0   mill ion ▁acres , ▁or ▁ 1 . 9   mill ion ▁square ▁kilom eters ) ▁were ▁devoted ▁to ▁b iod ies el ▁production ▁from ▁so y , ▁this ▁would ▁just ▁about ▁provide ▁the ▁ 1 6 0   mill ion ▁t onnes ▁required ▁( ass uming ▁an ▁optim istic ▁ 9 8   US   gal / acre ▁of ▁b iod ies el ). ▁This ▁land ▁area ▁could ▁in ▁principle ▁be ▁reduced ▁significantly ▁using ▁alg ae , ▁if ▁the ▁obst acles ▁can ▁be ▁overcome . ▁The ▁US ▁DO E ▁estimates ▁that ▁if ▁alg ae ▁fuel ▁replaced ▁all ▁the ▁pet role um ▁fuel ▁in ▁the ▁United ▁States , ▁it ▁would ▁require ▁, ▁which ▁is ▁a ▁few ▁thousand ▁square ▁miles ▁larger ▁than ▁Maryland , ▁or ▁ 3 0 % ▁greater ▁than ▁the ▁area ▁of ▁Belg ium , ▁assuming ▁a ▁yield ▁of ▁ 1 4 0 ▁t onnes / he ct are ▁( 1 5 , 0 0 0   US   gal / acre ). ▁Given ▁a ▁more ▁real istic ▁yield ▁of ▁ 3 6 ▁t onnes / he ct are ▁( 3 8 3 4   US   gal / acre ) ▁the ▁area ▁required ▁is ▁about ▁ 1 5 2 , 0 0 0 ▁square ▁kilom eters , ▁or ▁roughly ▁equal ▁to ▁that ▁of ▁the ▁state ▁of ▁Georgia ▁or ▁of ▁England ▁and ▁Wales . ▁The ▁advantages ▁of ▁alg ae ▁are ▁that ▁it ▁can ▁be ▁grown ▁on ▁non - ar able ▁land ▁such ▁as ▁desert s ▁or ▁in ▁marine ▁environments ,