The diagram illustrates the cyclical process of manufacturing ethanol, a type of biofuel.
Overall, the production of ethanol consists of ten stages, beginning with plants and trees absorbing energy sunlight and carbon dioxide and ending with vehicles emitting CO2 back to the atmosphere.
Initially, trees and plants are grown to soak up solar energy and carbon dioxide from the atmosphere through photosynthesis. Following this, they are harvested and subjected to pre-processing, where they are cut first into fragments and then into cellulose. In the subsequent stage, the cellulose is chemically processed into sugars. Microbes are then added to these sugars to facilitate fermentation, resulting in the production of ethanol.
Finally, the ethanol produced is used to fuel vehicles such as cars, trucks, and airplanes, which release carbon dioxide as a by-product. During the use of ethanol as fuel, carbon dioxide is released back into the atmosphere, which is then reabsorbed by plants and trees, thereby continuing the cycle.