Portugal is highly dependent on imported fossil fuels, which has stimulated diversification of the energy mix. The increased use of both natural gas and renewable energy sources is the main reason for the decline in greenhouse gas emissions since 2005. The challenge will be to sustain this reduction once economic growth resumes, with a view to achieving Portugal’s targets by 2020. Portugal has also actively supported energy efficiency and renewable sources, and it is poised to meet its ambitious renewable energy target.