This article is an update on modern wind-propelled ocean-going ships. This was previously discussed in the article, Cylindrical Sails, posted October 1, 2018.
Naval architects and marine engineers are continually working to make ocean transport of cargo more environmentally sustainable. The vast majority of the world’s cargo whether it is manufactured goods (farm machinery or transistors/semiconductors), raw material (food stuff or metal ore), or consumer products (small appliances or clothes) are transported from point of origin to buyer by ships.
The map above is a screen shot on a summer day in the Northern Hemisphere. The number of ships traveling between ports can be seen crowding the favored shipping lanes. Other areas of the ocean are nearly empty in comparison. These shipping lanes are crowded because they are the most direct routes between ports of call. The most famous route being the Great Circle Route.
I remember as a boy seeing the ship I was traveling on being marked on its daily passage with a magnetic ship on a wall size map of the oceans. When I asked why the ship was moving up towards the North rather than going straight across the ocean, I was told that we were on the shortest route, the Great Circle Route.
This route is the shortest distance across the globe of the Earth. By taking the shortest route the ship takes less time in its crossing, thereby saving expenses and fuel costs.
The graceful arc of a Pacific Great Circle Route is shown as a black arc between Asia and North America (California). The congestion of this route can be easily seen. These routes can be made between any two ports on an ocean. Although they become more flattened near the equator and form an upside-down arc in the Southern Hemisphere.
In the last half of the 20th century people began to realize the damage to the atmosphere due to the amount of fossil fuel being burned. This included ocean shipping which at the time burned “bunker oil,” a fossil fuel whose use and emission added tons of pollution to the atmosphere and to the sea each year.
Modern vessels use diesel generators and more efficient power plants to generate electricity that is use to drive the propellers that push these ships. The trend has been from direct drive systems for propulsion (a boiler generates steam to turn a geared shaft on which is mounted the propeller), to an indirect-drive (a diesel generator produces electricity which runs an electric motor to turn the shaft on which is mounted the propeller).
All of these systems use fossil fuels for their main power. Over the years the fuel efficiency of the ships and their engines has greatly improved. This was brought about through improved design of the vessels and their power plants. The results have been reduced operating costs as well as reductions in environmental contamination. At the same time the number of ships transporting cargo has greatly increased. The cargo tonnage offloaded in the Port of Los Angeles, California has significantly increased in the recent years. From 2000 to 2019 the general cargo off-loaded in the Port of Los Angeles more than doubled. It rose from approximately 82 million metric tons to more than 190 million metric tons. All of these goods were transferred by ships burning fossil fuel.
In order to reduce the effect of fossil fuel on the world’s atmosphere and oceans, a consortium being led by Wallenius Marine and including the KTH Royal Institute of Technology in Stockholm, Sweden and SSPA, a marine consultancy, have designed and tested models of the hull design for a modern sailing ship. These tests have been on the open water and in a testing basin.
The modern sailing vessel they are designing is a wind Propelled Car Carrier (wPCC). Wallenius Marine is leading the design of the wPCC. This type of vessel is used to transport manufactured cars and trucks. It is often referred to as a roll-on roll-off (RORO) vessel.
While the sail mentioned in the previous article was a spinning cylinder, the wPCC sails resemble the rigid sails of modern racing yachts. They are expected the propel the Car Carrier across the oceans and achieve a reduction in emissions is 90%. However it is noted that the vessel is slower than a standard RORO.
The sails have yet to come to a final design. These rigid sails will rise up from within the ship. They can also be lowered when the ship is under the control of tugs while in port.
And although I might think that I cannot wait another moment for my new Volvo to arrive, knowing that its transportation had a significantly reduced carbon foot-print is worth the small delay before I have the keys in my hand.
The initial article I read on this was from TNW (The Next Web) and can be found at https://thenextweb.com/shift/2020/09/10/swedes-boat-powered-by-wind-sailboat-ship-cargo-transatlantic/ .
A fact sheet on the wPCC may be found at https://www.sspa.se/sites/www.sspa.se/files/field_page_files/wpcc_fact_sheet_may_2020_v_1.0.pdf .
The map at the top is a screen shot of a maritime information map found at https://www.marinetraffic.com/en/ais/home/centerx:-12.0/centery:24.8/zoom:2 . It is noted that there is an agreement associated with the use of material on this web site.
Tonnage statistics for the Port of Los Angeles may be found at https://www.portoflosangeles.org/business/statistics/tonnage-statistics .