BERLIN

ACKNOWLEDGING that it makes little sense to spend billions to develop electric cars if charging their batteries produces roughly the same amount of carbon dioxide as the most efficient gasoline models, some European automakers are investing directly in renewable energy.

Wind farms, solar installations, hydroelectric power and so-called e-gas plants are among the experiments intended to demonstrate that zero-carbon transportation can be a viable alternative.

In Germany, several recent studies commissioned by the federal environment ministry concluded that in order for electric vehicles to help reduce the levels of greenhouse gases being produced, additional sources of renewably generated electricity must be created. In other words, the source of the electricity that charges electric cars and plug-in hybrids must not only be clean, but also new, beyond existing sources. Today, electricity from renewables accounts for 21 percent of all electricity in Germany.

With a goal of having six million electric cars on the road by 2030, German automakers have a strong incentive to make their newest E.V.’s as carbon neutral as possible. Daimler says its third generation of E-Smarts, the first that will be sold to the public, will be carbon-neutral in terms of driving.