What is biomass?

Biomass is a scientific term for living matter, and is also used for products derived from living organisms. Biomass used for heat and electricity production comes from recently grown plants and the waste from animal husbandry and includes agricultural and forestry residues, energy crops, and the biodegradable components of municipal and business wastes

Biomass can be used as a fuel to provide heat, electricity or fuels for transportation. Although biomass releases carbon dioxide (CO2) when burned it differs from fossil fuels in that the CO2 was recently absorbed from the atmosphere when the plants grew.

What is meant by bioenergy?

Biomass energy or bioenergy includes any solid, liquid or gaseous fuel, electric power and heat derived from organic matter. Because of the wide range of potential feed stocks and the variety of technologies to produce and process them, bioenergy is usually considered as a series of different feedstock and technology combinations.
In practice, we tend to use different terms for different end uses - for example electric power or transportation. Biopower describes power stations that use biomass feed stocks instead of fossil fuels like natural gas or coal to produce electricity. Biofuel is used mostly for liquid transportation fuels that substitute for petroleum products such as petrol and diesel. Other terms in use are renewable heat and renewable power.

How is biomass used to produce electric power?

In most power plants biomass is burned to produce heat, which boils water to generate steam, which turns turbines and drives generators of electricity.
New technologies now being evaluated include several types of biomass gasifiers, in which biomass is heated to convert it into a gas. This gas is used directly in a gas turbine, which drives a generator. In some cases, the waste heat from the gas turbine may be used to drive a secondary steam turbine, thus converting more of the fuel energy into electricity (a combined-cycle system).
Other processes use anaerobic digestion in which biomass is broken down by bacteria to produce a fuel gas that is used in engines to generate electricity.

How is biomass used to make liquid fuels?

The most common liquid fuel from biomass is ethanol (called bio-ethanol) produced by fermentation. Typically, sugars are extracted from the biomass feedstock (such as grain) by crushing and washing. The sugar syrup is then mixed with yeast and kept warm, so that the yeast breaks down the sugars into ethanol.