Analyzing the Environmental Benefits of Industrial Symbiosis

Studies of industrial symbiosis (IS) focus on the physical flows of materials and energy in local industrial systems. In an ideal IS, waste material and energy are shared or exchanged among the actors of the system, thereby reducing the consumption of virgin material and energy inputs, and likewise the generation of waste and emissions. In this study, the environmental impacts of an industrial ecosystem centered around a pulp and paper mill and operating as an IS are analyzed using life cycle assessment (LCA). The system is compared with two hypothetical reference systems in which the actors would operate in isolation. Moreover, the system is analyzed further in order to identify possibilities for additional links between the actors. The results show that of the total life cycle impacts of the system, upstream processes made the greatest overall contribution to the results. Comparison with stand‐alone production shows that in the case studied, the industrial symbiosis results in modest improvements, 5% to 20% in most impact categories, in the overall environmental impacts of the system. Most of the benefits occur upstream through heat and electricity production for the local town. All in all it is recommended that when the environmental impacts of industrial symbiosis are assessed, the impacts occurring upstream should also be studied, not only the impacts within the ecosystem.     

Toward a Carbon Dioxide Neutral Industrial Park

The industrial park of Herdersbrug (Brugge, Flanders, Belgium) comprises 92 small and medium‐sized enterprises, a waste‐to‐energy incinerator, and a power plant (not included in the study) on its site. To study the carbon dioxide (CO₂) neutrality of the park, we made a park‐wide inventory for 2007 of the CO₂ emissions due to energy consumption (electricity and fossil fuel) and waste incineration, as well as an inventory of the existing renewable electricity and heat generation. The definition of CO₂ neutrality in Flanders only considers CO₂ released as a consequence of consumption or generation of electricity, not the CO₂ emitted when fossil fuel is consumed for heat generation. To further decrease or avoid CO₂ emissions, we project and evaluate measures to increase renewable energy generation. The 21 kilotons (kt) of CO₂ emitted due to electricity consumption are more than compensated by the 25 kt of CO₂ avoided by generation of renewable electricity. Herdersbrug Industrial Park is thus CO₂ neutral, according to the definition of the Flemish government. Only a small fraction (6.6%) of the CO₂ emitted as a consequence of fossil fuel consumption (heat generation) and waste incineration is compensated by existing and projected measures for renewable heat generation. Of the total CO₂ emission (149 kt) due to energy consumption (electricity + heat generation) and waste incineration on the Herdersbrug Industrial Park in 2007, 70.5% is compensated by existing and projected renewable energy generated in the park. Forty‐seven percent of the yearly avoided CO₂ corresponds to renewable energy generated from waste incineration and biomass fermentation.     

Applying Industrial Symbiosis to Smallholder Farms

The study of industrial symbiosis (IS) has largely focused on the exchange of energy and materials among industrial processes in an effort to increase value and reduce environmental impact. Agricultural systems, particularly those located in developing countries, can benefit from the principles of IS. Relatively few studies have analyzed the potential benefits of integrated material and energy flows in smallholder farming, even though these systems are considered essential to the world's food supply and poverty reduction. Although the concepts can be applied to virtually any system, the study of industrial symbiosis has traditionally focused on industrialized systems in developed countries. The research presented here applies the principles of IS to smallholder farms using optimization techniques to maximize farm output while minimizing wastes. Our research links IS to the growing field of integrated farming research (IFR), which seeks to create new technologies that increase the production of farms by viewing the farm as a system. Bridging these fields enriches the potential for robust research outcomes in both areas and fills a current knowledge gap. IS benefits from exploring new applications and increasing its penetration into the developing world. IFR benefits from established IS tools to create alternate pathways for increased output based on symbiotic relationships. A small farming system in Liberia, West Africa, is used as a case study. System integration of individual unit processes shows increased productivity and decreased waste. The results of this analysis indicate that there are unrealized opportunities for IS in developing countries, and integration of IS techniques into smallholder farming operations has the potential for impacting sustainable development.     

Industrial symbiosis in the forestry sector: A case study in southern Brazil

Industrial symbiosis (IS) is an important concept in the field of industrial ecology that has disseminated worldwide as a practice to decrease the ecological impact of industrial processes through the exchange of by‐products and waste between units in a system. The forestry industry is the main economic activity in the region of Lages in southern Brazil. IS relationships have expanded with the use of waste material from wood processing and strengthened cooperation between companies in different sectors. The aims of this article were to: a) quantify the level of IS in the system, b) identify the benefits of IS for participants, and c) explain why the network further developed IS to the formation of an industrial ecosystem. A questionnaire was administered during visits to 24 forestry companies in order to analyze their products and processes, commercial relations, positive impacts, and local insertion. The industrial symbiosis indicator (ISI) was determined using waste stream data from the system to represent the level of symbiosis among the companies in this region. The results show that the companies participate in a symbiotic network, mainly involving the exchange of chips, bark, sawdust and shavings. In most cases, these exchanges occur between nearby companies, constituting an extensive industrial ecosystem.     

Environmental assessment of energy production from municipal solid waste incineration

Background, Aims and Scope During the combustion of municipal solid waste (MSW), energy is produced which can be utilized to generate electricity. However, electricity production from incineration has to be evaluated from the point view of the environmental performance. In this study, environmental impacts of electricity production from waste incineration plant in Thailand are compared with those from Thai conventional power plants. Methods The evaluation is based on a life cycle perspective using life cycle assessment (LCA) as the evaluation tool. Since MSW incineration provides two services, viz., waste management and electricity production, the conventional power production system is expanded to include landfilling without energy recovery, which is the most commonly used waste management system in Thailand, to provide the equivalent function of waste management. Results The study shows that the incineration performs better than conventional power plants vis-à-vis global warming and photochemical ozone formation, but not for acidification and nutrient enrichment. Discussion There are some aspects which may influence this result. If landfilling with gas collection and flaring systems is included in the analysis along with conventional power production instead of landfilling without energy recovery, the expanded system could become more favorable than the incineration in the global warming point of view. In addition, if the installation of deNO_x process is employed in the MSW incineration process, nitrogen dioxide can be reduced with a consequent reduction of acidification and nutrient enrichment potentials. However, the conventional power plants still have lower acidification and nutrient enrichment potentials. Conclusions The study shows that incineration could not play the major role for electricity production, but in addition to being a waste management option, could be considered as a complement to conventional power production. To promote incineration as a benign waste management option, appropriate deNO_x and dioxin removal processes should be provided. Separation of high moisture content waste fractions from the waste to be incinerated and improvement of the operation efficiency of the incineration plant must be considered to improve the environmental performance of MSW incineration. Recommendations This study provides an overall picture and impacts, and hence, can support a decision-making process for implementation of MSW incineration. The results obtained in this study could provide valuable information to implement incineration. But it should be noted that the results show the characteristics only from some viewpoints. Outlook Further analysis is required to evaluate the electricity production of the incineration plant from other environmental aspects such as toxicity and land-use.     

Industrial Wastes and By‐products as Alternative Fuels in Cement Plants: Evaluation of an Industrial Symbiosis Option

A ravenous fuel consumer, the cement industry may substitute fossil fuels by industrial wastes and by‐products, identifying the industry as a key example of industrial symbiosis (IS). Benefits from industrial waste alternative fuels (IWAFs) include safe disposal, fossil fuel cost savings, gate fees, and greenhouse gas credits. Poor IWAFs, (high moisture, ash and halogen content) bring higher gate fees, but lessen clinker production. Thermal rating and blower capacity constraints should be satisfied in such a case study of IS. Cement plants must comply with potentially tighter emission limits, compared to fossil fuel utilization, despite higher pollutant precursors in IWAFs. Emissions’ compliance, operational, and production implications are a few among several challenges when assessing multiple IWAF valorization as a symbiotic option from a systems’ perspective. A novel method is proposed to quantitatively assess critical trade‐offs. Species and energy transformations convey a rigorous picture of clinker level, kiln flue gas, and offgas volumes and lay the groundwork for screening, a priori selection, and process tuning. Necessary and sufficient compliance conditions and safety margins are presented in terms of process parameters and actual emissions’ data. Main challenges posed by high flue gas, high offgas volumes, high moisture, low heating value, increased nitrogen oxides emissions, and high halogen and metal content are quantified. As demonstrated in a case study of an actual 1.5 × 10⁶ tonnes per annum clinker plant in this paper, concurrent use of several IWAFs may increase clinker production, while satisfying operational constraints and maintaining compliance. The method may serve for devising IWAF preparation, or tuning mechanisms expanding IWAF valorization.     

Environmental Assessment of Refuse‐Derived Fuel Co‐Combustion in a Coal‐Fired Power Plant

Municipal residual waste (RW) produced in the Venice area undergoes mechanical‐biological treatment (MBT) in the Fusina plant to produce refuse‐derived fuel (RDF) that is then co‐combusted in a nearby coal‐fired power station. Being the first significant project for RDF co‐firing in power plants in Italy, a number of different testing phases were performed starting in 2003, aimed at evaluating differences between so‐called blank operation (i.e., with only coal feeding) and RDF co‐firing at different feeding rates. The analysis of data gathered during the industrial experimentation shows a savings of 0.7 tonnes (t) of coal per each tonne of co‐fired RDF; stack concentrations of some pollutants (hydrochloric acid [HCl], ammonia [NH₃], carbon monoxide [CO], chromium [Cr], and lead [Pb]) appear slightly higher during co‐combustion compared with blank operation, whereas concentrations of dust, sulfur oxides (SOx), and some metals (manganese [Mn], nickel [Ni], vanadium [V]) are lower. To assess the overall environmental performance of this practice, a life cycle assessment (LCA) study was then performed, where different strategies of energy recovery from RW were compared: production of RDF and its co‐combustion in the Fusina power plant, RW combustion without any pretreatment in a mass‐burn waste‐to‐energy (WTE) plant, and production of RDF and its combustion in a dedicated WTE plant. The LCA results show that co‐combustion of RDF performs better than the other strategies for all impact categories evaluated. The only exception is when the WTE plant operates in combined heat and power mode, with very high overall conversion efficiencies.     

Potentials and limits of mechanical plastic recycling

Plastics consumption continues to steeply increase worldwide, while resultant waste is currently mostly landfilled, discarded to the environment, or incinerated. This significantly contributes to global warming and causes negative health and ecosystem effects. Increasing the circularity of plastics can reduce these impacts. This study investigated to which extent plastics' circularity can be increased by mechanical recycling. For this purpose, future scenarios involving increased waste collection, improved product design, and improved waste sorting were assessed. The system studied consists of 11 plastic types in 69 product groups consumed and arising as waste in Switzerland. By means of a material flow analysis, the amounts of consumption, waste, and secondary material utilizable in product manufacturing were quantified for the year 2040. For the waste not mechanically recycled, treatment situations mainly involving energy recovery in waste-to-energy plants and cement kilns were modeled. A life cycle assessment of the complete plastic material flow system was conducted. We found that the mechanical recycling rate calculated based on the utilizable secondary material can be increased to up to 31%. This can lower the plastic carbon footprint by one quarter (1.3% of today's total Swiss carbon footprint) compared to no recycling. Important barriers to a further increase of the recycling rate were inaccessibility, the large diversity of plastic grades, and contamination. The remaining impact at maximum recycling is mainly caused by polyurethanes, polypropylene, and polystyrene production. In conclusion, the potential of mechanical plastic recycling is limited, but it can, as one of several measures, contribute to combating climate change.     

Transforming the Cement Industry into a Key Environmental Infrastructure for Urban Ecosystem: A Case Study of an Industrial City in China

Under the dual pressure of environmental constraints and increasingly thin profit margins, the cement industry in China is in a predicament. To alleviate the environmental and the economic pressure of the cement industry and to tackle the problem of delayed environmental infrastructure construction, this article introduced an urban ecosystem in which the cement industry was transformed into an effective complement to environmental infrastructure. The Xinfeng Cement Industrial Park in China, which has a production capacity of 5 million tonnes per annum (Mt/a) of clinker, was chosen as a case study. Our methodology involved proposing technologies to develop an efficient cement plant‐centered urban ecosystem; evaluating its environmental and economic performance; identifying barriers in its promotion; and proposing supportive policies. Results showed that the city's waste recycling ratio rose from about 50% to 70%, saving 0.6 Mt/a of coal equivalent and reducing about 3.0 Mt/a of resulting carbon dioxide (CO₂) emissions. The life span of the city's landfill site was extended by about 30 years. The total investment was 3.2 billion yuan (about US$480 million), 1 with an average payback period of 3 years. The Xinfeng Cement Industrial Park was transformed from an energy‐intensive consumer and a significant CO₂ emitter to a key industrial waste recycler, a crucial municipal waste co‐processor, an important new building material supplier, and a potential energy producer. Last, the “not‐in‐my‐back‐yard” (NIMBY) effect from constructing new environmental infrastructure was also avoided.     

Barriers to Industrial Symbiosis: Insights from the Use of a Maturity Grid

The concept of industrial symbiosis (IS) over the last 20 years has become a well‐recognized approach for environmental improvements at the regional level. Many technical solutions for waste and by‐product material, water, and energy reuse between neighboring industries (so‐called synergies) have been discovered and applied in the IS examples from all over the world. However, the potential for uptake of new synergies in the regions is often limited by a range of nontechnical barriers. These barriers include environmental regulation, lack of cooperation and trust between industries in the area, economic barriers, and lack of information sharing. Although several approaches to help identify and overcome some of the nontechnical barriers were examined, no methodology was found that systematically assessed and tracked the barriers to guide the progress of IS development. This article presents a new tool—IS maturity grid—to tackle this issue in the regional IS studies. The tool helps monitor and assess the level of regional industrial collaboration and also indicates a potential path for further improvements and development in an industrial region, depending on where that region currently lies in the grid. The application of the developed tool to the Gladstone industrial region of Queensland, Australia, is presented in the article. It showed that Gladstone is at the third (active) stage of five stages of maturity, with cooperation and trust among industries the strongest characteristic and information barriers the characteristic for greatest improvement.     

Modeling and Optimization of a Coal‐Chemical Eco‐industrial System in China

China is coal dependent, and this situation will persist for a long time. Because more and more attention has been paid to energy security, the coal‐chemical industry has become a hot topic and has developed quickly. To improve efficiency and reduce emissions, industrial symbiosis (IS) can be introduced when establishing a coal‐chemical eco‐industrial system to achieve harmonious development between nature, industry, and society. In order to learn the influence of IS on the current industrial system, a model of coal‐chemical eco‐industrial systems was built. Using scenario optimization and linear programming, the behaviors and optimal industrial structures of the system under different scenario settings were compared, and industrial ecological analysis was performed. By comparative analysis, results showed that the greatest proportional decrease in the use of coal for coking was 15% compared with actual data for 2005. The resource‐productivity and eco‐productivity were 828 yuan/ton and 2.51, which are much higher than the values of 548 yuan/ton and 1.23 in 2005. The symbiosis index and the link density were found to be 0.675 and 1.67, compared with 0.588 and 0.94 in 2005. Research results showed that the coal‐chemical eco‐industrial system achieved a high value‐added utilization of coal and an updated product profile. Such systems will constitute the main direction and the inevitable trend of China's coal utilization in the future, which will reduce the harm to the environment from increased coal use and benefit the energy industry, the economy, and society.     

Investigating Reasons for Differences in the Results of Environmental,Physical, and Hybrid Input‐Output Models

It is vital to find reasons for differences in the results of environmental input‐output (EIO), physical input‐output (PIO), and hybrid input‐output (HIO) models for industrial and environmental policy analysis. Using EIO, PIO, and HIO models, China's industrial metabolism is calculated. Four reasons were found to account for differences in the results of analysis using EIO, PIO, and HIO models: the manner in which they deal with residential consumption, service sectors, and waste recycling, and the assumption of unique sector prices. The HIO model, which treats residential consumption as sectors of the intermediate delivery matrix, is preferred to the EIO and PIO models for analyzing industrial and environmental policies. Moreover, waste recycling in five sectors—agriculture; the manufacture of paper, printing, and articles for culture, education, and sports activities; the manufacture of nonmetallic mineral products; smelting and pressing of metals; and construction—should be comprehensively considered when using the HIO model to study problems related to these five sectors. Improvements in the EIO, PIO, and HIO models and future work are also discussed.     

Energy Use and Greenhouse Gas Emissions of Air‐Source Heat Pump and Innovative Ground‐Source Air Heat Pump in a Cold Climate

This article compares climate impacts of two heat‐pump systems for domestic heating, that is, energy consumption for space heating of a residential building. Using a life cycle approach, the study compared the energy use and greenhouse gas (GHG) emissions of direct electric heating, a conventional air‐source heat pump, and a novel ground‐source air heat pump innovated by a citizen user, to assess whether such user innovation holds benefit. The energy use of the heat pumps was modeled at six temperature intervals based on duration curves of outdoor temperature. Additionally, two heat pump end‐of‐life scenarios were analyzed. Probabilistic uncertainty analysis was applied using a Monte Carlo simulation. The results indicated that, in ideal conditions, that is, assuming perfect air mixing, the conventional air‐source heat pump's emissions were over 40% lower and the ground‐air heat pump's emissions over 70% lower than in the case of direct electric heating. Although proper handling of the refrigerant is important, total leakage from the retirement of the heat‐pump appliance would increase GHG emissions by just 10%. According to the sensitivity analysis, the most influential input parameters are the emission factor related to electricity and the amount of electricity used for heating.     

Synergy Management Services Companies: A New Business Model for Industrial Park Operators

The concept of industrial symbiosis (IS) was introduced decades ago and its environmental and economic benefits are well established, but the broad acceptance of IS still faces significant barriers. This article provides a new approach to capture synergies within industrial parks by suggesting a new business model. Building on findings from a survey conducted by the authors and on literature, we first identify potential barriers to low‐carbon synergistic projects. Economic concerns of technically feasible synergies and financial issues turn out to be the largest barriers, because of long payback periods and fluctuating raw material and by‐product market prices. Existing business models do not offer easy ways to overcome or relax these barriers. We therefore introduce the concept of a synergy management services company (SMSCO), a synergy contractor and third‐party financing model, to overcome these barriers. This model shifts the financial risk of the synergistic project from collaborating firms to the SMSCO. We posit that this attribute of the SMSCO model makes it attractive for industrial park operators who seek long‐term solutions to secure future viability of their park.     

Industrial Waste Reuse and By‐product Synergy Optimization

By‐product synergy is a growing practice worldwide. It consists in the maximization of resources utilization with the replacement of raw materials by by‐products as inputs for industrial processes. In order to support decision making in such strategic projects, appropriate tools must be developed. This article presents the results of a research project, which includes the development of a multiobjective mathematical programming model for the optimization of by‐product flows, synergy configurations, and investment decisions in eco‐industrial networks. This model is evaluated using data related to the Kalundborg industrial symbiosis (IS) in order to illustrate its utilization, as well as to assess, in a retrospective manner, the behavior of the companies involved with respect to both economic and environmental benefits of synergies. The experiments also illustrate the influence of the municipality on synergy implementation and how a scenario‐based approach can be used to anticipate raw material price increase. The results are generally coherent with the actual timing of synergy initializations. Further, the considerable effect of water price on the length of investments’ payback period illustrates the impact of policies and regulations on IS.     

Scaling‐Up of Industrial Symbiosis in the Korean National Eco‐Industrial Park Program: Examining Its Evolution over the 10 Years between 2005–2014

In 2005, South Korea initiated the 15‐year National Eco‐Industrial Park Development Program in three stages to gradually transform aged industrial complexes into eco‐industrial parks (EIPs) by promoting industrial symbiosis (IS). Building upon the pilot experiences from the first 5 years, the second phase of the program focused on the scaling‐up of IS at a broader regional level. Key scaling‐up strategies included the expansion of target areas by connecting multiple industrial complexes, the standardization of processes and dissemination of learning, and the development of large‐scale projects that could contribute to the regional development. In this study, we examined the evolution of IS over the last 10 years between 2005 and 2014, primarily to understand the characteristics and impact of these scaling‐up strategies. Our findings showed that the scale of IS in the second phase had increased in various aspects in comparison to that in the first phase. The number of operating projects had increased from 52 to 159, the number of participating firms increased from 90 to 596, and the average distance of IS increased from 40 to 48 kilometers. The size of economic and environmental benefits also increased along with an increase in the private investment and government research funding. We further analyzed the role of the regional EIP centers as facilitators, how their activities influenced the scaling‐up of IS, and discussed the characteristics of the Korea's approach to IS.     

A Metabolic Profile of Peru: An Application of Multi‐Scale Integrated Analysis of Societal and Ecosystem Metabolism (MuSIASEM) to the Mining Sector's Exosomatic Energy Flows

The present Peru's metabolic profile study poses the specific question, What are the long‐term national energy system implications of the recent government‐supported growth of the mining sector? The question is addressed by analyzing interactions between human economic activity (in hours) and electricity input flows (in joules) in the mining sector of the Peruvian economy in 2000 and 2010, with a projection for 2020. The methodology is based on the multi‐scale integrated analysis of societal and ecosystem metabolism (MuSIASEM), which is an application of Georgescu‐Roegen's bioeconomics approach. Empirical results found for the national economy show: (1) the massive increase in size of the energy system, which is explained by exploitation of the Camisea natural gas (NG) reserves, and (2) the potential for establishing a carbon lock‐in in the electricity sector, owing to increasing construction of electricity plants based on NG as their primary energy source. Empirical results specific to the mining sector indicate: (1) the extremely high electricity metabolic rate of the mining sector (61.6 megajoules per hour in 2010), which was found to be 11 times the rate of electricity used per hour of human activity in the building and manufacturing sector in Peru, and (b) the potential increases in the proportion of electricity used in the mining sector (flow share), which could jeopardize the availability of high‐quality primary energy supplies for the rest of society. In light of these implications, it is argued that the Peruvian government's strong support for growth of the mining sector may have to be reconsidered.     

State dependence,personality, and plants: light‐foraging decisions in Mimosa pudica (L.)

Plants make foraging decisions that are dependent on ecological conditions, such as resource availability and distribution. Despite the field of plant behavioral ecology gaining momentum, ecologists still know little about what factors impact plant behavior, especially light‐foraging behavior. We made use of the behavioral reaction norm approach to investigate light foraging in a plant species that exhibits rapid movement: Mimosa pudica. We explored how herbivore avoidance behavior in M. pudica (which closes its leaflets temporarily when disturbed) is affected by an individual's energy state and the quality of the current environment and also repeatedly tested the behavior of individuals from two seed sources to determine whether individuals exhibit a “personality” (i.e., behavioral syndrome). We found that when individuals are in a low‐energy state, they adopt a riskier light‐foraging strategy, opening leaflets faster, and not closing leaflets as often in response to a disturbance. However, when plants are in a high‐energy state, they exhibit a plastic light‐foraging strategy dependent on environment quality. Although we found no evidence that individuals exhibit behavioral syndromes, we found that individuals from different seed sources consistently behave differently from each other. Our results suggest that plants are capable of making state‐dependent decisions and that plant decision making is complex, depending on the interplay between internal and external factors.