research article technical and socioeconomic potential...

Research ArticleTechnical and Socioeconomic Potential of Biogasfrom Cassava Waste in Ghana

Francis Kemausuor12 Ahmad Addo12 and Lawrence Darkwah23

1Department of Agricultural Engineering Kwame Nkrumah University of Science and Technology (KNUST) Kumasi Ghana2The Energy Center KNUST Kumasi Ghana3Department of Chemical Engineering KNUST Kumasi Ghana

Correspondence should be addressed to Francis Kemausuor kemausuorgmailcom

Received 18 July 2015 Accepted 4 November 2015

Academic Editor Mehmet Cakmakci

Copyright copy 2015 Francis Kemausuor et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

This study analyses technical potential and ex ante socioeconomic impacts of biogas production using cassava waste fromagroprocessing plants An analysis was performed for two biodigesters in two cassava processing communities inGhanaThe resultsshowed that the two communities generate an excess of 4500 tonnes of cassava peels per year Using approximately 5 of the peelsgenerated and livestock manure as inoculum can generate approximately 75000m3 of gas with an estimated 60methane contentfrom two separate plants of capacities 500m3 and 300m3 in the two communities If used internally as process fuel the potentialgas available could replace over 300 tonnes of firewood per year for cassava processing The displacement of firewood with gascould have environmental economic and social benefits in creating sustainable development With a 10 percent discount rate anassumed 20-year biodigester will have a Net Present Value of approximately US$ 148000 7-year Payback Period and an InternalRate of Return of 187 The project will create 10 full-time unskilled labour positions during the investment year and 4 positionsduring operation years

1 Introduction

Cassava is a major food crop especially in Africa About60 of the cassava produced all over the world is used forhuman consumption [1] and is consumed in different formsThe second largest consumer of cassava is the animal foodindustry which uses about 33 of the world productionTheremaining 7 is used by industries such as textile paperand fermentation [1] In 2012 cassava production amountedto more than 260 million tonnes globally [2] Nigeria is thelargest producer contributing over 20 to global productionGhana is the sixth largest producer with 55 of productionamounting to about 145 million tonnes in 2012 In terms ofproduction per capita cassava is the highest cultivated cropinGhana with per-capita production of 06 tonnes comparedto 03 tonnes per capita in Nigeria

In Ghana cassava is one of the critical staple foods and isprocessed intoused to prepare several foods many of whichcan be stored for up to several months The more common

foods made from cassava are fufu agbeli kaklo gari andkokonte Fufu is a staple food in most households in thesouthern parts of Ghana and is considered a delicacy that isalso served inmost restaurants across the country Among theindustrial uses starch is currently themore common outputsEfforts to use cassava to produce ethanol are also ongoing [3]Among the food uses gari is produced on commercial basisfor both local consumption and export Processing cassavainto gari is an agroindustrial activity that takes place on asmall- to medium-scale basis Small-scale processing oftenup to a few tonnes of cassava per year is done at the householdlevel Medium-scale production is done in agroprocessingplants that process up to a few thousand tonnes per year Itis estimated that about 25 of cassava harvested in Ghana isprocessed into gari [4] in communities in the southern partsof the country

In order to maximise output of cassava and other rootand tuber crops in Ghana the ldquoRoot and Tuber Improvementand Marketing Programmerdquo (RTIMP) (the programme is

Hindawi Publishing CorporationBiotechnology Research InternationalVolume 2015 Article ID 828576 10 pageshttpdxdoiorg1011552015828576

2 Biotechnology Research International

a follow-up of the Root and Tuber Improvement Programme(RTIP) which was implemented from 1999 to 2005 RTIMPis being sponsored for a period of 8 years (2007ndash2014) andwas expected to be implemented across 60 districts but thishas now been scaled up to 90 districts) was instituted in2007 RTIMP is supported by the International Fund forAgricultural Development (IFAD) and the Government ofGhana (GoG) through the Ministry of Food and Agriculture(MOFA) and seeks to develop downstream activities likeprocessing and marketing of cassava The programme hasassisted local entrepreneurs to establish cassava processingfactories (processing cassava into gari) in communities wherecassava is produced on relatively larger scale The factoriesthat receive assistance are known as ldquoGood Practice Centres(GPC)rdquo because they follow a strict code of practice to ensurethe production of hygienic gari that can also be exported toneighbouring countries

In most cassava processing communities several tonnesof cassava peels are generated as a waste product from theprocessing activity With an expected increase in cassavaproduction it is also expected that waste generation willalso continue to rise Even though cassava peels can beused as feed for livestock the quantities generated and theremoteness of many of the communities where processingtakes place leave behind a lot of waste which is left to rot oris burnt with environmental consequences

There is therefore the need to explore other measures tomanage the waste accruing from the process in order toensure good environmentalmanagement practices within theprocessing communities To this end RTIMP launched aproject dubbed ProVACCA (PROmoting a Value Chain Ap-proach to Climate Change Adaptation in agriculture inGhana) in 2013 which has two principal aims (details ofthe project PROmoting a Value Chain Approach to ClimateChange Adaptation in Agriculture in Ghana (ProVAC-CA) can be found at httpoperationsifadorgdocuments65401617060381-148f-4291-b04a-24511050954e) The firstaim is to prepare cassava and other roottuber farmers toadapt to changing climate and by so doing ensure food secu-rity The second aim is to encourage the use of cassava wasteas fuel for cassava processing To achieve the second aimRTIMP is in the process of constructing pilot biodigesters orgasification plants in two communities to generate energyThis study aims to further explore the impacts of usingcassava wastes to produce biogas in these communities

The use of cassava wastes as a biogas substrate has beenexperimented either as a standalone raw material or incombination with livestock manure Cuzin et al [5] haveconducted an experiment on the production of biogas usingcassava peels Other researchers have carried out experimentsusing cassava peels in combination with other feedstocksSome of the feedstocks that have been used include poultrymanure [6ndash8] cow dung [7ndash9] zebra droppings [10] pigdung [7 8 11ndash13] and cowpea [9]

Currently communities processing cassava use firewoodas the main heating source as is the case with many ruralcommunity agroprocessing activities in Ghana Govern-mentrsquos policy objective is to ensure that agroindustries shiftfrom the use of firewood to more environmentally friendly

fuels such as biogas for heating The countryrsquos StrategicNational Energy Plan [14] has proposed an increase inrenewable and modern biomass energy in the final energysupply to achieve at least 10 penetration by 2020This is alsocorroborated by the Renewable Energy Law of Ghana whichwas promulgated in 2011 [15] However the extent to whichresidues from processing plants could serve as feedstockfor energy has not been the subject of much research inGhana This study therefore examines the technical andsocioeconomic potential of generatingmethane from cassavawaste to replace firewood which is increasingly becomingscarce The specific objectives are to

(1) examine the availability of cassava waste from cassavaprocessing and its potential for methane production

(2) perform financial assessment of producing methanefrom cassava waste

(3) assess job creation potential and other social benefitsof biogas production from cassava process waste

2 Materials and Methods

21 Study Area The study was conducted in two agroindus-trial processing sites in Asueyi and Akrofrom both locatedin Techiman Municipality of the Brong Ahafo Region (seeFigure 1) Techiman Municipality is a major cassava produc-tion district in Ghana The two communities were selectedfor this study because they are also major cassava process-ing areas within Techiman Municipality Both communitiesreceive assistance from RTIMP and have been selectedto benefit from a pilot bioenergy conversion plant Bothcommunities have similar socioeconomic characteristics Asof the last census in 2010Asueyi community had a populationof 2402 and Akrofrom community had 1505 people Bothcommunities are agrarian with the majority of residentsengaged in farming activities Farmers cultivate cassavacocoa and cashew in addition to other staple crops andvegetables Cassava is a major crop because of its commercialvalue as rawmaterial for gari production Cassava processingis a vibrant economic activity in both communities

Asueyi community processes about 8000 t of cassava peryear producing about 1500 t of gari Akrofrom communityhas two processing sites However data for this work wasobtained from only one site which processes an excess of7000 t of cassava per year Between five and ten differentcassava varieties are processed in both communities Cassavais generally available all year round due to a planned cul-tivation and harvesting schedule Occasional shortages mayoccur due to transportation or logistical challenges but notfrom shortage of the produce Firewood is the only fuel forroasting and is purchased from suppliers The study site inAsueyi had forty roasting points and Akrofrom communitysite had thirty-five Each roasting point consists of a stove androasting pan and is manned by one person

22 Description of Cassava Processing Activity Figure 2 sum-marises the stages in cassava processing for gari productionThe first stage is peeling and washing of the cassava root

Biotechnology Research International 3

Asueyi

TechimanAkrofrom

0 55 11 165 22275(mi)

TownsTechiman

District roadsDistrict boundary

Northern Region

Brong Ahafo Region

Ashanti RegionVolta Region

Western Region

Eastern Region

Upper West Region

Central Region

Upper East Region

Greater Accra Region

Techiman

A map of Techiman Municipality

N

7∘40

9984000998400998400N 7

∘40

9984000998400998400N

2∘09984000998400998400W 1

∘40

9984000998400998400W

Figure 1 Map showing study locations

Water

Cassavaroot GratingPeeling and

washingPulverising and sievingFermentation Pressing Roasting

Peels Wastewater Chaff

Figure 2 Flowchart for processing cassava into gari

The peeled cassava is then grated using a motorized cassavagraterThenext stage is fermentationwhere the grated cassavais left to ferment for 24 hours at room temperature Thefermented paste is bagged and pressed to remove moistureusing hydraulic screw presses The coarse flour material ispulverized and then sieved to make it finer for roasting Theroasting is donemanually in large shallow stainless steel pansover a fire with constant stirring The stirring takes place for20ndash30 minutes and is done with a piece of broken calabashor wooden paddle carefully designed for the purpose Theroasted gari is sieved to obtain granules of uniform size andbagged for marketing

23 Assessment of Feedstock The first stage in the analysisof energy potential from cassava waste is the assessment ofquantities of waste generated An experiment was performedto assess the availability of peels from each of the processingplants The experiment was performed between April andJune 2014The assessment was performed for four varieties ofcassava which were processed during the period of the studyFor each variety of cassava thirty randomly selected samplesfrom three different truck deliveries (thus ten samples fromeach truck delivery to the plant) were weighed and peeledTheweight of the peels was then recorded Peelers used in theexperiment were randomly selected from among the existing


peelers at the processing plants As part of the assessmentobservations were made of the existing uses of cassavapeels during the study period to estimate amount of peelscollected for feeding livestock and amount discarded Peelsfrom each of the cassava varieties were collected for moisturecontent determination The moisture content (wet basis) wasdetermined using the oven method [16]

A survey was conducted in the two communities todetermine the availability of manure to serve as inoculumfor biogas production The survey was structured to solicitinformation on cattle housing systems and existing uses ofmanureThe questions ranged from numbers of cattle raisedhousing conditions existing uses of manure and cost ofmanure

24 Measurement of Firewood Use In order to assess theamount of firewood used for gari processing a fuel useexperiment was conducted Ten roasting points were purpo-sively selected from each processing facility based on consentto participate and agreement to observe the rules of theexperimentation Fuel use experiment was performed fromJune 16 to 23 and June 25 to July 2 2014 for Asueyi andAkrofrom respectively Experiment at each roasting pointtook seven full days requiring daily visits for eight daysFor each roasting point an amount of firewood (in excessof the daily requirement) was weighed daily and the leftoverat the end of the working day weighed again to determinehow much was used For each roasting point the amountof gari roasted for the day was also weighed The amount offirewood used and the corresponding gari roasted are used todetermine the amount of firewood per a unit of gari roastedData was analysed and the mean of the firewood recorded

25 Assessment of Biogas Production Both thermochemicaland biochemical technologies can be used to convert cassavawaste into useful energy forms The technologies availableinclude anaerobic digestion gasification and pyrolysis Theproducts from each of these technological processes differdue to the production thermodynamic parameters Thischanges the compositions of the various gases in eachtechnology Gasification process leads to the productionof producer gas which is composed primarily of carbonmonoxide (CO) hydrogen (H

2) and traces of methane

(CH4) Pyrolysis leads to the production of char bio-oil

and syngas which is again a mixture of mainly CO and H2

Anaerobic digestion leads to the production of biogas a gascomposed principally of CH

4and carbon dioxide (CO

2)

Anaerobic digestion was considered for the production ofbiogas in this study because it is more matured and lesscomplicated and there is local expertise for the constructionand maintenance of anaerobic digesters

Theoretical calculations on the composition of biogasproduced were determined using the Buswell equation basedon the chemical composition of the cassava peels Dataon the chemical composition of cassava peel was obtainedfrom a recent laboratory compositional analysis of Ghanaiancassava peels for methane potential [17] Before the substrateis introduced into a biodigester the cassava peels will have

to be reduced to particle size le1mm [13] High methaneproduction efficiency can only be achieved with inoculumEnsuring the right combination of cassava peels and animalmanure is key to ensuring maximum yield of gas Differentcombinations of cassava peel with manure from cattle pigsand poultry have been studied

Adelekan and Bamgboye [8] found that mixing cassavapeels with pig manure had better biogas yield than usingeither of these wastes as a standalone feedstock Using 1 1pig-manure-to-cassava-peel ratio had a gas yield three timeshigher than a ratio of 3 1 Ofoefule and Uzodinma [7] alsoinvestigated the effect of cattle poultry and pig manure onbiogas yield of cassava peels They found that mean gasyield increased from lowest 229 litres per total mass ofslurry for cassava peels alone to highest 827 litres total massof slurry when combined with pig manure Adelekan andBamgboye [8] experimented with different combinations ofcassava peels and manure using peels-to-manure ratios of1 1 2 1 3 1 and 4 1 For all the manure types the ratio1 1 gave the highest yield of biogas though the 2 1 ratiofollowed closely for all manure types For cattle manure forexample the 1 1 ratio yielded 213 Lkg-TS while the 2 1 ratioproduced 195 Lkg-TS Using the same weight of cassava peelalone produced paltry 06 Lkg-TS Other studies includingAdelekan [18] and Oparaku et al [11] have found similarresults

Due to the critical nature of manure requirement foreffective gas production a livestock production and housingsurvey was conducted in the two communities to determinemanure availabilityThe survey considered livestock thatwerepartially or fully housedwheremanure could be recovered forenergy purposes In the final analysis a 2 1 cassava-peel-to-livestock-manure ratio was used for computation in order toincrease the efficiency of biogas productionWhile a 1 1 ratioappears to be the best combination based on experimentalresults presented above the low level of manure productionin the study communities informed the 2 1 ratio of peel tomanure

The methane potential (119875methane) was estimated using (1)which is modified from Kemausuor et al [19]

119875methane = 119875AR ([119910Buswellglu lowast 119862glu]

+ [119910Buswellhem lowast 119862hem] lowast 120578scale)

+

119899

sum

119894=1

(119875live lowast 119910man lowast 120578rec lowast 119862TS lowast 119910BMP)119894

(1)

where 119875AR is the amount of cassava peel available 119910Buswellis the methane potential calculated with Buswellrsquos formula119862glu is the concentration of glucan (cellulose or starch) incassava peel119862hem is the concentration of hemicellulose 120578scaleis the average efficiency of continuous biogas production119875live is the number of specific livestock population 119910man ismanure produced of one specific livestock annually 120578rec isthe recoverability of manure for specific livestock 119862TS isthe total solids concentration of manure and 119910BMP is themethane potential of specific livestock manure Factors 119894 and119899 represent the manure and total number of manure types


(based on the livestock type producing it) respectively forwhich methane potentials are computed The efficiency ofbiogas production is dependent on the inoculum whichin this case is livestock manure The analysis assumes 60recovery of manure from pigs and cattle only during theperiod of housing For example cattle are housed only atnight so that 60 recovery of the manure produced duringthe night is considered All of the manure produced duringthe day is not considered as being available since the cattleare then not housed

26 Financial Feasibility Assessment To determine the finan-cial feasibility of the biodigester Net Present Value (NPV)Internal Rate of Return (IRR) and Payback Period (PBP)were used as indicators NPV is the sum of the present valuesof individual cash flows over the project lifetime The IRR isthe discount rate at which the incremental net benefit streamor incremental cash flow is equal to zero [20]

NPV is computed using

NPV =119899

sum

119905=1

119861119905minus 119862119905

(1 + 119894)119905 (2)

IRR is computed using (3) and is the discount rate ldquo119894rdquo suchthat

0 =

119899

sum

119905=1

119861119905minus 119862119905

(1 + 119894)119905 (3)

where 119861119905is the benefit in each year 119862

119905are the costs in each

year 119894 is the interest (discount) rate and 119905 are numbers from1 2 3 119899 where 119899 is the number of years (life of biogasplant)

27 Social Benefit Analysis One of the very important rea-sons for promoting the use of agroindustrial waste for energyproduction is to contribute to job creation and incomegeneration for rural communities These are some of thekey indicators of success in bioenergy development [21]The social benefit analysis assesses the number of jobs thatcould be created and the corresponding income from usingagroindustrial waste to generate biogas

3 Results and Discussion

This section presents the results from the study and discussesits implications for bioenergy development in Ghana

31 Cassava Peel and Biogas Potential The ratio of peels tocassava roots based on the experiment conducted at thetwo processing plants is shown in Table 1 The average peel-to-whole-cassava ratio obtained for four cassava varieties is0303 with a standard deviation of 0016 This means thatfor every tonne of cassava processed approximately 300 kgof peels is obtained ranging from 290 kg for Esam varietyto 321 kg forDakwari variety The data obtained corroboratesfindings by the FAO [22] which states that about 250 to 300 kgof cassava peels is produced per tonne of fresh cassava root

Table 1 Field determined ratio of peels to cassava

Variety Peel-to-cassava-root ratio Moisture contentBensere (Yensere) 0312 199Nkruwa 0288 2009Dakwari 0321 2022Esam 029 198Average 0303 2000Standard deviation 0016 0188

Table 2 Cassava peel and biogas production details

Parameter Unit Asueyi AkrofromAnnual cassava consumption t 8000 7000Peels generated t 2424 2121Estimated peels collected forlivestock feeding t 727 1414

Peels discarded t 1697 707Peels considered for biogasproduction t 97 148

Firewood used for gariproduction ww 085 085

Estimated annual biogasproduction m3 27463 45744

Amount of firewood displacedper annum T 119 198

processed However the figure obtained is slightly higherthan 025 peel-to-cassava-root ratio quoted by Jekayinfa andScholz [23]

Based on the peels-to-cassava-roots ratio shown inTable 1 peels generated in the two communities are shownin Table 2 Following the monitoring and interaction withthe managers of the processing sites it was estimated thatabout two-thirds of peels in Akrofrom are collected forlivestock feeding and only one-third are collected in AsueyiThe lower collection rate in Asueyi can be attributed to theremoteness ofAsueyi community with poor road connectionThis makes it difficult and expensive for livestock farmersto regularly commute to the processing site for collectionof peels resulting in the creation of a huge pile of cassavapeel within the communityThe processing site has attemptedto manage the waste by resorting to open combustion (seeFigure 3) which has health implications for residents

Based on the livestock survey only 20 cattle and 20 pigsare kept inAsueyi community InAkrofrom community thereare 45 cattle and 12 pigs The cattle in both communitiesare housed only at night and allowed to open-graze duringthe day The pigs are however housed 24 hours a day Theanalysis for manure availability therefore estimated manureproduction from cattle for only half the day and a full dayfor pigs Also for the period when manure generation isconsidered only 60 recoverability is estimated as it is notpossible to collect all of the manure generated Based on thisanalysis only 46 t of manure is available from Asueyi and 75 tfrom Akrofrom community per annum


Figure 3 Pile of cassava peels undergoing open combustion

The biogas production estimate is based on 2 1 peel-to-manure ratio following experiments conducted by Ofoe-fule and Uzodinma [7] Adelekan and Bamgboye [8] andOparaku et al [11] Even though there are abundant cassavapeels the limited availability of livestock manure restricts thesize of digester Based on the 2 1 peel-to-manure ratio only4 of the peel generated inAsueyi and 7 fromAkrofrom areestimated to be fed into a biodigester for biogas generationThis is very little compared to an estimated 65 discardedcassava peels in Asueyi and 33 in Akrofrom The combinedfeedstock (peels and manure) available in Asueyi can onlysupport a 300m3 plant whereas the feedstock in Akrofromcan support a 500m3 plant The annual potential of biogasfrom both communities is approximately 75000m3 of gaswith an estimated 60 methane content The ultimate aimfor generating methane is to replace the use of firewood forgari processingThe potential for firewood replacement at thegari processing factories is shown in Table 2

As mentioned earlier it is estimated that a quarter of thecassava produced in Ghana is used for the production of gariMeanwhile all gari production factories rely on firewoodwhich means that approximately 580000 t of firewood wasused for the production of roughly 682000 t of gari in 2012alone The firewood used for gari production alone in 2012amounts to approximately 13 of the estimated 456 milliontonnes of firewood [24] consumed in Ghana in the same yearExploring the use of cassava waste to produce fuel for theproduction of gari could replace firewood and result in socialand environmental benefits Table 3 shows a projection ofcassava production for Ghana with corresponding estimatedamount that could be used for gari production Table 3 alsoshows the estimated firewood that could be used to processthe potential gari using an average of the firewood amountused in the two communities It is expected that close to13 million tonnes of firewood could be needed for gariproduction by 2030 under a business-as-usual scenario Thisfigure is only indicative because there might be differencesin other processing sites due to social practices efficiencyof roasting stoves and other factors However this amountof firewood needed for gari processing by 2030 depicts theextent to which demand for firewood could rise in the gariproduction industry with alarming consequences for thecountryrsquos wood resources Clearly this could compete with

rural households for scarce wood resources and calls forurgent attention

32 Financial Assessment of Biogas Development There aretwo options for using the methane gas (1) internally forcassava processing and (2) by sale to households in thecommunity to be used as cooking fuel In large plantsboth options could be pursued The financial analysis istherefore performed from two perspectives The first oneinvestigates the extent to which gas produced could be usedwithin the plant and its cost implications (compared to usingfirewood for roasting gari) The second analysis examinesthe profitability of generating the gas for sale to householdswithin the community

The capital cost for the biogas digester and other keyfinancial indicators are summarised in Table 4 Capital costfor the 300m3 plant in Asueyi is approximately US$ 91000rising to about US$ 151000 for Akrofrom where a 500m3plant is envisaged The financial analysis is performed for a25-year period assumed to be the lifetime of the digesterThe analysis from the fuel use experiment shows that ittakes approximately 085 kg of wood to produce 1 kg of gariFirewood is purchased at US$ 145 per tonne (using anexchange rate of 1 US$ to GHC 281 at the time fieldworkwas conducted)Thus at present value it takes approximatelyUS$ 12325 of firewood to produce a tonne of gari TakingAkrofrom as an example within the 20-year assumed lifetimeof the biodigester the project will deliver useful thermalenergy (this is the effective energy used taking into accountstove efficiency) of about 35 million kWh at a total costof US$ 300000 resulting in a levelised cost of approxi-mately US$ 0081 per kWh Delivering the same amountof energy (35 million kWh useful energy) with firewoodwill cost US$ 472800 over the 20-year period resultingin a levelised energy cost of approximately US$ 0135 perkWh Thus the levelised cost of firewood is 40 more thanbiogas on an energy equivalent basis The situation is similarfor Asueyi

If the gas produced were sold to the community the NPVover the 20-year lifetime of the project is US$ 78697 with anIRR of 177 in the case of Asueyi The payback is reached inthe 8th year As shown in Table 4 discontinuing the projectafter 15 years still makes it profitable Discontinuing in the10th year however results in a negative NPV rendering theproject unprofitable for a commercial enterprise Also forAkrofrom community the project is profitable for the 20-yearand 15-year project duration periods but unprofitable for a 10-year duration Payback is in the 7th year

The financial analysis shows that to the extent thathouseholds are willing to purchase the gas for cooking alarger plant is more profitable than a smaller plant whichagrees with general economic principles This however isdependent on the availability of large quantities of manure inclose proximity to the locations where agroprocess wastes aregenerated Even though cassava peels are in abundant supplyin most cassava processing locations transporting manurefrom outside the communities where processing factories arelocated would increase the project costs


Table 3 Estimates of firewood needed for gari production

Parameter 2015 2020 2025 2030Projected cassava production (t) 17149547 21066444 25877948 31788382Estimated cassava for gari production 25 of total produced (t) 4287387 5266611 6469487 7947096Estimated gari (t) 803885 987490 1213029 1490080Estimated firewood needed (t) 683302 839366 1031074 1266568

Table 4 Key financial variables of the analysis

Output variable Project life Unit10 years 15 years 20 years

AsueyiNPV minus7004 35021 78697 US$IRR 83 150 177 Digester size 300 300 300 m3

Capital cost 90690 90600 90690 US$Average revenue per year 19066 25340 34259 US$

AkrofromNPV minus832 72550 147905 US$IRR 99 162 187 Digester size 500 500 500 m3


Digester establishment

acquisition)5048

Labour (operating digester)2963

Maintenance1732

Feedstock and water transport

257

(incl land

Figure 4 Distribution of total production costs over projectlifetime

The combined production cost for both plants is sum-marised in Figure 4 Over the lifetime of the project capitalcosts constitute 50 of total project costs This is followedby the cost of labour establishment Transportation costsare low because feedstock and water are available withinthe premises of the processing sites which reduces the needfor transportation over longer distances The analysis alsoassumes manure availability from within the communitywhich avoids the need for higher manure transportationcosts

33 Job Creation and Income Generation Potential Theimportant social benefits of a bioenergy programme in anagroindustrial setting are its ability to create employment

Table 5 Annual socioeconomic benefits of project

Socioeconomic indicator Unit Akrofrom AsueyiSkilled jobs investment year Man-hours 16088 9659Unskilled jobs investmentyear Man-hours 12873 7745

Skilled jobs annual Man-hours 1560 1560Unskilled jobs annual Man-hours 113843 103398Biogas available per year m3 45744 27463Amount of firewood displacedper year Tonnes 198 119

and therefore provide income for employees engaged tomanage and maintain plants Equally important is the abilityof modern bioenergy to displace traditional fuel use in small-and medium-scale agroindustrial settings Summary of jobcreation potential and firewood displacement from the twoplants are shown in Table 5 It is expected that unskilled jobswill be sourced from within the locality Details of direct jobsare presented in terms of man-hours per year The unskilledlabour requirement for both projects in the investment yearis equivalent to 10 people engaged full-time for all businessdays in the year In the operating years the projects wouldcreate approximately 4 permanent full-time unskilled jobsand part-time management position for regular monitoringof technical performance Labour services in the operatingyears include those for loading of feedstock and monitoringof digester performance and the collection of manure tothe project site The direct unskilled job creation stands atone job per 200m3 digester This is slightly higher thanthe calculated direct employment of around one job for 117family sized (ranging between 4 and 15m3) digesters built[25] The low unskilled job creation is attributable to thefact that feedstocks meant for the digesters are producedon site and would not have to be transported over longerdistances

Income effects are directly related to the number ofjobs created on the project Unskilled labour man-hour rateis estimated at US$ 05 For an 8-hour working day thisexceeds Ghanarsquos minimum wage for the year 2014 which isGHC 6 or approximately US$ 214 per day (using exchangerate of 1 US$ to GHC 281 on May 1 2014 when newminimum wage was announced) (exchange rate informa-tion from httpwwwoandacomcurrencyconverter) Thehourly wage is also higher than current labour rate inthe study communities which is less than US$ 03 perhour


4 Discussion

Wood fuel continues to be the main fuel source in Ghanatoday contributing more than 75 to total fuel needs in 2010[26] According to data from the Ghana Energy Commissionper-capita consumption of wood fuels in 2013 amounted to415 kg [27] Even though per-capita consumptionmay reducegradually due to the increasing adoption of gas as cookingfuel growing population could result in an increase in thenational consumption Presently it is estimated that cassavaprocessing for gari alone contributes about 13 to the totalwood fuel consumption But the production of gari is justone way of processing cassava at the agroindustrial levelOther industrial uses such as the production of starch arealso dependent on the use of wood fuel Many other smalland medium agroindustrial activities such as the productionof palm oil and palm kernel oil are very much dependenton firewood as fuel source The wood fuel needs for theseactivities would have alarming consequences looking at thefact that the countryrsquos wood resource base is diminishingEstimates show that Ghanarsquos net increase in forest degrada-tion averaged about 115000 hayr during the period 2000ndash2005 [28] To prevent a disaster in the forestry sector effortsmust be made to explore the use of agroprocess residuesfor energy production As has been shown in this studythis has the opportunity to not only reduce the amount ofwood fuel used in the processing of cassava but also createjob opportunities for poor rural households and add incometo these communities Another important benefit of biogasproduction is the effluent which can be returned to cassavaand other crop fields as organic fertiliser after appropriatetreatment This extra activity could be considered in order tocreate a near-zero waste system

Presently there is no proper motivation for agroindus-tries to invest in biodigesters to supplement or replace theirprocessing fuel needs The state should examine financialstructures to assist agroprocessing plants to explore optionsof deploying biochemical or thermochemical biomass tech-nologies for generating energy from their waste resourcesOne option is by introducing a funding scheme to providesome capital subsidy This is one of the tools proposed in theRenewable Energy Law [15] to scale up the uptake of renew-able energy in the country Under the Renewable Energy Lawan RE Fund has been created to provide capital subsidies torenewable energy projectsWhat government must do now isto ensure the flow of resources into the fund and to provideappropriate funding to projects with bankable proposalsThere is also the need for assistance in the preparation ofbankable project proposals from agroindustries to providethem with source funding not only from the RE Fund butalso from bilateral and multilateral donor agencies that offerdevelopment assistance to the country

Apart from subsidies the state could also use environ-mental taxes and associated incentives to push for the uptakeof bioenergy technologies The introduction of environmen-tal taxes could encourage companies to shift to cleaner fuelsfor agroprocessing especially those that are located withinthe urban centres whose waste streams have polluting effectson the environment especially water bodies Next would be

the introduction of a gradual ban on the use of wood fuel foragroindustrial processing starting from large urban centresThis should go hand in hand with the granting of tax breaksfor modern bioenergy interventions Tax breaks could alsocome in the form of duty-free clearing of imported bioenergyplants The Energy Commission Environmental ProtectionAgency (EPA) and other appropriate agencies could lumpthese projects together and trade for carbon credits to partlydefray the cost of any subsidies and tax breaks

This study has shown that even though there couldbe enough cassava peels for the production of gas theunavailability of enough manure in cassava processingcommunities limits the amount of peels that could beutilised One of the models that could be used to obtainmanure for bigger biogas plants is a peel-manure exchangeprogramme where processing plants will come to somearrangement with livestock farmers to convey manure tocassava processing sites in exchange for cassava peels tofeed livestock This could make cheap manure available inlarge quantities for the production of biogas In the end itbecomes a win-win situation for both sectors as livestockfarmers have also had difficulty managing their manure[29]

The development of biodigesters to provide moderncooking fuels in rural communities has been a success in Asiawith notable success stories in China India andNepalThesesuccess stories were supported by government legislation andwere aimed at reducing forest degradation and introducingenvironmentally friendly fuel to an ever growing rural popu-lation Fortunately recent legislation in Ghana is supportiveof such schemes Tomove from the present to the stage envis-aged will require substantial funding and it is hoped that gov-ernment will provide the necessary incentives to make thisa reality

5 Conclusions

Agroprocess industries continuously generatewaste through-out the year which can be used for the generation of biogasor other energy carriers This study analysed the possibilityof using cassava peels from gari production industries forthe production of biogas The study was conducted in twocommunities in Techiman Municipality in Ghana The twocase study agroprocessing plants in the two communities eachprocess between 7000 and 8000 t of cassava per annumgenerating an excess of 4500 t of waste This study hasestimated that a combined total 800m3 digester for bothprocessing plants could displace a little over 300 t of firewoodper year and create both skilled and unskilled jobs in thecommunities Based on the amount of firewood currentlyused for gari production it has been shown that over a20-year period utilising firewood will cost 40 more thanusing biogas on an energy equivalent basis In a business-as-usual scenario this study has shown that approximately 13million tonnes of firewood will be needed by 2030 to producegari in Ghana The displacement of firewood with gas couldhave environmental economic and social benefits in creatingsustainable development


Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

This work was supported with a grant from Danida Fellow-ship Centre (DFC) of the Danish Ministry of Foreign Affairsas a part of the project ldquoBiofuel Production from Lignocellu-losic Materials 2GBIONRGrdquo DFC Journal no 10-018RISOslashFor additional information see http2gbionrgdk

References

[1] A Pandey C R Soccol P Nigam V T Soccol L P S Van-denberghe and R Mohan ldquoBiotechnological potential of agro-industrial residues II cassava bagasserdquo Bioresource Technologyvol 74 no 1 pp 81ndash87 2000

[2] FAO ldquoGlobal crop production datardquo 2014 httpfaostat3faoorgfaostat-gatewaygotodownloadQQCE

[3] F Kemausuor A Addo and J O Akowuah ldquoBiofuels produc-tion in Ghana opportunities and challengesrdquo in Proceedingsof the 4th National Conference on Agricultural Engineering pp301ndash320 University of Cape Coast Coast Ghana September2008

[4] FoodResearch Institute CassavaMarket andValueChainAnal-ysis Ghana Case Study 2013 httpwwwvalue-chainsorgdynbdsdocs859GhanaCassavaMarketStudy-FinalFebruary-2013 anonympdf

[5] N Cuzin J L Farinet C Segretain and M LabatldquoMethanogenic fermentation of cassava peel using a pilotplug flow digesterrdquo Bioresource Technology vol 41 no 3 pp259ndash264 1992

[6] S B Adeyemo and A A Adeyanju ldquoImproving biogas yieldusing media materialsrdquo Journal of Engineering and AppliedSciences vol 3 no 3 pp 207ndash210 2008

[7] A U Ofoefule and E O Uzodinma ldquoBiogas production fromblends of cassava (Manihot utilissima) peels with some animalwastesrdquo International Journal of Physical Sciences vol 4 no 7pp 398ndash402 2009

[8] B A Adelekan and A I Bamgboye ldquoComparison of biogasproductivity of cassava peelsmixed in selected ratios withmajorlivestock waste typesrdquo African Journal of Agricultural Researchvol 4 no 7 pp 571ndash577 2009

[9] P A Ukpai and M N Nnabuchi ldquoComparative study of biogasproduction from cow dung cow pea and cassava peeling using45 litres biogas digesterrdquo Advances in Applied Science Researchvol 3 no 3 pp 1864ndash1869 2012

[10] V Okudoh C Trois and T Workneh ldquoThe potential of cassavabiomass as a feedstock for sustainable biogas production inSouthAfricardquo inProceedings of the 12th International Conferenceon Sustainable Energy Technologies (SET rsquo13) Hong KongChina August 2013

[11] N F Oparaku A Ofomatah and E C Cokoroigwe ldquoBiodi-gestion of cassava peels blended with pig dung for methanegenerationrdquo African Journal of Biotechnology vol 12 no 40 pp5956ndash5961 2013

[12] A A Adeyanju ldquoEffect of seeding of wood-ash on biogasproduction using pig waste and cassava peelsrdquo Journal of

Engineering and Applied Sciences vol 3 no 3 pp 242ndash2452008

[13] P Panichnumsin A Nopharatana B Ahring and PChaiprasert ldquoProduction of methane by co-digestion ofcassava pulp with various concentrations of pig manurerdquoBiomass and Bioenergy vol 34 no 8 pp 1117ndash1124 2010

[14] Energy Commission ldquoStrategic National Energy Plan 2006ndash2020 Main Report Energy Commission of Ghana 2006rdquo 2006httpwwwenergycomgovghfilessnepMAIN20REPORT20final20PDpdf

[15] Ministry of Energy Renewable Energy Act Act 832 Parliamentof the Republic of Ghana 2011 httpenergycomgovghfilesRENEWABLE20ENERGY20ACT20201120(ACT20832)pdf

[16] Y Zhang A E Ghaly and B Li ldquoPhysical properties of cornresiduesrdquo American Journal of Biochemistry and Biotechnologyvol 8 no 2 pp 44ndash53 2012

[17] S T Thomsen Z Kadar and J E Schmidt ldquoCompositionalanalysis and projected biofuel potentials from common WestAfrican agricultural residuesrdquo Biomass and Bioenergy vol 63pp 210ndash217 2014

[18] B A Adelekan ldquoCassava as a potent energy crop for theproduction of ethanol and methane in tropical countriesrdquoInternational Journal of Thermal amp Environmental Engineeringvol 4 no 1 pp 25ndash32 2011

[19] F Kemausuor A Kamp S T Thomsen E C Bensah andH Oslashstergard ldquoAssessment of biomass residue availability andbioenergy yields in Ghanardquo Resources Conservation and Recy-cling vol 86 pp 28ndash37 2014

[20] J P Gittinger Economic Analysis of Agricultural Projects JohnHopkins University Press Baltimore Md USA 2nd edition1982

[21] Global Bioenergy PartnershipTheGlobal Bioenergy PartnershipSustainability Indicators for Bioenergy Environment ClimateChange and Bioenergy Division GBEP Secretariat FAORome Italy 1st edition 2011 httpwwwglobalbioenergyorgfileadminuser uploadgbepdocsIndicatorsThe GBEP Sustaina-bility Indicators for Bioenergy FINALpdf

[22] FAO Proceedings of The Validation Forum on The Global Cas-sava Development Strategy Food and Agriculture Organizationof the United Nations International Fund for AgriculturalDevelopment Rome Italy 2001

[23] S O Jekayinfa and V Scholz ldquoPotential availability of energet-ically usable crop residues in Nigeriardquo Energy Sources Part ARecovery Utilization and Environmental Effects vol 31 no 8pp 687ndash697 2009

[24] Energy Commission National Energy Statisticsmdash2000ndash2013Energy Commission of Ghana 2013

[25] E Buysman Anaerobic digestion for developing countries withcold climates [MS thesis]WageningenUniversityWageningenThe Netherlands 2009

[26] Ghana Statistical Services ldquo2010 Population and Housing Cen-sus Summary of Final Resultsrdquo 2012 httpwwwstatsghanagovghdocfiles2010phcCensus2010 Summary report of finalresultspdf

[27] Energy Commission National Energy Statistics 2000ndash2013The Energy Commission 2014 httpenergycomgovghfilesNational20Energ20Statistics 2014finalpdf


[28] FAO ldquoGlobal forest resources assessment Food and agricultureorganisation of the United Nationsrdquo FAO Forestry Paper 1632010

[29] F Kemausuor Assessment of technical potential and selectedsustainability impacts of second generation bioenergy in Ghana[PhD thesis] Kwame Nkrumah University of Science andTechnology (KNUST) Kumasi Ghana 2015

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anatomy Research International

PeptidesInternational Journal of


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International Journal of

Volume 2014

Zoology


Molecular Biology International

GenomicsInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


BioinformaticsAdvances in

Marine BiologyJournal of



Signal TransductionJournal of


BioMed Research International

Evolutionary BiologyInternational Journal of



Biochemistry Research International

ArchaeaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Genetics Research International


Advances in

Virolog y

Hindawi Publishing Corporationhttpwwwhindawicom

Nucleic AcidsJournal of

Volume 2014

Stem CellsInternational



Enzyme Research



Microbiology


a follow-up of the Root and Tuber Improvement Programme(RTIP) which was implemented from 1999 to 2005 RTIMPis being sponsored for a period of 8 years (2007ndash2014) andwas expected to be implemented across 60 districts but thishas now been scaled up to 90 districts) was instituted in2007 RTIMP is supported by the International Fund forAgricultural Development (IFAD) and the Government ofGhana (GoG) through the Ministry of Food and Agriculture(MOFA) and seeks to develop downstream activities likeprocessing and marketing of cassava The programme hasassisted local entrepreneurs to establish cassava processingfactories (processing cassava into gari) in communities wherecassava is produced on relatively larger scale The factoriesthat receive assistance are known as ldquoGood Practice Centres(GPC)rdquo because they follow a strict code of practice to ensurethe production of hygienic gari that can also be exported toneighbouring countries

In most cassava processing communities several tonnesof cassava peels are generated as a waste product from theprocessing activity With an expected increase in cassavaproduction it is also expected that waste generation willalso continue to rise Even though cassava peels can beused as feed for livestock the quantities generated and theremoteness of many of the communities where processingtakes place leave behind a lot of waste which is left to rot oris burnt with environmental consequences

There is therefore the need to explore other measures tomanage the waste accruing from the process in order toensure good environmentalmanagement practices within theprocessing communities To this end RTIMP launched aproject dubbed ProVACCA (PROmoting a Value Chain Ap-proach to Climate Change Adaptation in agriculture inGhana) in 2013 which has two principal aims (details ofthe project PROmoting a Value Chain Approach to ClimateChange Adaptation in Agriculture in Ghana (ProVAC-CA) can be found at httpoperationsifadorgdocuments65401617060381-148f-4291-b04a-24511050954e) The firstaim is to prepare cassava and other roottuber farmers toadapt to changing climate and by so doing ensure food secu-rity The second aim is to encourage the use of cassava wasteas fuel for cassava processing To achieve the second aimRTIMP is in the process of constructing pilot biodigesters orgasification plants in two communities to generate energyThis study aims to further explore the impacts of usingcassava wastes to produce biogas in these communities

The use of cassava wastes as a biogas substrate has beenexperimented either as a standalone raw material or incombination with livestock manure Cuzin et al [5] haveconducted an experiment on the production of biogas usingcassava peels Other researchers have carried out experimentsusing cassava peels in combination with other feedstocksSome of the feedstocks that have been used include poultrymanure [6ndash8] cow dung [7ndash9] zebra droppings [10] pigdung [7 8 11ndash13] and cowpea [9]

Currently communities processing cassava use firewoodas the main heating source as is the case with many ruralcommunity agroprocessing activities in Ghana Govern-mentrsquos policy objective is to ensure that agroindustries shiftfrom the use of firewood to more environmentally friendly

fuels such as biogas for heating The countryrsquos StrategicNational Energy Plan [14] has proposed an increase inrenewable and modern biomass energy in the final energysupply to achieve at least 10 penetration by 2020This is alsocorroborated by the Renewable Energy Law of Ghana whichwas promulgated in 2011 [15] However the extent to whichresidues from processing plants could serve as feedstockfor energy has not been the subject of much research inGhana This study therefore examines the technical andsocioeconomic potential of generatingmethane from cassavawaste to replace firewood which is increasingly becomingscarce The specific objectives are to

(1) examine the availability of cassava waste from cassavaprocessing and its potential for methane production

(2) perform financial assessment of producing methanefrom cassava waste

(3) assess job creation potential and other social benefitsof biogas production from cassava process waste

2 Materials and Methods

21 Study Area The study was conducted in two agroindus-trial processing sites in Asueyi and Akrofrom both locatedin Techiman Municipality of the Brong Ahafo Region (seeFigure 1) Techiman Municipality is a major cassava produc-tion district in Ghana The two communities were selectedfor this study because they are also major cassava process-ing areas within Techiman Municipality Both communitiesreceive assistance from RTIMP and have been selectedto benefit from a pilot bioenergy conversion plant Bothcommunities have similar socioeconomic characteristics Asof the last census in 2010Asueyi community had a populationof 2402 and Akrofrom community had 1505 people Bothcommunities are agrarian with the majority of residentsengaged in farming activities Farmers cultivate cassavacocoa and cashew in addition to other staple crops andvegetables Cassava is a major crop because of its commercialvalue as rawmaterial for gari production Cassava processingis a vibrant economic activity in both communities

Asueyi community processes about 8000 t of cassava peryear producing about 1500 t of gari Akrofrom communityhas two processing sites However data for this work wasobtained from only one site which processes an excess of7000 t of cassava per year Between five and ten differentcassava varieties are processed in both communities Cassavais generally available all year round due to a planned cul-tivation and harvesting schedule Occasional shortages mayoccur due to transportation or logistical challenges but notfrom shortage of the produce Firewood is the only fuel forroasting and is purchased from suppliers The study site inAsueyi had forty roasting points and Akrofrom communitysite had thirty-five Each roasting point consists of a stove androasting pan and is manned by one person

22 Description of Cassava Processing Activity Figure 2 sum-marises the stages in cassava processing for gari productionThe first stage is peeling and washing of the cassava root


Asueyi

TechimanAkrofrom

0 55 11 165 22275(mi)

TownsTechiman


Northern Region

Brong Ahafo Region


Western Region

Eastern Region

Upper West Region

Central Region

Upper East Region


Techiman


N

7∘40

9984000998400998400N 7

∘40

9984000998400998400N

2∘09984000998400998400W 1

∘40

9984000998400998400W


Water

















2)









+

119899

sum

119894=1


(1)






NPV =119899

sum

119905=1

119861119905minus 119862119905

(1 + 119894)119905 (2)


0 =

119899

sum

119905=1

119861119905minus 119862119905

(1 + 119894)119905 (3)






































acquisition)5048


Maintenance1732


257

(incl land










4 Discussion







5 Conclusions





Acknowledgment


References







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


Asueyi

TechimanAkrofrom

0 55 11 165 22275(mi)

TownsTechiman


Northern Region

Brong Ahafo Region


Western Region

Eastern Region

Upper West Region

Central Region

Upper East Region


Techiman


N

7∘40

9984000998400998400N 7

∘40

9984000998400998400N

2∘09984000998400998400W 1

∘40

9984000998400998400W


Water

















2)









+

119899

sum

119894=1


(1)






NPV =119899

sum

119905=1

119861119905minus 119862119905

(1 + 119894)119905 (2)


0 =

119899

sum

119905=1

119861119905minus 119862119905

(1 + 119894)119905 (3)






































acquisition)5048


Maintenance1732


257

(incl land










4 Discussion







5 Conclusions





Acknowledgment


References







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology











2)









+

119899

sum

119894=1


(1)






NPV =119899

sum

119905=1

119861119905minus 119862119905

(1 + 119894)119905 (2)


0 =

119899

sum

119905=1

119861119905minus 119862119905

(1 + 119894)119905 (3)






































acquisition)5048


Maintenance1732


257

(incl land










4 Discussion







5 Conclusions





Acknowledgment


References







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology





NPV =119899

sum

119905=1

119861119905minus 119862119905

(1 + 119894)119905 (2)


0 =

119899

sum

119905=1

119861119905minus 119862119905

(1 + 119894)119905 (3)






































acquisition)5048


Maintenance1732


257

(incl land










4 Discussion







5 Conclusions





Acknowledgment


References







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




















acquisition)5048


Maintenance1732


257

(incl land










4 Discussion







5 Conclusions





Acknowledgment


References







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


4 Discussion







5 Conclusions





Acknowledgment


References







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




Acknowledgment


References







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology











Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

research article technical and socioeconomic potential...

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