Commercial scale cogeneration of bagasse energy in Mauritius

In this paper, a brief review is presented of bagasse energy development in Mauritius. Mauritius is an island where 90% of the arable land is under sugar cane and produces around 600,000 tonnes of sugar a year by processing around 5.8 million tonnes of cane. Around 1.8 million tonnes of bagasse are thus available on an annually renewable basis and efforts have consistently been made over the past 40 years or so to exploit this resource for energy generation for export to the public grid. This report reviews this development as from 1957, when the first sugar factory sold electricity to the grid, until the year 2000. The most significant development has taken place from the year 1988 onwards, following the success achieved in large-scale firm power generation at one sugar factory and in continuous power generation from two other factories. The government in that year clearly defined its policy vis-a-vis bagasse energy and enacted legislations which made provisions for fiscal incentives for energy conservation and utilisation within sugar factories and energy export to the public grid. These incentives were enhanced over time, each constraint to development being identified and dealt with appropriately. These are highlighted in the paper. Significant progress was achieved following these enactments in a number of energy-related issues within the factory. These issues include exhaust steam consumption in evaporation, use of bled vapour for juice heating and sugar boiling, boiler pressure and temperature resulting in either bagasse saving or increased export of energy to the grid. For example, equivalent bagasse used for electricity generation increased from around 150,000 tonnes in the late eighties to more than 500,000 tonnes in the late nineties. Concurrently the electricity export to the grid from bagasse increased from around 65 GWh to around 210 GWh between the two periods. These are equivalent to 10 and 49 kWh/t cane respectively. With implementation of additional projects, it is estimated that 800 GWh of electricity could potentially be generated annually from the sugar industry in Mauritius. Such projects have significantly increased the revenue of the sugar industry, crucial in this era of trade globalisation and low price of sugar in the world market. The gross revenue derived from sale of electrical energy now represents 90% of that derived from processing of cane into sugar by the millers in Mauritius.