A Study of the Effect of Gas Turbine Emissions on the Economics of Natural Gas Pipeline Transportation

Natural gas seems to be the cleanest fossil fuel today and consequently receiving tremendous rise in demand for both industrial and domestic energy requirements. The availability of natural gas requires it to be transported from the production area through processing plant to the consumers; this requires compressor station mostly driven by gas turbine. The gas turbine used as prime movers produces emissions which constitute environmental hazard and are usually taxed. This paper seeks to investigate the consequences of the emission tax on the economics of a natural gas pipeline project. For the present study, a 609.8 mm (24″) pipe size and a throughput of 4.5 million m³ per day of natural gas over a distance of 512 km (320 mile) were employed. A brief review of prime movers employed in natural gas transportation is presented. An existing emission code was adopted and integrated with a thermodynamic performance module of a gas turbine. A FORTRAN code was developed to integrate the emission module, the thermodynamic performance module and an economic module developed to handle the pipeline economics as well as analyzing the tax on the emissions produced by the gas turbine. The results presented shows that the negative effect of the emission tax on the transportation cost of natural gas is far higher than on Net Present Value (NPV) considering a project life of 30years. An increase of about $160.5 per m³ in transportation cost was established owing to the emission cost. Since the tax charge on emission varies from region to region, the model developed can be used to assess the impact of emission tax on the economics of a pipeline project and a decision reached as to whether a prime mover with no on-site emission is preferred for a particular project after due consideration of other controlling parameters.