The diagram illustrates the production procerdure of a biofuel named ethanol.
As it is shown from the diagram, when plants and trees are grown up, after many processing procedures, they finally turn into the biofuel ethanol,which can be used as fules for various vehicles.
To be more detailed, the plants and trees need energies such as sunlight and carbon dioxide for growth. Then, when they are grown up, people will harvest them and pre-process them to form the cellulose. Next, after carefully processing, the cellulose will become sugars, which requires one more step to yeild the final product. By adding microbes into sugars, the whole process has been completed, which refers to the creation of ethanol. The final production can provide fuels for many kinds of transportations, like cars, trucks and even airplanes. All these vehicles will emit carbon dioxide, which in turn will be the energy to benefit the growth of the original source of ethanol, namely the plants and trees.