Biomass in Biology Meaning and Ecological Role

Biomass energy refers to energy produced from organic matter. It is found in the form of living or recently living organisms, organic mass and waste. The energy produced from biomass is called bioenergy. Materials used to produce this bioenergy refers to feedstock which is mostly plants or animal material. Different types of feedstocks have different physical compositions but Carbon, water and organic volatiles are common in all. 

Biomass can be defined as the organic life and mass means weight, so biomass means the total quantity or the weight of organisms in a given area or volume. Now, we are familiar with biomass and biomass definition.

Types of Biomass

Biomass comes from a variety of sources. Some of the different types of biomass example are:

1. Agricultural Residues

These are the Biomass sources or materials that are left in an agricultural field or orchard after the cro harvesting. The residues include stubble like leaves, stems, stalks, and seed pods. These residues are used as biomass for bioenergy production.

2. Animal Waste

Animal waste is an important source of nutrients and renewable energy and is a valuable biomass feedstock. Animal waste has chemical energy stored in it just like plants and when it is burnt, it releases bioenergy in the form of heat and fuel. Animal wastes are generally the excreted materials from living animals and can also include hay, straw, organic debris and wood shavings.

3. Forestry Residues

It is the residue which is left over from logging operations that may include branches, tree tops, sawdust and stumps. These can be obtained in two forms including primary forestry residues and secondary forestry residues. Forest residues comprise of branches, tops and unmerchantable wood left after cleaning, final felling or thinning of forest stands. These are some of the important Biomass examples.

4. Wood Wastes

It is the portion of the waste stream which comprises discarded wood products, stumps, whole trees or pruned branches obtained during park or street maintenance. Therefore, a vast portion of wood waste can be collected to use as biomass and bioenergy production.

5. Industrial Wastes

It is defined as the waste which is generated by manufacturing or industrial processes. It includes a variety of waste including dirt, gravel, cafeteria garbage, concrete and masonry, scrap metals, oil solvents, trash, chemicals, wood, weed grass, trees, etc. A careful selection of the industrial waste to generate bioenergy is advised for prevention to bad impact on human health.

6. Municipal Solid Wastes and Sewage

Also known as trash or garbage, it is the everyday items that we use and throw away such as grass clippings, furniture, clothing, newspapers, appliances, paint, batteries, product packaging, kitchen waste, etc. Sewage sludge is a type of wastewater produced from a sewer or treatment plant. All of these are used as biomass feedstock for bioenergy production.

Biomass Conversion Process

For bioenergy production from biomass, multiple biomass conversion processes are used:

1. Combustion: 

Feedstock is burnt in the presence of air to release heat. Eg: heating wood, and steam heating to generate electricity

2. Gasification: 

It is the process of using heat, pressure and partial combustion to convert feedstock into combustible gas mixture called syngas (can be used as natural gas/electricity/other uses).

3. Pyrolysis: 

The process of heating feedstock in high temperature in the absence of oxygen. As oxygen is not present, organic material does not combust and it converts into 3 forms: bio oil (solid), bio-char (solid) and syngas.

4. Anaerobic Digestion or Biodigestion: 

Here, the feedstock is burnt which then gets converted into biogas with the help of bacteria in the absence of oxygen. The residue is called digestate and is a great fertilizer.

5. Fermentation: 

The process of converting feedstock or the plant glucose into an alcohol called ethanol by utilization of yeast. Ethanol produced is a biofuel that can be used in the automotive industry.

The usage of the specific process for a specific feedstock depends upon the availability of the resources and desired form of energy. Prior to the industrial revolution, biomass was the primary source of our energy. Now, it is a small percentage of the total energy usage. However,  for approx 2.5 billion people, it still remains the primary source of energy for cooking and heating. As earlier stated, resources availability, availability of technology and economic viability are drivers of biomass use. 

Disadvantages of Biomass

Biomass usage is highly environment-friendly and budget-friendly, also depending upon the feedstocks and technology type used. Some of the disadvantages of using biomass are discussed in the following points:

• Since the combustion process results in high carbon dioxide emissions leading to harmful impact on humans whereas waste energy biomass production process releases less carbon dioxide, being environment-friendly.

• Biomass production, due to lack of awareness and appropriate measures, especially among poor regions, may result in serious health hazards or risks to human health.

• Depending on the resources used, deforestation, land degradation and assaultation can be the major problems associated with biomass production.