Development of an evaluation technology of CO2 fixation around an artificial upwelling area


The increasing of CO2 sinks in the ocean is studied for the mitigation of global warming in RITE. In the present research, we study the application of an artificial marine structure to generate an upwelling. It can be considered a nature-friendly technology because it is based on the utilization of natural nutrients from the deep layer combined with natural tidal energy. The purpose of this research is to develop an evaluation technology of CO2 fixation around an artificial upwelling area. In order to clarify the limiting factors of the CO2 fixation in the area, field observations, laboratory experiments, and model calculation were carried out. As a result of the research and development of three years (FY2003- FY2005), the evaluation technology composed of the following four technologies was proposed.

(1) Technology of parameter measurement in artificial upwelling area

This is a measurement technology of various parameter in the artificial upwelling area used for the model simulation. Moreover, it is a technology using environmental monitoring in the artificial upwelling area between before and after construction. There are observational techniques of a physical parameter and measurement techniques of the primary production in this technology.

(2) Calculation technology of amount of CO2 absorption

This is a technology for calculation of the amount of the CO2. It is composed of the transport model and generation and the resolution model. This model can calculate a biological process, a physical process, and a chemical process of the artificial upwelling area overall. The amount of the CO2 absorption in the artificial upwelling area is calculated as a difference between the case of after construction of artificial structures and case of before construction.

(3) LCA evaluation of amount of CO2 emission

This is a technology that calculates the CO2 emission according to manufacturing and the installation of the structure. This can calculate the CO2 emission from the parameter of the structure scale, the manufacturing place, and the installation sea area. In addition, the CO2 balance of the artificial upwelling system can be calculated by combining with this technology and the calculated amount of the CO2 absorption.

(4) Mapping technology of artificial upwelling area

This is a technology that selects the sea area where the artificial upwelling system is applied. This is composed of upwelling index technology and oceanographic data GIS. The amount of the CO2 absorption can be evaluated by combining four technologies proposed by this research and development. However, the accuracy of individual technologies should be going to improve in the future, and the overall evaluation technology be improved.

When this technology was applied to the artificial upwelling sea area near the Ikitsuki island of Japan, the effect of the plus of the CO2 balance (It was not an exhaust but it is absorption) was confirmed. It is necessary to develop the technology that can adequately select the best structure scale and the installation sea area. Moreover, it is necessary to improve this technology at a high technological level at which the effect of the food production increase can be used together with the effect of the CO2 absorption.

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