Friday, June 8, 2012

8 Ha Biofuel Farm in Davao

We have taken a long-term lease on 8 hectares with coconut palms and a fish and prawn farm south of Davao with a view to operating a fully sustainable, self-sufficient farm. This is the plan, which may take up to two years to execute (mainly because the palms trees need to flower before we can tap them):

  1. We source prawn fry from the Vannamei hatchery next door. The prawn ponds get an upgrade with HDPE liner, which increases the number of cycles from two per year to three, and facilitates maintenance of the ponds. The ponds are flushed on a monthly basis following the lunar tidal cycle. Waste gets trapped in a receptacle and tipped into the biogas digester; prawn waste is rich in nitrogen. Probiotics are employed to kill the contaminating bacteria after each cycle, but no hormones or antibiotics are used in the actual prawn production.
  2. 20 goats and ten heads of cattle consume weeds and add carbon-rich manure to the biogas digester, supplemented with nitrogen rich waste from the poultry farm next door - waste that would have otherwise been released into the sea. 
  3. Nipa sap is harvested via a 'milking machine' system of tubes and pipes, keeping the sap protected from insects, bacteria and rain. The sap is fermented in tanks, in preparation for distillation to ethanol, OR boiled down to syrup and mixed with protein to make shrimp feed.
  4. 4-5 hectares are planted with Aromatic Dwarf Coconut and sugarpalm with companion species, mainly nitrogen fixing legumes. We deploy the usual bag of tricks using microorganisms in the soil (mycorrhiza, frankia etc).
  5. Palm trees are 'milked' for sap, which is either boiled for palm sugar production, or fermented and distilled in the ethanol plant.
  6. Fermentation process produces CO2, which is piped in to the greenhouse to create a CO2 enriched environment. This turbocharges photosynthesis.
  7. Ethanol production targets about 70-80% purity. Stillage is treated in the biogas digester.
  8. Solar troughs heat palm oil which is circulated through coils in a vacuum cooker that evaporates the sugar juice to 80 Brix syrup; vacuum is created with a 12V solar pump. The steam from the evaporation process is captured and piped into the crystallization pan, or the distillation unit for ethanol production. 
  9. Biogas digester is kept at 50-60 degrees Celsius using the surplus heat generated in the sugar and ethanol plant. It produces biogas as a back-up thermal power source for the sugar and ethanol plant and liquid fertilizer for the crops. Surplus biogas produces electricity through a biogas generator. If power is generated in sufficient quantity it may be sold back to the grid.

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