  We present a Circular Energy Recovery Collider (CERC) as an alternative
approach for a high-energy high-luminosity electron-positron collider to
current designs for high-energy electron-positron colliders either based on two
storage rings with 100 km circumference or two large linear accelerators. Using
Energy Recovery Linacs (ERL) located in the same-size 100 km tunnel would allow
a large reduction of the beam energy losses, and therefore a reduction of the
power consumption, while providing higher luminosity. It also opens a path for
extending the center-of-mass (CM) energy to 500 GeV, which would enable
double-Higgs production, and even to 600 GeV for production and measurements of
the top Yukawa coupling. Furthermore, this approach would allow recycling of
not only the energy but also of the particles. This feature opens the
possibility for colliding fully polarized electron and positron beams.
