[The idea is that the earnings from the Fund would replace the energy taxes as oil and gas resources are depleted]. Of course this requires a critical mass of savings (built up over a period) to generate sufficiently large income flows.
There is no risk-free path for monetary policy. The biggest risk of tightening too early or too fast is that the economy may weaken more than expected, forcing the central bank to reverse course. The record of central banks lifting off from the zero lower bound suggests caution in this regard.