  The efficiency of a Brownian particle moving in periodic potential in the
presence of asymmetric unbiased fluctuations is investigated. We found that
there is a regime where the efficiency can be a peaked function of temperature,
which proves that thermal fluctuations facilitate the efficiency of energy
transformation, contradicting the earlier findings (H. kamegawa et al. Phys.
Rev. Lett. 80 (1998) 5251). It is also found that the mutual interplay between
asymmetry of fluctuation and asymmetry of the potential may induce optimized
efficiency at finite temperature. The ratchet is not most efficiency when it
gives maximum current.
