Engineer Vikram Seebaluck of the University of Mauritius and energy technology Dipeeka Seeruttun of the Royal Institute of Technology, in Stockholm, Sweden, have demonstrated that an optimal blend of sugarcane agricultural residues (30%) mixed with 70% sugarcane biogases (the fibrous residue left after sugar production) can be used to generate electricity at a cost of just 0.06 US dollars per kilowatt hour. That figure is on a par with the costs of other renewable energies, including wind power at $0.05/kWh.

Sugarcane is a giant perennial grass of the genus Saccharum that can be found in wet and dry tropical and partially subtropical regions. It consists of an above-ground bamboo-like stalk with trash, cane tops and leaves and underground rhizomes and roots. 30 tones per hectare of fiber and sugarcane juice are sent to factories for sugar production, which leaves 24 tones per hectare of waste biomass. Currently, sugarcane biogases is burnt for onsite heat and electricity production at sugar factories and surplus electricity is exported to the grid. That still leaves 24 tones per hectare of waste in the fields.

This waste has a similar energy content to biogases, Seeruttun says, which could make it technically viable to use this material together with biogases in a more effective way for electricity production. The 30:70 mixture of waste and biogases reduces the risk of fouling or slagging of the furnaces used to burn the material.

"The combustion of SARs for the production of electricity is technically and economically feasible and creates opportunities for increasing the renewable energy share in sugarcane-producing countries," the researchers explain.

The researchers analysis of the economics and technology required to exploit sugarcane waste products effectively suggests that bioenergy expansion from cane biomass would create rural jobs, reduce costly energy imports, and cut greenhouse gas emissions overall. Its use in electricity generation displaces the equivalent of 230 kg of coal for the equivalent amount of energy generated and 560 kg of carbon dioxide per tone.

They caution that harnessing this bioenergy and biomass potential will require significant increases in investment, technology transfer and international cooperation. Nevertheless, its high efficiency and concentration, mostly in the developing world, should be viewed as a global resource for sustainable development.