Biogas: The prolific renewable energy resource of modern day
July 13th, 2015 | Naveed Mushtaq, Zoraiz Tanveer and Dr. Nasir Ahmad Khan | No Comments
BIOGAS NORMALLY refers to a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen. Biogas can be produced by raw materials such as agricultural waste, plant material, manure, municipal waste, sewage, and food waste etc. It is a renewable energy source from organic waste materials for a small labor input, replacing firewood or fossil fuels.
In the conversion process, pathogen levels are reduced and plant nutrients made are more readily available, thus better crops can be grown while existing resources are conserved. This is because producing heat using biogas is advance efficient than producing it using combustion, and therefore more agricultural and unseemly waste pledge be returned to the land by farmers as organic fertilizer.
Biogas is mainly methane (CH4) and carbon dioxide (CO2) and may have small amounts of moisture, hydrogen sulphide (H2S) and siloxanes. The gases carbon monoxide (CO), methane, and hydrogen (H) can be oxidized or combusted by oxygen. The released energy permits biogas to be used as a fuel; it can be utilized for any heating purpose, like cooking. It can also be used in a gas engine to convert the energy in the gas into electricity and heat. Biogas can be compressed; the same approach natural gas is compressed to CNG, and utilized to power automobiles. Just like In the UK, biogas is projected to have the potential to replace about 17% of automobiles fuel. It can be used in vehicle transportation.
In Switzerland, and Germany, Sweden compressed biogas is extensively used. A biogas-powered train, termed Biogastaget Amanda has been in service in Sweden. In 1974, a British documentary film titled Sweet as a Nut detailed the biogas production process from pig manure and showed how it fueled a custom-adapted combustion engine. In 2007, an estimated 12,000 automobiles were being fueled with advanced biogas global. It qualifies for renewable energy subsidies in some parts of the world. Biogas can be cleaned and promoted to natural gas standards, once it becomes bio methane. Likewise, one cow can produce enough manure in one day to produce 3 kilowatt hours of electricity; simply 2.4 kilowatt hours of electricity are needed to power a single 100-watt light bulb for a single day. Moreover, by utilizing cattle manure into methane biogas, global warming gases could be reduced by 99 million metric tons or 4%.
Biogas can also be utilized for electricity production on sewage works, in a CHP gas engine, where the unused heat from the engine is conveniently used for heating the digester, cooking, space heating, water heating, and process heating. It can replace compressed natural gas for usage in automobiles, where it can fuel a fuel cells or internal combustion engine and is a much more effective displacer of carbon dioxide than the normal use in on-site CHP plants.
Domestic biogas plants exchange livestock manure and night soil into slurry and biogas, the fermented manure. This technology is affordable for small holders with livestock producing 50 kg manure each day, an equal of about3 cows. This manure has to be collectable to mix it with water and feed it into the plant. Toilets can also be linked. Another precondition is the temperature that affects the fermentation procedure. With an optimum at 36 C° the technology especially applies for those living in a tropical climate. This makes the technology for small holders in developing countries often suitable.
Depending on size and location, a classic brick made fixed dome biogas plant can be fixed at the yard of a rural household with the investment stuck between US$300 to $500 in Asian countries and up to $1400 in the African context. A high quality biogas plant requires minimum repairs costs and can yield gas for at least 15-20 years without major problems and re-investments. For the user, biogas provides clean cooking energy, reduces indoor air pollution, and decreases the time desired for traditional biomass collection, especially for children and women. Slurry is a clean organic fertilizer that actually increases agricultural productivity. Domestic biogas technology is a sure and established technology in various parts of the world, especially Asia.
Pakistan lends itself to biogas production because of the climate and feed stocks available. Processing of large-scale crops such as palm oil, sugarcane and maize stalk produce large amounts of waste water heavy with organic matter which readily breaks down to produce methane-rich biogas. Pakistan has low forest cover. About 4% of total land is covered by forest, in which only 5% area is protected. 90% of countrys wood production is used as fuel. In Pakistan each year around 7000 ha of land is reforested. Adoption of biogas is a best technology to control reforestation in Pakistan. These actions will not only be valuable to the human health but will also have positive impact on the environment.
Published in: Volume 06 Issue 28
Short Link: http://www.technologytimes.pk/?p=13813