Eco & Expedition Cruising
Low Impact Cruising Idea
By ew101, July 11, 2019 in Eco & Expedition Cruising
ew101
USA Midwest
There has been recent environmental publicity, legal action and even protests focused at Carnival Corporation in particular and the impact of cruising in general. The problems range from stack emissions, sulfur, plastics, to sewage, etc.
They may be some people interested in purchasing a "lower impact" cruising product offer. It would for the moment be filled with compromises, and there are not a lot of breakthrough technological tools on the shelf, that are not already in use. This has been validated by our local experts and fact checkers.
The modern cruise experience uses a lot of electrical power. Power is used for propulsion (85%+), and hotel loads. And space aboard is limited.
The idea would be to design and or rebuild a modest ship that would use a mash-up of technologies. This has been done recently, at least at the design level. Not much new ground has been broken, but it should be considered a 1.0 effort.
http://ecoship-pb.com/technology/ 
The big problem, as has been pointed out by ChengKP75, is the propulsion load. The ship needs megawatts and the solar and wind arrays produce kilowatts. The propulsion issue is significant. After decades with a five ton, 13 hp sailboat, I think massive motors are not required, unless you are in a big hurry. Think cruising not crossing. World War II vintage Liberty Ships were 410 feet long, 14,000 tons and had a single 2500 hp. engine. The top speed was 11 knots.
https://en.wikipedia.org/wiki/Liberty_ship#Propulsion
There was an interesting number in Wikipedia - 2500hp = 1900kw. The latest Tesla commercial Powerpack provides around 200 kWh per chest freezer sized battery module (if I am reading it right).
https://en.wikipedia.org/wiki/Tesla_Powerwall#Powerwall
If you had small engines, could you leave the dock with and or make along the way, enough energy for a modest cruise, from say Miami to The Bahamas? The cruise line would store up and or buy solar or wind at the ports for charging. You could add in help from Flettner rotors, sails etc. We cannot of course support 3000 passengers, ice skating rink, etc. But it can be a cruise.
Edited July 11, 2019 by ew101
Canuker
I'm no engineer nor do I know much about the subject of this thread.
But I suspect that, in open water, at least, the amount of polution created to drive the pair of propellors/pods on a typical cruise ship is but a fraction of the total polution.
And I'm not just referring to what emerges from spent fuel.
Carnival has paid huge fines for continuously dumping waste into the sea.
Also, what emerges from the funnel is not just from the combustion of fuel.
Lastly, the fuel used is,generally, of extremely low grade and produces high proportions of polutants compared with, say, what is burned in a car.
Ever been up early on a cruise ship and seen all that black gunk on the rear decks - before it is washed off the deck - to guess where.
Why do they do all this? Because they can.
Yet they portray themselves as clean global citizens.
It's not true.
What can we do, as cruise passengers, to mitigate the effects of cruising on the global (and local) environments?
Yes you are on the right track here. The cruise industry is growing at 6% a year and the regulations say it is fine to burn a barge load of low grade bunker fuel every voyage. As consumers the handful of us who understand what is happening need to be vocal. And vote with our wallets. It may require the founding of a new cruise line. I think an old ship could be converted. The idea is to use wind turbines and batteries and to operate at reduced speeds. The message is that brand new diesel ships are operationally efficient but uncool.
One personal dilemma- if I board a scheduled ship does that produce net new CO2- not. But if the line says wow we are sailing full time to order a new diesel ship- that is bad. Or if ships are sailing empty do they scrap them.