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Biomass Energy - Energy from Plants and Animals
- Biomass consists of all forms of animal and plant organic matters: wood/dead plants, animal remains, leaves, living plants, vegetable oils, wastes from agricultural, residential and industrial sources and so on. Biomass is different from fossil fuels, even though they are both from plant and animal matters. While scientists believe that fossil fuels come from matters that have undergone numerous changes over several millions of years, biomass originates from recently dead or living plant and animals.
Biomass energy or Bio-energy (or energy from biomass) is derived originally from the Sun. Plants use light from the Sun during their feeding process called photosynthesis.
Energy stored from the process can be transformed to other forms of energy for home heating, cooking or for providing electricity at a later date as required. Both living plants and recently dead plants can be used to provide bio-energy. Some plants are planted specifically for the purpose of deriving biomass energy from them.
Renewable and Non-Renewable: Biomass is renewable; it can easily be replaced in a human lifespan. Fossil fuels, on the other hand, takes very long to form and cannot be replaced in a lifespan, hence fossil fuels are non-renewable.
Biomass and the Environment: Bio-energy is considered environment friendly because biomass fuels (see further details below) do not release as much pollutants and Green house gases (GHGs) to the environment as do fossil fuels. Some biomass fuels (e.g. garbage, saw dust and wood) produce smoke during burning and therefore need to be burnt in a controlled fashion to prevent release of pollutants to the atmosphere. Moreover, biomass extraction without regular replacement can create imbalance in the carbon cycle. For instance, if wood is constantly obtained from the forest by cutting down trees without immediate planting of new trees, the forest ceases to provide the needed sink that reduces CO2 concentration from the environment.
Forms of Biomass Energy/Fuels: Biomass fuels or bio-fuels are in various forms:
- Solid :- Wood, sawdust, garbage
- Liquid:- Ethanol and Methanol
- Gas:- Biogas or swamp gas (mainly Methane gas)
Solid Bio-fuels - include wood, sawdust, garbage, animal remains etc. Living plants store considerable amounts of chemical energy during photosynthesis. The process takes place in the presence of sunlight, therefore it can be concluded that the original source of biomass energy is solar. The chemical energy in the plant can be released as heat when the wood from a dead plant is burned or when the living plant is converted to useable energy. Some plants are specifically planted to provide bio-fuels (details below); this are usually processed to liquid and gaseous forms of bio-fuels (see below).
Wood is a suitable fuel for heating and cooking. It is in common use in several parts of the World (particularly the developing world) providing heating, cooking and electricity for house-hold and commercial/industrial uses. Alternate deforestation and reforestation is required to ensure that energy from wood is sustainable or renewable.
Liquid Bio-fuels- The common Liquid Bio-fuels are Ethanol and methanol which are highly flammable alcohols. Another alcohol type gaining recognition is butanol. They can be made from direct sugar plants (e.g. sugar cane and sugar beets), starch crops (e.g. corn, sorghum etc) and plants’ cellulose, a fibre-like substance that present in plant cells.
Alcohol is produced in large heated tanks called digesters. Plant materials and chemicals/enzymes and yeasts are added to the tanks. For simple sugar sources, the yeast ferments the sugar to ethanol; for cellulose sources, the cellulose is first converted to sugar by the enzymes and the yeast ferments the sugar to ethanol.
Practical applications of ethanol and methanol have been in the auto industry. Ethanol or methanol amended gasoline fuels are now being sold in a number of gas stations in North America and some parts of Europe. The mixture of alcohol (ethanol and methanol) and gasoline is sometimes referred to as “gasohol". Ethanol is used in the engines of formula 1 racing cars. Ethanol has found more usage than methanol in the industry.
Another common liquid biofuel is biodiesel. While ethanol or butanol are considered the alternatives to gasoline fuel, biodiesel is the alternative to the petroleum diesel fuel.
Follow these links to read more about ETHANOL and BIODIESEL
Gaseous Bio-fuel is called biogas. Biogas consists mainly of methane and carbon dioxide. It is highly flammable and is produced through the anaerobic (without oxygen) decomposition of organic materials from plants and animals.
Biogas can be obtained naturally from:
- wetlands (e.g. swamps and marshes), hence the name swamp gas;
- sewage sludge; and
- solid waste dumps or landfill sites.
Various techniques are being developed for the abstraction of Biogas from these sources.
Biogas is also being produced (artificially) using biogas generators. Biogas generators are large tanks used to simulate the natural processes that produce biogas, by allowing the digestion of organic matters from plants and animals under anaerobic (without oxygen) conditions. The processes are as follows:
- Plant materials and animal wastes are shredded and placed inside the biogas generator.
- Water is added and the tank is closed and properly sealed to allow no air into the tank.
- After several days, biogas begin to form at the top of the tank due to the activities of some bacteria usually termed “methanogenic” bacteria (i.e. methane forming bacteria).
- The Biogas that is formed is piped into a storage location where it can be used as needed.
- As the production of biogas in the generator slows down, old feeds of organic materials are taken out and new feeds of organic matters and water added to the generator.
- The old feeds can be dried and used as soil manure or fertilizer.
Biogas is similar, in most respect, to the fossil fuel's natural gas. Natural gas, just like biogas, consists mainly of methane. After undergoing some purification, biogas can be used as natural gas is used for heating and cooking at homes and industries.
For in-depth discussion on biomass as energy source, we recommend that you get a copy of Clean Energy Fuels a book written by Dr. Dele Morakinyo one of the contributors to EnvironBusiness.com.
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