Increasing power generation with enhanced cogeneration using waste energy in palm oil mills

Enhancing power generation using waste energy promotes sustainability. Bio-waste from palm oil mills (POMs) has been used as a renewable energy (RE) source to produce steam and electricity in Thai POMs for decades. Because the amount of generated bio-waste normally exceeds the amount that can be used internally by the POMs, energy-efficient practices in the cogeneration plant, which includes waste heat emitted by sterilization steam venting and the biogas engine in the power plant, are disregarded. However, a government policy that allows operators to sell electricity back to the grid has been enacted, and plant owner's attitudes toward cogeneration have since changed. Increased attention has been focused on fuel conservation and energy-efficiency practices, and this study is a product of that increased interest. This work aims to increase power generation from POMs by integrating waste energy through an improved cogeneration system. A standard 45-t/h fresh fruit bunch (FFB), POM in southern Thailand was selected as a case study. The steam consumption and boiler and turbine efficiency were measured and analyzed along with the data on the engine waste heat, and a power generation model for the POMs was then proposed. The analysis results showed that the surplus electricity can reach 2.834 MW and 4.223 MW with and without crude palm oil (CPO) production, respectively. The operational rate of the cogeneration plant is also suggested to be extended to 7,500 continuous hours per year instead of the 4351 intermittent hours implemented at present.