The diagram displays the process of producing a biofuel called ethanol.
Overall, the process consists of 9 steps and is a never ending cycle. It involves harvesting and processing plant material to produce ethanol, and utilising and emitting carbon dioxide, which restarts the cycle.
At stage 1, plants and trees are grown, which requires energy from the sunlight and carbon dioxide. Then, the trees are harvested with combiners and undergo the pre-processing at stage 3, which transforms these plants into cellulose. Having been pre-processed, cellulose is transported to the laboratories where some chemical reactions take place. As a result, sugar is extracted. At stage 7, specific microbes are added to turn sugar into ethanol.
As a popular biofuel, ethanol is used to power various means of transportation, from cars, vans and other vehicles to planes. All the mentioned means of transport release large amounts of carbon dioxide into the atmosphere, which can be later used for growing new plants and trees. Consequently, the process does not have an end.