COST BENEFIT ANALYSIS
For the water lifting and for the generation of the electric current, in the remote rural villages, the following solutions can be considered competitors of the animal traction:
- Stand alone photovoltaic plants
- Fuel engines generator sets
- Pedal generators, i.e. foot crank generators.
Further, for water lifting and seed crushing, the draught animal power can be considered an efficient substitute of the work of women and children.
Unless here not examined, the evaluations here done could be considered consistent also with other solution, such as biomass or wind power.
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THE BASIC DATA FOR THE COST BENEFIT ANALYSIS
There are several articles and experiences on the use of animal traction for the generation of electric current.
Among them there is the article, at page 60 of the n. 40 of Draught Animal News, the magazine published by the Center for Tropical Veterinary Medicine of University of Edinburgh, that discusses very deeply the subject.
The article is HARNESSING AND IMPLEMENTS Power transmission unit for efficient utilisation of draught animal power in rotary mode of operation and the authors are C.P.Doshi, G. Tiwari, R. N. Verma, Rajiv Garg and Hemant Shrimali of the Department of Farm Machinery and Power Engineering of the College of Technology and Engineering, Maharana Pratap University of Agriculture and Technology.
Although not the most recent, it seems to be one of the most complete in the analysis of the perspectives of the use of draught animal power in rotary mode operation. Other more recent articoles are mentioned in the here proposed specific literature .
Further, dozens of patensts have been issued, in several countries, the more ancient of which is of 1925.
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DRAUGHT ANIMAL POWER ENERGY OUTPUT
According the most recent mentoned bibliography it is possible to do the following evaluations.
Some authors has been observed that a pair of oxen can generate approximately 45 ampere at 12 volts of electric energy, i.e. approximately 540 watts. The same authors observe also that, in the case shown, battery and inverter have more than 80% efficiency as expected.
In our contest it is possible to consider that the main aim of an electric current generator in remote villages should be the water lifting and the seed crushing.
In this case we can observe that the dc electric motor, of the pump and of the crusher, don’t need the battery. In this case we have not to consider the loss of efficiency due to the battery and to the inverter, than, it could be considered that the expected output, with the use of a pair oxen, could be 675 watts, i.e. (540w/80 *100)
According to the same authors is viable to consider 6 hours the working time per day of an animal, mule, came or ox.
Then, considering the data here elaborated, we can say that, using two different pair of animals, the daily output of one system could be of 8.100 wh/d (675*2*6).
Assuming an utilization of the equipment for 250 days per year we can obtain from the same equipment approximately 2.025 Kw/y.
To evaluate the costs for this source of energy the following consideration are proposed.
Within the village the animals work approximately for 120 days per year, then they are available for supplemental work for the remaining approximately 250 days.
Then their supplementary nutrition costs are represented by the difference between the food ration during working days and the food ration during not working days.
It shall be considered also that in several conditions, the animals are not fed in the stable, in fact they are fed at pasture and it shall be considered also that they exploit poor pastures otherwise unusable. Then we can consider that their supplementary feed costs are negligible.
The cost of the farmer work devoted to this task is represented by few minutes a day for the harnessing of the animals and for an overall watching of the same.
The yearly supplementary cost of these element has been here considered conventionally as equal to € 100, i.e. (i) no cost for pasture and super feed and (ii) few minutes a day of extra work for the farmer of the village. The farmer work cost has been assessed on the basis of a daily wage of a worker in those areas. The cost of the equipment could be considered negligible and depreciable in ten years.
The here mentioned cost have been defined supplementary because the animal - as already said - are already present in the villages and there utilized. Then their cost is amortized with their 120 days/year work already now performed.
Then, in the conventional determination of € 100 for the yearly cost of the system, we have considered the positive contribution that has the increase of the value of the animals. They in fact became productive – in the farm activity - not only for the said 120 days, as now, but for a larger amount of days.
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A COMPARISON WITH A PHOTOVOLTAIC STAND ALONE PLANT
A comparative assessment between the cost of the kwh produced through a draught animal powered electric generator and a standalone photovoltaic plant is here proposed.
The starting data for sun radiation have been assumed by the map Photovoltaic Solar Electricity Potential Mediterranean Basin, Africa and Southwest Asia published by the Institute for Environment and Sustainability of the Joint Research Center of the European Union.
According to the said map in the Equatorial Africa we can assume that with a 1 kwp (kwpeak) photovoltaic plant we can produce approximately 1.500 kwh a year or, that is the same, an average production of 4.1 kwh/d.
This means that to reach the same amount of energy that can be produced by a draught animal powered generator (8.100 wh/d as above) we need a photovoltaic plant of approximately 1.975 wp (8.100/4.1).
However in the following box there are the reasons for which, for the comparison, a little bigger dimension of the plant, 2.500 wp, has been choosen.
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The above sizing could be considered very prudential and then has been integrated for the following reasons:
• an average production of 1.975 kwh a year does not mean a daily effective production of 8.100 kwh/d because the current generation varies for the weather condition and the seasonal sun hours. So an extra sizing is necessary
• the accumulation could have an efficiency of 80%
• other regions northern then central Africa or with a monsoonal weather have a smaller sun factor, far smaller in winter season.
• the deep valleys areas have equally a smaller sun factor
• the animal driven system can work, with different pair of animals, for more 250 days per year or for more of 12 hours a day as above mentioned.
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STAND ALONE PHOTOVOLTAIC PLANT PURCHASE COST
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Modules | wp | 2500 | € 0,75 | € 1.875,00
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frame | | | | € 250,00
| cables and fittings | | | | € 70,00
| inverter 1 kw | | | | € 700,00
| batteries | a | 675 | € 0,70 | € 472,50
| tranport, installation and maintenance | | | | € 1.000,00
| TOTAL | | | | € 4.367,50
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COMPARATIVE KWH PHOTOVOLTAIC COST
To determine the kwh cost generated by a photovoltaic plant
trought the caluclation of the Net Present Value the above purchase cost has been considered togheter with cost and the lifecycle of the other components.
To determine the yearly cost of the plant, the said Net Present Value has been divided by 15. Then the yearly cost of the photovoltaic plant can be considered € 319,91.
Dividing this amount by 365 days and by the daily production of 8,1 kwh, we obtain a cost of the photovoltaic kwh of € 0.11.
The € 100 considered in the cash inflow is represented by value of the energy producible in the village by a draught animal powered generator.
Furthermore, if we consider the Net Present Value only in terms of resources spent outside the village, we can delete the € 100 from the Cash Inflow column. In this case the yearly foreign cost of the photovoltaic plant becomes € 389,11 and the cost of the kwh becomes € 0.13.
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| Discount Rate
| 5%
| Initial Investment
| € 4.367,50
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| Cash Inflow | Cash Outflow | Total |
| Year 1
| € 100
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| € 100
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| Year 2
| € 100
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| € 100
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| Year 3
| € 100
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| € 100
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| Year 4
| € 100
| € 472,50
| € 372,50
| Batteries
| Year 5
| € 100
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| € 100
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| Year 6
| € 100
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| € 100
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| Year 7
| € 100
| € 700,00
| € 600
| Inverter
| Year 8
| € 100
| € 472,50
| € 372,50
| Batteries
| Year 9
| € 100
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| € 100
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| Year 10
| € 100
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| € 100
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| Year 11
| € 100
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| € 100
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| Year 12
| € 100
| € 472,50
| € 372,50
| Batteries
| Year 13
| € 100
|
| € 100
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| Year 14
| € 100
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| € 100
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| Year 15
| € 100
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| € 100
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| Net Present Value
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| -$4.798,65
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Power
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kw
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0,75
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Tank capacity
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l
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4,2
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Autonomy
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h
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5,8
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Draught Animal generator power
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kw
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0,675
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hourly consumption of the fuel engine generator at the rate of the draught animal generator
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l/h
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0,65
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yearly hours of production (2*6h*250d)
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h/y
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3.000
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yearly consumption
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l/y
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1.955
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cost of fuel per liter
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€
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0,9
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cost of energy per year without considering the purchase cost of the engine
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€
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1.759,66
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kwh/y
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h
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2.025
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kwh cost
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€
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0,87
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PHOTOVOLTAIC VERSUS FUEL ENGINE GENERATOR
AN EU JOINT RESEARCH CENTER ASSESSMENT
To support the present discussion on the cost analysis for fuel engine generators and photovoltaic generator a good information arrives from the work of S Szab´o, K B´odis, T Huld and M Moner-Girona, Energy solutions in rural Africa: mapping electrification costs of distributed solar and diesel generation versus grid extension published in Environ. Res. Lett. 6 (2011) 034002.
The authors show in the maps, there presented, the cost of photovoltaic and fuel engine generation in Africa.
In those maps is possible to see that in a lot of areas the costs of photovoltaic and fuel engines generation is more expensive of the cost here proposed. This confims the cost advantages of a draught animal powered generator.
This confirms that the values calculated, in the present report, for engines and photovoltaic, are very Prudential.
Further it is also to be considered that the Joint Research study shows the cost of production of large plants for minigrid distribution, then plants with a very significant economies of scale.
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PEDAL CRANK GENERATOR
The pedal crank generators are having a certain success for their indubitable advantages.
Crank generators are moved by men by their legs movements. Then pedaling few minutes, the generator produces an amount of energy sufficient to feed batteries to light several households for several hours.
They are considered high viable for very small generation and very well appreciated for their usefulness. However they are capable to generate only a small quantity of energy not comparable with the energy that can be produced through the animal traction.
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WOMEN AND CHILDREN WORK
The animal traction, in certain condition, can substitute the work of women and children that now are very often engaged in water lifting and seed crushing. This can really improve the quality of life within the villages.
The following picture shows the reality of horticulture in certain areas (Lake Retba, Senegal 2008). In the second picture the hole of the well is magnified.
These pictures are presented to show the potential of a transportable animal traction generator for lifting water.
In fact it is envisageable that a small entrepreneur, owner of a draught animal powered generator, could help a farmer to lift water from the well. In this case the farmer, with a hose, can distribute faster the water to his field better then with the buckets.
Once the irrigation of the field is concluded the entrepreneur can move the equipment to other fields so increasing the production of the land and the productivity of the farmers.
Then, in the cost benefit analysis, for water lifting and seed crushing, certainly a comparison must be done between the use of animal traction and women and children work.
No problems in terms of productivity for which the superiority of animal traction is easy demonstrable.
Differently sometimes ethical questions have been posed for the use of working animals.
But is possible to say that the animal welfare is not compromised by this kind of work.
At this regard is of patent evidence that working animals have been selected in the millennia for cooperating in a proper way with the mankind.
This selection has conducted to very patient animals that do not suffer for a monotonous and tedious work.
Different manuals and FAO documents however mention the hours of daily work that does not compromise the welfare of the animals. Different documents suggest six hours, other suggest four hours with tree quarter of hours runs and an interval of 15 minutes.
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