Bioenergy Definition, Source, Comparison, and Examples
Bioenergy (also bio-energy or bio energy) is renewable energy that is derived from organic matter through conversion. This article discusses bioenergy definition, principle, source, comparison, and examples.
-Bioenergy Definition: 9 Ways to Define Bioenergy
-Bioenergy Working Principle: How Bioenergy Works
-Difference Between Bioenergy, Biomass Biofuel
-Examples of How Bioenergy is Used
Bioenergy Definition: 9 Ways to Define Bioenergy
Bioenergy is energy from organic materials.
The term ‘organic materials’ in the above definition, refers to the various sources of bioenergy. Some of these sources are mentioned in the following bioenergy definition;
Bioenergy is a form of renewable energy that is gotten from plant, animal, and microbial biomass, such as microalgae, corn, wood chippings, agricultural waste, animal manure, and municipal organic waste [9].
Some studies have described bioenergy as a biological form of energy that occurs in all forms of organic life, reactions and processes. The following bioenergy definition shows this perspective;
Bioenergy is renewable energy that is recycled across the trophic levels of the energy pyramid in an ecosystem, in the form of biomass and chemicals [12].
An alternative perspective of the bioenergy definition is based on technologies and facilities used to produce this form of energy;
Bioenergy is energy that is produced in a biorefinery through the use of various biomass conversion methods, and in the form of heat or biofuel [13].
The next bioenergy definition is based on its importance for the generation of electricity;
Bioenergy is a type of energy that is gotten from renewable biomass, and can be used to generate electricity in biofuel-fired power plants.
Various possible uses of bioenergy exist. Some of these are mentioned in the following bioenergy definition;
Bioenergy is renewable energy from organic matter, which can be used for heating, cooling, power supply, and cogeneration.
The fact that bioenergy has diverse uses and sources, means that it can be utilized in multiple sectors of the economy. In the following bioenergy definition, some of these sectors are mentioned;
Bioenergy is energy from renewable biomass, which can be used for various purposes like heating, cooling, and electricity generation; in various sectors including residential, transport, industrial, energy, and commercial sectors.
All definitions of bioenergy so far, have highlighted the fact that it is ‘renewable’. This means that we can classify bioenergy among other renewable forms like solar energy, geothermal energy, wind energy, wave power, and hydro energy.
As a renewable form of energy, bioenergy should be one of the alternative options that are aligned with the sustainable development goals and the general effort to achieve global sustainability. The following bioenergy definition highlights this perspective;
Bioenergy is a renewable form of energy from biomass, that can play a major role in the achievement of sustainable development in the environment, economy, and society at large [8].
Lastly, the following bioenergy definition is based on its potential as a substitute for fossil fuels;
Bioenergy is a relatively clean and renewable form of energy that can be used in place of fossil fuels for various purposes, and in the form of sustainable alternatives like biodiesel and bioethanol, with lower greenhouse gas emissions [6].
Bioenergy Working Principle: How Bioenergy Works
Bioenergy works by production, ingestion, combustion or conversion of biomass to release chemicals, heat and power.
An example of bioenergy in chemical form is Adenosine Tri-Phosphate (ATP). Other forms in which bioenergy occurs are heat and electricity or power.
The four main aspects of the bioenergy working principle are discussed briefly below;
1). Bioenergy Production
The primary source of bioenergy is the Sun.
Bioenergy is first captured by chlorophyll-bearing organisms from sunlight in a process called photosynthesis [4]. This process basically involves the conversion of solar energy to chemical energy, through biochemical reactions.
The bioenergy that is produced by this process, is stored in the form of a chemical compound called Adenosine Triphosphate (ATP) [1]. This compound is produced alongside biomass, in the form of starch, with oxygen as a byproduct.
6CO2 + 6H2O → C6H12O6 + 6O2 —(1)
Organisms which produce bioenergy through photosynthesis include algae and green plants. After bioenergy has been produced by conversion of solar energy in these organisms, it is subsequently transferred from one point to another in the form of biomass.
This occurs naturally in the ecosystem when herbivorous organisms like rabbits feed on plants, and are subsequently consumed by carnivorous and omnivorous organisms as bioenergy is transferred from one group of organisms or one trophic level to another.
Based on this explanation, it can be said that bioenergy is responsible for sustaining life in all ecosystems including rivers, oceans, deserts, grasslands and tundras.
2). Biomass Ingestion
After it has been produced by green plants and algae, bioenergy works through feeding, ingestion and assimilation.
This is the natural process through which organisms derive energy for their survival.
The carbon cycle, food chain, food web, and energy pyramid are all used to represent bioenergy transfer in natural systems [2].
As animals feed on plants, algae and other animals, they ingest and assimilate bioenergy. This energy is released when the organisms excrete or die and undergo biodegradation. Through biodegradation, microorganisms like bacteria, breakdown biomass and assimilate the bioenergy that is released in the process.
At the same time, the microorganisms return nutrients and carbon to the soil, which enable plants to grow and continue to carry out photosynthesis. This continuous loop of bioenergy production, ingestion, assimilation, breakdown and release, is what enables bioenergy to be recycled naturally in a sustainable manner.
3). Biomass Combustion
Combustion is the simplest and earliest artificial process used to extract bioenergy from biomass.
Biomass combustion is simply the burning of organic matter to produce bioenergy in the form of heat [11]. Here, biomass is used as a fuel without any conversion.
Various forms of biomass can produce energy by combustion. These include firewood, wood chippings, sawdust, and forest residue.
The amount of bioenergy that is produced through combustion depends on the quality, type, source and volume of biomass that is undergoing combustion. Generally, the most energy is produced from solid, dry, high-quality combustible organic matter, when this organic matter is burnt in large volume.
Compared to other methods of energy production, biomass combustion is a primitive method that is mostly practiced in rural, developing or under-developed regions where other sources and methods of energy production are inaccessible. Its application is usually for domestic purposes, for space heating and cooking.
A major disadvantage of the use of biomass combustion to produce bioenergy is the environmental impact of this approach.
Studies have shown that burning of organic matter is a cause of greenhouse emissions, which leads to global warming and climate change [7]. Various respiratory illnesses have also been linked to biomass combustion [10].
Some power plants have been designed to increase the energy efficiency of biomass combustion and reduce the environmental and health risks associated with this practice. These plants may employ two-stage combustion with the use of a secondary combustion chamber [5].
4). Biomass Conversion
Biomass conversion is the most efficient and sustainable, artificial way to derive bioenergy from organic matter. Through conversion, energy conservation can be achieved in the process of extracting and utilizing bioenergy.
It involves the use of any of various methods that include pyrolysis, anaerobic digestion, fermentation, liquefaction, hydrolysis and gasification, to convert organic matter into energy, biofuel, and bio-based chemicals as well as other byproducts [3].
Facilities and equipment needed for biomass conversion include boilers, reactors, catalytic chambers, biomass-fired power plants, and biorefineries.
Biomass conversion is possible because of the dynamic physical, chemical, and biochemical characteristics of organic matter. The method of conversion that is used in any scenario depends on the nature of organic matter or ‘feedstock’ involved, and the desired end-products.
With biomass conversion, a broad variety of types of organic matter can be used to produce bioenergy. These include wastewater, plant and animal biomass, sewage sludge, and solid organic waste from municipal, agricultural and industrial sources.
The products of biomass conversion are also diverse. They include biogas, bioethanol, biodiesel, heat energy, digestate, and biochar. These products are useful in energy production, soil conservation, sustainable farming, and manufacturing.
What Bioenergy is Made From
Bioenergy is made from biochemicals, biomass and biofuel, through various methods and processes. The sources of bioenergy are discussed as follows;
1). Biochemicals as a Source of Bioenergy
Adenosine triphosphate (ATP) is the primary and most important biochemical source of bioenergy.
It is produced by chlorophyllous organisms through photosynthesis, and is involved in all biochemical processed of energy transfer.
2). Biomass as a Source of Bioenergy
Biomass can release bioenergy through biodegradation, and combustion, among other processes.
All forms of biomass contain bioenergy. However, the types that are commonly used as bioenergy sources include lignocellulosic and cellulosic plant matter, and animal waste.
3). Biofuel as a Source of Bioenergy
Biofuels are produced from organic feedstock (biomass) through conversion.
Examples of these biofuels include biodiesel, bioethanol and biogas. The combustion of these materials produces bioenergy, in a process that is cleaner and more energy-efficient than the combustion of unprocessed organic matter.
Difference Between Bioenergy, Biomass Biofuel
The difference between bioenergy and biomass is that bioenergy is derived from biomass. This means that biomass is the storage medium for bioenergy.
The difference between bioenergy and biofuel is that bioenergy is produced from the combustion of biofuel. Biofuel is a refined, processed derivative of biomass, which also stores bioenergy, but releases this stored energy in a cleaner, more sustainable way.
The table below summarizes the differences between bioenergy, biomass and biofuel;
| Comparison Criteria | Bioenergy | Biomass | Biofuel |
| Definition | Renewable energy from biomass | Organic matter from plants and animals | Energy-rich gas, solid or fluid derived from biomass |
| Primary Source | The Sun (Solar energy) | Photosynthesis | Biomass |
| Relationship | Derived from biomass and biofuel | Is the source of biofuel and bioenergy | Derived from conversion of biomass |
| Uses | Plant and animal survival, heating, cooling, cooking, electricity generation | Biofuel production, bioenergy production | Bioenergy production |
Examples of How Bioenergy is Used
Bioenergy is used either directly through assimilation and combustion, or indirectly through energy conversion and electricity generation.
These examples of how bioenergy is used are discussed below;
1). Direct Use of Bioenergy
Bioenergy is used directly either through assimilation or combustion of biomass.
These two processes involve breaking down the molecules and compounds of organic matter to release stored energy.
In assimilation, organisms ingest and breakdown organic matter through biochemical, metabolic processes like digestion and biodegradation. The energy released in these processed is assimilated and absorbed into the cells of the organism to enable it survive.
Combustion is similar to assimilation, by involving breakdown of organic matter. It is usually a human-induced process and leads to the release of bioenergy in the form of heat. Combustion of biomass is the earliest use of bioenergy.
2). Indirect Use of Bioenergy
Bioenergy is used indirectly when it is converted from its heat form into other forms of energy.
This occurs in electricity generation systems that convert heat from biomass or biofuel to mechanical energy that is used to spin a turbine or rotor, and start an electric generator.
Cases where this type of conversion occurs include biofuel/biomass-fired power plants, and biofuel-based vehicles.
Conclusion
Bioenergy is energy derived from plant or animal biomass, through ingestion, assimilation, combustion or conversion.
The processes that describe how bioenergy works are;
- Bioenergy Production
- Biomass Ingestion
- Biomass Combustion
- Biomass Conversion
Bioenergy is made from biochemicals, biomass and biofuel.
Examples of how bioenergy is used are;
- Direct Use; by assimilation, and combustion
- Indirect Use; by conversion from heat form to mechanical form.
References
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