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03 Nov 2017

ALTERNATIVE DRIVE UNITS: NOT AN EASY SOLUTION

Since cities like Paris, Madrid, Athens and Mexico have announced the ban on diesel vehicles from their city centres, the possibilities of alternative drive units for long-distance coaches are being more and more explored. Electricity seems not immediately an option. Biodiesel, hybrid and LNG offer more perspective at first sight, as appears from the results of a comparative study presented at the International Coach Conference of IRU and Busworld Academy.

As ordered by IRU and others, Riccardo Enei of the Italian study agency Isinnova presented the preliminary results of a comparative study of alternative drive units for coaches that are deployed for long distances. CNG, biodiesel and hydrogen were taken into consideration and hybrid concepts were looked at as well. Electric powering was disregarded because that is more suitable for urban traffic. For the time being, CNG seems to be the best option in the short term because the technology is known, the investment cost is relatively limited and the supply is guaranteed. For biofuel, there is currently still a shortage of high quality biodiesel and availability.


The more expensive purchase price of hybrid vehicles is playing tricks because two power lines must be integrated that combine electric with gas, diesel and electricity (battery cost) as well as the further evolution to more economical and more efficient engines which will co-determine the future.


During the subsequent panel discussion, it was pointed out that account should also be taken of the country in which you are driving, the route that you take and the type of transport provided (intercity bus service, shuttle, round trip). It was also argued that currently no fully-fledged alternative drive unit is available for coaches while they already exist for freight transport. Once again, it was emphasized that the image of the environmentally friendly Euro6 engine has been conveyed insufficiently so far. If all Euro3 or older buses would be replaced by Euro6, a much greater impact on the environment might be achieved than a limited transition to alternative drive units. It was rightly mentioned that the current studies pay too little attention to possible new types of powering that are being developed. People also wondered whether there is room for a second drive unit within the available volume and admissible weight of a coach and whether there would still be enough space for passengers and their luggage.