  In active transport molecular communication (ATMC), information particles are
actively transported from a transmitter to a receiver using special proteins.
Prior work has demonstrated that ATMC can be an attractive and viable solution
for on-chip applications. The energy consumption of an ATMC system plays a
central role in its design and engineering. In this work, an energy model is
presented for ATMC and the model is used to provide guidelines for designing
energy efficient systems. The channel capacity per unit energy is analyzed and
maximized. It is shown that based on the size of the symbol set and the symbol
duration, there is a vesicle size that maximizes rate per unit energy. It is
also demonstrated that maximizing rate per unit energy yields very different
system parameters compared to maximizing the rate only.
