The mobility sector is currently undergoing a revival thanks to the funds available for fleet renewal. The funds placed on the table for modernising the bus fleets in Italy alone amount to more than 7.5 billion euro. A large part of these funds are intended to finance the purchase of zero-emission vehicles. In other words, the country is turning over a new leaf by partially turning off the diesel taps. But what are the technological alternatives to the traditional diesel engine? More than one. The first, the most popular in urban areas, is electric cars, although the cost and time required to build the infrastructure have slowed down the transition process for the time being. Hydrogen, which in Italy is spreading like wildfire, is also zero-impact. The largest Italian fleet is Sasa Bolzano, while Tper Bologna is ready to put a fleet of 127 hydrogen-powered buses into service. The options of natural gas and liquefied gas, which, although based on the traditional internal combustion engine, allow a decisive reduction in exhaust emissions, are still valid. Hybrid buses (mainly gas-powered), which guarantee a reduction in emission of approximately 20 per cent are not zero-impact, but nevertheless are sustainable technologies.

But is diesel really at the end of the line? For urban use, it would seem so. For other mission profiles, there are still few funds to be spent (quickly). Yet, there would be a solution. In fact, there is a 'natural' diesel on the market that could make a decisive contribution to the goal of making public transport increasingly sustainable. Its name is HVO (Hydrotreated Vegetable Oil), a biofuel made from waste raw materials and vegetable residues and from oils generated by crops that do not compete with the food chain. HVO is capable of being used in Euro 5 and Euro 6 diesel engines with a 90% reduction in emissions. Its popularity is held back by the fact that there is no excise discount and its cost at the pump is higher than traditional diesel. Traditional diesel, which until recently was capable of providing a horizontal response to operators (from urban to long-distance lines), unlike the new technologies that respond, instead, to specific operational needs. The watchword for the near future? Energy mix. Where HVO will also find a place, as has already happened in Germany.