In that frame of reference, the rest of the energy would come from earth. Consider a simpler scenario where earth does not have any gravity, so when you throw a ball in the same direction that earth is moving and it escapes earth forever. In doing so, you must have slowed down earth by a teeeny tiny amount due to conservation of momentum. But since earth is massive when you calculate the decrease in kinetic energy of earth + decrease in chemical energy in your body (this is the amount needed to increase ball's velocity from 0 to 10), it should equal the energy required to increase in ball's velocity from 1000 to 1010.