By the beginning of the 2030s, the entire bus fleet should be completely emission-free. BVG is relying mainly, but not exclusively, on battery-electric drives. "I can't yet say whether 80, 85 or 90 percent of the conversion will be battery-powered," said BVG boss Henrik Falk a few months ago. Tests are currently being carried out with fuels made from used vegetable and cooking oil, known as HVO, in order to keep newer diesel vehicles running for longer. The company has so far left open the question of whether hydrogen drives will also be an option in the long term.