## 4 Conclusions  
This study discussed how the reduction in petroleum consumption required to achieve the 1.5 \({}^{\circ}\)C target could affect the domestic supply and demand of petroleum products and by-products. The findings of this study are described below. 1. Data pertaining to petroleum refining, petroleum product manufacturing, and plastic product manufacturing processes in 2019 were collected to create a material flow diagram that provides a consistent picture of the current state of domestic petroleum supply and demand. The material flow also covered the production of sulfur, a petroleum by-product, as well as dry ice, one of the uses of carbon dioxide gas. 2. The domestic production of plastic resins in 2019 was approximately 10,500.00 thousand ton, and the production in 2030 will be approximately 7511.00 thousand ton, if the reduction in petroleum consumption that contributes to achieving the 1.5 \({}^{\circ}\)C target is achieved. The JMOE is planning to recycle waste plastics and produce biomass plastics in its plastic resource recycling strategy. However, this requires further separation of waste plastics and reduction of production costs through mass production of biomass plastics. 3. Hydrogen is produced and consumed during the petroleum refining process, with hydrogen produced in an adjacent hydrogen plant. Hydrogen is produced in the amount of 14.02 billion Nm\({}^{3}\), but is consumed entirely on site. At maximum operation of this hydrogen plant, there is a potential external supply of 2.14 billion Nm\({}^{3}\), which would decrease to 1.53 billion Nm\({}^{3}\) in 2030 if petroleum consumption were to decrease at the rate targeted for the reduction. 4. Domestic production of dry ice derived from petroleum by-products in 2019 was approximately 157.00 thousand ton, which would decline to approximately 61.00 thousand ton in 2030 if the above target is achieved. There are many import and technological challenges to cover the shortfall, and it is expected to be difficult to secure supply to achieve the expected increase in demand. 5. Domestic sulfur production from petroleum by-products in 2019 was approximately 1629.00 thousand ton. This would decrease to approximately 1165.00 thousand ton in 2030 if the above target is achieved. Since domestic demand for sulfur has remainedat approximately 500.00 thousand ton, the majority of which is exported, the future domestic demand could be achieved by adjusting the volume of exports. This study has a limitation in that only plastic products, hydrogen, dry ice as carbon dioxide, and sulfur are the focus, but it has shown that reducing petroleum consumption might affect the supply and demand of these products. Although this study was conducted in Japan, it is not a unique case, especially in countries where petroleum refining and the production of plastics, etc. are the mainstay of their industries. It is important for other countries to calmly assess the impact on their own industries and societies to achieve the 1.5 \({}^{\circ}\)C target, and then to consider the impact on their own economies and societies. Measures need to be taken to minimize the impact. Japan has adjusted to produce petroleum products that meet domestic demand by selecting the type of petroleum to be imported, before decomposing and reforming it [50]. However, perfectly matching the production of all petroleum products with demand is difficult, and the supply of naphtha is covered by imports. This situation is the same for plastic products made from naphtha and dry ice. In the future, petroleum treatment might be reduced to achieve the goal of the 1.5 \({}^{\circ}\)C target, and the gap in demand might be widened. The Japanese government should support the minimization of the economic and social impacts by adjusting the import volume, securing the supply volume, and funding the development of products that replace conventional petroleum products and petroleum by-products, such as biomass plastics.