(i) Biogas plants solve the problem of disposal of animal and agricultural wastes: the animal and agricultural wastes are used as the feed-material in biogas plants.
(ii) Biogas produced in a biogas plant can be used as a fuel and as an illuminant: Biogas on burning gives smokeless flame and leaves no ash. So, biogas can be used as a fuel for heating, cooking, for running tube-well engine and as an illuminant in a gas lantern.
(iii) Spent dung can be used as a manura in agricultural fields: The spent dung (spent slurry) left in the biogas plant is rich in nitrogen and phosphorus compounds. This can be used as manure by the farmer. This saves the farmer a lot of money which should have been otherwise spent on chemical fertilizers.
Thus, the biogas plants are considered a boon to farmers.