The zero-emission car is still utopian, but every technology is making significant environmental progress. It is essential to develop the circulating car fleet. But how much (and how) do cars produced today really pollute?
The car industry is at the beginning of a phase of technological and ecological renewal which is now more necessary than ever as regards environmental sustainability in a sector, that of transport, in which progress has always been the order of the day.
Does this mean that we will soon have truly 100% green solutions? Although it is being promised somewhere – even in the short term – at the moment the reality tells us that today there is no technology ready to zero impact and we are still quite far from the goal.
But it is also true that all the technologies on the market today are progressing significantly in this direction, from the diesel world (where they are experimenting with different solutions that aim to save the market and its reputation, the latter now at an all-time low) to the world of electricity. For this reason, it is already essential today to implement a sudden renewal of the fleet of cars on the road with new generation cars and ecologically much better performance, as we have already explained in a previous article.
In this article we try to collect and publish some data to help the reader understand something more among all the theories and counter-theories on the subject that proliferate on the web, going to analyze the different technologies and the main pollutants.
THERE’S A POLLUTION WITHOUT COMBUSTION (AND NOT EVEN LITTLE)
Before reviewing the various types of engines and their ecological performance, it should be noted that an important part of PM10 emissions, about a quarter of those present in the air, are due to factors unrelated to the combustion or traction of the vehicle and are therefore present in every vehicle, regardless of the force that pushes them: we are talking about the fine dust produced by the wear of tires and brakes and the abrasion of the asphalt.
These particles have a size that presumably varies between 3-30 microns and today all together represent about 24%-26% of the PM10 produced by vehicular traffic on the total road.
This is the estimate of the various factors, reported on the website of Legambiente PD:
- 74 – 76 % due to combustion;
- 5 – 6 % due to brake consumption;
- 9 – 10 % due to tyre wear;
- 9 – 10 % due to abrasion of the road surface.
The data in this table, as mentioned above, refer to total traffic pollution; it therefore includes a large proportion of older generation vehicles with high PM10 emissions from combustion. In more modern vehicles, the incidence of PM10 is significantly lower.
BENZINE: How much does it pollute?
As a first reference, let’s analyze how cars with petrol engines behave, still very appreciated by the Italian market today, where registrations have remained almost stable despite the new technologies emerging on the market.
We underline that the values reported refer to the polluting factors produced by the latest generation cars, which are far better, from an ecological point of view, than the older cars. For petrol engines, therefore, we have:
- PM10 from combustion: 5 mg/Km
- NOX: 60 mg/km
- CO2: 2,380 g per litre of petrol consumed
There’s no point in going around it: diesel is the technology that has been most questioned in recent months. It must be said, however, that a clear distinction must be made between old and new generation vehicles, particularly for diesel cars.
The oldest diesel cars (from Euro 4 down, but we can also include Euro 5 in this reasoning) have much higher pollutant values than Euro 6 diesel cars and in particular the Euro 6d-Temp.
As we will see in the table, new generation diesel vehicles produce less CO2 than petrol and are significantly better in terms of NOx emissions than the previous Euro 5 certification.
The following table shows the maximum emission values of diesel cars in order to be classified as Euro 6, compared with those of petrol cars:
- PM10 for combustion: comparable to petrol
- NOX: +25% emissions compared to petrol vehicles;
- -55% emissions compared to Euro 5 diesel;
- -85% emissions compared to Euro 3 diesel;
- CO2: -10/-15% emissions per km travelled compared to petrol vehicles.
- What makes the difference is the better performance, i.e. the lower consumption, of diesel compared to petrol
NATURAL GAS (Methane): How much does it pollute?
It is probably the most ready technology, especially for the Italian market, in terms of eco-sustainability: combustion particulate emissions are practically non-existent for natural gas.
Methane, like electricity, does not have any impact on surface traffic: it is transported by pipelines and does not require large storage facilities, unlike other petroleum products.
The following table shows the performance of methane in relation to the main polluting factors:
- PM10 from combustion: free
- NOX: – 70% compared to Euro 6 diesel
- CO2: – 25% per km travelled compared to petrol
LPG: How much does it pollute?
LPG (liquefied petroleum gas) consists of a mix of butane and propane: we can not consider it a real alternative fuel because its production comes mainly from the processing of oil but still has much lower pollutant values than diesel and gasoline. From an ecological point of view it is not to be equated with the other gas, methane, but it has in common with the latter the absence of pm10 emissions from combustion.
The values of the polluting factors for LPG cars:
- PM10 from combustion: free
- NOX: – 50% compared to diesel Euro 6
- CO2: – 10% per km travelled compared to petrol
ELECTRICAL CAR: How much does it pollute?
This technology is certainly the best in terms of combustion emissions, which are zero. That is to say:
- zero CO2
- zero PM10 from combustion
- zero NOX
But can it really be considered eco-sustainable and zero impact?
If we consider the global impact on the environment, to date the answer is definitely no. So much so that a recent eco-test by ADAC, the German car club, has revealed how, for example, the Fiat Panda in Methane is less polluting than some electric cars, taking into account all the polluting factors in addition to mere emissions on the road.