Dear Peter,
1) The issue of altitude is partly dealt with by the heavy multiplier
inflicted on the 747 emissions which is based on the impacts of higher
level emissions especially contrails, though you are right, there may
also be other issues with the heights.
2) and 3) Actually my starting point, which I could have explained
better, is that I know some people who have taken the liner in the
belief that it is better, and others who recommend it as a lower
emission transport. I have tried to compare the main current options -
though there are also passenger cabins on cargo ships which would have
lower impacts.
The staff are not included because they are part of the 'fixed'
emissions of the trip as currently offered. Certainly it is true that
the ocean liners are luxury vessels with very high staffing levels, but
the comparison you make is not quite right. There are far more people
than the cabin crew involved with each flight but they do not need to be
on the plane. The mechanics, cleaners, cooks, reception staff baggage
handlers can all stay on the ground. So the real question is: if we
converted the QE2 into an 'economy' vessel how many more passengers (or
less staff) would it have? My impression is that even though the public
spaces are large, the cabins are not and
that even a no thrills ships would still need quite high levels of
staffing to manage a 6 day voyage safely.
So if we imagine that we double the number of passengers on the QE2- we
turn the casinos into cabins, and everyone gets burger and chips for a
week. Even
so, emissions are still lower on a plane. The food may be no better but
at least you only suffer for a few hours.
All this being said, boats have a huge POTENTIAL advantage over planes-
planes are now pushing at absolute limits of what is technically
possible in terms of fuel efficiency. It is hard to imagine a major
technological breakthrough that could increase efficiency/reduce
emissions
dramatically
- airships will be slow with low payload, I suppose in theory one could
use biofuels in
jet/prop engine, but there is nothing in sight. Boats can go a long long
way in reducing energy- Dr Paul Upham of Tyndall Centre replied to my
e-mail as follows- I hope I can share it:
Different transport modes have different potential for improvement
through re-design and alternative fuels: aero-engines have been the
subject of intense fuel-efficiency-oriented R&D for many years, with
substantial public and private investment. I don't think this is the
case for other modes, and it is likely that aero-engines will also be
the most difficult to fuel-switch. So the QE2 of the future?
Computer-controlled, wind-assist sail with bio-diesel for the engines?
The latter must be a near-term option, even if the first is not.
Yours
George
Dr Peter Troxler wrote:
> hmmm ... interesting
>
> (1) what about the QE2 travelling at sea level and the 747 at some 13km above? I think should be considered when you ask whether emissions are "better or worse" (notably not more or less).
> (2) why don't you take the crew into account (~920 on QE2, 20...30 on a 747)
> (3) are you actually comparing means of transport or are you comparing different lifestyles, i.e. luxury cruiser vs economy flight and then telling us that a luxury lifestyle produces more CO2 emission? now that's a surprise ;-)
>
> / Peter
>
> On Jul 18, 2005, at 13:42, George Marshall wrote:
>
> Dear friends,
>
> I have been distracted by a question which has been puzzling me for a long time: are emissions from a ship actually better or worse than flying? In materials and discussions we often assume uncritically that ships are technologically superior to ships in emissions terms.
>
> So I have done a simple and undoubtedly conjectural comparison between a transatlantic journey by 747 and by the QE2- and it doesn't look good for ships.
>
> 747s and the QE2 are of similar age in technology. The QE2 had the then most efficient engines installed when refitted 15 years ago. Because I am comparing technologies,not actual emissions I have assumed 100% occupancy of both 747 and QE2
>
> OK the figures:
>
> The QE2 holds maximum 1,800 passengers. It burns 433 tonnes of oil per day at sea, says Cunard, and takes 6 days for the southhampton to new york trip. This is 2.88 tonnes of oil per person for a return trip. 1 tonne of marine fuel contains 0.85 tonnes carbon, or converted to Co2 (x3.72) this is 3.16 tonnes co2/tonne. So, a return atlantic trip on a full QE2 will be 9.1 tonnes of CO2 per passenger.
>
> This is at the highest end of the estimates I have seen, a full 747 will emit up to 800 tonnes CO2 on the same return route. If we assume a further 'uplift' due to contrails, nitrous oxides etc and multiply by 2.7 (the IPCC's reckoning) that is 2160 tonnes of CO2 equivalent. A 100% full jet with 1st, business and economy classes has 406 seats. So a return atlantic trip on a full 747 will have a climate impact of 5.3 tonnes of CO2 per passenger. But, here's the crunch, this is high because it allows a lot of space for the first and business passengers. If all passengers were in economy seating, there would be 600 seats, which would be 3.6 tonnes per person.
> The emissions per passenger of the QE2 are therefore 2.5 times greater than economy passengers flying.
>
> Of course, one could argue that the QE2 is a luxury vessel and wasteful of space etc. However, it is also relevant that it is an extremely large vessel, carrying 5 times more passengers that a 747 (not to mention all the support staff), so it should be able to achieve far higher economies of scale than a small vessel like a 747. If we wanted to compare luxury with luxury, we can consider that first class passengers on a 747 take twice the space of economy passengers. So, even if the 747 were totally first class, passenger emissions would still be lower than the QE2 at 7.2 tonnes CO2 per person.
>
> And there is reason to believe QE2 emissions may be higher still. Whilst the 747 has been penalised for the 'uplift' caused by contrails, nitrous oxides etc, the QE2 has only been judged for CO2. I have charitably assumed 100% conversion of fuel, but if any of the carbon is released as particulates that too will have a powerful multiplier effect. Marine engines are usually extremely dirty,although the CO2 will be at the cleaner end I imagine.
>
> This is not the end of the comparison. There is the matter of embodied energy. The aluminium (80% of the total weight) of jumbo is 75 tonnes (embodied emissions- assuming not HEP powered, are 27kgco2 per kg aluminium). So the embodied emissions in a 747 are 2,025 tonnes CO2, or 5 tonnes per passenger place.
>
> Now the QE2 on the other hand, weighs 70,327 tonnes. I have no idea what percentage is steel, but to be charitable, I will assume 80% again. The embodied emissions of steel are 3.2 kg CO2/kg steel. So the embodied emissions of the QE2 are 180,037 tonnes CO2, or 100 tonnes per passenger place.
>
> All in all I think there are grounds to seriously question whether we can say that boats have lower emissions for intercontinental travel. What we can say is that people will not be popping over to New York for a shopping weekend if they had to take 2 weeks to get there and back and pay through the nose, but are there not ways to discourage flying which have a similar effect?
>
> Any thoughts or challenges to my figures?
>
> Love
>
> George
>
>
> --
>
> George Marshall
> Co-Executive Director
> The Climate Outreach and Information Network (COIN)
> 16B Cherwell St. Oxford, OX4 1BG, UK.
> Telephone 01865 727 911
> Mobile 0795 150 4549 (I will return your call to save you high calling charges)
> E-mail [log in to unmask]
> Web: www.COINet.org.uk
>
> COIN is a charitable trust, registration number 1102225. It supports initiatives and organisations that increase public understanding and awareness of climate change.
> Internal Virus Database is out-of-date.
> Checked by AVG Anti-Virus.
> Version: 7.0.300 / Virus Database: 266.11.17 - Release Date: 5/25/05
>
> ------------------------------------------------------------------------
> Internal Virus Database is out-of-date.
> Checked by AVG Anti-Virus.
> Version: 7.0.300 / Virus Database: 266.11.17 - Release Date: 5/25/05
--
George Marshall
Co-Executive Director
The Climate Outreach and Information Network (COIN)
16B Cherwell St. Oxford, OX4 1BG, UK.
Telephone 01865 727 911
Mobile 0795 150 4549 (I will return your call to save you high calling
charges)
E-mail [log in to unmask]
Web: www.COINet.org.uk
COIN is a charitable trust, registration number 1102225. It supports
initiatives and organisations that increase public understanding and
awareness of climate change.
--
Internal Virus Database is out-of-date.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 266.11.17 - Release Date: 5/25/05
|
