Integration of renewable energy in the electricity market poses significant challenges on power grid management due to the volatility of these sources. In fact, the mismatch between renewable power generation and load curves, along with the need for grid stability, may lead to substantial curtailments when potential electricity supply exceeds demand. In this respect, the surplus from renewable energies can be conveniently exploited to produce hydrogen via electrolysis. This concept can be referred to as "Power-to-Gas" and "Power-to-Liquid" when synthetic grid gas and liquid fuels are respectively produced via syngas hydrogenation processes and is rapidly emerging as a promising measure in support of renewable energy penetration, leading to the decarbonisation of energy generation without affecting grid reliability. This study evaluates the impact of Power-to-Gas and Power-to-Liquid systems on future CO2-reduced scenarios, characterised by increasing shares of renewable energies and electric vehicles under a holistic Smart Energy System perspective. Results show potential synergies among crucial energy sectors in terms of CO2 emissions, curtailments and costs. Among the proposed options, synthetic grid gas produced by biomass gasification, and subsequent hydrogenation, leads to the best techno-economic scenario with a reduction of CO2 emission of 30% with negligible change in yearly total costs. (C) 2019 Elsevier Ltd. All rights reserved.