Biomass is probably the oldest and most well known renewable source of energy, especially in rural areas of developing and under-developed countries. Biomass in simple terms is the biological waste or material from living organisms or recently alive organisms. Biomass is mainly constituted of carbon and is composed of a mixture or organic molecules containing hydrogen, usually including other inorganic atoms of oxygen and nitrogen.
Sometimes it also consists of other atoms, alkaline earth and heavy metals. The carbon that makes up the biomass is processed in plants through photosynthesis, using energy from sun and by absorbing the carbon dioxide (CO2) from atmosphere. After breaking down of the biomass, it releases carbon dioxide back to the atmosphere. These processes together form a part of what is known as the carbon cycle. Fossil fuels are also derived from biological material, which have been present since many years, but they must not be confused with biomass because of one simple reason, biomass is easily renewable whereas fossil fuels are depleting at an alarming rate.
What are the categories of biomass ?
There mainly five basic categories of materials which come under biomass:
- Forest residues like dead wood, branches, tree stumps and wood chips
- Energy crops : Crops with high yield grown specifically for producing biomass
- Agricultural residues : residues from agricultural harvesting and processing
- Household waste and food waste from food preparation and processing, and post-consumer waste
- Industrial waste and co-products.
The largest source of biomass energy is wood energy which is derived from a second generation bio fuel called lignocellulosic biomass fuel. The pulp and paper industry produces a waste called pulping liquor or more commonly known as ‘black liquor’, which is the most widely used source of wood energy. Another main contributor to the biomass energy pool is waste energy. Waste energy comprises of biomass energy derived from municipal solid waste (basically organic waste generated in our households), industrial manufacturing organic waste and landfill gas (the CH4 or methane gas released is further processed to produce biomass).
How is biomass energy harnessed?
Biomass has one of the widest applications amongst all types of fuels today due to the simplicity of obtaining it and processing it. 
Biomass can be used to generate electricity through production of steam or it can have a completely different application of being the main component in industrially producing other bio fuels like bio ethanol and biogas.Due to so many applications there have been many technologies developed to tap the vast usage of the renewable biomass energy. There are three key conversion processes of converting biomass to energy – thermal, chemical and biochemical conversion processes.
The most common simple technology made for usage of biomass is through thermal conversion of biomass energy. This involves application of heat to convert biomass into other chemical forms or to cause a chemical reaction to derive useful energy.
Another set of processes for converting biomass is through chemical conversions. Biomass is converted to other useful compounds by a set of reactions and thus exploiting it completely, for example, it can be used to produced ethanol which can be transported and stored easily, and can also be used more conveniently.
Another new process is the biochemical way of conversion which involves the use of enzymes or bacteria to convert biomass to a more feasible source of energy. The most popular biochemical conversion process is the anaerobic digestion process which is used to produce biogas or methane gas. Other biochemical processes are also being developed like converting waste vegetable oil to biodiesel through trans-esterfication. Alcohols (similar to bio ethanol) are also being made from breaking down the sugars in the biomass (mainly through energy crops).
Biomass : Applications and advantages
Ease of usage : The biggest advantage of biomass compared to other fuel sources is that it can be used for applications ranging from a simple household use of fuel for cooking in rural households, to a more complicated application of being used in electric power plants. The industry is the biggest user of biomass today using over half the biomass produced. Almost one-fifth of industrial use is for power generation. Another main use of biomass is for transportation purposes in producing bio ethanol and biodiesel. In cold nations, wood biomass is used widely to heat the homes and other places.In United States, based on the data of 2009, 50% of renewable energy consumed came from biomass. Wood and derived fuels contributed the highest closely followed by biofuels and then by biomass through waste.
Waste to Energy : Since it makes sense to reuse waste as much as possible, it makes it advantageous to use biomass as it’s basically waste generated by the us and the nature. The use of biomass helps us to reduce the biological waste on our planet by directing its energy to places where it can be used efficiently. Since biological waste will always be generated by us, biomass will always exist making it a trustworthy renewable source of energy. Another major advantage of biomass is the cheap cost of it. Since its all waste, obtaining biomass and converting it into another form is very cheap and feasible. Use of biomass ensures that the pressure in fossil fuels is reduced, hence extending the life of the most widely used fuel today.
Major drawbacks and limitations of biomass
Although biomass has so many applications and advantages, there are many disadvantages associated with it, mainly due to its crudeness. The main problem why biomass isn’t used as widely as other forms of fuel especially fossil fuels is because it is tough to generate enough waste to produce biomass to replace most of the fossil fuels’ applications. The amount of bio-waste that needs to be generated to make biomass a worthy replacement for fossil fuel is not feasible and hence this is a big disadvantage for biomass as an effective source of renewable source.
Another problem with biomass is that although it is renewable, it is also a contributor to global warming. Since biomass is mainly used by burning it in either for power generation or at homes, it generates greenhouse gases similar to fossil fuels and hence loses out to more environment friendly sources of energy like solar and wind energy. As research is being done every day in the field of solar and wind power, to make them cheaper and more feasible for wide public usage, biomass is becoming more and more obsolete, and lesser environment friendly, which is the need of the hour for our planet.
What lies ahead?
Even though biomass is facing stifling competition, it has a promising future because of the research being conducted to reduce its carbon footprints and to develop alternative applications for it. A few areas where research is being conducted for alternative application of biomass are bio plastics, plant fibres to replace insulating and conventional plastics used in automobiles, and cellulose textiles which are derived from wood. The conventional uses and sources of energy are also getting overhauls to ensure biomass can be used as an energy source without having to burn it and hence reduce its greenhouse emissions.
As a conclusion for all that has been written above for and against biomass, it can be said confidently that biomass will be an integral part of many of our lives in the future too, as it has been in the past. Biomass will continue to exist in form or the other supporting other renewable energy sources and making its mark on the energy needs of the world.