With the progress of science and technology, the research and development of unconventional oil and gas resources in the world has developed rapidly. In particular, the successful development of shale gas and tight oil in the United States has brought a wide and far-reaching impact on the world. In China, after shale gas，the success of conventional oil and gas in the United States has affected the research and development of tight oil becoming quite active. However, because of the special characteristics of the tight oil, tight oil has different development methods and reservoir evaluation with traditional petroleum, which increasing difficulty of development. In order to improve economic development, evaluation zone of tight oil reservoir should be appreciated. In this paper, based on the virtual data of the tight oil reservoir zone and that of concentrated zone, which are given by random numbers whose ranges are taken from actual data, and previous studies, we conducted discriminant analysis to evaluate concentration zone of tight oil reservoir in China. The evaluation method is rational and the results based on the virtual data were consistent with the actual tendency. Proposed method is expected to play important role when actual data are accumulated and become available.

This study evaluated global impacts of current climate and energy policies (CPs) in major economies and the Nationally Determined Contributions (NDCs) on global energy-related CO₂ emission and energy systems by using a global energy systems model: DNE21+. CPs could contribute to reduction of global cumulated energyrelated CO₂ emissions in 2011-2030 by 41 Gt-CO₂ relative to baseline, and achieve about half of the target of that of NDCs. Expansion of renewables and improvement of energy efficiency in power and transportation sectors are mainly promoted in an NDC scenario in consideration of CPs. Compared with an optimized scenario which focuses only on CO₂ emissions reduction, measures taken in power and transportation sectors for the NDC scenario seem excessive and increase measure costs of climate mitigation. Comprehensive measures, e.g., increase of gas-fired power plants including carbon capture and storage and nuclear power plants, improvement of energy efficiency in industry sector, and increase of gas use and electrification in residential and commercial sector are assessed to be cost-efficient. Although energy policies do not always aim at climate mitigation, coherent and inclusive policy design by considering cost-efficient global decarbonization and other national policy objectives in order to achieve sustainable development will become significantly important under the Paris Agreement.

The present study assesses the CO₂ reduction potential of solar water heating systems (natural circulation) for single-family houses considering the natural and social conditions of local areas in Japan. The life cycle CO₂ reduction is estimated by municipality when installing solar water heaters instead of conventional water heaters (i.e. oil, LPG, natural gas and electricity) used at present. The estimation results reveal that the CO₂ reduction potential greatly varies from 156 to 589 [kg-CO₂/household/yr] depending on the local areas. The CO₂ reduction rate is also in the wide range of 11.1% to 28.7%. The total CO₂ reduction potential in Japan is estimated to be 6.73 million [t-CO₂/yr]. Local CO₂ reduction potential is mainly affected by the three local factors: fuel-types of conventional water heaters, feed water temperature and air temperature. The local areas where electric water heaters are widely used (e.g. Chugoku region) have high CO₂ reduction potential. Similarly, the local areas with low water temperature have high CO₂ reduction potential (e.g. Hokuriku region). However, when air temperature is extremely low, the CO₂ reduction potential is small because solar water heaters do not operate due to freezing (e.g. Hokkaido region).