At what speed etc is co2 measured at?
Discussion
It's done using a standardised (but not very realistic) test, which includes a verity of speeds. It tends to favour smaller engined cars (due to the light loads and slow acceleration) hybrids (as they can be fully charged when they start the test, they should really start with 0 charge unless they are a plugin) and autos (as the car is allowed to change gear when it wants, cars with manual transmissions have to change at certain speeds)
See here:
http://en.wikipedia.org/wiki/Fuel_economy_in_autom...
ETA: I am assuming the CO2 figure is measured in the same way/at the same time as the fuel economy is. This should be possible since in a modern car the amount of CO2 produced is directly proportional to the amount of fuel used.
See here:
http://en.wikipedia.org/wiki/Fuel_economy_in_autom...
ETA: I am assuming the CO2 figure is measured in the same way/at the same time as the fuel economy is. This should be possible since in a modern car the amount of CO2 produced is directly proportional to the amount of fuel used.
Edited by varsas on Friday 6th May 21:15
It takes a bit of reading but it's described in that Wiki page.
All cars are driven over a specific trace of load and speed on a certified emissions rolls (like a rolling road dyno) and the emissions from the exhaust are measured using gas analysers connected to the tailpipe. The amount of CO2 produced over this test is a direct correlation to the amount of fuel used during the drive.
The drive cycles in Europe differ slightly from the US (Federal) ones.
All cars are driven over a specific trace of load and speed on a certified emissions rolls (like a rolling road dyno) and the emissions from the exhaust are measured using gas analysers connected to the tailpipe. The amount of CO2 produced over this test is a direct correlation to the amount of fuel used during the drive.
The drive cycles in Europe differ slightly from the US (Federal) ones.
Macd355 said:
Miles less than the amount created by breathing.
1) It's not really the same thing. Where did that CO2 come from? Plants etc you have eaten so it was in the atmosphere very recently. CO2 produced from cars comes from oil, the CO2 being released was last in the atmosphere millions of years ago. That's what upsets the balance.2) Even if (1) were not true, just saying 'well, x produces y amount of CO2, I'm not going to cut mine until they do something about theirs' isn't helpful. We all need to do 'our bit'.
3) Even if (1) and (2) were not true, there are many many people (most of whom are very poor) who must breathe to stay alive. There are a small amount of people (all of whom are rich) in the UK who like driving to support their life style. Who should be targeted to cut their emissions?
Legacywr said:
One of the cars I'm looking at is around 245g/km, how worried about it's effect on the enviroment should I be?
The easy way to look at this is :There is a certain amount of oil in the world
This oil, when burned, will produce a certain amount of Co2
By using a less economical car, you are simply ensuring that the oil is turned into Co2 sooner, rather than later. as oil runs out there will be progressively more moves towards alternitive fuels, more economical cars, and so on. So by driving a thirsty car (and 245g/km isn't really very thirsty), you're actually helping the environment, by encouraging the development of alternitive fuels
McSam said:
varsas said:
1) It's not really the same thing. Where did that CO2 [from breathing] come from? Plants etc you have eaten so it was in the atmosphere very recently.
Sorry? 
It's created very simply by chemical reactions, combining oxygen (from the air) and carbon.
The carbon part comes from the food you eat.
So, a plant grows. As it does so, it takes in Co2 and coverts it to carbon to make leaves and stuff. A person then comes along and eats the plant, digests it, and then re-releases the carbon as Co2.
What does that mean? Well, basically, that the Co2 you emit was last in the atmosphere very recently. Over the course of a year, the amount of Co2 in the atmosphere caused by you is balanced out by the plants you eat taking in Co2.
You can only emit as much Co2 as has been taken in by the plants you have eaten. Neat, hu? Unfortunately, that is not true of cars. They do have an engine inside them which is making Co2 out of practically (in terms of the Co2 eco-system) nothing.
I have simplified things slightly, I haven't covered methane production. Also the system only remains balanced within certain limits but I believe what I have written is basically sound?
Legacywr said:
How much of the worlds CO2 is produced by cars?
Carbon dioxide in the atmosphere = 0.039% by volume.Carbon cycle proportion of carbon dixoide contributed by mankind 3.4% (IPCC)
UK contribution to global emissions 2% (DEFRA)
Proportion of this due to cars = 16% (DEFRA again)
So cars in the UK are responsible for 16% of 2% of 3.4% of 0.039% which is precisely bugger all.
Globally - just take out the 2% and it increases from bugger all to naff all.
HTH.
Carbon dioxide in the atmosphere = 0.039% by volume.
So because there's not much, we shouldn't worry about making more? What if I increased the amount of iron in your bloodstream? After all, you don't have much so making more won't be a problem for you, right?
Carbon cycle proportion of carbon dixoide contributed by mankind 3.4% (IPCC)
But that is 100% of the 'extra' Co2. See my explanation of the Co2 eco-system.
UK contribution to global emissions 2% (DEFRA)
Per person, the UK emits a huge amount of Co2. We account for far less then 2% of the worlds population, so that number is actually very large.
Proportion of this due to cars = 16% (DEFRA again)
Everyone should do their bit. Why shouldn't cars be targeted? What proportion of your personal carbon footprint comes from your car?
So cars in the UK are responsible for 16% of 2% of 3.4% of 0.039% which is precisely bugger all.
again, that is one way of looking at it, I believe it's not really accurate. the third figure should be 100%, and the last is irrelevant (the OP wants to know the change his car might make, what is already there doesn't matter to that), for example.
Globally - just take out the 2% and it increases from bugger all to naff all.
HTH.
I understand you were just answering the OP's question, which you did however I believe putting it in the way you did could be misleading.
So because there's not much, we shouldn't worry about making more? What if I increased the amount of iron in your bloodstream? After all, you don't have much so making more won't be a problem for you, right?
Carbon cycle proportion of carbon dixoide contributed by mankind 3.4% (IPCC)
But that is 100% of the 'extra' Co2. See my explanation of the Co2 eco-system.
UK contribution to global emissions 2% (DEFRA)
Per person, the UK emits a huge amount of Co2. We account for far less then 2% of the worlds population, so that number is actually very large.
Proportion of this due to cars = 16% (DEFRA again)
Everyone should do their bit. Why shouldn't cars be targeted? What proportion of your personal carbon footprint comes from your car?
So cars in the UK are responsible for 16% of 2% of 3.4% of 0.039% which is precisely bugger all.
again, that is one way of looking at it, I believe it's not really accurate. the third figure should be 100%, and the last is irrelevant (the OP wants to know the change his car might make, what is already there doesn't matter to that), for example.
Globally - just take out the 2% and it increases from bugger all to naff all.
HTH.
I understand you were just answering the OP's question, which you did however I believe putting it in the way you did could be misleading.
Edited by varsas on Wednesday 11th May 09:06
varsas said:
When you breathe, you release Co2. But where did that CO2 come from? It's not like you have a little nuclear powered reactor inside you making Co2.
It's created very simply by chemical reactions, combining oxygen (from the air) and carbon.
The carbon part comes from the food you eat.
So, a plant grows. As it does so, it takes in Co2 and coverts it to carbon to make leaves and stuff. A person then comes along and eats the plant, digests it, and then re-releases the carbon as Co2.
What does that mean? Well, basically, that the Co2 you emit was last in the atmosphere very recently. Over the course of a year, the amount of Co2 in the atmosphere caused by you is balanced out by the plants you eat taking in Co2.
You can only emit as much Co2 as has been taken in by the plants you have eaten. Neat, hu? Unfortunately, that is not true of cars. They do have an engine inside them which is making Co2 out of practically (in terms of the Co2 eco-system) nothing.
I have simplified things slightly, I haven't covered methane production. Also the system only remains balanced within certain limits but I believe what I have written is basically sound?
What you say is quite true, the carbon dioxide comes from somewhere, but surely I'm right in saying that not all of the carbon in our bodies comes from plants - and then not even much of that would actually have been "loose" carbon dioxide taken in? I'm prepared to be educated on this one, but I believe quite a lot of the carbon dioxide we breathe out is made from carbon using the oxygen we breathe in, carbon that was not previously loose in the atmosphere as carbon dioxide?It's created very simply by chemical reactions, combining oxygen (from the air) and carbon.
The carbon part comes from the food you eat.
So, a plant grows. As it does so, it takes in Co2 and coverts it to carbon to make leaves and stuff. A person then comes along and eats the plant, digests it, and then re-releases the carbon as Co2.
What does that mean? Well, basically, that the Co2 you emit was last in the atmosphere very recently. Over the course of a year, the amount of Co2 in the atmosphere caused by you is balanced out by the plants you eat taking in Co2.
You can only emit as much Co2 as has been taken in by the plants you have eaten. Neat, hu? Unfortunately, that is not true of cars. They do have an engine inside them which is making Co2 out of practically (in terms of the Co2 eco-system) nothing.
I have simplified things slightly, I haven't covered methane production. Also the system only remains balanced within certain limits but I believe what I have written is basically sound?
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