Technological Feats of Agricultural Engineers in
Nigeria II
Dryers and Solar Cookers
Nigeria, one of the
Tropical countries is blessed with plentiful sunshine all the year round. In a
research work led by Prof. R. N. Kaul of blessed memory in Ahmadu Bello
University Zaria in the 19970s, it was reported that Nigeria received an
average amount of 490 w/m2/day of solar power. This made Nigeria to be a country with high potential
for the development of solar energy. On a one hectare piece of land with an
assumed fifty percent reception efficiency of solar power, Nigeria has a
potential of tapping a huge amount of 2.45 megawatts of solar energy. Again, it
was also reported that the
maximum amount of solar power obtainable in Nigeria per square meter is 940 w/m2/day
depending on the geographical location of the area because of the cloudy nature
and the forestation of the considered location. Sunlight is a renewable energy
source that has been used in many traditional technologies for centuries. It
has a widespread of uses especially where other sources of energy supplies are
absent, such as in remote locations and rural areas. The primary forms of solar
energy are heat and light. Secondary forms and effect include photosynthesis, wind,
the hydrologic cycle, fossil fuels and electricity. Some of the technologies
developed by Agricultural Engineers using solar energy are notably the dryers
and solar cookers.
Dryers of various capacities for drying different
agricultural commodities have been developed and tested in many higher
Institution and research centres. In the
IAR workshop of Ahmadu Bello
University (ABU), Zaria alone, fifteen
natural, force convection and hybrid
dryers for multi-crops were designed and fabricated in recent times. The
natural convection dryers use solar energy alone for the drying, the force convection dryers use blowers to pass the heated air
over the drying materials while the hybrid uses a combination of solar collector, fossil fuel exchanger
and blower for the drying of the
commodities. The capacity of the fabricated
dryers range from small-scale with drying chamber capacity of 25 – 50 kg of
crops to medium scale with capacity up to 250 kg of crops. One of the most efficient and locally fabricated
dryers is the IAR forced convection solar energy dryer which was constructed using aluminium sheet and other locally
available materials. It is a Low cost &
low energy demanding dryer for vegetable crops and was found to be saving 115% drying
time when compared with traditional
sun drying. Another important feat is the development of forced convection
solar dryer for drying of meat (kilishi).
This dryer can dry a batch of 20 kg meat in six hours in a highly hygienic
condition. The dryer was developed by Bello N. Babalola, a 2014 ABU
Agricultural Engineering graduate.
Solar cooker is a device which uses the energy of direct sunlight to heat, cook or
pasteurize food or drink. Many solar cookers presently in use are relatively
inexpensive, low-tech devices, although some are as powerful or as expensive as
traditional stoves, and advanced, large-scale solar cookers can cook for
hundreds of people. Solar cooking is a form of
outdoor cooking and is often used in situations where minimal fuel
consumption is important, or the danger of accidental fires is high, and the
health and environmental consequences of alternatives are severe. The concept
of solar cooking started more than 100 years ago and was used by the French
foreign legion in the 1870s. All solar cookers works on the same principles of
concentrating the direct solar rays to raise food or counter to cooking
temperature. In Nigeria, many Agricultural Engineers and other scientists
developed solar cookers as alternative cooking devices for rural dwellers.
Among the recent ones are the cookers developed by Engr Ajewole Joachim, a
graduate of Rufus Giwa Polytechnic, Owo, Ondo State, Engrs Ocheche Edwin and
Engr Mulikat Shuaibu Abubakar,
both are graduates of Ahmadu Bello University Zaria.
Generally, Solar cookers are
classified into two categories. One is the
box type and the parabolic reflector focusing type. The cooking ability of the box type, seems to be satisfactory in comparison to cost involved. Parabolic reflector
focusing type cooker needs frequent
adjustment to track the apparent motion of the sun, for these reasons this type
of parabolic reflector solar cooker is not much popular. The technology for a solar box cooker is simple,
it is a box made from a heat
retaining material (plywood, cardboard, etc). The top of the box consist of one to two layers of clear
glass or plastic and on the bottom is a black collector plate made
ideally of metal upon which a cooking pot
(black pot) rests. The solar cooker developed by the ABU graduates is a
simple box with a single reflector mirror, to direct the sunrays through a
double glass surface, into an enclosed box with a black pot enclosed. During
testing, it was able to boil water at 115OC, cook rice within a
period of 75 minutes to 2 hours depending on the cooking time in the day. Using
the solar energy for cooking has many advantages especially in a developing
country like Nigeria; it preserves food nutrient because of moderate cooking
temperature, reduces risk of fire accident and injuries in search for fire wood
and other local fuel, it is economical and prevents desertification, since the
wood would be left to check desert encroachment. However, its major
disadvantage is that it cannot be used when there is no sunlight.
Farm Operations Machinery
No doubt, the use of farm machinery to execute farm
operation increases amount of land to be cultivated, resulting in increased
food production. Thus, use of farm machinery ensure a continuous cropping
system as it is unlikely that large areas of cultivated land will be abandoned.
Right from planting to harvest and post harvest operations; different
capacities of the farm machinery were developed by Agricultural Engineers in
the last three decades for adoption by small scale farmers. These categories of
farmers have always been the major focus of the Engineers considering the level
of agricultural development nationally. In
2014 and 2015, engineering graduates of ABU, Zaria developed an animal drawn
single and double row planters. The single row planter has a capacity of 0.114
ha per hour with field efficiency of 66%, which was modified to double row
planter with a capacity of 0.298 ha per hour and efficiency of 91%. Within the
same period, a single row planter - cum- fertiliser applicator was developed by
the same organisation. The machine can successfully plant seeds at rate of
0.1064 hectare per hour as well as apply fertiliser at the rate of 115 kg per
hectare.
Weeding operation is one of the most tedious farm
operation that makes farming unattractive to many people especially the youths
because of drudgery. Agricultural Engineers have made tremendous effort in
developing animal drawn mechanical weeders. Two examples are suffice; IAR Animal Drawn Straddle Row Weeder and EMCOT Rotary
Weeder with capacities of weeding a quarter of hectare per an hour each.
Obviously, the target of this weeding technology is small and medium scales
farms who constitute more than 80% of the farming population. (to be
continued)
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