Combustibles Fuels 81 Combustibles fs̤iles 42 Fossil fuels 42 Industria del petrl̤eo 30 Petroleum industry 30 Energy sources 23 more ... Fuentes de energa̕ 23 Gas natural 23 Natural gas 23 Industria petroqum̕ica 22 Petrochemical industry 22 Energa̕ 21 Energy 20 energa̕ 20 energy 20 gas natural 19 energy sources 18 fuentes de energa̕ 18 Petrl̤eo 17 petrl̤eo 17 natural gas 16 oil 16 petroleum 16 Oil 13 Biocombustibles 11 Esquistos bituminosos 10 Shale oil 10 biofuels 10 Monetizacin̤ de gas natural 9 less ...