The bio-energy conversion technologies that are widely used include direct-combustion, gasification, anaerobic digestion, pyrolysis and modular systems [36]. Based on the survey analysis, almost 77% of palm oil mills in Malaysia are using combustion or
CHP systems or a combination of both, while only 5% of plants are fitted with a gasification system. A study by Trummer [32] asserts that CHP technology at these facilities is designed for the electricity and heat demand of the plant. Even though some facilities are operating a conventional boiler system with above 70% efficiency,
most installations in the existing plants are still running with low-pressure boilers that are less than 40% overall cogeneration efficiency [19,32]. This matches the survey findings where more than 69% of plants are using relatively old technology,
which has been in operation for more than 10 years (Fig. 6).