  Two robots stand at the origin of the infinite line and are tasked with
searching collaboratively for an exit at an unknown location on the line. They
can travel at maximum speed $b$ and can change speed or direction at any time.
The two robots can communicate with each other at any distance and at any time.
The task is completed when the last robot arrives at the exit and evacuates. We
study time-energy tradeoffs for the above evacuation problem. The evacuation
time is the time it takes the last robot to reach the exit. The energy it takes
for a robot to travel a distance $x$ at speed $s$ is measured as $xs^2$. The
total and makespan evacuation energies are respectively the sum and maximum of
the energy consumption of the two robots while executing the evacuation
algorithm.
  Assuming that the maximum speed is $b$, and the evacuation time is at most
$cd$, where $d$ is the distance of the exit from the origin, we study the
problem of minimizing the total energy consumption of the robots. We prove that
the problem is solvable only for $bc \geq 3$. For the case $bc=3$, we give an
optimal algorithm, and give upper bounds on the energy for the case $bc>3$.
  We also consider the problem of minimizing the evacuation time when the
available energy is bounded by $\Delta$. Surprisingly, when $\Delta$ is a
constant, independent of the distance $d$ of the exit from the origin, we prove
that evacuation is possible in time $O(d^{3/2}\log d)$, and this is optimal up
to a logarithmic factor. When $\Delta$ is linear in $d$, we give upper bounds
on the evacuation time.
