Geezer

There is a quiz on BBC news today about carbon emissions in the UK, generall about flights.

One of the questions is "A flight from London to Malaga emits how many tonnes of carbon dioxide into the atmosphere? "

a) 27 tonnes
b) 7 tonnes
c) 17 tonnes

They reckon it's 27 tonnes.

Now, I thought that was a bit high, so after a quick look, based on a Boeing 737 (fairly standard mid-range plane yeah?), I got the following figures......

Fuel load is 20,104 ltrs (roughly 15 tonnes)
Range is 2370 miles
London Gatwick to Malaga is 1024 miles.

So, by my reckoning, it's using about 7.5 tonnes of fuel (I accept that may be simplistic, but there you go)

So, if 100% conversion of fuel to carbon dioxide was achieved (is that possible? I doubt it) we have just reached the smallest figure they said. How do they get away with it?

Have I missed something fundamental here?

Geezer

cottonfoo

Usual "statistics", they don't fully explain their sources or what they're counting or basing it on, and they've probably used someone else's figures as a baseline and not verified them (this happens all the time). If they include say, all the fuel used for all those passengers to get to the airport, plus whatever resources the airport needs to make that flight, then they whack it all together and call it that.

alcazar

iTrader: (2)

It's like the rest of the "global warming" arguments: lies and bull****

Lets look at it another way: The density of carbon dioxide is 1.98 kg/cu m

And since volume is given by mass/density

the amount of carbon dioxide released is 27000/1.98

which gives 13,636 cu m of carbon dioxide. I find that a little hard to believe, since jet fuel is a hydrocarbon, so at least HALF of what it gives out when burnt, at least in VOLUMES, must be water!

Alcazar

SJ_Skyline

d) Who gives a "flying" ****?

andys

Guys you need to study chemistry. You need to convert the amonut of fuel to mols. Then based on the equation for the full combusation of jet fuel you will get the ratio of fuel to co2 produced. This will give you the number of mols of of Co2 which you can then convert to a mass.

TopBanana

andys: show your workings!

PeteBrant

It's far more complex than that. You aren;t just dealing with Density mass and volume (And Density = Mass /volume therefore Volume =Mass X Desinity) - you are dealing with chemistry and molecules.

For example - When 1.0g of ethane is burnt, 2.93g of C02 is produced.

To work out how much CO2 is produced from burning jet fuel, you need to know the chemical reaction equation for burning jet fuel.

It could easily work out at 27 tonnes.

PeteBrant

Spot on

Look here for someone to explain it far better than i could

Mole (unit - Wikipedia, the free encyclopedia)

SJ_Skyline

You're making an assumption of full combustion as well - surely there is also a percentage of incomplete combustion giving off CO as well as unburnt fuel or are jet engines that efficient?

kingofturds

iTrader: (1)

We are

scunnered

iTrader: (1)

Global warming is not man made, it's all about orbital variation (Milankovitch theory). CO2 is produced by many natural means, and is essential for our crops, forests, jungles etc. Man made CO2 emmissions are only a very small percentage of the total.
Anyway, its about brainwashing the population into feeling guilty about the environment so that when all the corrupt money grabbing governments introduce new and ever crippling taxes, we'll pay up without moaning.

Leslie

The weight of kerosene burned to get to Malaga at that range is about 8500 lbs max or around 4.25 tons as an estimate. So you can do the calculations for the CO2 from there. The Vulcan burned about 3500 lbs/hour average on the high level cruise and the VC10 being a heavier machine than a 737 would use more than that of course and it had older designed engines anyway. A lot of the emissions would be water vapour of course so how they could get 27 tons out of all that is hard to believe.

Who are we to spoil a good story though, they have to screw the cash out of us somehow!

Les

SJ_Skyline

True, true

PeteBrant

Go on, then.

Find out the equation of chemical reaction for burning kerosene,
find out what elements make up kerosene, find out the atomic weight for those elements, convert using the mole system. Next find out the molecular mass of carbon times that by the earlier cacluation where you worked out the amount of mols of carbon you created, and bingo, theres your answer.

Or you could use the simpler method of just asserting that "no way could it be 27 tonnes".

andys

Right here are the calcs. I bit rusty as I have not done it for a few years.

assuming 7.5 tonnes burnt => 7,500,000 grams

Assuming Kerosene fuel based of C12H14 number of mols =

12*12+14 = 158 molecular mass

Moles = 7,500,0000 / 158 = 47468.35 moles

Equation for complete combustion

2C12H14 + 31O2 => 24 CO2 + 14H2O

Ratio of fuel to Co2 is 2 /24 or 1/12

So 47468.35 *12 = 569620.2 moles of CO2 produced

molecular mass of CO2 = 16 + 16+ 12 = 44

Mass of Co2 = 44 * 569620.2 = 25063288.8 g = 25.06 tonnes

Geezer

So still not 27 tonnes then, lying BBC barstewards

Geezer

PeteBrant

Excellent work Dr Andy, have a house point.

I look forward to seeing all the retractions from people saying it couldn't possibly be 27 tonnes and that the BBC are being bribed to tell lies

PeteBrant

2 tonnes is probably accounted for by people ****ting themselves in a bit of turbulence.

TelBoy

Why on earth would the BBC deliberately misrepresent it anyway..??

Paul3446

Can anyone slagging off the BBC on this thread please now apologise? Or have you all disappeared now you've ben made to look a bit thick.

cottonfoo

I never said it was a lie, I just said most stats were crap and baseless, although in this case they weren't too far off

KiwiGTI

Rework the figures - it is a lie. Jet A fuel has a molecular mass of 110, not 158

LG John

And whilst man was calculating and scratching his head over what his plane had done to the environment the sun had a 0.000000003% fluctuation in the surface temperature in an area facing the earth resulting in a 300m long ice sheet breaking off and a 3mm overall rise in sea levels. No doubt next weeks 0.000003% fluctuation will burn the earths surface into moulten rock. Man made Global Warming - lol. We WISH we had that level of influence over our environment

powerman1

its all just a sales pitch to raise money from the masses

TelBoy

You wish you could be so sure we aren't.

There are six BILLION of us, Kenny.

Not one.

Not six.

Not six hundred.

Not six thousand.

Not six hundred thousand.

Not six million.

Not sixty million.

Not even six hundred million.

Six THOUSAND million.

And YOU'RE the authority on what we can and cannot do to the environment??

Geezer

Mmmm, I don't think anyone has been made to look a bit thick, only unfamiliar with the process of CO2 production. That's why I asked if I had missed something fundamental.

However, I am quite happy with the explanation, and now my knowledge has been broadened, which is never a bad thing

Would be interesting to see to an accurate molecular mass for aviation fuel though, as mentioned above.

As for apologies, I don't think so. The Beeb has yet to run a story from the other side, where half of the worlds respected climatologists refute the data completely.................

Geezer

TelBoy

With respect, bollocks. I'm paying no more in taxes as a result of green initiatives than i was say five years ago. So where does THAT leave your assertion??

LG John

Never said I was. In this world hardly ANYTHING is certain. We make judgements and must stand by our beliefs, whatever they may be, until we are presented with evidence that is significant enough for us to change that belief. This has been the way of science, life, religion, etc since time began.

I believe, and remember I'm a planning officer so this is absolutely contrary to my everday work, that global warming is all bull-f^cking-sh*t. I'm not saying GW isn't happening, I'm just saying I don't believe for a minute mans impact is responsible in whole or in part.

There may be a good number of us but ultimately nature can and does kick our *** any time it wants.

Dream Weaver

Global warming is pure bollocks, sorry.

This planet will be here many many years after we've all killed each other and disappeared.

Global temp has only increased by 0.5 degrees over the last 300 odd years apparently - hardly cause for concern.

AND - this country is cold enough as it is, so if GW does exist, bring it on

TelBoy

If what you see outside your window isn't enough to make you think we're even 0.0000000000000000000000000000000001% responsible for it, can i just ask what event or events WOULD make you think, hmmm, hang on a minute, something's not QUITE right here? And if you're ultimately wrong, who's going to put it right?? Your kids? Your grandchildren? Or "someone else"?