1 Lima, F., Portugal-Pereira, J., Lucena, A. F.P., Rochedo, P., Cunha, J., Lopes Nunes, M. and Szklo, A. S. (2015), Analysis of energy security and sustainability in future low carbon scenarios for Brazil. Nat Resour Forum, 39: 175–190. doi:10.1111/1477-8947.12081 Analysis of energy security and sustainability in future low carbon scenarios for Brazil Abstract This study estimated a series of indicators to assess the energy security of supply and global and local environmental impacts under different mitigation scenarios through 2050 in Brazil, designed with the integrated optimisation energy system model MESSAGE-BRAZIL. The assessment of interactions between environmental impacts and energy security dimensions was complemented through the application of life cycle assessment (LCA) methodology. Overall results imply energy security establishes more synergies than trade-offs in increasingly stringent mitigation scenarios, especially patent within the sustainability dimension, which increases energy security and provides additional benefits regarding climate change mitigation and air pollution emissions. It is still necessary to extend analysis to other energy sectors in addition to the power supply sector, to promote a better understanding of repercussions of energy scenario expansion in energy security. Keywords: Energy assessment modelling; energy security of supply; life cycle assessment; climate change mitigation; Brazil. 1. Introduction Historically, Brazil has been at the forefront in the use of renewable energies. The share of non- fossil resources, including hydropower, bioenergy and sugarcane ethanol has made up, on average, some 45% of the country’s primary energy supply portfolio over the last ten years (EPE, 2014). However, this contribution has been declining. Over the past ten years, final energy consumption has increased by 43%, from 182 to 260 million tonnes of oil equivalent (MTOE), greatly due to a rise in quality of life, typical for an emerging economy such as Brazil. On the other hand and on the supply side, the expansion of hydropower and bioenergy projects has been limited due to socio-environmental restrictions (Soito and Freitas 2011; Von Sperling, 2012; Nogueira et al., 2014; Lucena et al., 2015) and economic constraints (Moreira et al. 2014). As a result, whatever new hydroelectric projects yet to be built in the country should adopt run- of-the-river technologies without pump-storage mechanisms, which implies in a lower capacity the regulation of monthly fluctuations of power demand and a reduced ability to mitigate the impacts of extreme weather events, such as droughts and floods (Lucena et al., 2009; Lucena et al., 2015). In recent years, Brazil has faced serious weather events, which have reduced production from hydropower and ethanol distilleries, highlighting the vulnerability of the country to climate change and weather uncertainty (Lucena et al. 2009; Schaeffer et al. 2012).