▁generate ▁enough ▁electric ity ▁to ▁power ▁ 6 0 0 ▁U . S . ▁homes . ▁Wind ▁energy ▁is ▁also ▁becoming ▁more ▁afford able , ▁as ▁prices ▁have ▁decre ased ▁over ▁ 8 0 % ▁since ▁ 1 9 8 0 ▁and ▁are ▁expected ▁to ▁keep ▁decre asing . ▁The ▁oper ational ▁costs ▁associated ▁with ▁wind ▁power ▁are ▁also ▁low . ▁ ▁However , ▁conflicts ▁can ▁arise ▁concerning ▁land ▁use , ▁as ▁the ▁wind ▁tur b ines ▁use ▁between ▁ 3 0 ▁and ▁ 1 4 1 ▁acres ▁per ▁meg aw att ▁of ▁power ▁output ▁capacity . ▁Some ▁oppon ents ▁of ▁wind ▁energy ▁argue ▁that ▁the ▁land ▁could ▁be ▁better ▁used , ▁although ▁the ▁land ▁can ▁still ▁be ▁used ▁for ▁gra zing ▁liv est ock , ▁agricult ure , ▁and ▁high ways . ▁Another ▁issue ▁regarding ▁wind ▁energy ▁concerns ▁the ▁disturb ance ▁to ▁wild life . ▁Many ▁studies ▁have ▁been ▁done ▁to ▁assess ▁the ▁impact ▁of ▁wind ▁tur b ines ▁on ▁bird ▁and ▁bat ▁populations , ▁and ▁the ▁disturb ance ▁of ▁wind ▁tur b ines ▁has ▁been ▁found ▁to ▁be ▁relatively ▁low ▁and ▁does ▁not ▁pose ▁a ▁threat ▁to ▁species ▁population . ▁ ▁Sol ar ▁energy ▁▁ ▁Sol ar ▁energy ▁is ▁another ▁commonly ▁used ▁renew able ▁energy ▁source . ▁It ▁could ▁provide ▁well ▁over ▁the ▁energy ▁needed ▁to ▁power ▁our ▁world - ▁the ▁surface ▁of ▁the ▁earth ▁receives ▁ 1 2 0 , 0 0 0 ▁ter aw att s ▁of ▁solar ▁radiation , ▁which ▁is ▁ 2 0 , 0 0 0