented these systems in order to keep up their competitive power, as computer applications in various fields of production systems are more widely used than before. Unfortunately, these companies have met some problems in their implementation processes, such as a lack of welleducated personnel, in sufficient management support, wrong implementation strategies and techniques, and so on. In order to overcome these problems, in this paper a systematic structure for the implementation and analysis of CAx systems is presented to eliminate--or at least reduce--these kinds of problems. In addition, some techniques, such as the analytic hierarchy process (AHP), benchmarking and simulation approach are used together to make the implementation and analysis studies more effective, easy and applicable for the companies. The objectives of the research are: first, to use the AHP technique for the evaluation of the hardware and software components for a targeted CAx system, secondly, to use a simulation generator integrated with the AHP in order to try the alternatives that are ranked by the AHP study, on a real-life product organization model of a company, until a model is found that provides the best performance values as determined by the company's management.     

Evaluating flexible manufacturing systems using a combined multiple attribute decision making method

This paper presents a logical procedure to evaluate alternative flexible manufacturing systems for a given industrial application. The procedure is based on a combined multiple attribute decision making method using TOPSIS and AHP methods together. A ‘flexible manufacturing system suitability index’ is proposed that evaluates and ranks flexible manufacturing systems for the given industrial application. The methodology is illustrated by means of an example.     

Recent progress in the development of solid catalysts for biomass conversion into high value-added chemicals

In recent decades, the substitution of non-renewable fossil resources by renewable biomass as a sustainable feedstock has been extensively investigated for the manufacture of high value-added products such as biofuels, commodity chemicals, and new bio-based materials such as bioplastics. Numerous solid catalyst systems for the effective conversion of biomass feedstocks into value-added chemicals and fuels have been developed. Solid catalysts are classified into four main groups with respect to their structures and substrate activation properties: (a) micro- and mesoporous materials, (b) metal oxides, (c) supported metal catalysts, and (d) sulfonated polymers. This review article focuses on the activation of substrates and/or reagents on the basis of groups (a)–(d), and the corresponding reaction mechanisms. In addition, recent progress in chemocatalytic processes for the production of five industrially important products (5-hydroxymethylfurfural, lactic acid, glyceraldehyde, 1,3-dihydroxyacetone, and furan-2,5-dicarboxylic acid) as bio-based plastic monomers and their intermediates is comprehensively summarized.     

航空行李自动贴标机的设计与实现

目的 为定量评价包装设计方案的可持续性,提供一种基于AHP和TOPSIS的最优方案筛选方法。方法 充分考虑包装产品设计中的材料、生产、运输、销售、处理及回收等环节,构建可持续包装设计方案的三级评价体系。将AHP与TOPSIS有机结合,建立可持续包装设计方案的评价模型,采用AHP法构建判断矩阵,确定包装设计方案指标的权重,采用TOPSIS法计算评价指标最优集和最劣集,得到不同设计方案的优劣排序。结果 实例分析了同一茶叶产品的3种可持续包装设计方案,得出3种设计方案的优越度分别为0.7182, 0.7503, 0.2673,牛皮纸和加厚卡纸设计的泡袋礼盒的设计方案为最优方案。结论 实验表明,AHP和TOPSIS构建的评价模型,能够合理、高效地对可持续包装设计方案的优劣进行排序,为可持续包装设计方案的优化提供了有益参考。     

Management of sustainable manufacturing systems-a review on mathematical problems

The ever-growing awareness of environmental protection has significantly influenced the method of manufacturing products. Due to the introduction of new processes, the management of sustainable manufacturing shows different characteristics to those of traditional systems. Sustainable manufacturing systems have attracted a great deal of attention in the past 20 years as an emerging manufacturing approach. Particularly in the last 10 years, the number of papers focusing on the topic of sustainable manufacturing systems’ management has increased rapidly. More and more practical factors have been considered and integrated into this area which makes it more complex, but closer to reality. This paper aims to classify the mathematical problems dealing with the management of sustainable manufacturing systems. More than 100 related papers mainly from 1994 to 2015 have been selected and reviewed and divided into three categories according to the main elements in a manufacturing system: production planning and control, inventory management and control and manufacturing network design. The development of each category is summarised and the corresponding mathematical problems are discussed to provide a general overview of the relevant research fields and identify future research directions.     

Integrating AHP with QFD for robot selection under requirement perspective

Selection of a robot is an important task, as improper selection may adversely affect a firm's production by reducing the quality of the product, thereby reducing productivity as well as profitability. To effectively select a robot for a specified job, several factors have to be considered. The objective of this paper is to explain how, using a combined AHP/QFD model, the authors are able to determine if the deployment of robots in industry helped in performance enhancement from requirement perspective. Incorporating a simple and novel cost factor measure in the proposed integrated AHP/QFD model aids justification of the implementation of a robotic system in a manufacturing firm from an economic point of view also. The proposed integrated approach also identifies technical requirements followed by customer requirements. In this paper, an integrated model combining AHP and QFD has been delineated for the industrial robot selection problem. Seven technical requirement factors have been considered for the case study.     

Methodology for examining potential technology breakthroughs for mitigating CO2 and application to centralized solar photovoltaics

Aggressive reductions in US greenhouse gas emissions will require radical changes in how society generates and uses energy. Technological breakthroughs will be necessary if we are to make this transition cost effectively. With limited resources, understanding the breakthrough potential of various alternative technology options will be critical. One common approach for comparing technology options is via their relative levelized cost of electricity. This measure does not account for many of the complexities of the landscape in which the technologies compete, however. As an alternative, we describe the use of an energy system model within a nested parametric sensitivity analysis. The approach is applied to examine the breakthrough potential of a specific class of technology, centralized solar photovoltaics (CSPV). We define a “breakthrough” as being a tangible reduction in the system-wide cost of meeting a CO₂ mitigation target. As “tangible” is a subjective term, we characterize the relationship between technology cost reductions and system-wide cost reductions for several mitigation targets. The results illustrate the importance of considering contextual factors in evaluating and comparing technologies. For example, the critical role that fuel switching and vehicle electrification play in mitigation scenarios is shown to affect the competition between CSPV and baseload technologies for market share. This breakthrough analysis approach can be applied to other technologies and is expected to be useful in assessing and comparing breakthrough opportunities across the energy system, including both energy production and use.