The first batch of buses running on bio-diesel took to the road in Helsinki on Friday.
Six vehicles utilizing the second-generation bio-diesel developed by the Finnish state-owned oil refining company Neste Oilare took part in the experiment, the Finnish daily Helsingin Sanomat reported.
The number of buses running on bio-diesel will increase to around 60 in the coming weeks.
The idea behind the experiment is to reduce emissions from public transport in the capital. The nitrogen oxide and particle emissions of bio-diesel are lower than that of regular diesel.
There are nearly 1,400 buses operating in the Greater Helsinki Area's public transportation system. The aim of the experiment is to make every second bus run on biofuel by the year of 2010.