For Obelisk of Power Battlefield, can you get channel 1 rune every turn?

No, you cannot get a channel effect from the Obelisk of Power battlefield every turn.

According to the card text for Obelisk of Power, its ability states: "At the start of each player's first Beginning Phase, that player channels 1 rune."

Because the effect is restricted to the "first" Beginning Phase, it only triggers once per player during the game, rather than every turn.