The Sierra Club magazine reports that Eberhard feels that an electric fuel tank (the battery pack) is the "ultimate multi-fuel" system. "You can use natural gas to generate the electricity. You can burn coal. If you don't want any part of that, you can use wind power or put solar panels on your roof."
Eberhard has answers for concerns about lithium ion batteries. To counter the fire threat, he says all the batteries are individually wrapped to isolate a hot cell and prevent further problems. Further, he says, lithium ion batteries are considered "landfill safe" though he rightly prefers they be recycled instead. In fact, Tesla will recycle them.
[Source: Sierra Club]