The Karratha Gas Plant (KGP) is a complex integrated facility which produces liquified natural gas (LNG), domestic gas (Domgas), condensate, propane and butane products. The multi-train facility has been operating for 40 years with several phases of expansion resulting in a range of gas turbine technology and energy efficiency levels across the facility. The challenge for the next phase of KGP operation is to manage declining North West Shelf (NWS) feed gas levels, and the addition of Other Resource Owners feed gas while reducing emissions and maintaining energy efficiency. A flexible emissions forecasting tool has been developed which allows unit and whole of facility emissions reduction and energy efficiency options to be assessed. The tool builds on current quarterly timestep production forecasts and models ambient temperature, unit turndown and turn-off strategies, and potential implementation of lower emissions technology. The ability to generate and compare life of field emissions profiles for extrapolated operating modes and proposed modifications allows unit strategies and phasing of emissions reduction modifications to be investigated and screened before further economic assessment and creation of marginal abatement cost curves (MACC).