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Thursday, October 28, 2004

Sweet sorghum, another excellent biofuel crop

Here at the BioPact we are closely monitoring tests and experiences with tropical bioenergy and biofuel crops. A few days ago, we reported on a field trial with a new variety of Sorghum in the Philippines, that is showing interesting results. Today, we focus a bit more in depth on the widely used plant.

According to the Sorghum profile in the Handbook of Energy Crops, the plant grows well in a wide range of climates and ecozones, from Cool Temperate Steppe to Wet through Tropical Thorn to Wet Forest Life Zones. Even though it is adapted to tropical and subtropical summer rainfall climates with rainfall from 25–125 cm annually it is of little importance in more humid areas with higher rainfall. This is important because it means that Sorghum does not grow in tropical rainforest areas. (Critics often focus on biofuel crops only from this perspective, perpetuating the myth that all bioenergy crops destroy the last remaining rainforests.) It also means that the vast Sahel region, where plenty of land is currently unused, may become a Sorghum energy hotspot.

Seed yields may be as high as 6,000 kg/ha, depending on cultivars and growing conditions. It yields great forage for silage as well (around 50MT/ha) and with the advent of cellulose ethanol, this biomass may be used as a biofuel feedstock (besides the grain). But the grain alone produces a lot of feedstock for "first generation" ethanol: a good sorghum hectacre will produce 5000 litres of syrup out of which some 4500 litres (500 gallons per acre).

Sorghum map:

Derived from the FAO's Land Suitability Maps for Rainfed Cropping database.

Full article