[CliffordK (OP)]

If whales can derive motive power from Plankton.
Would it be possible to power ships using it?

Perhaps separate out the fish and return them to the sea.
Centrifuge out the saltwater. 
Then dry the plankton.
Then burn it, or perhaps use it in some kind of an electric fuel cell?
Save millions of dollars worth of fuel oil.

[bizerl]

You could tether your ship to a whale and try to train it. []

[RD]

Like the whales they'd have to follow the plankton ...

[Average] Distribution of Plankton
Global distribution of chlorophyll averaged over the period from 1 January 2002 to 31 January 2008 using data collected from MODIS on the Aqua satellite. Chlorophyll values range from 0.01 mg/m3 (purple) to 60 mg/m3 (red). From NASA Goddard Space Flight Center.

http://oceanworld.tamu.edu/resources/oceanography-book/phytoplanktondistribution.htm

[CliffordK (OP)]

So, one could harvest the most plankton along the coasts, and North Atlantic and North Pacific crossings.

I may have been incorrect about blue whale diets.  Apparently the blue whales feed on zooplankton including krill.  Not necessarily phytoplankton. 

Nonetheless, it would be good to follow the phytoplankton.

[cheryl j]

Regarding the picture, I can see why it would be more in shallow coastal areas, but why is there so much more in the north? And I would have expected more in the Gulf of Mexico. That's interesting.

[CliffordK (OP)]

There is an explanation in the link above.

It is not clear when the snapshot is.  It says it covers a year, but perhaps the plankton grows in surges.

The winter in the North is characterized by total darkness, and harsh storms to mix up the nutrients.  It is likely followed by a large algae bloom in the spring when the sun comes back for very long days.  It would also be a reason why so many ocean species are migratory. 

It is quite possible that the central latitudes never get the large algae blooms due to more mild year-around temperatures.  So, the peak concentration would never be as high. 

Would there be nutrients, but little life under the ice, so one would get nutritious water around the edges of the ice?

[imatfaal]

Clifford - the ships I look after burn between 20 and 100 metric tonnes of fuel per day .  Thats compared to 3-4 (peak fattening period) for a blue whale.  So would need 5-25 times more plankton - and that is without taking into account the energy density difference between Marine Fuel Oil and Krill and the amazing efficiency we have achieved in diesel engines.  There are also more large ocean going ships than blue whales.  So whilst it might be possible - the ships would soon exhaust the nutrient base of the oceans. 

Large ocean-going ships are amazingly efficient ways of transporting cargo (in many cases moving quarter of a million tonnes of cargo at a time) - let's start with other methods of seeking efficiency gains. 

[Don_1]

I have to agree with imatfaal here, Clifford. Ships may consume a good deal of energy, but not when you take into account how much they can transport from A to B.

But its imatfaal's point on depleting the oceans of the most important food source that would be the real concern. As would the loss of the most important carbon sink.

[CliffordK (OP)]

But its imatfaal's point on depleting the oceans of the most important food source that would be the real concern. As would the loss of the most important carbon sink.

Near the coastlines and bays (usually river channels), there is actually a problem with too much algae.  Harvesting some of the algae would actually make the oceans healthier. 

Mid Ocean, however, it is a good point that one would not wish to deplete the oceans of vital nutrients. 

However, keep in mind that the oceans are quite vast (but obviously not infinite).  However, say the pathway of a single ship is relatively narrow compared to the ocean. 

The goal would be to harvest hydrocarbons.  Other nutrients would be returned to the ocean (although, perhaps displaced from the coastline as appropriate).  The limiting factor for algae growth in the oceans is not sunlight, but rather a lack of nutrients.  So, if the nutrients were recycled in place, the impact may not be that great.  Especially if the ships would also add air and carbon dioxide to the water.  If one used a steam engine, there would be the temptation to save the ash for use as fertilizer.  Not as good for the oceans locally, but it may be good for the overall fertilizer balance on the planet.

As far as the "Carbon Sink" with the oceans.  There are two parts of it.  The carbon cycle from plants, and the dissolved carbon dioxide.

Removing plants that would be quickly replaced depending on available sunlight and nutrients would not greatly impact the living carbon cycle.  Removing some non-photosynthesizing plankton may in fact improve it slightly. 

Dissolved carbon dioxide would be unaffected by the change.  Presumably the exhaust is released underwater.

The big thing would be reducing the thousands of tons of fossil fuels each ship uses.

As far as blue whales.  The historic population was somewhere around a quarter million.  Now there are less than 10,000.  That is a big niche to fill, not that humans haven't already demonstrated our capacity to overwhelm local animal populations.

[Spacetectonics]

Perhaps separate out the fish and return them to the sea.
Centrifuge out the saltwater. 
Then dry the plankton.

So far you have used lots of energy!
I think it is more helpful of producing and adding plankton to the ocean  decreasingCO2 (solving global warming problem by absorbing more CO2!)

[CliffordK (OP)]

We are much better off releasing less fossil CO2 in the air (or water) than we are harvesting and using carbon from an organic carbon cycle.

While the ocean can absorb excess CO₂ to some extent, one should never consider plants as a "sink", but rather part of the carbon cycle.  And it still takes time to distribute the excess CO₂ throughout the several mile depth of the oceans, with the high surface CO2 levels being problematic.

Algae & relatives are some of the fastest growing plants.  But, like with may things, too much algae is bad.  We are actually good at fertilizing algae near the coastlines.  While one would think it would oxygenate the water, as it dies and sinks, decomposers actually remove the oxygen from the water creating dead zones which are very problematic. 

In the middle of the oceans, perhaps the main limit for algae growth is nutrients.  If the carbon was burnt out of algae, and the rest of the nutrients were returned to the water, the algae would likely regrow quickly.

Keep in mind that oil production isn't free energy.  Getting bunker fuel oil from the bottom of a well to a refinery, and then out to a ship in the middle of the ocean might take the energy equivalent of half the oil.

Nonetheless, it is a good point that whales may be more efficient at extracting "fuel" from plankton than our ships would be.