This is how wine, beer, and liquor are made. Wine is just fermented grape juice. Conversion Biomass can be converted into gas or liquid fuels by using chemicals or heat. In India, cow manure is converted to methane gas to produce electricity. Methane gas can also be converted to methanol, a liquid form of methane.
Most biomass used today is home grown energy.
But any organic matter can produce biomass energy. Other biomass sources include agricultural waste products like fruit pits and corn cobs. There is nothing new about people burning trash. What's new is burning trash to generate electricity. This turns waste into a usable form of energy.