Elon Musk unveiled a new home-based battery that can store electricity and serve as a backup generator.

Cars used to be the ultimate symbols of freedom. A century ago Henry Ford’s Model T liberated millions of people from drudgery and slower modes of transport.

Since its arrival on the scene, Tesla has offered its well-heeled customers a different type of freedom, one that is gaining more currency as awareness of climate change and the ill effects of fossil fuels rise. That is the freedom from gas stations, from gasoline and oil, from gas taxes, from emissions.

Tesla’s new battery could finally sever the chain between transport and fossil fuels.  Energy storage is stationary. And a giant, expensive battery pack installed in your home doesn’t really enhance mobility. But it does contribute to freedom in two ways. First, it enables more people to liberate themselves from the electrical grid and fossil fuels at home. Second, it offers the potential to finally sever the chain between transport and fossil fuels.

Having an independent power source at home has become a bigger issue for people all over the country in recent years, as storms and floods tend to make electricity unavailable for longer periods of time.

A loud, fossil fuel-burning generator is comforting. But it would be more efficient—and more pleasing, and more green, and more quiet—to have a powerful battery in the basement that could kick in at times of need. Solar power is famously intermittent, which is a fancy of way of noting that the sun doesn’t shine for a big chunk of the day.

Storage in conjunction with solar achieves two goals. First, excess power created during daylight hours, if not sold to the grid, can be used to charge the battery. The battery can be used in times of emergency. Or, in theory, it could be tapped at night, to pick up the smaller electric load of a sleeping household—thus further reducing the need for dependence on the grid.