Yasunori Kikuchi

Hierarchical Activity Model for Risk-Based Decision Making

For the practical implementation of the assessment of environmental impact, actual procedures and data requirements should be clarified so that industrial decision makers understand them. Researchers should consider local risks related to processes and environmental impact throughout the life cycle of products simultaneously to supervise these adverse effects appropriately. Life cycle assessment (LCA) is a useful tool for quantifying the potential impact associated with a product life cycle. Risk assessment (RA) is a widely used tool for identifying chemical risks in a specific situation. In this study, we integrate LCA and RA for risk-based decision making by devising a hierarchical activity model using the type-zero method of integrated definition language (IDEF0). The IDEF0 activity modeling language has been applied to connect activities with information flows. Process generation, evaluation, and decision making are logically defined and visualized in the activity model with the required information. The activities, information flows, and their acquisitions are revealed, with a focus on which data should be collected by on-site engineers. A case study is conducted on designing a metal cleaning process reducing chemical risks due to the use of a cleansing agent. LCA and RA are executed and applied effectively on the basis of integrated objective settings and interpretation. The proposed activity model can be used as a foundation to incorporate such assessments into actual business models.

Industrial Symbiosis Centered on a Regional Cogeneration Power Plant Utilizing Available Local Resources: A Case Study of Tanegashima

Plant‐derived renewable resources have the potential to enable the simultaneous generation of high‐value‐added products, such as foods, with energy, such as electricity and thermal power. Much of the heat cogenerated from renewables in power plants has been discarded because of the geographical and temporal gaps in heat supply and demand. In this study, we aim to devise an effective industrial symbiosis (IS) for a regional combined heating and power (CHP) plant utilizing local renewable resources. For the actual region of IS, the island of Tanegashima in Japan was adopted, where sugarcane is planted as a base industry. Through a thermodynamic analysis of the energy flows in a sugar mill, it was demonstrated that large amounts of heat were discarded from the sugar mill, even though the quality of heat was high enough for power generation or other energy demand. This is partly because some of the renewables have been regarded as wastes in the production of foods or other high‐value‐added products. At the same time, scenarios were defined and analyzed on the integrated use of locally available lignocellulosic biomass to increase the operation ratio of an existing bagasse‐based CHP system. Through both periods with and without sugar production, additional heat and power can be made available by decreasing the energy loss and through IS.

Design of recycling system for poly(methyl methacrylate) (PMMA). Part 1: recycling scenario analysis

IntroductionIn this series of papers, we present a poly(methyl methacrylate) (PMMA) recycling system design based on environmental impacts, chemical hazards, and resource availability. We evaluated the recycling system by life cycle assessment, environment, health, and safety method, and material flow analysis.PurposePrevious recycling systems have not focused on highly functional plastics such as PMMA, partly because of lower available volumes of waste PMMA compared with other commodity plastics such as polyethylene or polypropylene. However, with the popularization of PMMA-containing products such as liquid crystal displays, the use of PMMA is increasing and this will result in an increase in waste PMMA in the future. The design and testing of recycling systems and technologies for treating waste PMMA is therefore a high research priority. In this study, we analyze recycling of PMMA monomers under a range of scenarios.MethodsBased on the differences between PMMA grades and their life cycles, we developed a life cycle model and designed a range of scenarios for PMMA recycling. We obtained monomer recycling process inventory data based on the operational results of a pilot plant. Using this process inventory data, we quantified life cycle greenhouse gas (LC-GHG) emissions and fossil resource consumption, and we calculated the LIME single index.Results and discussionPMMA produces more than twice the amount of GHG emissions than other commodity resins. Through scenario and sensitivity analyses, we demonstrated that monomer recycling is more effective than mechanical recycling. Operational modifications in the monomer recycling process can potentially decrease LC-GHG emissions.ConclusionsHighly functional plastics should be recycled while maintaining their key functions, such as the high transparency of PMMA. Monomer recycling has the potential to achieve a closed-loop recycling of PMMA.

A graphical representation for consequential life cycle assessment of future technologies. Part 1: methodological framework

PurposeTo construct future visions of how innovative technologies should be used in the envisioned sustainable society while being aware of system-wide environmental impacts, consequential life cycle assessment (c-LCA) is useful. To systematically evaluate the technologies being aware of uncertainties in choice of technologies made in the future, in this article, we propose a novel graphical representation for theoretical range of impacts that contain results from c-LCA studies. This approach allows analyses of the consequences of the technology introduction without conducting detailed modeling of consequences.MethodsWe stand on an assumption that the future environmental impacts reduced by a new technology depends on (1) how much the efficiency of the technology is improved, (2) how much of less-efficient technology is directly and indirectly replaced by the new technology, and (3) how much product is needed in the envisioned future. The difficulty in c-LCA is that items 2 and 3 are uncertain from various socioeconomic reasons that are often difficult to predict. By organizing the results from product LCAs in a systematic way, the proposed methodology allows exhibiting the range of consequential changes in environmental impact associated with a technology innovation, taking into account of those uncertainties on a plain coordinated by the amount of product needed in the future and environmental impact on horizontal and vertical axes, respectively.ResultsPart 1 describes the methodological framework in detail, whereas part 2 elaborates on the applications of the methodology. By taking transportation technologies assuming various energy sources in Taiwan, choices of technologies and evaluation of technology improvements serve as the case studies to demonstrate the application of the methodological framework.ConclusionsBy using the proposed method to organize the assumptions in c-LCA, discussions on different choices of technologies are made more systematic. In this way, stakeholders can focus on visions of the future society, which lead to different choices of technologies.

Integration of CAPE and LCA Tools in Environmentally-Conscious Process Design: A Case Study on Biomass-Derived Resin

Abstract Life cycle assessment (LCA) is a strong tool for quantifying the environmental impact associated with a product life cycle. To implement LCA into environmentally-conscious process design, the lack of inventory data should be addressed by computer-aided process engineering (CAPE) tools. This study proposes the process design framework integrating CAPE and LCA tools. Missing inventory data is estimated by process simulation with design information extracted from literatures and design heuristics. At this time, the sensitivity of design settings to LCA results should be analyzed to generate design requirements for further process design stages. This study demonstrates the proposed procedure by a case study on biomass-derived polypropylene (PP). In the case study, it is demonstrated that the potential of biomass-derived resin to reduce environmental impact due to the production of PP. At the same time, it was also revealed that the environmental impact could be increased by implementation of biomass resource as raw material, because of the increase of GHG emission in biomass cultivation site.

Analysis of supercritical water oxidation for detoxification of waste organic solvent in university based on life cycle assessment

Spray incineration and supercritical water oxidation (SCWO) processes have been used for detoxifying waste organic fluids in the University of Tokyo. In this study, we aim to elucidate the environmental aspects of these waste treatment processes by life cycle assessment (LCA). Through the investigation of actual plants, the inventory data and other characteristics of actual plants were collected and analyzed. To confirm the potential of SCWO, three modification types of the process and operation were considered and assessed on the basis of estimated inventory data. The results demonstrate that spray incineration has less environmental impact than SCWO in all scenarios. However, SCWO has various advantages for installation as a treatment process in universities such as negligible risk of creating dioxins and particulate matter. Proper choice of the treatment method for organic waste fluid requires a comprehensive analysis of risks. Spray incineration poses the risk of providing dioxins and particulate matter, while SCWO has such risk at negligible level. This means that waste including concerned materials related to such emission should be treated by SCWO. Using the right technologies for the right tasks in the detoxification of hazardous materials should be implemented for sustainable universities.

Distributed Cogeneration of Power and Heat within an Energy Management Strategy for Mitigating Fossil Fuel Consumption

Distributed energy sources, such as self‐power generation, steam boilers, and combined heat and power production (CHP), are operated to manage the supply of energy by optimizing the costs of meeting the demand for electricity and heat. This article was written in conjunction with reports by the United Nations Environment Programs International Resource Panel that quantifies and compares the environmental and natural resource impacts and benefits of using demand‐side efficient technologies for greenhouse gas mitigation scenarios from now until 2050. In this article, we examine the potential of using distributed energy sources in future energy systems. First, we reviewed the existing research into several energy technologies, especially into cogeneration systems for CHP, using a bibliometric analysis. The current energy supply/demand in the demand‐side sectors in Japan is also reviewed using available statistical data, and an investigation into the energy requirements of industrial manufacturers was performed. After systematizing the results of our review on progress in current research, a scenario analysis was conducted on the potential of distributed energy sources to clarify the contribution of the various technology options. A mismatch between the quality of energy produced, especially heat, or any benefits arising from scale from other energy technologies, can decrease the incentive to implement distributed energy technologies. As a requirement of a regional energy system design and management, distributed energy sources should be considered so that the appropriate technology options can be adopted for the desired energy supply in the demand‐side sector. The possibility exists to replace conventional single‐generation technologies, such as boilers or power generators, with multigeneration technologies. A change in the grid power mix is one of the most sensitive parameters affecting the performance of cogeneration technologies.

Design Method of Alarm System for Identifying Possible Malfunctions in a Plant Based on Cause-Effect Model

Abstract A new alarm system design method is proposed, in which it is assumed that the sign patterns and alarm sequences generated by the alarm system are invariant for each possible plant malfunction in a plant. The proposed method gives the most sets yet provided of plant malfunctions that operators can distinguish using the alarm system. We applied the proposed method to select alarm variables for a simple chemical plant. Results showed that the method provides more alarm variable combinations that can identify possible malfunctions than a previously used method.

Monitoring and Analysis of Solvent Emissions from Metal Cleaning Processes for Practical Process Improvement

OBJECTIVES Industrial cleaning processes are a major source of emissions of chlorinated organic solvents in Japan. Solvent emission mechanisms from metal cleaning processes were analysed to support process improvement aimed at emission reductions. METHODS The amounts of solvents directly emitted from a washing machine and solvents taken out by metal parts to be cleaned were measured in laboratory experiments using an industrial washing machine. Direct emissions to a local ventilation system and to the workplace were analysed, while several process conditions were changed. The drying rate of solvents on surfaces was analysed for seven metal parts to clarify the effects of their materials and shape. RESULTS The results for direct solvent emissions show that solvents emitted because of the movement of metal parts inside a washing machine can be mainly exhausted through a local ventilation system, while the operation of an ultrasonic device can increase solvent diffusion to the workplace. Lowering the cooling water temperature can be effective in avoiding such solvent diffusion to the workplace. The results also show that the heat capacity and shape complexity of metal parts can affect the drying rate of solvents on their surfaces. CONCLUSIONS Analysis of the results shows the effectiveness of using a local ventilation system and cooling pipes in controlling solvent emissions for several work tasks. The minimum time required to dry all solvents on the surface of metal parts was also estimated. Analyses of the emission mechanisms in this study clarified the major factors in solvent emissions and the effectiveness of process modifications for emission reductions. The findings are applicable to practical process improvement aimed at emission reductions in cleaning sites.

Forestry and Wood Industry

Excessively rapid socioeconomic changes in Japan have disrupted national policies related to the management of biomass resources. During the twentieth century, the Japanese forestry and wood industry transformed from producing wood for fuel to wood for construction to support national reconstruction in the postwar era. During this period, conifers were planted on most mountains. However, by the time sufficient conifer forests had grown to supply wood for construction, demand had declined because of the growth in imports. In the meantime, energy security and reduction of carbon emissions have become important issues, leading to the establishment of the “Biomass Nippon Strategy (2002)” and “Feed-in Tariff (FIT) Scheme for Renewable Energy (2012),” which have redirected interest back to the use of woody biomass for energy. However, the age class composition of wood resources in the forests is imbalanced because of the aforementioned transformation. Sustainable forest resource use demands a balanced structure and full use based on efficient collection of wood biomass generated in the supply chain, i.e., from forest to sawmill. It also demands the use of the best available technologies while maintaining other functions such as environmental conservation and watershed protection. In this study, we propose a road map to facilitate development of a sustainable forestry and wood industry that could satisfy demands for energy and construction.