  To understand the mechanism allowing for the long-term storage of excess
energy in proteins, we study a Hamiltonian system consisting of several coupled
pendula in partial contact with a heat bath. It is found that energy storage is
possible when the motion of each pendulum switches between oscillatory
(vibrational) and rotational (phase-slip) modes. The storage time increases
almost exponentially to the square root of the injected energy. The relevance
of our mechanism to protein motors is discussed.
