Popular Mechanics, my favorite tech magazine (well Popular Science comes close) has an excellent article on the new Parasail Technology that promi9ses to reduce fuel consumption in shipsar: http://www.popularmechanics.com/outdoors/boating/4235055.html The German Skysail system http://www.skysails.info/index.php?L=1
featured in the article is designed to be fitted to virtually any of today's cargo ships and promises a reduction in fuel consumption of 35% on each voyage. The system is certainly good enough to be improved even further and the German engineers who have designed it must be hard at work fine tuning the technology or even designing vessels to be powered exclusively by it. There was already a move in Congress to impose fuel efficiency regulations on recreational boats, a very good idea if you ask me, and the IMO has been toying with similar recommendations for large ships. There are proposals to intriduce fuel cell driven ships but with fuel cells still some way away from commercial production that may be something for the future.
In the meantime, a French company has gone to the real thing: full fledged sailships carrying wines to other European markets as this article from Treehugger describes: http://www.treehugger.com/files/2008/08/slow-freight-joins-slow-movement.php
My feeling is that it is a question of time before goods that do not need to be rushed from one location to another are moved by sail. I have seen sailboats go nearly as fast as diesel powered ones on Lake Michigan and while I am no expert in this area and do not know how a particular engine displacement would compare with say a certain surface area for a sailboat's sails or whatever, the fact is that we have a centuries-old tradition of using wind power to deliver cargo. In her day, the last British Tea Clipper, the Cutty Sark http://www.cuttysark.org.uk/ often beat steamships hollow across the seas. Granted, there should be much faster vessels these days, they would hardly do what they do as cheaply as a sailship would. And with oil temporarily down but still expensive (yes, it cost me $ 41 for a tankful of gas today despite a "reduction" in pump prices) I think that it is a question of time before sailships become more common. Right now, some of the sailships use diesel gensets to keep food cargo cool. In the future, there could be one or another of the solar powered designs that are used. It is a question of integrating technologies and it is only a question of time before something very concrete comes out. Engineers are impatient and fiercely competitive people. I don't expect them to keep off fiddling with different energy-saving technologies in their rush to make the most advanced ships possible in the future.
Yes, I am a boy who comes from a seaside town where, in the mornings, children still go to the beach to watch fishermen bring their catch in and sell it to fishmongers. I have seen vessels from small catamarans (the name comes from the Tamil "kattu maram") to huge oil tankers at the port in Chennai. While I did see the last of the coal-fired steamships when I was a boy and even traveled from India to Sri Lanka by sea, the era of sail had died when I was growing up some four plus decades ago. I cannot, but, be excited about a future where sailships are visible on the horizon. What would I give to be outside Fort St George in Chennai looking out into the Bay of Bengal for sailships coming in to the port! As boys in school we were made to memorize John Masefield's "Sea Fever." I can feel it coming on as I wait for sail's second coming.