Expectation for renewable energy is increasing. There are several studies that have considered renewable energy installation in Japanese power grids as a whole. However, renewable energy presents problems with regard to load following capability and regional geographic characteristics. This study presents the optimal installation region of renewable energy in Japan by using a multi-regional optimal generation planning model. Additionally, a renewable energy installation strategy to reduce CO₂ emission by Japan’s electricity sector is proposed. First, a CO₂ emission constraint scenario is executed. Next, two scenarios are implemented: a Natural Gas Combined Cycle plants constraint scenario and a residential photovoltaics constraint scenario. The result shows three important factors for the selection of an installation region for renewable energy, i.e., the composition of energy resources of each regional electricity power supplier, the plan of power generation plants of each regional electricity power supplier and the introduction amount of residential photovoltaics. Results indicate that information-sharing among electricity power suppliers, renewable energy suppliers and government is important to achieve a low-carbon grid.

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Cement industry is one of the key sources of air pollution and it is an energy intensive industry. Life cycle impact assessment (LCIA) is one of the basic steps in life cycle assessment methodology (LCA). Based on the method of LCA, this paper presents a comparative study of the LCIA of different life cycle inventories (LCI) for the cement industry of whole China from 2000 to 2008. This also discusses LCA for 22 individual provinces, 5 autonomous regions and 4 municipalities in China for the year 2008. Second, a regional based comparative study of life cycle impact (LCIA) of different gases (CO₂, SO₂, NO_x and particulate matter) was conducted using CML methodology developed by Leiden University. The impact of cement manufacturing was divided into 4 separate categories namely, greenhouse effects, acidification, eutrophication and the toxicity to the human being. The total environmental impact related to cement manufacturing was calculated by summation of the above mentioned four categories. The calculated impact result of China shows the severity of environmental problems of the cement industry in China compared to the EU and Japan. Pollution reduction of cement industry is still a great challenge for China.

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In recent years, hydrogen is expected as an attractive energy to achieve a low-carbon society. By-product hydrogen in oil refinery is one of the promising resources to produce hydrogen. It is needed to evaluate an environmental burden, especially CO₂ emission, of the by-product hydrogen. Analysis of the environmental burden in oil refinery is complicated because manufacturing processes in oil refinery have some recurrent flows. A matrix method is useful to analyze consistently environmental burdens on refinery processes including recurrent flows. In this study, the method is applied to investigate CO₂ emissions of by-product hydrogen in oil refinery in Japan. The emission is analyzed for two different hydrogen concentration of off-gas. The effect of changing feedstock of hydrogen production unit(HPU) is analyzed from LPG of an internal production material to natural gas of an external raw material. The result shows that most of CO₂ burdens emitted from some processes which require a lot of heat energy in the refinery. The study also estimates CO₂ emissions of the by-product hydrogen, which is about the same amount as that of the gasoline.

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