Researchers are looking to wind power for the next generation of ships

August 6, 2015 by Tristan Smith, The Conversation
Credit: University of Tokyo

In many ways, it's an obvious solution. For many centuries, world trade over the oceans was propelled by wind power alone. Now that we're seeking an alternative to the fossil fuel-burning vehicles that enable our modern standard of living, some people are turning again to renewable solutions such as wind to power our tankers, bulk carriers and container ships. Globalisation and economic growth might mean a direct reversion to the wooden sailing boats of yore makes no sense, but there are several 21st-century ideas that could make wind-powered shipping commonplace again.

Ship design certainly has a way to go to return to its heritage and take advantage of the 's free, renewable resource in the same way we have reinvented the windmill to produce electricity. However, it's worth remembering wind turbines took a long time to evolve into the structures optimised and deployed at scale we have today. In fact, they're still developing. Scientists and engineers have debated for years about the relative merits of two, three or more blades, of horizontal versus vertical configurations, and of onshore versus offshore generation.

For ships, the design process for wind technologies is potentially even more complicated and multi-dimensional. There are soft sails, rigid "wing" sails, flettner rotors (a spinning cylindrical vertical column that creates lift using the Magnus effect, originally conceived by Flettner in the 1920s) and kites all vying for a share of this market. Soft sails are fabric sails, most reminiscent of existing sailing ship designs, examples include the Dynarig and Fastrig. Rigid wing sails replace the fabric with a rigid lifting surface like a vertically mounted aircraft wing - for example the oceanfoil design.

A flettner rotor is a vertical cylinder rotated by a motor. The rotation modifies the air flowing around the cylinder to generate lift much like the lift generated by an aircraft wing (it's referred to as the Magnus effect). While there are many examples of all four, so far it's the kites and the flettners that have seen the most significant implementation on large merchant ship designs.

Enercon’s E-Ship 1 with flettners. Credit: Carschen/Wikimedia Commons, CC BY-SA

Notable examples include the work that Cargill and Wessels have done trialing kite systems , and the experience of two separate operators, Enercon and Norsepower with installations of different flettner designs on different ships. These trials have produced important full-scale experience, lessons about costs, performance data, and evidence for investment cases. All of which are undoubtedly taking us closer to the tipping point when wind once again becomes a 'no brainer'.

Trials of these new technologies, in combination with the history of wind turbines, can help us understand why any transition to modern wind-powered ships won't happen overnight. For one thing, no one yet knows which of the many candidate designs will be the most successful.

Modern wind-powered shipping technology also carries a significant engineering challenge that don't: it needs to be mobile. It's not as simple as bolting a rig to the deck. The highest safety standards have to be maintained and the rig must pose no constraints to loading and unloading cargoes in an uncertain and wide range of different ports (many of which might be obstructed by bridges).

Resolving these issues will take time, money and investors with the appetite for risk and stamina to see an emerging technology from a prototype to a fully developed new product. But I believe the change will happen because of the price of and environmental regulation. Wind power is free so the technology will become a worthwhile investment once it can be clearly evidenced that the saving from moving away from fossil fuels outweighs the costs of installing and operating a wind-powered ship.

Many think that threshold oil price has already been achieved and exceeded, as evidenced by the large and growing number of projects proposing wind propulsion solutions, even allowing for the recent fall in oil prices.

While there is currently only weak regulation on shipping's greenhouse gas emissons, the sector – like all those producing carbon dioxide – is likely to face more stringent controls as its emissions continue to grow. Exactly what form such controls will take remains the subject of further ongoing work. But any meaningful regulation would reinforce the case for wind-powered shipping as a favourable investment.

Shipping is a vital, if somewhat hidden, part of modern economies. Decarbonising those economies is the only way to avoid destroying them (and the environment). Wind power presents an astoundingly obvious and elegant solution to these combined challenges. But it will languish in the sidelines until we see rapid change from investors, politicians, or ideally both.

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Returners
3 / 5 (2) Aug 06, 2015
Wind power is free so the technology will become a worthwhile investment once it can be clearly evidenced that the saving from moving away from fossil fuels outweighs the costs of installing and operating a wind-powered ship.


There are some "conflict of interest" issues. The slower the ship travels, the fewer round-trips it can make between ports, therefore the less revenues it can generate. Less revenues means less profits, simply because it takes less freight per year.

So even if the wind power is technically "cheaper" it won't necessarily be implemented until it becomes so much cheaper as to offset the loss of revenues per ship.

Compounding the problem is that longer round trips means more wages per round trip for the crew of the ship, which eats into company profits per round trip even more.

Diesel powered ships travel about twice as fast as the fastest possible pure wind-power ship.

Newer Diesel ships are around 50% efficient, cleaner than automobiles
Returners
1 / 5 (1) Aug 06, 2015
By the way, I agree that at some point Wind and Solar are going to have to be implemented again for Shipping, it's just a matter of time. I guess you can coat the sails with solar PV, and use the generated electricity to power the ships electronics, or to power complimentary electric motors. They won't be as powerful as the existing diesel engines. I've done the math on that and for that (enough power to equal a diesel during the day,) you would need solar "wings" to collect enough power to equal a diesel, but that adds more mass and surface area, which slows the ship down and increases risk in storms.

Soooo, Wind would provide the majority of the non-fossil fuel energy, and solar could be used to power electronics to remove a small amount of the burden from the diesel engine, since you would no longer need to use it as an electric generator, it would become more efficient as a mechanical motor.
Returners
1 / 5 (1) Aug 06, 2015
Besides direct Wind and Solar, you could use large wind and solar farms on the ocean to power electrolysis of water, capture the Hydrogen, and then have the ships run on electric engines powered by hydrogen fuel cells. The advantage of this is it provides the same "power density" of the ship's existing on-board engines, but produces no pollution, and the "true" energy generators, the wind and solar, are off-board, so that the ship has no added mass or encumberances.

Or...you could always switch the ships to being nuclear powered, but that comes with its own set of problems, such as needing a squad of security soldiers on every vessel so as to avoid terrorists trying to hijack a ship to make a dirty bomb, etc.

If Rossi could ever scale up his e-cat technology, you might be able to use a small generator to catalyze the reaction and produce massive amounts of heat to use via his LENR process to power a ship.

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