Bacalah paragraf berikut: 'Solar power, wind energy, and hydroelectricity are gaining traction globally. These sources harness natural phenomena, offering sustainable alternatives to fossil fuels. While initial setup costs can be high, their long-term environmental benefits and reduced operational expenses make them increasingly attractive for a greener future.' Manakah ide pokok yang paling menyeluruh yang mencakup seluruh isi paragraf tersebut?