Christian East African Economic Development

January 2012 Trip to Uganda Update

Notes from January 2012 trip to Uganda …

  • Jatropha farm project …We visited the Jatropha farm. Plants are larger than when last seen, probably 6 to 8 ft tall. There are still 10 acres planted.  A 6.5 ft diameter by 15 ft deep tank is being installed near the river to provide a year-round source of water for irrigation. We installed a section of drip irrigation piping just to demonstrate how it can be done. The pump for moving water from the river-tank to the irrigation system has been purchased but not installed as yet.  Last year’s crop amounted to only 1500 kg (150 kg/acre). Hopefully irrigation and fertilization will improve the yield. Some harvesting takes place throughout the year.
  • Jatropha press … to extract the bio-diesel fuel oil from the seeds: We visited the Hoima machine shop that had built the press based on drawings supplied by Graham. They did a beautiful job. We tested the press and found the following:
  • Input = 12” dia x 3.5” deep bowl of seeds … bulk volume = 0.23 ft^3.
  • Output = 250 ml of oil (required about 10 minutes of press operation)
  • Assumptions: Each bag of Jatropha seeds weighs 50 kg (110 lbs) with dimensions of approximate 3 ft x 2 ft x 1.5 ft (= 9.0 ft^3). Then the approximate bulk density of the seeds is:  110 lbs/9.5 ft^3 = 11.6 lbs/ft^3.
  • Using this bulk density, the seeds we used weighed: 0.23ft^3 x 11.6 lbs/ft^3 = 2.67 lbs.
  • The oil produced = (250g)/(454g/lb)x 0.82 (specific gravity of oil vs. water) = 0.45 lbs.
  • Then the yield of oil from seeds = (0.45lbs/2.67 lbs) = 16.9%.
  • Total oil estimated from this years’ crop = (1500kg)x(2.2lbs/kg)x(0.169) =  557.7lbs.(or … 557.7 lbs at 6.15 lbs/gal = 90.7 gallons).


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