<![CDATA[Grist - Comment Feed for Umbra on planes and cars]]> Grist Comment Feed en Comment #1 by jennyhall98006 http://www.grist.org/article/jet-vs-vette/ Wed, 17 Oct 2007 12:32:36 -0700 http://www.grist.org/article/jet-vs-vette/1 Dimmer switches

I have heard that having a dimmer switch on a light switch is inefficient.  Is that true even when the light is not dimmed?  What about 3-way bulbs?

]]> Dimmer switches

I have heard that having a dimmer switch on a light switch is inefficient.  Is that true even when the light is not dimmed?  What about 3-way bulbs?

]]> Comment #2 by scatter http://www.grist.org/article/jet-vs-vette/ Wed, 17 Oct 2007 18:45:13 -0700 http://www.grist.org/article/jet-vs-vette/2 RFI

Just a quick comment on non-CO2 emissions and RFIs. The 2.7 figure you quoted has been widely picked up but is quite shaky (even if it did come from Nobel prize winners ;) and not the correct way to quantify non-CO2 effects. What is certain is that there are effects which go beyond the CO2 emissions. How strong they are is a topic of fierce discussion.

If you're really keen, an attempt to explain it can be found in the following document but I warn you that it's a little dry, and the climate scientist who pointed me towards said "it is a complex issue and one needs to understand the details of RF calculations for this to 'click'". I'm still scratching my head...

http://snipurl.com/aviationandrfi (p29 onwards)

There's a much more user friendly discussion here (and lots of other interesting aviation & climate related info):

http://snipurl.com/pandd

]]> RFI

Just a quick comment on non-CO2 emissions and RFIs. The 2.7 figure you quoted has been widely picked up but is quite shaky (even if it did come from Nobel prize winners ;) and not the correct way to quantify non-CO2 effects. What is certain is that there are effects which go beyond the CO2 emissions. How strong they are is a topic of fierce discussion.

If you're really keen, an attempt to explain it can be found in the following document but I warn you that it's a little dry, and the climate scientist who pointed me towards said "it is a complex issue and one needs to understand the details of RF calculations for this to 'click'". I'm still scratching my head...

http://snipurl.com/aviationandrfi (p29 onwards)

There's a much more user friendly discussion here (and lots of other interesting aviation & climate related info):

http://snipurl.com/pandd

]]> Comment #3 by ClosetEnvironmentalist http://www.grist.org/article/jet-vs-vette/ Thu, 18 Oct 2007 02:22:04 -0700 http://www.grist.org/article/jet-vs-vette/3 What about # of passangers?

I'm just wondering, is the number of passengers included in those g/p-Km numbers?  It seems to me that because long haul planes have a much higher capacity than short haul, large planes would be more efficient than small ones. So my question is, are these numbers calculated assuming the planes are the same size, or are capacity and fuel consumption differences taken into account?

]]> What about # of passangers?

I'm just wondering, is the number of passengers included in those g/p-Km numbers?  It seems to me that because long haul planes have a much higher capacity than short haul, large planes would be more efficient than small ones. So my question is, are these numbers calculated assuming the planes are the same size, or are capacity and fuel consumption differences taken into account?

]]> Comment #4 by scatter http://www.grist.org/article/jet-vs-vette/ Thu, 18 Oct 2007 05:10:59 -0700 http://www.grist.org/article/jet-vs-vette/4 Load factor is very important

Don't forget larger aircraft need to burn more fuel to carry their load.

Load factor (% of seats full) is very important. From the UK to Europe with our crazily cheap flights, load factors on the low cost airlines average around 80% (Easyjet 82%). The large traditional operators are maybe 75% (BA 77%, Virgin 73%) and the charter operators are as high as 90% (First Choice 91%).

(stats from http://www.caa.co.uk/statistics 2006)

However the carbon factor (gCO2/km) doesn't just depend on the load factor but also the distance flown. An aircraft flying on a 1 hour sector will spend a greater proportion of its time climbing at high throttle. An aircraft on a 7 hour sector will spend a long time at the most efficient cruising altitude. After a certain distance, the carbon factor starts to creep slowly up again because you have to burn more fuel to carry that extra bit of fuel for the end part of the journey (if you get my drift). This is illustrated on the Atmosfair methodology graph here:

http://snipurl.com/atmosfairmeth (p10)

Even more important is the load factor of the car you're comparing flying against. If you've got a car that puts out 200g per vehicle-km and you fit 4 people in it you've got 50g per passenger-km. If the choice is 1 person driving or flying then it's quite possible that flying is better. If it's 2 people then the balance starts to shift towards driving. 3 or more and driving is most likely the best option. But it all depends on so many factors and the data simply doesn't exist to make an informed decision.

]]> Load factor is very important

Don't forget larger aircraft need to burn more fuel to carry their load.

Load factor (% of seats full) is very important. From the UK to Europe with our crazily cheap flights, load factors on the low cost airlines average around 80% (Easyjet 82%). The large traditional operators are maybe 75% (BA 77%, Virgin 73%) and the charter operators are as high as 90% (First Choice 91%).

(stats from http://www.caa.co.uk/statistics 2006)

However the carbon factor (gCO2/km) doesn't just depend on the load factor but also the distance flown. An aircraft flying on a 1 hour sector will spend a greater proportion of its time climbing at high throttle. An aircraft on a 7 hour sector will spend a long time at the most efficient cruising altitude. After a certain distance, the carbon factor starts to creep slowly up again because you have to burn more fuel to carry that extra bit of fuel for the end part of the journey (if you get my drift). This is illustrated on the Atmosfair methodology graph here:

http://snipurl.com/atmosfairmeth (p10)

Even more important is the load factor of the car you're comparing flying against. If you've got a car that puts out 200g per vehicle-km and you fit 4 people in it you've got 50g per passenger-km. If the choice is 1 person driving or flying then it's quite possible that flying is better. If it's 2 people then the balance starts to shift towards driving. 3 or more and driving is most likely the best option. But it all depends on so many factors and the data simply doesn't exist to make an informed decision.

]]> Comment #5 by amc89 http://www.grist.org/article/jet-vs-vette/ Thu, 18 Oct 2007 05:32:34 -0700 http://www.grist.org/article/jet-vs-vette/5 I am a proud Amtrak Guest Rewards member

I live on the east coast, so when I'm just doing trips up and down the coast, Amtrak usually works out the best. May take longer than flying but you do spend less time in security, and the stations are usually in downtown locations so are usually closer to your final destination than the airports, and you don't have to worry about airsickness.  

]]> I am a proud Amtrak Guest Rewards member

I live on the east coast, so when I'm just doing trips up and down the coast, Amtrak usually works out the best. May take longer than flying but you do spend less time in security, and the stations are usually in downtown locations so are usually closer to your final destination than the airports, and you don't have to worry about airsickness.  

]]> Comment #6 by Greta http://www.grist.org/article/jet-vs-vette/ Thu, 18 Oct 2007 07:18:50 -0700 http://www.grist.org/article/jet-vs-vette/6 Yes, but...

...when you factor in the extreme aggravation of trying to use the Amtrak website, train is no option.  Heck, I could walk to my destination faster than I could find information about the point-to-point travel on their website.  Well, then, I guess that Amtrak is better for the environment as it makes you prefer to walk.

]]> Yes, but...

...when you factor in the extreme aggravation of trying to use the Amtrak website, train is no option.  Heck, I could walk to my destination faster than I could find information about the point-to-point travel on their website.  Well, then, I guess that Amtrak is better for the environment as it makes you prefer to walk.

]]> Comment #7 by AlexS http://www.grist.org/article/jet-vs-vette/ Thu, 18 Oct 2007 09:45:40 -0700 http://www.grist.org/article/jet-vs-vette/7 paper. etc.

Dear Umbra,

Which are there more of--farm animals, or wild animals (excluding
non-cephalopod invertebrates?)

Will habitat disrupters (global warming, deforestation, mining,
overfishing, chopping down trees with nests, and cattle grazing) mean
there will be permanently be less anmals suffering, or will it mean
there will permanently be
more animals suffering?
(Or will new species adapt?)

Does cattle grazing mean fewer net animals?
Whose lives would be better--the animals otherwise eliminated by
grazing, or free-range cattle?

How much suffering does the West cause, (as much as by factory farming?)
Would I cause more suffering than good if I become an author , or
other job involving paper, or a movie maker--even if I contribute to
animal rights organizations?

Once factory farming is abolished, will the life of each human still
mean the suffering of more than one creature?

Warmest regards, Alex











]]> paper. etc.

Dear Umbra,

Which are there more of--farm animals, or wild animals (excluding
non-cephalopod invertebrates?)

Will habitat disrupters (global warming, deforestation, mining,
overfishing, chopping down trees with nests, and cattle grazing) mean
there will be permanently be less anmals suffering, or will it mean
there will permanently be
more animals suffering?
(Or will new species adapt?)

Does cattle grazing mean fewer net animals?
Whose lives would be better--the animals otherwise eliminated by
grazing, or free-range cattle?

How much suffering does the West cause, (as much as by factory farming?)
Would I cause more suffering than good if I become an author , or
other job involving paper, or a movie maker--even if I contribute to
animal rights organizations?

Once factory farming is abolished, will the life of each human still
mean the suffering of more than one creature?

Warmest regards, Alex











]]> Comment #8 by racc http://www.grist.org/article/jet-vs-vette/ Fri, 19 Oct 2007 02:26:13 -0700 http://www.grist.org/article/jet-vs-vette/8 Missing the Point

This is like asking the question "Which side of the Titanic was it best to sink on?"

Neither forms of long distance travel are sustainable. We all need dramatically reduce the use of both planes and automobiles.

A great high-speed rail system would be much better than both planes and automobiles.

]]> Missing the Point

This is like asking the question "Which side of the Titanic was it best to sink on?"

Neither forms of long distance travel are sustainable. We all need dramatically reduce the use of both planes and automobiles.

A great high-speed rail system would be much better than both planes and automobiles.

]]>