High-efficiency air separation unit that con-currently produces liquefied nitrogen and liquefied oxygen. Our decentralized, regional industrial gas supply network of the VSUs has been installed nation-wide at major bases, enabling CO2 reduction through the reduction of tank lorry transportation. The unique process has greatly reduced electric power consumption rate.The integrated storage tank has a large, space-saving structure in which multiple numbers of independent storage tanks are provided in the outer tank that has vacuum thermal insulation.