Okay, Tesla has shown that the Model S battery pack can be swapped out quickly and elegantly, to the accompaniment of thumping techno music. However, there are a lot of questions about how this is going to work in the real world, so after Thursday’s live demonstration, CEO Elon Musk stuck around to offer some answers.

A “pack swap” will be a premium service for travelers in a hurry. The cost will be comparable to a large tankful of gas at the going local rate, currently about $60-80, and will be billed to a credit card on file, so drivers never have to leave their cars.

Swapping will be available as soon as the end of 2013, starting with the California corridor and eventually rolling out to every Supercharger location. Each swap station will have about 50 batteries in stock, and no reservations will be required. Musk expects each location to cost the company about $500,000.

Of course, batteries do age over time, so a swapper may be making an unequal trade. Tesla envisions several scenarios. If you come back to the same station on the return leg of your journey, you can simply have your original battery pack replaced (for another swap fee). Or, you can have your original pack returned later for an unspecified “transport fee.” If you choose to keep the pack you received in the swap, and it’s newer than your original, Tesla will bill you for the difference in value.

This side benefit of swapping eliminates one objection for potential EV buyers: the fear of getting stuck with an old, tired battery (Nissan, take note). Pack swapping amounts to a fast and convenient (if not cheap) way to upgrade your battery any time you like. You can even swap your 60 kWh pack for an 85 kWh pack, and pay the difference.

For industry observers, one of the major objections to swapping is that it seems like a transitional technology. Don’t worry, Musk has thought of that. He conceded that, by the time Tesla’s third-generation vehicle comes on the market, charging technology may have advanced to the point that there won’t be much demand for battery swapping.

At the moment however, it may just be a way to eliminate the biggest obstacle to wider EV ownership. “I think it’s important for us to address the reasons people are not buying electric cars,” said Musk. “People need to feel they have the same level of freedom they have with gasoline cars. If they need to get somewhere in a hurry, they can do that. In fact, they can get there faster.”

None other than Forbes opined that “pack swapping seems to doom range anxiety to the technology graveyard, along with other concerns of yesteryear like running out of hard-drive space.” May it rest in peace.

Sources: Tesla, Green Car Reports, Forbes