If you immediately try to go renewable 100%, you'll run into the problem that wind is intermittent, the sun doesn't shine at night and solar cells provide less power in bad weather, etc. But in the summertime, solar provides the most power just when you need the most A/C to power air conditioning. If you have to burn fossil fuel to cover the gaps, that's OK; you're covered and you don't need to import nearly so much from unstable or hostile regimes.
In the long term, there are a number of possible mechanisms for energy storage to handle uneven availability of wind or solar. In addtion to batteries, you can pump water uphill to store both water and energy, use flywheels, reward people for using energy when it's highly available, etc.
We'll end up using a mix of technologies, and that's a good thing, just like it's a good idea to diversify your investments.