The diesel controversy

Now that is an example of a really closed mind.

We need to solve the PM problem not scream "my diesel car is not the problem".

Using any fossil fuel for road transport, really, has to be one of the most wasteful ways of using that resource anyway ( maybe just short of open fires ).

And as for using it for air travel , humping half empty aircraft through the skies, l then go apoplectic.

Diesels will always be filthy things, yes even your modern 'Euro 6' things with all their save the planet claims by the manufacturers.

Long or even 'zero' service intervals on emission control systems mean any exhaust treatment on cars will be severely compromised compared to larger vehicles such as buses and HGV's who have the facility to top up with adblue (for example) on a regular basis.

So the really big polluters in our towns and cities are diesel cars of all ages and not the fewer but significantly larger vehicles some point their fingers at.

If you have the time this is one of the original reports on the huge discrepancy between the lab results and the real world and how some manufacturers like BMW are significantly more compliant than others. VW do not coming out smelling of roses. (If this is the one I recall it was the manufacturers are not actually named, but the identity is revealed by engine size data and photos of the test gear in situ)

**LINK**

Ady1,

"You can't burn carbon "away" it will always be present

Carbon has the highest melting point of the elements, and when you melt carbon you are on the way to making a diamond"

Carbon burns by reacting with oxygen to form the gas CO2 and with nitrogen to form gaseous NOx. in an engine where combustion is always incomplete some carbon will remain as a fine particulate. This particulate and the NOx gases are the main problem with diesel engines. Yes the latest diesels are god but only by the use of additives and periodic burning off of the particulate filter. Both are a question of regular maintenance and will probably suffer as the engine gets older and more worn.

Diamond burns very easily leaving no residue as it has fully reacted with the oxygen to form CO2.

I suggest anyone who wants to know more about carbon and its properties to read Stuff Matters by Mark Miodownik.

Carbon cannot burn with Nitrogen to form NOx. Carbon cannot burn with Nitrogen under normal conditions and probably any conditions.

I am trying to keep away from this thread. It is a bit too close to my working career.

JA

Edited By JA on 03/05/2017 14:24:04

Where's the 'C' in 'NOx'? Just asking!

Best regards,

Swarf, Mostly!

You do not specifically need Carbon to produce NOx, just something like air that contains nitrogen and oxygen. The NOx is only formed because of the combustion temperatures. Warm air up sufficiently by whatever means and you will get NOx. Lower the combustion temperatures and you reduce the NOx. Diesels generally have much higher combustion temperatures and pressures hence more NOx.

JA and Swarf,

Quite correct - slip of the mind I meant to say nitrogen reacts with oxygen to form NOx

OK.

Would those diesels be acceptable if burning waste chip oil in the cities instead? The carbon is coming from renewable resources and there'd be no net emissions.

I suspect the answer is 'no'. It's the particulates that are the problem, not the ultimate source of them. I am sure there is a technological solution, but I am not sure it's worth it. This from someone who last year bought a diesel and doesn't want to be banned from using it. The question I'm left thinking is 'Do I care that people in overcrowded, stinky cities are dying prematurely?'. Probably. So what to do?

We can be certain that if politicians have any say in the matter, the least rational and most expensive response will be adopted.

Regards,

Richard.

It's never as simple as we are told, emissions come from a number of sources of which diesel cars only form a small part, most seem to ignore things like gas/oil central heating. While on the face of it EV may seem to be the way to go but that comes with it's own set of problems not least the electricity supply network and that electricity still needs to be generated. There is concern that the amount of electricity demand could go up by as much as 30% in the next 30 years. The average UK home uses around 4,000 kWh/year but add in a charging system for an EV and it increases considerably, mind you we probably use more than the average home with all our machines.

"Now that is an example of a really closed mind.

We need to solve the PM problem not scream "my diesel car is not the problem"."

What on earth prompted that Teddy thrown from the pram??

This constant (and only relatively recent) wittering on about 'diesel pollution', as distinct from all the other rubbish spilled into the atmosphere, may well have some political convenience (keep the plebs arguing about something, anything) but is very much a child of the moment. I have no particular axe to grind pro-diesel but the realistic alternative IS petrol, NOT electric. Straight amps are almost entirely dependent on wiggly amps and they cause pollution in production. I should, perhaps, point out that I come from an era when a half day in a clean white shirt needed a replacement and when buses had to be guided by a pedestrian!

Pollution? - you don't know the half of it!

rgds

Bill

Interesting subject and also a difficult one really as no matter what what you do it produces pollution and we need transport. We live on a road and the 38t lorries are quieter (road noise and engine) than the average private car and also looking at figures produce less pollution as all seem to comply to Euro6 with Adblue .

This report makes interesting reading especially P7 & 10, perhaps someone can comment on it.

Peter

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/579200/Emissions_airpollutants_statisticalrelease_2016_final.pdf

An extract from it is below.

"Most of the emissions from residential, public, commercial combustion in these last 3 years – 79 per cent for both pollutants - are from the use of wood as a domestic fuel"

Very political though.

They can ban diesel cars and force you to move to petrol or hybrid but how about vans and lorries ?

There are no petrol vans sold in this country other that possibly a few rare ones and certainly no lorry's.

So are these going to be exempt ? if so it makes a farce of it.

All it will take is two lorries on every motorway slip road and every road into London, lock them up and go home for the day.

Edited By John Stevenson on 03/05/2017 18:57:23

I think I must agree with Mick's comment above. There do seem to be a few predjuces being viewed on this thread. Just a few points:-

1. Many modern car diesels use urea injection (Adblue) as well as pretty much all commercial diesels. This implies that they have NOx reducing catalyists, which use the ammonia formed by the dissulution of the urea to reduce the NOx to N2 and H2O. Adding extra urea is simple, cheap and isn't needed often. It's no more a maintenance issue than keeping the tyres inflated.
2. All modern road diesel engines have particle filters, which work perfectly well when cold (it's a filter, not a valve). They do need regeneration, by burning off the captured particles. This is done aither with a separate injector into the exhaust or by modifiying the fuel injection timing to increase the exhaust temperature. This process normally takes place when the vehicle is running steadily at 50mph or more and is carried out when the filter back pressure rises beyond the desired amount. Filter and catalyst replacement on a diesel is identical to catalyst replacement on a petrol engined car.
3. Older vehicles with higher pollution get replaced with newer ones with lower pollution, whether they are petrol or diesel powered. There is an issue with freight vehicles, taxis and busses because these often have a longer working life and far higher milage within their life.
4. The current Euro 6 standards for cars are effectively identical for petrol and diesel, with 33% more NOx allowed to the diesels and twice as much CO allowed to the petrols. Euro 7 will almost certainly be identical for both.

Note:- I'm not completely unbiased, I'm very happy with my real 60mpg in mixed motoring and 80mpg in motorway cruising.

Edited By Mark Rand on 03/05/2017 19:06:13

Edited By Mark Rand on 03/05/2017 19:08:36

20+ years ago, I used to maintain a computer for an organisation that was based on the Euston Road in London. It was on the 3rd floor and the room housing it had no air conditioning. They used to keep the window open 24 x7. How that machine every kept running I don't know. It used to get through tape drives (remember them) at a crazy rate. If you had to pull a PCB (again when computers had more than one), you couldn't even see the chips for the thick layer of sooty dust. It certainly put a new meaning on particulate pollution.

Phew! More hot air in this thread than come out of my exhaust!

Probably the most useful post in the above discussion

I went to LPG to reduce my emissions because the higher H:C ratio means less CO2.

Then I went diesel because the greater efficiency meant even lower CO2 (I managed 60mpg on a trip to Devon and back recently, I was lucky to hit 27mpg on LPG).

Now I discover I was suckered into believing the hype around 'clean diesels'.

As one or two people have mentioned, trucks manage not to produce a fraction of the pollutants per gallon of diesel that cars do. This is not because big engines are more efficient, it is because the test the manufacturers have to build them to pass are carried out under real road conditions instead of the totally artificial circumstances car are tested on.

Proper testing of diesel cars in the answer, it will mean they bring in decent particulate filters and adblue - but if they siphon off a fraction of the budget for heated steering wheels and 'apps on your dashboard'...

The real answer is electric, because even if the power is generated from fossil fuel, the emissions will still be lower.

There were more electric cars than IC cars on Victorian roads. As someone asked on the radio, what if the electric car had 120 years of development like the IC car has...

Neil

I think the reply would be "what's the quickest way into your wallet" rather than trying to preserve resources, the Victorians would've thought our world numbers to be absurd and impossible to support, so they wouldn't buy the argument that resources needed to be preserved, precisely because they believed in a future world where similar numbers of them would be around in their day.

Some early electric cars seemed ungainly, the appeal of IC fuels is the high amount of energy they contain that allows them to exceed the horse power of any electric motor. But I don't doubt it is a good idea and definitely very underrated considering what we know now about putting excessive waste gasses into our atmosphere.

You might put it like this, they were driven by their ambition to provide fast transport, and they saw the potential in petrol and knew they could pull it off if they tried hard enough. Every car company was building cars that competed against each other with speed in mind. 

Electric cars on the other hand, probably didn't seem like it had potential for that, they didn't have the "goal" that we have now to provide cheap and energy efficiency in their transport. So therefore, without the goal, means no ambition, no ambition means it never happened. 

Michael W

Edited By Michael-w on 03/05/2017 21:58:48

The electrics are the easy bit, just the back end of a VFD with some fancy software to allow for bidirectional power flow. The main limitation is battery technology. That's one reason the automotive industry is looking at mild hybrids, rather than pure electric. Another reason is that the smaller battery packs are usually around 42V, so below SELV limits. The pure electric vehicles I worked on had battery voltages in the range of 200-400V. I can tell you that from a practical point of view they can be a shocking experience.

Andrew