The diagram depicts the cyclical procedure by which ethanol, a biofuel, is manufactured from plant biomass, mapping each stage from vegetation growth through industrial conversion to end-use fuel combustion and the recycling of carbon dioxide.
Overall, the production cycle comprises three main phases: cultivation and harvesting of biomass, mechanical and biochemical processing that converts cellulose into ethanol, and the subsequent use of the fuel in transport, with carbon dioxide emitted during combustion re-entering the atmospheric loop.
The sequence begins with plants and trees harnessing sunlight and atmospheric carbon dioxide to produce cellulose-rich biomass. Once mature, this vegetation is mechanically harvested and delivered to pre-processing facilities, where it is fragmented and treated to isolate cellulose. The diagram illustrates that cellulose is the principal intermediate material extracted at this stage and is forwarded to a dedicated processing plant for further transformation.
In the processing phase, cellulose undergoes chemical or enzymatic breakdown into fermentable sugars, after which microbes are introduced to catalyse fermentation and generate ethanol. The finished ethanol is then transported and used as a motor fuel for cars, trucks and aircraft; combustion of the fuel releases carbon dioxide, which is shown returning to the atmosphere and being taken up again by growing plants, thereby completing the depicted cycle.