Welcome to the second part of my blog about diesel cars. In this blog I will explore in detail why promoting diesel cars turned out to be such a bad decision for the environment, and what government action is being taken around the world.
The scandal started with Volkswagen in 2015 with their emissions cheating device used to pass the emissions test. This really got the world interested about the negative effects of diesel cars. How the device works is shown in figure 1.
It was found that in America, emissions from the VW cars with this device were 40 times higher then legally allowed and affected 11 millions cars worldwide. This was clearly a serious problem and made the emission standards unreliable. It wasn't only VW; Porsche Audi and even lorry brands have now also been found to have been using the device.
Figure 1, Source
Why are diesel cars worse then petrol for the environment ?
On the one hand diesel cars do produce less CO2 than petrol, this was the whole point of Europe's vision to help meet the Kyoto protocol, but this protocol did not focus on introducing controls on black carbon and this is the problem.
The particulate matter produced by diesel cars contains a mean of 61.5 % black carbon content, and the boom in diesel cars after 1996 with Euro 3 regulation engines meant that compared to its petrol equivalent these cars were producing a 20 times increase in PM and 60 times more BC.
Jacobson M (2002) found that diesel cars with the particulate standards at the time in 2001 would warm the climate in the next 100 years more then petrol cars even with introducing tougher emissions standards, diesels still fall short. Soot from fossil fuels adds around 16 % to global warming. Laws that favour diesel cars are promoting global warming and also damaging human health in the eyes of Jacobson. Its funny how its took until 2017 for governments around the world to take action.
Research conducted by Shindell et al., (2012) found that if efforts were put in to reduce tropospheric ozone, CH4 and black carbon emissions substantially, there would be a clear reduction in global mean temperatures as particles like BC have a short atmospheric life. This means that the results would be felt much sooner compared to CO2 for which any reduction won't have any effect till at least 2040.
There was so much investment in diesel engine fuelled cars that if the same amount was invested in developing small turbo charged petrol engines, the CO2 gap between diesel and petrol cars would have been very low. In the period between 1995 and 2005 the gap was 5 to 10 %, by 2010 due to investment in petrol engines the gap has reduced to 1.5 % so diesel cars really don't have have large CO2 saving anymore.
Cames M & Helmers E (2013) agree that the switch to diesel fuels had a negative effect in mitigating climate change. Furthermore there are millions of pre 2011 Euro 5 engines without any particulate filters on the road. In many developing countries like India with no strict standards it means diesel cars are sold without an diesel particulate filter ( more info on this in next section).
Instead over loading you with more text I have included a summary the main global climate effects of black carbon on the planet in figure 2, I cover this in more detail in another blog.
Figure 2, Source Bond et al (2013)
Don't cars now require a diesel particulate filter which will stop the dangers ?
Yes that is correct Euro 5 and 6 emissions standards require a diesel particulate filter to be fitted in every car, you may be wondering what these are ?.
The filter traps these small particulates before they can escape out of the exhaust from a car so it should be better for the environment and human health. The problem with these filters is that in order to burn the particulate matter off at high temperature, you need to include some longer drives above 50 mph.
This means for thousands of people who live in city centres and do very short journeys in stop/start traffic mean these filters can't function as required, it will clog up over time and need replacement which is very expensive around £1000. A recent investigation has found that thousands of drivers in the UK have illegally removed these filters and not bothered to replace them, meaning the public are at increased risk from particulates. Below are some great recent news articles on this growing issue/scandal.
1) Click here
2) Click here
Next Blog
I will explore what action governments are now taking to try and reduce air pollution in cities.
The scandal started with Volkswagen in 2015 with their emissions cheating device used to pass the emissions test. This really got the world interested about the negative effects of diesel cars. How the device works is shown in figure 1.
It was found that in America, emissions from the VW cars with this device were 40 times higher then legally allowed and affected 11 millions cars worldwide. This was clearly a serious problem and made the emission standards unreliable. It wasn't only VW; Porsche Audi and even lorry brands have now also been found to have been using the device.
Figure 1, Source
Why are diesel cars worse then petrol for the environment ?
On the one hand diesel cars do produce less CO2 than petrol, this was the whole point of Europe's vision to help meet the Kyoto protocol, but this protocol did not focus on introducing controls on black carbon and this is the problem.
The particulate matter produced by diesel cars contains a mean of 61.5 % black carbon content, and the boom in diesel cars after 1996 with Euro 3 regulation engines meant that compared to its petrol equivalent these cars were producing a 20 times increase in PM and 60 times more BC.
Jacobson M (2002) found that diesel cars with the particulate standards at the time in 2001 would warm the climate in the next 100 years more then petrol cars even with introducing tougher emissions standards, diesels still fall short. Soot from fossil fuels adds around 16 % to global warming. Laws that favour diesel cars are promoting global warming and also damaging human health in the eyes of Jacobson. Its funny how its took until 2017 for governments around the world to take action.
Research conducted by Shindell et al., (2012) found that if efforts were put in to reduce tropospheric ozone, CH4 and black carbon emissions substantially, there would be a clear reduction in global mean temperatures as particles like BC have a short atmospheric life. This means that the results would be felt much sooner compared to CO2 for which any reduction won't have any effect till at least 2040.
There was so much investment in diesel engine fuelled cars that if the same amount was invested in developing small turbo charged petrol engines, the CO2 gap between diesel and petrol cars would have been very low. In the period between 1995 and 2005 the gap was 5 to 10 %, by 2010 due to investment in petrol engines the gap has reduced to 1.5 % so diesel cars really don't have have large CO2 saving anymore.
Cames M & Helmers E (2013) agree that the switch to diesel fuels had a negative effect in mitigating climate change. Furthermore there are millions of pre 2011 Euro 5 engines without any particulate filters on the road. In many developing countries like India with no strict standards it means diesel cars are sold without an diesel particulate filter ( more info on this in next section).
Instead over loading you with more text I have included a summary the main global climate effects of black carbon on the planet in figure 2, I cover this in more detail in another blog.
Figure 2, Source Bond et al (2013)
Don't cars now require a diesel particulate filter which will stop the dangers ?
Yes that is correct Euro 5 and 6 emissions standards require a diesel particulate filter to be fitted in every car, you may be wondering what these are ?.
The filter traps these small particulates before they can escape out of the exhaust from a car so it should be better for the environment and human health. The problem with these filters is that in order to burn the particulate matter off at high temperature, you need to include some longer drives above 50 mph.
This means for thousands of people who live in city centres and do very short journeys in stop/start traffic mean these filters can't function as required, it will clog up over time and need replacement which is very expensive around £1000. A recent investigation has found that thousands of drivers in the UK have illegally removed these filters and not bothered to replace them, meaning the public are at increased risk from particulates. Below are some great recent news articles on this growing issue/scandal.
1) Click here
2) Click here
Next Blog
I will explore what action governments are now taking to try and reduce air pollution in cities.
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