Supply nanobubbles (ultrafine bubbles) of carbon dioxide (CO2) to water. Nanobubbles are air bubbles on the order of nanometers. These bubbles do not rise to the surface of the water, but remain in the water.

Then oxygen turns into ozone. When ozone reacts with a photocatalyst, active oxygen such as hydroxyl radicals are generated. This active oxygen reduces carbon dioxide gas to carbon monoxide. 2CO2 ⇒ 2CO + O2 (Reaction 1) Photocatalyst decomposes water and produces hydrogen and oxygen. 2H2O ⇒ 2H2 + O2 (Reaction 2) Reactions 1 and 2 result in CO2 + H2O ⇒ CO + H2 + O2 (Reaction 3), generating carbon monoxide, hydrogen, and activated water in a radical state that easily causes chemical reactions.

Additionally, carbon dioxide gas from the air is also absorbed. Next, the carbon monoxide and hydrogen produced in step 3 undergo a chain reaction through radical polymerization, producing hydrocarbons (petroleum). nCO + (2n+1) H2 ⇒ CnH2n+2 + nH2O (Reaction 4) Therefore, nCO2 + (n+1) H2 ⇒ CnH2n+2 + nO2 (Reaction 5) When left to stand, it separates into an aqueous layer and oil layer.