Biomass comes from recently living organisms. It is an integral part of the Earth’s carbon cycle. The process of exchanging carbon between all the layers (atmosphere, hydrosphere, biosphere, and lithosphere) of Earth is the carbon cycle.
Biomass is derived from timber, agriculture, and food processing wastes. Biomass can be used for facilities such as electric power generation, heating, along with combined heat and power.
It comprises materials like agricultural residues, wood from various sources, human and animal waste. So, how is electricity generated from biomass?
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Converting Biomass to Energy
Solid biomass resources like wood and garbage are burned directly to produce heat. Biomass can be converted to a liquid called biofuels or into a gas called biogas. Later, these fuels can be burned for energy generation.
How is Electricity Generated from Biomass?
There are many techniques through which biomass can be converted to electric power. The most commonly used technique is the combustion of biomass materials (agricultural waste or woody materials).
A few other techniques for generating electricity from biomass include pyrolysis, gasification, and anaerobic digestion.
It gives a type of tar, also known as bio-oil by heating the biomass rapidly. The biomass is heated at a temperature of 200°C to 300° C in the absence of oxygen. This keeps it from combusting and alters biomass chemically. The biochar produced during this process is valuable in agriculture and environmental use.
Biomass can directly be converted to energy through the process called gasification. It produces a synthesis gas with viable energy. This is obtained by heating the biomass to more than 700° C with much less oxygen compared to the amount needed for complete combustion.
- Anaerobic Decomposition
Once the organic matter is decomposed by bacteria, it produces a renewable natural gas. This is a process where microorganisms, mostly bacteria, break down the materials in the absence of oxygen. It is important in scenarios where biomass needs to be crushed and compressed creating an anaerobic environment, like landfills.
Biomass is the one renewable energy source that can be turned into liquid biofuels. Biofuels can be used to power vehicles and are produced in countries like Austria, Sweden, and the United States.
Biomass Electricity Generation Plant
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The total installed capacity of power generation by biomass in the states has reached 1610 kilo-watts. It was ranked number one in the world and is considered to have 7.1 quadrillions Btu of biomass with prices below $5 per million Btu.
Biomass Resources of the U.S.
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How Much Biomass is used for Fuel?
In 2017, biomass fuels contributed about 5% of the total energy consumed in the U.S. About 47% of which came from biofuels and about 44% was from wood and wood-derived biomass. The rest came from the biomass in municipal waste.
Sources of Biomass
- Wood waste
- Twigs in forestry
- Cotton stalks
- Agricultural straws
- Bagasse from sugar factories
- Rice husks on farms
- Municipal waste
- Wood chips processing plants
Examples of Biomass with their Uses
- Wood and Wood Processing Waste: Burned to heat buildings and generate electricity.
- Agricultural crops and waste materials: Burned as fuel or turned into liquid biofuels.
- Animal manure and human sewage: Turned into biogas that can be burned as fuel.
- Food, yard, and wood waste in the garbage: Burned to generate electricity from power plants or converted biogas in landfills.
Advantages and Disadvantages of Biomass
|Does not produce sulfur or mercury.||Energy plants use land that can be used for conservation, farming, and housing.|
|Releases less nitrogen than coal.||The release of CO2 needs to be monitored to keep it from exceeding limits.|
|Low cost.||It is not entirely clear as it releases methane gas.|
|Reduces the need for centralized power.||Uncontrolled biomass production can result in deforestation.|
|Bio-oils can be used in plastics or medicines.||It needs extensive and costly irrigation infrastructure for mass production.|
Comparison between a Biomass Power Plant and Other Power Plants
|Biomass Power Plant||Other Power Plants|
|Abundant resources from agricultural waste or forestry.||Coal-based thermal power is a highly convenient source of electric power.|
|Only renewable energy that can be stored and transported.||Hydro-powers rely on water sources that are not guaranteed. It requires larger investments and a higher requirement of a geographical environment.|
|Nearly zero CO2 emission and very low SO2 emission.||Nuclear leakage causes nuclear radiation. The cost of nuclear power equipment is much higher.|
|It is cost-effective.||Natural gas power has a higher cost and natural gas shortage.|
|Wind power is unstable with a lower conversion rate and occupies a larger land area.|
Environmental Effects of Biomass
Biomass energy generates air emissions, and it varies depending on the fuel and technology used during the process. When wood is the biomass resource, a low amount of SO2 comes out of the stack.
Whereas Nox emissions depend on the design and controls of combustion facilities. A high NOx rate is one of the many concerns related to biomass.
Efficiency of Biomass Power Plants
Biomass can be used to generate electricity as well as heat. Any traditional gas engine offers an efficiency of 30-35 percent. While gas turbines and steam turbines offer around 50 percent of efficiency.
Countries like Germany and the Netherlands, with governments that are supportive of renewable energy, have plants combining heat and power production from biomass.
Although biomass energy comes with many benefits, burning it releases carbon monoxide, nitrogen oxides, carbon dioxide, and other pollutants. These pollutants need to be captured and recycled or burning biomass can result in smog and release more pollutants than fossil fuels.
Unlike other renewable resources, biomass energy is stored inside an organism. So, you can harvest it when in need. It has a low energy density compared to fossil fuels. Biomass plants need fossil fuels to work in an economically efficient way.
(Last Updated on October 11, 2022 by Sadrish Dabadi)