Volkswagen new boss has said he is committed to driving the auto maker’s transformation from gasoline-powered cars to electric ones. But Oliver Blume has also been a big backer of a different approach to lower emissions: electrofuels.

Electrofuels are a type of synthetic fuel that produce energy the same way gasoline and diesel do. They combust as part of a conventional power drive. But they are manufactured by mixing water and carbon dioxide to create a low-carbon replacement fuel for diesel or gasoline engines. Right now, they are too expensive to make economically. Some experts believe they will never be as cheap as battery electric cars.