CO2 LIFECYCLE EMISSIONS, AVOIDED EMISSIONS, AND ENERGY PAYBACK TIME FOR PHOTOVOLTAIC SYSTEMS IN BRAZIL

Abstract

Photovoltaic (PV) systems, which convert solar energy into electricity, are an alternative for reducing greenhouse gas emissions. The installation of these systems is growing worldwide and in Brazil, as well. Although they are considered emission-free during their operation phase, life cycle CO2 emissions are of concern. Modules’ manufacturing consumes energy, which might come from fossil fuels, and release CO2 during combustion. Thus, to determine the real environmental contribution of photovoltaic systems, life cycle assessments (LCA) seek to calculate emissions and energy payback time (EPBT) of systems installed around the world. In this work, we carry out a review of the LCA literature for PV systems and harmonize the EPBT and CO2 emission results for systems installed in Brazil, considering the range of solar radiation on the national territory. The availability of solar radiation in Brazil varies and affects the avoided emissions by PV systems, which also depends on the emissions of the installed technologies. Even considering these variations and the average grid electricity emission factor, photovoltaic installations in Brazil avoid 346 to 366 g of CO2 per kWh of electricity generated by PV systems. The median energy payback time ranges from 1.2 to 8.9 years, according to the maximum and minimum irradiation values, respectively.