The gas produced by the fermentation of biomass is: 

Energy generated or produced by living or once-living organisms is referred to as biomass energy. Plants, such as corn and soy, are the most common biomass materials used for energy. These organisms' energy can be burned to generate heat or converted into electricity. 

Biomass fuel is made from organic materials and is a renewable and sustainable source of energy that can be used to generate electricity or other forms of power.

Biogas is the gas produced by the fermentation of biomass.