Marginal emissions factors in a country with high penetration of renewables: The case of Brazil

In this paper we assess the intensity of carbon emissions in Brazil, using the empirical framework of marginal emissions factor (MEF). Drawing on hourly time series for electricity generation and emissions, we show that Brazil's system-wide marginal emissions are remarkably low, reflecting the country's high penetration of renewable energy sources. This picture changes substantially, however, when focusing exclusively on the subset of thermal power plants. Under this refined estimation, the marginal emissions associated with thermal dispatch are sufficiently high to be fully comparable to those observed in European countries and the United States. The analysis also uncovers pronounced spatial and temporal heterogeneity across Brazil's four regions, with the South exhibiting the highest marginal factors. These findings carry important policy implications: broad, undifferentiated expansion of renewable capacity (such as photovoltaic generation) yields limited emissions reductions unless it directly displaces thermal generation, whereas targeted, region- and season-specific energy-efficiency interventions can deliver significant decarbonization benefits.