Industrial energy efficiency improvement through cogeneration: A case study of the textile industry in Thailand

Natural gas cogeneration presently appears to be a promising alternative to satisfy the energy utility requirement of the process industries thanks to the favorable energy policy of the Government of Thailand. In this paper, we detail a case study in a textile factory where use of gas-turbine cogeneration with a post-combustion heat recovery system is found to be the most suitable solution. This system has not only the highest thermal efficiency, but it can also provide flexibility in operation. Financial analysis of the most suitable cogeneration configuration provides the net present value (NPV), pay-back period (PBP) and internal rate of return (IRR) with values of 310 million Baht, 5.3 years and 26.6%, respectively. The thermal-matching option is not found to be attractive because the sale price of electricity to the state electric utility is not high enough to absorb the additional investment required for the prime mover. Incorporation of an absorption chiller in the cogeneration system does not bring in any additional advantage as there is no excess waste heat available in this factory.