In my view, the earth is accelerating upwards simply because that is what we observe it to be doing.
Sorry, what do You observe? You observe things accelerating towards each other: a man, a ball and the earth. But you cannot decide, which of these is moving and which is at rest.
E.g., I was sitting in a train at the station, waiting for departure. Looking out the window, I suddenly had the impression, the train departs but accelerates in the wrong direction. A few moments later I noticed, my carriage was still at rest, it was the other train on the neighbor track moving out of the station.
While the Quantum Mechanics and General Relativity gravity explanations of "graviton puller particles" and "bendy space" provide equivalent explanations to the results of the above experiments, those things are are completely undiscovered, and so, are decidedly less empirical.
What's not empirical on the effect of gravity? It has been measured, observed and tested in various experiments.
What's missing is a theory for the "reason" of gravity. You don't need to cite latest physical theories to explain your experiments. The effect of gravity alone, as empirical verified, can explain your observations.
Per the question of where the energy for comes from; that is a question easily left as unknown.
If You accuse the gravity model, that physicist still searching for the "reason", than I accuse FET not providing the "reason" for the acceleration of earth.
The phenomenon of pushing is well established and long known to science. The phenomenon of push can occur with existing physics, whereas pulling particles or bendy space requires new physics.
Ahem ... "push" can occur for electromagnetic forces, between equal polarized charges or magnetic fields.
These forces can also "pull" when differently polarized.
Other "fundamental interactions" or forces: Gravity, strong and weak nuclear force, I would attribute a "pull" only.