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Welcome > Themes > Clean Buses > Opinion > A CNG bus is clean. A diesel is even cleaner.

A CNG bus is clean. A diesel is even cleaner.

Stefan Saalmink, MindsinMotion.net <stefan.saalminkSPAMFILTER@mindsinmotion.net>

Tuesday 04 November 2008

Buses that run on natural gas are less clean and more expensive than modern diesels, so it is better to opt for the latter, argues professor Maarten Steinbuch of the Eindhoven University of Technology.

In last Tuesday’s NRC Handelsblad, a Dutch daily newspaper, Maarten Steinbuch explained why he thinks the uptake of natural gas buses by communities around the Netherlands is a waste of money and even yields worse emission reduction results than the most modern diesel buses. Join the discussion by dropping a comment below!

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“The additional costs for each CNG bus are 25,000 EUR, and for each CNG bus put on the road instead of a diesel bus, the Treasury misses out on 12,000 EUR of diesel taxes. This adds up to many millions of Euros that we could spend far more efficiently to achieve our environmental goals.

The fact is that for all emissions except for NOx (nitrogen oxide), a modern diesel bus scores better than a CNG bus. Research from the province of Overijssel shows that only at one out of four locations tested is there a slightly reduced emission of NOx. For all other emissions, the diesel buses do significantly better.

Surprising as these results may seem, the explanation is straightforward. The energy density of CNG is about 40 per cent lower than that of diesel. Therefore, you need much more of it. Furthermore, a CNG bus carries heavy tanks that need to be able to withstand hundreds of bars of pressure. All in all, this means that about twice the amount of natural gas is needed to cover the same distance as diesel.

The choice for natural gas seems to be politically motivated and not based on facts. Perhaps decision makers at provinces and municipalities do not know any better.

It is a pity that investing in CNG buses leaves less money to be invested in other promising innovative technologies, such as hybridisation. The Eindhoven University of Technology, DAF trucks and TNO automotive are conducting research in the field of truck hybridisation. The Netherlands could establish itself as an exporter of technologies for clean diesel buses as it has done before in the field of LPG technologies."

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Comments

Less money for innovative technologies?

Wouter van der Laak

Thursday 27 November 2008

I think the professor isn't up-to-date about the millions of euro's are spent for innovative automotive technology. This money comes from the provinces, the Netherlands and Europe. Take for example the subsidy scheme HTAS (High Tech Automotive Systems).
The pronouncing by the professor that "nvesting in CNG buses leaves less money to be invested in other promising innovative technologies, such as hybridisation" is a little to simple according to me.
And, when we are discussing about emissions, we have to take into account the emissions from well-to-wheel.



CNG versus Diesel

Bouwe de Boer Provence of Fryslân (NL)

Saturday 15 November 2008

This professor is not very informed. Ofcourse Diesel is improving in clean outlet.
But CNG is now already better, cheaper in use and: most important:
replaceable by biogas.
Diesel is a fossile fuel. Biogass is not.
Why are there allready so big numbers of this busses in Sweden, Germany, spain and potugal and Italy?
and in india already 8000 in Delhi, 300 in Lille (france)
The answer is above.

heavy tanks?

Henk Daalder

Wednesday 12 November 2008

A CNG tank does not need to be much more heavy than a diesel tank.
But CNG needs some additional processing, expanding and heating, that is not necessary for diesel. If the additional volume is also included in the calculation, then.....

But al the talk about money by a scientist, may be an indication that he was exluded for a research grant.
He could then present his arguments here on this website.

Strange numbers

Researcher

Wednesday 12 November 2008

I don't really understand where does Professor Steinbuch base his figures on. It is true that Dutch natural gas has a lower energy density than for example Russian natural gas (DNG ~42Mj/Kg and RNG 46 Mj/Kg), but it is definetely not 40 % lower than diesel's (~43 Mj/Kg). Also I would like to know where did he get these emission figures. A modern CNG busses (Stoichiometric) emit the same or even less toxic emissions (CO, HC (NMHC), NOx, PM) than a modern diesel bus (not to mention old diesel busses). Several reports can be found to confirm this. I believe that Professor Steinbuch is making statements out of his field of work.

treasury

P. Nicholsson, Sweden

Tuesday 04 November 2008

Using the treasury argument is really weird: maybe we then should not campaign against smoking as well because we miss out on tax revenues? Agreed that we should judge each and every solution to its merits, but why then not strive for a taxation system based on actual emissions? Set targets, see who complies in whichever way.