Kiyoshi Dowaki

Comprehensive comparison of efficiency and CO2 emissions between biomass energy conversion technologies - position of supercritical water gasification in biomass technologies.

Abstract Efficiency and CO 2 emissions between various methods of biomass energy conversion are compared from the viewpoint of life-cycle evaluation. As for electricity generation, efficient processes are thermal gasification combined cycle, supercritical water gasification combined cycle, and direct combustion in order of efficiency for low moisture content biomass. Supercritical water gasification combined cycle is the most efficient for high moisture content biomass. Battery electric vehicle, gasoline hybrid electric vehicle, and gas full cell vehicle (FCV) show high efficiency in automobiles. Biomass FCV shows high efficiency in the vehicles utilizing biomass. Biogas combustion is the most efficient for heat utilization. Then, the position of supercritical water gasification in various technologies of energy conversion is examined by modeling an overall energy system. The tradeoff between CO 2 emissions and total cost of technologies is analyzed so that the most cost-effective technology can be determined for different CO 2 emissions constraints. Computed results show that biomass is mainly consumed for electricity and heat generation so as to utilize finite biomass resources efficiently. Transportation fuels are generally made from fossil fuels. Cost-effective processes for CO 2 reduction are thermal gasification and reforming when the present efficiency and prices are assumed. Supercritical water gasification is also one of the optimal processes when the relative cost to fuel cell decreases. Improving heat exchange efficiency also contributes toward enhancing the position of supercritical water gasification in biomass technologies.

Materials Selection in Appropriate Technology Four Focuses in Design Thinking

Appropriate technology is widely recognized as a good solution in providing alternative technology for underdeveloped people who live in a very limited circumstance. However, it is often seen as an idea without clear explanation from engineering perspective. One of critical process in appropriate technology design process is materials selection. This study aims to provide applied logic for selecting materials in the design process. The logic is constructed by surveying previous notions from researchers. Reasoning techniques are explored by using design thinking. This study reveals that there are four focuses which must be applied to find sufficient materials for an appropriate technology. This study also concludes that, unlike pure engineering efforts which tend to substitute materials given in a technology design with locally available ones, appropriate technology start from existing resources to produce its design. It requires soft selection by involving local people in exploring any potential materials which already available in their own area. By looking at previous studies which tended to ignore the contribution from local people in exploring potential materials, this study embraces their involvement and then emcourages insights for further research around it.

New Topology for DC–DC Converters Used in Fuel Cell–Electric Double Layer Capacitor Hybrid Power Source Systems for Mobile Devices

An improved topology for dc-dc converters used in hybrid power source systems, which consist of a fuel cell (FC) and electric double-layer capacitors (EDLCs), is proposed. The new topology has three transistors, and switch timing for this topology and a control method for power management between the FC and EDLCs are discussed. This new topology overcomes the two drawbacks of the previous topology with two transistors and a diode: the slightly higher load voltage and insufficient EDLC charging under low-load conditions. The introduction of two switching modes allows for the bidirectional current of the EDLCs and enables power distribution between the FC and EDLCs. A pseudo FC and bipolar power supply that imitate the EDLCs and load are used to measure the static characteristics and show that the proposed topology with switch timing operates as designed. In addition, the dynamic characteristics are measured for actual EDLCs and a bipolar power supply into which waveforms are programmed as selected functions when an actual smartphone is operated to verify that the proposed control method can distribute power to both the FC and EDLCs and manage the state of charge of the EDLCs.

Environmental Forensics on Appropriate-Technology-Enhanced Supply Chain of Rural Commodities

Rural commodities have become important in any kind of rural development. Considering the common difficulties happen in rural areas, and by looking at common uneven distribution of profit margin in many long supply chains of rural commodities, rural governances have begun to apply Appropriate Technology (AT) to pull such distribution back to rural communities as the producers of rural commodities. Such applications become more interesting in term of environmental forensics. Due to the different characteristics between environmental forensics on supply chain and AT, this study aims to integrate such characteristics into a single map of forensics. Characteristics of each kind of forensics are completely taken to deliver a holistic framework. Previous approaches in each forensics are explored to discover the potential integration. Based on such exploration, the cross-sections between forensics are carefully explained to avoid inaccuracy of assessment. The result provides an integrated framework to assess environmental impacts imposed both through supply chain and AT. By looking at previous researches, this study significantly contributes to the common understanding of environmental forensics on supply chain. Then, this study will be expanded by including cost-based approach to evaluate the unit emission per unit-distributed value added throughout a supply chain due to AT application.

Physiological Concept: Visible Modeling for Feasible Design

Conceptual design plays an important role in design stage as an initiation to interpret an abstract idea into a design concept. However, conceptual modeling in previous engineering designs provided premature detailed modeling. Such methodologies delivered almost pure quantitative techniques to do the modeling, which have made it difficult to do agile design process for specific-purposed products. Such products require unique approach for each situation. This paper proposes physiological concept modeling to overcome such phenomenon by combining process and functional modeling with qualitative interpretation. Physiological modeling incorporates derivation to transform idea into a design concept with almost no quantitative postulates. A case study on competition-based electric car is also provided to show an overview of application. The study concludes that there are seven steps required to do physiological modeling. The derivation can also bring flexibility for dynamic or continuous system by introducing cyclical & dynamic relationship between processes, including interventions from outside observed system and function of residue to accommodate side residues. By looking at previous techniques, this study brings a new light to produce design concept which is feasible but can be visibly modeled even by novice designers.

Materials Research in Appropriate Technology: In the Midst of Science, Engineering, and Technology

Materials research is often characterized as a pure scientific activity. However, such approach cannot be applied when materials researchers must deal with Appropriate Technology (AT) development. Science and engineering which focus on pure scientific background must be integrated with appropriateness of AT in engineering and technology levels. This study aims to discover such integration by investigating right positioning of materials research to AT development at the intersections between materials research and AT in Science, Engineering, and Technology research areas. Seven pillars of survivability which describe the tiers of appropriateness are also taken as the basis of exploration. They are coupled with the intersections to deliver complete overview of research positioning of materials research in AT development. This study concludes that materials researchers become the inventors (Science), innovators (Engineering), and constructors (Technology) of materials used in AT. They have to produce materials for AT that that must be able (Science), feasible (Engineering), and visible (Technology) to improve local activities through a technological solution. By looking at the discussion, this study contributes in several issues at once: AT, materials research, and research design, including all aspects considered as the fundamental principles of survivability, by taking these issues in the positioning of materials research in AT development.

The 10th International Conference on EcoBalance (EcoBalance 2012) - Challenges and Solutions for Sustainable Society, November 20-23, 2012, Tokyo, Japan

The 10th International Conference on EcoBalance (EcoBalance 2012), organized by The Institute of Life Cycle Assessment, Japan, was held during November 20–23, 2012 at the Hiyoshi Campus of Keio University in Yokohama City. The conference was co-hosted by Keio University and The Ecomaterial Forum, and backed by the Cabinet Office; the Ministry of Education, Culture, Sports, Science and Technology; the Ministry of Agriculture, Forestry and Fisheries; the Ministry of Economy, Trade and Industry; the Ministry of Land, Infrastructure, Transport and Tourism; and the Ministry of Environment. It was also supported by 74 related societies and associations. The Commemorative Organization for the Japan World Exposition ‘70 and the Life Cycle Assessment Society of Japan provided monetary aid for the management of the conference. In addition, the event was co-sponsored by the following eight corporations and groups:

A business feasibility study on a paprika with carbon footprint label

Recently, the carbon-footprint on the agricultural products such as vegetables would become attractive. Especially, Ministry of Agriculture, Forestry and Fisheries (MAFF) tries to promote eco-friendly scheme to agricultural sector, since they have interests in the global warming protection and/or the abatement of CO2 emissions by 2011. Also, due to the carbon-footprint for agricultural products, the added value for CO2 emission reduction might be brought.

Developing a new topology for the DC-DC converter used in fuel cell-electric double layer capacitor hybrid power source system for mobile devices

The polymer electrolyte membrane fuel cell (PEMFC) has a potential to be an alternative power source for smartphones and other mobile electronic applications. However, PEMFCs cannot quickly response against fast load change of electronic devices. To resolve this issue, we have proposed a hybrid power source system, in which super capacitors and a PEMFC are combined using DC-DC converter. The converter is controlled by a micro-controller so that the power flows are managed. However, in low load condition, voltage became slightly higher than the target value and the super capacitor was not able to be charged. To challenge these drawbacks, in this study, we develop a new type topology for the converter, which use three switching devices, and control method. We also demonstrated the behavior of the system. The results showed that the drawbacks mentioned above is resolved and power conversion efficiency of the converter is improved under various load profile.

Technological solution for vulnerable communities: How does its approach matter?

Vulnerability is an emerging term for both scientific communities and practitioners. Vulnerabilities attributed to a particular community are then aggregated to state it as a vulnerable community. Vulnerability-related study is recognized as an interdisciplinary one due to the complex characteristics of vulnerabilities in each contextual situation. In common understandings, technology is recognized as an interdisciplinary solution, making it possible for supporting any activity in eradicating vulnerability. This study aims to observe such possibilities. Literature survey is taken to investigate the interconnection between vulnerability eradication and technology. Brief comparison between several developing countries and particular focus on Indonesia become a medium of further investigation to reveal issues surrounding technology-related efforts for vulnerability eradication in vulnerable communities. The study reveals that developing countries, particularly Indonesia, tend to adopt approaches from Northern hemisphere, including transferring technologies from developed countries without proper propagation. It means that local knowledge and power are largely ignored in the pursuit of local problem solving for vulnerability eradication. These facts become a signpost to emphasize that approach in implementing technological solution for such purpose is the critical mechanism to ensure the success in every contextual situation. Then, looking at the results of this brief study, its emphasis indicates further requirements to shift the paradigm of typical community development to contextual community empowerment in order to ensure the continuity of every technological solution for a consistent eradication of local vulnerabilities, including possible changes of required approach alongside the shift.