  We present a study comparing the energy carried away by a coronal mass
ejection (CME) and the radiative energy loss in associated flare plasma, with
the decrease in magnetic free energy during a release in active region NOAA
10930 on December 13, 2006 during the declining phase of the solar cycle 23.
The ejected CME was fast and directed towards the Earth with a projected speed
of 1780 km/s and a de-projected speed of 3060 km/s. We regard these as lower
and upper limits for our calculations. It was accompanied by an X3.4 class
flare in the active region. The CME carried (1.2-4.5)x10^32 erg
(projected-deprojected) of kinetic and gravitational potential energy. The
estimated radiative energy loss during the flare was found to be 9.0x10^30 erg.
The sum of these energies was compared with the decrease in measured free
magnetic energy during the flare/CME. The free energy is that above the minimum
energy configuration and was estimated using the magnetic virial theorem. The
estimated decrease in magnetic free energy is large, 3.11x10^32 erg after the
flare/CME compared to the pre-flare energy. Given the range of possible
energies we estimate that 50-100% of the CME energy arose from the active
region. The rest of the free magnetic energy was distributed among the
radiative energy loss, particle acceleration, plasma and magnetic field
reorientation.
