Pyrolytic conversion of agricultural and forestry wastes in Ghana, a feasibility study

THIS STUDY IN GHANA DEMONSTRATED THAT WOOD, SAWDUST, GROUND NUT SHELLS, OR RICE STRAW CAN BE CONVERTED TO CHARCOAL, OIL, AND GAS BY PYROLYTIC CONVERSION. A SIMPLE, SELF-SUSTAINING, CONTINUOUS-BATCH PROCESS IS SPECIALLY APPLICABLE IN GHANA. A SYSTEM BASED ON THIS PROCESS COULD BE CONSTRUCTED WITH MANY "OFF-THE-SHELF" ITEMS, ALONG WITH COMPONENTS READILY FABRICATED IN GHANA. GHANA IS GENERATING 2.7 MILLION TONS OF WASTE MATERIALS EACH YEAR THAT ARE SUITABLE FOR PYROLYTIC CONVERSION. THOSE COULD PRODUCE 342,000 TONS OF CHARCOAL AND ABOUT 275,000 TONS OF OIL. THE AMOUNG OF ENERGY GENERATED BY THE CONVERSION WOULD EXCEED THE TOTAL ENERGY PRODUCED IN GHANA IN 1973. THE DEMAND FOR DOMESTIC CHARCOAL IN GHANA WAS ESTIMATED AT 250,000 TONS IN 1975, WITH AN ANNUAL GROWTH RATE OF 2.7%. MORE THAN 99% OF THIS DEMAND WAS MET BY LOCALLY PRODUCED CHARCOAL, USING EARTH MOUNDS THAT ARE PRIMITIVE AND WASTEFUL. THE CHAR YIELD OF MODERN PYROLYTIC CONVERTERS IS MORE THAN DOUBLE THAT OF THE EARTH MOUND METHOD. IN ADDITION, THEY PRODUCE BOTH OIL AND GAS FUEL. THE OIL MAY BE USED AS FUEL FOR BOILERS, FURNACES, AND OTHER INDUSTRIAL USES. ANY SURPLUS OIL CAN BE EXPORTED. THE CHAR AND OIL MIXED TOGETHER CAN ALSO BE USED IN PLACE OF COAL IN RUNNING TRAINS AND FERRIES. GAS GENERATED BY PYROLYTIC CONVERTERS IS MOST PRACTICALLY USED ON SITE IN DRYING FEED MATERIALS OR IN UTILITY BOILERS. THIS REPORT INCLUDES A DESCRIPTION OF A PYROLYTIC CONVERSION SYSTEM THAT WOULD USE AN INPUT OF SIX DRY-TONS OF SAWDUST PER DAY WITH A CREW OF 11 WORKERS PER SHIFT. IT WOULD RUN THREE SHIFTS PER DAY, 300 DAYS PER YEAR, AND PRODUCE 450 TONS OF CHARCOAL AND 350 TONS OF OIL A YEAR. CAPITAL REQUIREMENTS, GROSS RETURNS, NET PROFIT, AND PAYOUT TIMES ARE DISCUSSED