The given diagram represents the production of ethanol, a biofuel.
Overall, the manufacturing of biofuel includes nine steps with manual as well as industrial processes, starting with the use of carbon dioxide and also ending emitting the same gas.
First of all, plants consume sunlight and carbon dioxide, from the atmosphere, for its overall development. After attaining certain maturity, those trees are harvested and taken to the industry for further processing.
In the industries and factories, pre-processed plants are converted into cellulose, which later is treated with different chemical substances and processed to form sugars. Microbes are added in the solution. It composes the solution into required outcome, afterwards. In this way, ethanol is manufactured and used as fuel in vehicles such as cars, trucks, and planes. Later, the same vehicles become the source of carbon dioxide, which again is absorbed by trees and the cycle of formation of ethanol repeats.