Introduction to Biomass
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:
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.
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.
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.
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.
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.
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:
Combustion:
Feedstock is burnt in the presence of air to release heat. Eg: heating wood, and steam heating to generate electricity
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).
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.
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.
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.
FAQs on Biomass Definition
1. What is biomass in the context of biology?
In biology, biomass refers to the total mass of living or recently living organic material within a specific area or ecosystem. This includes plants, animals, and microorganisms. It is essentially stored solar energy, as plants capture the sun's energy through photosynthesis. This makes it a key component in understanding energy flow and is considered a renewable energy source because it can be replenished over a relatively short period.
2. What are the primary types or examples of biomass used for energy?
Biomass for energy production comes from various organic sources. The main types include:
- Wood and Forestry Residues: This is the largest source, including logs, wood chips, sawdust, and leftover materials from logging.
- Agricultural Residues: Materials left after crop harvesting, such as corn stalks, wheat straw, and rice husks.
- Energy Crops: Specific plants grown solely for their energy potential, like switchgrass or poplar trees.
- Animal Waste: Manure and other waste from livestock farming, which can be converted into biogas.
- Municipal Solid Waste (MSW): The organic portion of household and industrial garbage, such as paper, food scraps, and yard trimmings.
3. How is biomass converted into usable energy?
Biomass is converted into usable energy, known as bioenergy, through several processes. The most common methods are:
- Combustion: The direct burning of biomass, usually wood, to produce heat. This heat can be used directly for warmth or to create steam that turns a turbine and generates electricity.
- Gasification: Heating biomass at high temperatures with limited oxygen to produce a combustible gas called syngas.
- Anaerobic Digestion: Using bacteria to break down wet organic matter (like manure or sewage) in the absence of oxygen, producing biogas (mostly methane) that can be burned for heat or electricity.
- Fermentation: Using yeast to convert the glucose in certain crops (like corn or sugarcane) into ethanol, a liquid biofuel.
4. What is the fundamental difference between biomass and bioenergy?
The key difference lies in what they represent. Biomass is the physical raw material—the organic matter itself, such as wood, crops, or waste. In contrast, bioenergy is the usable energy that is extracted or released from that biomass. For example, a log of wood is the biomass, while the heat and light produced when it is burned is the bioenergy.
5. Why is biomass technically considered a renewable energy source?
Biomass is considered renewable because it is part of the natural carbon cycle. Plants absorb carbon dioxide (CO2) from the atmosphere during photosynthesis. When this biomass is burned for energy, it releases that same amount of CO2 back into the atmosphere. As long as the biomass is replenished by new plant growth at the same rate it is used, the process is considered carbon neutral and sustainable over time, unlike fossil fuels which release carbon that was stored for millions of years.
6. What are the most significant advantages and disadvantages of using biomass energy?
Using biomass for energy has both important benefits and notable drawbacks.
Advantages:
- It is a renewable resource that can be sustainably managed.
- It helps in waste management by converting agricultural, industrial, and municipal waste into energy.
- It is generally considered carbon-neutral, helping to reduce the net release of greenhouse gases compared to fossil fuels.
- Large-scale harvesting can lead to deforestation and habitat destruction if not managed sustainably.
- Burning biomass can release air pollutants if not done with proper technology.
- Using land to grow energy crops can compete with land needed for food production, potentially impacting food prices and availability.
7. How can relying on biomass for energy lead to unintended negative environmental consequences?
While often promoted as 'green', biomass energy can cause significant environmental harm if not managed with extreme care. For instance, classifying large-scale forest clearing as renewable can be misleading, as it destroys ecosystems and releases large amounts of stored carbon immediately, while regrowth takes decades. Furthermore, the intensive agriculture required for energy crops can lead to soil degradation, water pollution from fertilisers, and a loss of biodiversity. Inefficient combustion technologies can also release harmful air pollutants, such as particulate matter and nitrogen oxides, impacting local air quality and human health.
