Kana Kuroda

Comprehensive Assessment of the Utilization System for Marine Biomass Resources Using Exergy Flows

Abstract − In recent years, serious environmental problems occur in coastal area due to high pollution loadsfrom human activity in land. Marine biomass utilization system therefore has been proposed to prompt materialcirculation between land and sea. Comprehensive assessment is necessary to determine that the proposed systemis suitable and sustainable. This study introduces thermodynamic concept exergy, which expresses energy quality,to describe material and energy flowing in the material circulation system. This study presents material, energy andexergy flows in the material circulation system at Sakai city located in the middle of Osaka in Japan. It is foundthat exergy helps a better understanding of what is a key role is in exergy-efficient material circulation system.Keywords: Comprehensive assessment(포괄적인 평가), Energy(에너지), Exergy(엑서지), Marine biomass(해양 생물체), Material balance(물질 균형), Material circulation(물질 순환) 1. INTRODUCTION Industrialized world is heavily dependent on fossil fuels,which are major sources of energy and related products. As aresult, we face the shortage of energy resources. To overcomerecent crisis, attention is increasing to marine biomasses asenergy resources. In a land basis, human community has beenrecently shifting to a recycling society. On the other hand, dis-charged waste from land to sea such as carbon and nutrient(e.g., nitrogen and phosphorus) is not reused and stocked as asediment organic matter in an enclosed sea. Natural purifica-tion capacities, therefore, are overloaded and thus it causesserious environmental problems such as red tide, and “greentide”, which is similar to red tide and is a phenomenon thatgreen algae propagate explosively. One of the proposed mea-sures to solve these serious problems is to take them up fromsea to land and to use them as energy resources in land. Greenalgae decrease nutrient concentration of seawater since theystore carbon and nutrient. Marine biomass utilization systembased on above concept has attracted recent attention since itwould contribute to improve marine environment and lead to asustainable society without relying on fossil fuels. From theenvironmental point of view, Otsuka [2010] mentioned that this

Life cycle exergy analysis of an anaerobic digestion system using marine biomass

In this study, we propose a marine biomass utilization system and describe anaerobic digestion system using marine biomass and food waste. Anaerobic digestion system includes collecting biomass, anaerobic digestion, and growing vegetables. Four scenarios are presented varying the amount and the suppliers of biomass. We apply life cycle exergy analysis, which combine life cycle assessment and exergy concept, to investigate the feasibility of the system from the viewpoint of energy. We present exergy balance of the system and evaluate total exergy efficiency and the exergy ratio of fossil fuel consumption to biomass.

A study for effective utilization system of digestive sludge from methane fermentation using marine biomass

In this paper, authors have focused on safety and uniformity as the basis of utilization system for digestive sludge from marine biomass. At first, when marine biomass is used as materials of methane fermentation, safety and uniformity problems of digestive sludge are investigated. Furthermore, in order to solve the problem, a method of extracting useful materials is examined experimentally.

An example of assimilation technique for monitoring in marine environment

This work deals with application of assimilation method in investigation of phytoplankton distribution in particular to the stratified ocean. The measured data such as temperature, salinity as well as phytoplankton, are assimilated into the mathematical model, the typical diffusion and advection equation including biological process model, in terms of diffusion coefficient, advection velocity and biological parameter. The method is generalized as an optimizing problem in variant method and is examined in detail in estimating of empirical parameter, such as a diffusion coefficient.