6Cow Dung _ Water Hyacinth Sludge (Ajibola & Suley)

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Jan-Mar 2012 Journal of Sustainable Development and Environmental Protection Vol.2 No.1

49

COW DUNG WATER HYACINTH SLUDGE: A VERITABLE

SOURCE OF RENEWABLE ENERGY

Olawale O.E. Ajibola and Eniola O. Suley

Department of Systems Engineering, Faculty of EngineeringUniversity of Lagos, Akoka, Yaba, Lagos, Nigeria.

Traditionally, cows excreta have been used as manure in the fields for ages. With increasingdemands for energy coupled with depletion of existing fossil fuel, the quest for renewableenergy has taken the centre stage the world over. Cow excreta have been identified as viablesource of energy with additional quality that greenhouse emissions are reduced significantly.Being used in developing countries for over three decades now, cow dung and by extension,biomass has a lot of potential to reduce carbon footprint by capturing and storing CO 2 from

biogas into the ground thus turning the biogas carbon negative and scrubbing the past CO 2emissions out of the atmosphere. In this work, we have done a comparative analysis of energycontent of excreta of various kinds of animals, man inclusive, and have chosen cow dung. Wehave excogitated the chemical content of cow dung with a view to extracting its energy contentwith the ultimate goal of producing electricity thus providing sustainable energy especially forthe rural populace where energy requirement is low due to absence of industries.

renewable energy, excreta, fossil fuel, greenhouse emissions, carbon footprint,biomass, sustainable energy, conference and fair.

Energy is the ability of a system to do work,

Gibbs K. (2004). It is the property of asystem that enables the system to functionand to change form; shape, position andchemical composition, Halliday et al (2004).Energy is required for every human activity;

from talking to running, jumping or evenreading. Some important forms and sourcesof energy include: the solar energy, derived

from the sun; chemical energy; electricalenergy; mechanical energy which basicallymanifest as kinetic energy (i.e. energy dueto motion) and potential energy (i.e. storedenergy) to mention but a few. One of the

most important of these forms of energy isthe electrical energy due to its highertransmissible power, its ability to readilytransform to other forms of energy and thehuman capability to facilitate its storage.Electricity features everywhere in our lives.It lights up our homes, cooks our meals,powers our computers and other electronicdevices and Electricity from battery keepsour cars running. For these reasons Energy

Consumptions worldwide depends on thequantum of electrical energy generated. The

issues connected with the growth in EnergyConsumption, Energy Conservation, andFinding Environmentally benign ways ofenergy production the world over. This mayarguably be the most significant challenge

facing mankind in the 21st century, Ibidapo-Obe and Ajibola (2011).

Nigerias Unreliability of Supply and Declinein Traditional Fossil Fuel Production,combined with very grave Environmentalmatters and Continued uncharted economicand population growth makes it imperative

to search for Alternative Forms of Energy.Whilst we proceed with increasing thegeneration capacity, transmission anddistribution of existing traditional energysources through the development of energysystems and policies that enhance social,economic and environmental performance;it is appropriate to focus on alternative tothe traditional energy sources which amongother things is capital intensive, and the


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technology required becomes obsoletewithin a short space of time therebyrequiring intensive overhauling of themachineries or better still a completereplacement of the existing technology witha newer innovation leading to colossalwaste of fund. However, the answer to thepresent imbroglio may be found inrenewable and sustainable energy formsboth for rural and urban areas of the

country, Ibidapo-Obe and Ajibola (2011).Currently exploration in the renewableenergy field is the lowest of the existingsources of energy. Figures 1 and 2 give asummary of the contributions of varioussources of energy. Figure 2 presented thevisual summary only in percentages sinceno two sources of energy have the samepercentage contribution in Figure 1.

Oil 34.10%

Coal 22.50%

Natural Gas 21.60%

Traditional biomass 10.00%

Large Hydro 5.70%

Nuclear 3.80%

New renewable 2.30%

The significance of the research is to

promote a cost-effective andenvironmentally friendly alternative to theworld-wide acclaimed hazardous fossil-fuelbased energy generation processes usingbiogas technology with animal dung andwater hyacinth that are readily available inour local communities as the baseingredients. The purpose of this researchwork is to exploit the potentials in animaldungwater hyacinth sludge which makes it

a viable source of renewable energy byextracting biogas from the slurry of the

sludge for the sole purpose of producingelectricity.

The word renewable emanated from renewwhich implies to give new strength tosomething. Renewable Energy thus mean:Energy that can be given new strength to.


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Renewable Energies derivable from thenatural movements and environment suchas: sunshine, wind, the heat of the earth, themovement of seas and rivers and thegrowth/movement of plants and animals. Arenewable energy system transformsincoming solar energy and its primaryalternate forms (wind and river flow), usuallywithout pollution-causing combustion intoreadily usable form of energy such aselectricity, Ibidapo-Obe and Ajibola (2011).Some renewable energy forms are: Solar,Wind, Micro-Hydro, Fuel Cells, Biomass andGeothermal Energy, Uppal and Rao (2009).However, some energy forms are non-renewable. Major nonrenewable energy

forms are the Fossil Fuels. These are thetraditional sources of energy such as coal,oil and natural gas. Fossil Fuels arenonrenewable since they cannot berecycled. Once they are spent they cannotbe recovered again. A comparative analysisof renewable and nonrenewable energy issummarized as follows:

Renewable energy from wind, solar,and hydroelectric power emits nopollution or carbon dioxide (althoughthe building of the components does)

Even though Biomass is a form ofrenewable energy, Biomasscombustion emits CO2 and other

pollutants

Renewable energy is sustainableindefinitely, unlike long-storedenergy from fossil fuels

Fossil-fuel energy that took millionsof years to create that much fuel willdeplete in the future; since the rateof depletion is far greater than therate of creation

US oil production peaked about1974; world energy reached itspeaked between 2004 and 2009

Nuclear energy is not renewable, butsometimes it is treated as though itwere because of the long period ofdepletion

In view of the comparisons above,Renewable energy will eventually become

mandatory, and our lifestyles may change. Itis inevitable that transition to renewableenergy must occur well before a crisisoccurs. A viable renewable source ofenergy is biomass and its derivatives.According to the International EnergyAgency, bio-energy (biogas and biomass)have the potential to meet more than aquarter of world demand for transportation

fuels by 2050. Biogas technology is a verygood solution to rural energy needs, and itprovides significant benefits to human andecosystem health. A good example in time isthe Denmark experience.

According to EcoFriend, (2007), biomassbecame an increasingly important energysource in Denmark over the last 25 years.Being a carbon neutral energy source, it has

already helped make a significantcontribution to the reduction of Danishcarbon emissions. The conversion of morebiomass at power stations will help Denmarkreach its target of 30% renewable energy by2020. Today, biomass accounts forapproximately 12% of world energyconsumption. It is imperative to note thatthe potential of using biogas has so far beenunexploited, especially in the form oflivestock manure in the agriculture system.Denmark, known for its farming industry;approximately 65% of the land is used foragriculture, emitting 18% of all greenhousegases here, through methane and nitrogen.So farming has an important part to play inthe transition to a fossil fuel free society.The Danish government now wants up to50% of livestock manure to be made into thisgreen energy supply. Currently, one of theworlds largest biogas plants is currentlybeing built in North West Jutland, in one ofDenmarks most important agriculturalareas. The Maabjerg Bioenergy, due forcompletion in 2012, will convert 500,000tons of biomass into pure energy. The bigplant is a co-operation between agriculture,

local government and district heat stationsand will purify livestock manure, while at thesame time produce heat and electricity tothe nearby cities of Holstebro and Struer.When operational, Maabjerg Bioenergy willprovide both environmental andemployment benefits. Helping reducecarbon emissions, provide clean greenenergy and enable local farmers to maintain


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current herds, with potential for futurecattle increases. With biogas currentlyexempted from Danish taxation, it is hopedthat over the next ten years there will be upto fifty new large scale biogas plants inDenmark. In April 2011, the Centre for Iceand Climate, Niels Bohr Institute, Universityof Copenhagen received for a second centreperiod, a grant of 55 million kroner from theDanish National Research Foundation to

facilitate the research for electrifying thecountry using biomass.

The energy content of animal excreta isamazingly enormous. It is thereforeimperative that a scientific analysis of solid

excreta from selected readily availableanimals, man inclusive, is considered.Figure 3 reveals the derivable gas content ineach of the chosen animal dung.

1 Cattle 0.023-0.040

2 Pig 0.040-0.059

3 Poultry (Chicken) 0.065-0.116

4 Human 0.020-0.028

And Figure 4 contains the samples of Cow dung and Water hyacinth in their natural forms beforethe anaerobic biodgradation of the sludge formed from the two took place.

The targeted objectives of the researcheffort are stated below:

To enumerate the cost and benefits ofusing Renewable energy sources asopposed to fossil fuels based on existingliterature

To design a prototype model forgenerating biogas from naturalresources

To obtain electricity from the prototypemodel described in aforementionedobjective, and

To identify the limitations of ourresearch effort.

The method adopted in the work is purelyempirical. The schematic model of thebiogas electrical energy producing systemis shown in the Figure 5 below. The modelcomprises of a biogas digester, a boiler, anelectricity generating system (a dynamo andits compatibles) and an electric bulb. Biogas


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is generated in the digester; the gas is thenused to boil water in the boiler in order toproduce steam. The steam is provides the

mechanical force that drives a turbine whichin turn drives the dynamo that producesdirect current.


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The material deployed for the purpose ofthis research include: Plastic Bucket,Reducer, M6 bolt (or screw plug), Funnel,PVC thread sealer, M6 wing/butterfly nut,025mm PVC T-joint, inch flat bar, Woodenbase, 025mm PVC cap, Bearing, ABROkwik-set epoxy, Cow dung, Bearing block,

Auto-base enamel varnish, Water hyacinth,240 x 08mm shaft, Thinner, Topgit PVC gun,30 x 08mm bushing, Wood lacquer polish,Gas Nozle, 070 fishing reel flywheel, Owlet6V-3Whub dynamo, Fire Extinguishercylinder, 0100 x 27mm drive wheel, Plasticwing blade, Nipple and Coupler.


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The materials are arranged and coupled asshown in Figure 9 above. The biogasproduced with impurities leave the Digestertraversing the Activated Charcoal chamber

for drying, and the Calcium Hydroxide[Ca(OH)2] for scrubbing, to the gas holder

for direct usage for burning of water intosteam for the purpose of turning the turbine

that in turn supplies the mechanical energythat activates the dynamo. The output of thedynamo is evident by the powering of the

small electric fan that completes the design.Scrubbing is necessary to get rid of H2S andCO2 which are inimical to both the processand a healthy environment. Figure 8terminates the process of electricityproduction at the two-way tap; the point atwhich the biogas produced from thedigester is either channeled to a gas holderor the pump in order that the producedbiogas (i.e. methane (CH

4

)) may be storedand used for domestic purposes such ascooking or sundry purposes.

The mathematical considerations made inrespect of the research effort were done atthe following levels of execution of thedesign:

The governing equation for heat energy

required: TcmcmQ ccwW

(1)The heat required to produce steam:

LVmLQ s2 (2)


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The pressure required to produce torque:2

4 dgVP ww (3)

The torque that causes rotation is:2

ffrm (4)

The governing equation for electricity

generation: BANE (5)

And by MATLAB-based simulation, thegraph of Electrical Energy against AngularVelocity is given in Figure 11, while Figure12 shows the relationship between ElectricEnergy generated when the concentrationof the slurry from the sludge is altered withincreasing volume of water.


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This Project identifies and analyses theproblem of energy supply. It discusses theneed to move from the usage of non-renewable energy sources such as fossil

fuels: coal, crude oil, to renewable energysources; the economic and environmentalbenefits. The project proposes a way

forward; the option of recycling waste toproduce biogas and the use of biogas as fuel

for energy production. The performanceevaluation showed that cow dung-waterhyacinth slurry gas is rich in methane andmay be used in rural areas and elsewhere toprovide a renewable and stable source ofelectricity. It was found to be cheap andenvironment friendly. The biogas producedis a clean energy source for household use

and the raw materials are readily available.

The renewable energy derived from the cowdung-water hyacinth slurry is green energy.It reduces the hazardous emissions from

fossil fuels and minimizes unethical humanpractices embarked upon in order to satisfymans day-to-day energy requirements andthus contributes positively to the fight

against global warming energy. It reducesdeforestation thus reducing greenhouseeffect, Ollor et al (2009). And it is a boosterto productivity in the agriculture sectorsince the bi-product is cleaner and lesstoxic manure compared with the synthetic

fertilisers and it is by implication anexcellent fertilizer for use on the farm,Gustavsson, M. (2000). Analyticalconsideration of the process reveals apositive slope where necessary. Forinstance, the study agrees with existing onthe point that the higher the angular velocitythe higher the systems energy output asenumerated in Figure 11. The graphicalanalysis in Figure 12 shows that the lessconcentrated the slurry of the cow dung-water hyacinth sludge the less the gasproduction and therefore the lower the

energy output, Sughra et al (2003). Otherworks, confirmed the viability and theimperativeness of the research work sinceany nation that must ascend the ladder ofeconomic productivity, achieve andmaintain the millennium development goalsin the futurity must strive to imbiberenewable energy in the nonse. Some of thelimitations of the study are the unavailabilityof standard equipments to use for the


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purpose of achieving optimally, the aims andobjectives of a research and the process ofaccessing research grant in Nigeria.

According to Okafor and Joe-Uzuegbu(2000), the National energy supply is atpresent almost entirely dependent on fossil

fuels and firewood (conventional energysources) which are depleting fast. In theiraccount, recent estimates indicated that thereserve for crude oil stood at about 23

billion barrels in 1998, natural Gas 4293billion cubic metre at the beginning of 1999,made up of 53% associated gas and 47%non associated gas. Coal and lignite stoodat 2.7billion tones, tar sands at 31 billionbarrels of oil equivalent and large scalehydropower at 10,000MW. For Nigeria togrow energy for its citizenry, the leadershipmust be focused and renewable energyresearch must be accorded the attention itdeserved.

With the conclusion of this study, a majorsocio-economic problem was identified:inadequate energy supply; and a way

forward has been proposed in the form ofthe generation of biogas and its applicationin electricity generation. It is our sincere

belief that if power generation is the onlyproblem the current regime in Nigeria cansolve, it will be a giant step towardsactualizing vision 20:2020.

EcoFriend (2007);Move over Wind and SolarEnergy, Cow dung is here to stay!http://www.ecofriend.com/entry/mooove-over-wind-and-solar-energy-cows-poop-is-here-to-stay/

Gibbs, K. (2004); Advanced level physics,

2nd edition. Cambridge Press. London.

Gustavsson, M. (2000); Biogas technology:

solution in search of its problem. A

study of small-scale rural technology

introduction and integration.

Department for Interdisciplinary

Studies of the Human Condition,

Goteborg University, Goteborg.

Halliday, D., Reswick, R. and Walker, J.

(2004); Fundamental of physics, 6th

edition. John Willey and Sons Press

Inc., USA.

Ibidapo-Obe, O and Ajibola, O.O.E. (2011);Towards a renewable energydevelopment for rural power

sufficiency. International Conferenceon Innovations in Engineering andTechnology (IET 2011). pp. 894 905.

Johansson, T.B. (2006); Renewable energysources for fuels and electricity.Island Press. Washington D.C.

Khemani, H. (2009), ed. Stonecypher, L.:

Working of bio-gas generator or

biogas plant. Bio-gas Generator

(Image source:

www.gobartimes.org).

Okafor E.N.C.and Joe-Uzuegbu C.K.A.(2010); Challenges to developmentof renewable Energy for electricpower sector in Nigeria.International Journal of AcademicResearch. Vol. 2. No. 2. pp. 211 216.

Ollor, W.G., Jack, P.O., Utsumi, T. andHerren, H.R. (2009); Nigeria energypolicy analysis: modeling Nigeriasenergy policy response dynamics.Nigeria Energy Policy Analysis withThreshold 21_v3 copy.

Sughra F., Ahmed I., Kanwal S. and Ateeq U.(2003); Effect of Different Levels ofCow Dung on Growth Performanceof Major Carps. Int. J. Agricultureand Biology, Vol. 5, No. 2, pp. 194

195.

Uppal, S.L. and Rao, S. (2009); Electricpower systems: generation,transmission, distribution, protectionand utilization of electricity energy.Khanna Publishers, New Delhi.
http://www.ecofriend.com/entry/mooove-over-wind-and-solar-energy-cows-poop-is-here-to-stay/http://www.ecofriend.com/entry/mooove-over-wind-and-solar-energy-cows-poop-is-here-to-stay/http://www.ecofriend.com/entry/mooove-over-wind-and-solar-energy-cows-poop-is-here-to-stay/http://www.ecofriend.com/entry/mooove-over-wind-and-solar-energy-cows-poop-is-here-to-stay/http://www.ecofriend.com/entry/mooove-over-wind-and-solar-energy-cows-poop-is-here-to-stay/http://www.ecofriend.com/entry/mooove-over-wind-and-solar-energy-cows-poop-is-here-to-stay/http://www.ecofriend.com/entry/mooove-over-wind-and-solar-energy-cows-poop-is-here-to-stay/http://www.ecofriend.com/entry/mooove-over-wind-and-solar-energy-cows-poop-is-here-to-stay/http://www.ecofriend.com/entry/mooove-over-wind-and-solar-energy-cows-poop-is-here-to-stay/http://www.ecofriend.com/entry/mooove-over-wind-and-solar-energy-cows-poop-is-here-to-stay/http://www.ecofriend.com/entry/mooove-over-wind-and-solar-energy-cows-poop-is-here-to-stay/http://www.ecofriend.com/entry/mooove-over-wind-and-solar-energy-cows-poop-is-here-to-stay/

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6Cow Dung _ Water Hyacinth Sludge (Ajibola & Suley)

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