Biogas production and its benefits

  

Date Posted: 2/16/2017 3:54:39 PM

Posted By: Abced  Membership Level: Gold  Total Points: 1085

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Biogas is produced whenever organic matter is decomposed anaerobically. This means organic wastes are broken down in the absence of oxygen. Biogas is composed of Methane(about 70%),Carbon dioxide(about 25%),Nitrogen(<5%),Oxygen(<1%),Hydrogen sulfide(<1%) and Ammonia(<1%). The gas mainly made of methane and carbon dioxide is burnt as fuel because it reacts with oxygen to produce energy.Popularity of biogas plants is increasing due to its many benefits to people and environment.The process of biogas production takes place in anaerobic conditions and in different temperature diapasons. There are psychrophilic (temperature diapason 10-25°C), mesophilic (25-40°C) and thermophilic (50-55°C) regimes of bioconversion. Biogas production in a thermophilic regime is much higher than for the mesophilic and psychrophilic regimes. Modern thermophilic bioreactors can produce 2-6 m3 per m3 of installation, which amounts to 5-15 kg of waste on a dry mass base . For mesophilic biogas installations, these values are 0.2-0.4 m3 per m3 of installation and 5-10 kg of wet mass. Biogas reactors, working in a thermophilic regime, can be introduced in agricultural farms where the number of livestock exceeds five. Biogas produced on such farms can be used for cooking and heating water,as well as production of electricity.

Below are waste pretreatment techniques to achieve efficient biogas production:

1.Physical pretreatment:Mechanical,Thermal,Ultrasound and Electrochemical pretreatment.

2.Chemical pretreatment: Alkali,Acid and Oxidative pretreatment.

3.Biological pretreatment:Anaerobic Microbiological,aerobic microbiological,fungal,and Enzymatic pretreatment.

4.Combined processes:Steam explosion,Extrusion,Thermochemical pretreatment.

The advantages of biogas production include the following;

1.A renewable source of energy.The gas can only get depleted when wastes and sewage depletes.It is impossible for the depletion to occur since plants and animals, the source of organic wastes can never get depleted.

2.Reduction of uncontrolled forest cutting thereby reducing risks such as landslides and massive soil erosion contributing to the value of the standing forest saved.

3.Improved living conditions

for the population.The energy produced can be used in lighting bulbs hence saving on buying paraffin.

4.It is environmental friendly.Wastes decompose in the absence of oxygen meaning the atmospheric oxygen doesn't take part in the reaction.On the other hand,the gas doesn't pollute the environment.

5.Reduces garbage heaps. Wastes are collected to produce biogas in biogas reactors.

6.Better access to information: with electricity from biogas, the rural population can watch TV, which is a vital source of information.

7.Reduced greenhouse gas emissions by avoiding methane emissions and using wood in heat production and electricity,but instead, biogas will be used.

8.Creation of employment opportunities. Biogas production plants can create jobs for unemployed people.

9.Reduces commercial fertilizer requirement and costs.The residue that remains after decomposition acts as manure.

10. Efficience use of organic bio products. Nitrogen and phosphorus are recycled naturally by being used up in the biogas production. Recirculation of nitrogen by this method reduces the need to use fossil fuels to extract the nitrogen from the atmosphere. Recirculation of phosphorus reduces pressure on limited phosphorus resources.

11.Transport sector. Biogas can be compressed as CNG(compressed natural gas) and used as fuel to propel transport vessels.

Some of the main factors that promote or facilitate the establishment of biogas reactors are listed below:

1.Average annual temperature above 20°C.Temperature should be above 20°C to enhance faster anaerobic decomposition.

2.Daily amount of manure in excess of 30 kg.Rear at least 3 cows to produce such amount of wastes,which will in turn form manure after anaerobic decomposition.

3.Need for fertilizers in form of manure.The residue that remains after generation of biogas is used as manure.

4.Need to construct a bioreactor in the proximity of a cowshed and kitchen.This will utilize the wastes generated by livestock

5.Affordable local construction costs. Labour force and construction materials should be affordable.

6.Interest of farmers in energy efficiency and environmental protection. Farmers should be taught the importance of biogas production on the environment.

7.Existence of local building materials and gas stoves. Materials to set up biogas should be available.

8.Existence of qualified constructors in the village or town.Skilled personnel in the sector of biogas production must be available.

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