Energy from Biomass

The biomass is organic material made from plants and animals. It includes garbage, industrial waste, crop residue, manure, wood, sewage and dead parts of living objects. Like all other sources of energy, it also contains stored energy from the sun. Therefore, biomass is also a very good source of energy.

How biomass contains sun's energy? The plants absorb sun’s energy in a process called photosynthesis. The chemical energy in plants gets passed on to animals and people who eat them. On burning the biomass, the chemical energy stored in it is converted into heat energy. The thermal energy released from biomass can be used to provide heat to industries and homes, and also to produce steam for generating electricity.

Burning biomass is not the only way to release its energy. Biomass can be converted to other useable forms of energy, such as biogas or methane, ethanol and biodiesel. Methane is the main ingredient of natural gas as well. The smelly stuff like rotting garbage, and agricultural and human wastes release methane gas - also called "landfill gas" or "biogas". Like liquid petroleum gas (LPG), the biogas is also used for cooking and lighting.

Biofuel including biogas and bio-diesel is another important fuel produced from leftover food products like vegetable oils and animal fats. Biofuel is made mainly in two ways. The first is when large amounts of crops high in sugar or starch content are grown, and then fermented with yeast to produce ethyl alcohol or ethanol. Plants like corn, soybeans, rapeseed, wheat, sugar cane and sugar beet are used to produce ethanol. Ethanol can be used as an alternative fuel in petrol engines, but it is very corrosive and so can be harmful to engine parts and components. The other option is that it can be mixed with petrol to produce a more bio-friendly fuel which can be used in engines. In the second method, plants high in vegetable oils are grown and then the vegetable oil is processed to produce bio-diesel.

Biomass can be used as a source of energy in the following three ways:

  1. by burning dry biomass directly to produce heat, or generate steam.
  2. by decomposition of biomass in the absence of oxygen to produce methane gas.
  3. by producing bio-diesel from the plants high in vegetable oils.

Advantages of Biomass as Source of Energy

Biomass is an inexhaustible energy source because we can always grow more trees and crops, and waste will always exist. Using biomass as a source of energy has following advantages:

  • When direct combustion of biomass is not used to generate energy, there is hardly any environmental impact.
  • Biodiesel and other fuels produced by biomass are viable and a clean source of energy.
  • Biomass is easily available throughout the world.
  • The residue from biomass plants can be used as manure.

Limitations of Biomass as Source of Energy

Though biomass is a clean and renewable source of energy, it has certain limitations. Some of them are:

  • The bio-fuel or ethanol produced from biomass is not as energy efficient as petrol.
  • If the biomass is directly burnt, it may contribute to global warming and increase emissions causing environmental pollution.
  • The main ingredient of biofuel i.e. methane is harmful to the environment.
  • Biomass is a relatively expensive source for generating energy, both in terms of producing the biomass and converting it to ethanol.