The conversion/utilization of waste carbon dioxide is seen as a complementary option to the well-known capture, sequestration and storage strategies (CSS) to substantially reduce atmospheric CO2 (environmental concern). This approach is attractive regarding CCS strategies because CO2 can be transformed into a valuable chemical (economic benefit). Among the options available, methane and methanol are important chemicals that could be obtained from CO2 hydrogenation and used for energy production/storage or as intermediaries to other chemicals.A thermodynamic analysis regarding the hydrogenation of CO2 into CH4 or CH3OH was carried out. The analysis was performed to check the limitations and optimal conditions when converting CO2 from flue gas exhaust streams without previous removal of unnecessary species present in significant amounts (e.g. N2, H2O and O2). The present analysis supports that, from the thermodynamic point of view, the conversion of CO2 into 2 CH4 is favoured in comparison to the CH3OH valorisation strategy, for the considered pressure and temperature ranges.

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Energy policies established in 2005 have made Portugal one of the top renewable power producers in Europe, in relative terms. Indeed, the country energy dependence decreased since 2005, although remaining above EU-19 and EU-28 countries in 2015 (77.4% vs. 62.4% vs. 54.0%, respectively). Data collected from governmental, statistical, and companies’ reports and research articles shows that renewables and natural gas assumed a growing importance in the Portuguese energy mix along time, while oil followed an opposite trend. Recently, the country remarkably achieved a full 70-h period in which the mainland power consumed relied exclusively on renewable electricity and has several moments where power production exceeds demand. Currently, the main option for storing those surpluses relies on pumped hydro storage plants or exportation, while other storage alternatives, like Power-to-Gas (PtG), are not under deep debate, eventually due to a lack of information and awareness. Hence, this work aims to provide an overview of the Portuguese energy sector in the 2005–2015 decade, highlighting the country’s effort towards renewable energy deployment that, together with geographic advantages, upholds PtG as a promising alternative for storing the country’s renewable electricity surpluses.

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