Reunion Island aims to achieve electricity autonomy by 2030 to limit its heavy dependence on fossil fuel imports. Currently, coal and oil account for 64% of electricity production in Reunion Island. In order to break this dependence, this study aims to analyse the integration of renewable energies into the electricity system and in parallel to study the economic and environmental efficiency of the proposed scenario using the LEAP energy modelling tool and the OSeMOSYS optimization model. In this work, two scenarios were developed. The business as usual (BAU) scenario refers to the trend scenario based on the import of conventional fuel. Whereas, the biomass scenario favours electricity self-sufficiency in 2030 by replacing coal and oil with local biomass and waste. Results show that by setting intermittent production at 30%, electrical autonomy in 2030 can be achieved through high levels of production from biomass and waste, which will represent 57.61% of total electricity production. Moreover, the biomass-based scenario has a low production cost and a low greenhouse gas (GHG) emission rate compared to BAU scenario. The integration of biomass and waste into the electricity system leads to a 91% and 91.6% reduction in the cost of electricity and GHG emission respectively in 2030.