Exergoenvironmental analysis of a combined cycle power plant fueled by natural gas from an offshore platform

Abstract

This study presents a detailed, disaggregated Life Cycle Assessment for natural gas obtained from an offshore area in Rio de Janeiro/Brazil, based on the Eco-indicator 99 method. The stages of production, transmission, purification, distribution, and final use of natural gas are considered. Environmental data are used to develop an exergoenvironmental assessment, which unravels the formation of environmental impacts throughout the energy system. The results of the Life Cycle Assessment indicate that the environmental impacts associated with offshore natural gas are quantified as 336 mPts/kg, where the majority of impacts are related to purification at the refinery (249) mPts/kg, followed by extraction at the platform (59.3 mPts/kg) and distribution (19.5 mPts/kg). The results of exergy and exergoenvironmental assessments quantified the environmental impacts associated with electricity production from natural gas in a combined cycle power plant as 61.9 mPt/kWh. These impacts can be reduced by considering a 50% decrease in flaring/venting as well as air and liquid emissions, resulting in 59.8 mPt/kWh. These findings are applicable to the assessment of natural gas power plants and the exploration of alternative abatement options (such as CO2 capture systems).