An energy efficiency evaluation of a bagasse gasification system for the South African sugar industry

The sugar industry in South Africa has been in existence for over a century. During this period, it has experienced different challenges both in production and market value, but recently; it is experiencing some difficulties in terms of relying solely on the sugar market. Recently, with South Africa undergoing energy-mix processes, the sugar industry has identified an opportunity for the utilization of this excess bagasse. The generation of excess electricity can then be exported into the national grid after all factory electrical requirements have been fulfilled. Several studies have been conducted to develop a system that would be more efficient than the current system which is the direct combustion of bagasse and coal in some factories. This research followed a case study approach. Two systems, direct bagasse combustion and bagasse gasification, were evaluated for their thermal efficiency and their impact on the operation of the sugar industry. According to the available data, bagasse gasification system is said to be at least 50% more efficient than the current direct combustion system. The gasification system utilizes a bagasse gasifier instead of a conventional direct combustion boiler. The gasifier is used to gasify bagasse into synthetic gas, also known as syngas. This gas can be used in gas turbines to generate electricity, and it can be integrated into an existing steam system as a source of steam for process operations. The system analysis showed bagasse gasification system thermal efficiency as 55% as compared to the direct bagasse combustion system thermal efficiency of 19.68%. The knowledge contribution of this study was that of a practical evaluation of the current direct bagasse combustion system and the theoretical evaluation of the bagasse gasification system with similar inputs to identify the benefit of the utilizing the bagasse gasification system.