The world has a variety of energy resources: conventional power (in yellow), and renewable energy (blue and green, green is the best) sources. These are icons to show all that. This is from the American EPA's old website (thus public domain) before it got wiped by current politics.
能源
biogas、biomass、change、chart、climate、coal、energy、EPA、gas、geothermal、global、hydropower、icon、natural、nuclear、power、school、solar、sources、symbol、thermal、warming、wind
沼氣、生物質、更改、圖表、氣候、煤、能源、EPA、加油站、地熱、全球、水電、圖標、自然、核、功率、學校、太陽能、來源、符號、熱、變暖、風
資料來源：openclipart ( https://openclipart.org/ )