Vietnam’s first solar-powered bus started picking up passengers in the northern city of Haiphong on February 10.

The bus service, which is free for now, runs four times a day on the tourist island of Cat Ba.

The city said that the bus doesn’t produce greenhouse gas emissions and can be charged when solar energy is insufficient due to bad weather.

Once the battery is fully charged, the bus can carry up to 50 passengers for 160 kilometers.

The port city plans to have 10 solar buses next year before expanding the fleet to 30 by 2020. The project is a partnership between the city and the Japanese city Kitakyushu.