Las fiestas patronales de las colonias del Pacífico sur en Cali

The pathway for the production of 1 MJ of Jatropha biodiesel fuel is in figure 6.3

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6.2.5.1 Jatropha Farming System

Because of the absence of data concerning agricultural practices and the low commercial scale of Jatropha plant in Nigeria, a generic and hypothetical Jatropha farming system had to be developed to guide this study This assumes a multiple small- scale farming system for Jatropha in Ogun-State, Nigeria. Three scenarios have been examined which include: i) a rain-fed base-case, ii) an irrigated base-case, iii) and a large scale farming system.

Jatropha seedlings were assumed to be grown in polythene bags on nursery beds using seeds with a 80% survival rates. Field preparation in Nigeria includes activities such as tree felling, clearing, stump removal, ploughing and harrowing: these are usually achieved, by manual labour, over several days with the use of axes, hoes and cutlasses. Hence, in the base-case rain-fed scenario, manual labour involving 5 men ha-1 day-1 was assumed whereas field preparation in large-scale plantations would be undertaken by mechanized farming. Eshton et al. [2013] and Gm¨under et al. [2009; 2012] reported diesel consumptions of 12-15 litres of diesel fuel ha-1 for land preparation, whereas Prueksakorn and Gheewala [2008] concluded that the range is 25-40 litres of diesel fuel ha-1. In Nigeria, farm machinery is rarely new and often improperly managed. There is also a tendency that farm tractors have high rates of fuel consumption. Hence, twin run of a farm tractor with diesel fuel requirement of 25 litres ha-1 run-1was assumed in the present analysis.

Fertilizer application is not a common practice on small-scale farms in Nigeria due to the costs involved and because good fertilizers are rarely produced locally. This study assumes 122, 47,134 kg ha-1 yr-1 of Nitrogen (N), Phosphorus (P), Potassium (K) [Prueksakorn and Gheewala, 2008; Reinhardt et al. 2007] is applied twice per year for the first three years of the plantation, after which the residues from Jatropha plantation such as husks and seedcake are returned to the field in order to achieve a higher yield. As opposed to popular opinion about the protective insecticidal and microbicidal properties of Jatropha plant, Terren et al. [2012] reported pest and diseases to be prevalent in Jatropha farming: Jatropha plants do not appear to be protected by their insecticidal and microbicidal properties. Thus, insecticide applications of 0.04 g plant-1 yr- 1

of Chloropyrifos 20EC is assumed to be applied every 3 years based on local availability and herbicide application of Glyphosphate (3 litres ha-1 yr-1) and Paraquat (2 litres ha-1 yr-1) [Gmunder et al. 2012]. Weeding and harvesting are assumed to be

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accomplished manually, twice a year for the first five years, involve 5 men ha-1 day-1 [Prueksakorn and Gheewala, 2008], and annually, with an average of 50 kg of dry seeds per worker-1 day-1.

The energy expended by manual labour was calculated using the average daily food- intake of 2120 kcal (8.9 MJ) capita-1 day-1, as estimated for a West Africa adult [van Wesenbeeck et al. 2009]. All other forms of manual labour, such as those relating to the operation of equipment were not included in the present study for both the Jatropha system and the reference diesel-fuel system. An additional gasoline consumption of 60 litres ha-1yr-1 was included in order to account for the transportation of workers in and out of the farm, as well as miscellaneous activities, such as power generation on the farm. Irrigation is not considered in the base-case scenario because the average annual precipitation in Ogun-State exceeds 1000 mm. In the irrigated scenario, irrigation is assumed to be supplemented daily with 8 litres of water per plant per application during the dry season that lasts up to six months between October and March. For large-scale farming systems, irrigation is practised for the six months of the dry season and involved the use of farm machinery and equipment requiring 250 litres ha-1 of diesel fuel for all farm operations aside from miscellaneous activities, such as (power generation, transportation of workers.

Because, a yield range of 3 to14 tonnes of dry seed is reported [Jingura et al. 2011, Ogunwole, 2014] for good soil and as low as 0.7 tonnes for poor soil or wasteland [NBS, 2011], this study assumes an average yield of 3.5 tonnes of dry Jatropha seeds ha-1 yr-1 is produced over the life (~20 years) of the considered plantation. Although this is a pessimistic yield value in view of the current rapid advancements in Jatropha farming, spoilage is nevertheless likely during and after harvesting due to poor storage facilities, especially during high-humidity conditions. Also, the temperature in Nigeria is favourable for microbial growth. Other losses such as product theft could be incurred by farmers: this would result in an overall low-seed recovery. Furthermore, an oil-seed yield of 35% was assumed, although, Umaru and Aberuaba [Jingura et al. 2011] reported a yield of 53%, Aransiola et al. [2012] reported a value of 52%, whereas Ogunwole [2014] recorded a yield of 37% for Jatropha curcas plants grown locally.

Farming location are primarily near villages and far distant from cities. Thus, this study assumes a centralized fruit cracking and expelling facility for multiple Jatropha farming, where transportation distances are up to 50 km from the plantation field and an additional

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50 km to the biodiesel production facility. Here, fruits are assumed to be transported by a farm truck of 20 tonnes capacity and a fuel consumption of 20 mpg, to the oil extraction facility.

6.2.5.2 Oil Extraction

Available power is a limiting factor in Nigeria. Thus small-scale farmers will likely choose the least expensive and readily available technology for expelling oil. Thus seeds were assumed to be sun-dried and harvested by manual labour. The technology assumed, in this study, for extracting oil from dry seed is cold pressing. The process begins with the use of a fruit cracking machine to remove the seed shells, followed by an oil expeller that ejects oil from the seeds, and finally a filtering unit is used to purify the oil. It is deduced that 3.5 tonnes of dry Jatropha seed will yield 1.11 tonnes of crude seed oil, 0.92 tonnes of seed cake and 1.42 tonnes of seed husk, with oil and husk yields of 35% and 42%. The residue (i.e. seed cake) is returned to the field to supplement the applied inorganic fertilizer. The product yields resulting from Jatropha production are presented in Table 6.3.

Table 6.3: Output for Jatropha Biodiesel Fuel Production

1

Brittaine and Lutaladio, 2010; 2Jingura et al. 2011; 3Prueksakorn et al. 2010; 8Wang et al. 2011; 5Kessom et al. 2009

Product t ha-1yr-1 MJ/kg Seed cake 0.92 25[1] Shell Hull 1.88 11.1[2] Husk 1.47 16.0[2] Glycerine 0.1 25.6[3] Biomatter (Leaves) 2.06 3.62[28] Biomatter (Stem) 4.19 3.93[28] Seed 3.5 24.0[3] Seed Oil 1.11 39.7[5]

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6.2.5.3 Oil Conversion and Use

The crude oil obtained from extraction of Jatropha seeds is transported to a biodiesel plant located 50km away from expelling facility location. The oil is assumed to be first pre-treated to reduce the fraction of free fatty acids by reacting with methanol and sulphuric acid [Eshton et al. 2013], followed by a base-catalyzed transesterification reaction in an 80 Litre biodiesel batch–reactor, which has a 97% efficiency, where electricity requirement is 4 kWh/batch [Whitaker and Heath, 2009; Prueksakorn et al. 2008]. The mixture of glycerol and biodiesel produced is separated in the presence of excess water. The fuel produced is then transported by road over 50km to the power plant to be used. The fuel is combusted in a 109 MW sited rated gas turbine (126MW ISO rating with thermal efficiency of 34.1%). The direct GHG emissions from fertilizer application are stated in Table 6.4.

Table 6.4: Life cycle GHG Emissions from Jatropha Biodiesel Production

Process CO2 kgCO2 kg -1 CH4 kg CO2 eq.kg -1 N2O kg CO2 eq. kg -1 Total Fertilizer application 1.93 0 0.0965 2.03

Emission factor for CO2, and N2O per N fertilizer are 0.2 kg kg-1[29] and 0.01 kg kg-1 for CH4 respectively.