Sunbird Bioenergy (SL) has successfully completed a series of trials to test the suitability of locally sourced sustainable biomass feedstock to produce power in the company’s 32 MW power plant. The boilers were originally designed for bagasse, but in order to extend the power production beyond the sugarcane harvesting season, the company has tested other sustainable feedstock including; napier grass, wood chips, palm kernel shells and rice husks.
Napier grass proved to be an effective and sustainable alternative biomass feedstock to bagasse. When tested in the boilers designed and built by, Isgec, it was found to have similar combustion characteristics, and could produce the required steam for the 32 MW Siemens power generator.
Furthermore, naper grass (Pennisetum purpureum, also elephant grass) is a species of perennial tropical grass native to the African grasslands and has similar growth characteristics. This has the advantage of enabling the company to use the existing harvesting, transportation and processing equipment.
The existing transportation hauls the harvest napier grass from the fields to collection and storage points.
The napier grass remains at the collection point for several days allowing the water content to reduce naturally in the warm air. This enables more effective combustion in the boilers.
It is then transported to the factory, where is is weighed on the weigh bridge and added to the biomass inventory.
The napier grass then enters the mill (the same as with sugarcane) where it is shredded in preparation for the boilers. The shredded napier grass is approximately 2cm in length which is the ideal size for the boilers.
The biomass operations team operate 24 hours a day and are responsible for delivering 25 tonnes of biomass per hour to the factory. This volume of feedstock allows the power plant to operate at its designed capacity, and continuously export Power to Freetown via the national grid.