A new take on ancient tech as sail power makes a comeback

9 April 2019

In the last few years, the maritime media has been full of articles about the rise of robot ships. But the future face of the shipping industry could be very different, with sail power staging a remarkable comeback...

As shipowners struggle to comply with increasingly strict environmental requirements, a growing number of operators are embracing the use of wind propulsion technology to cut their carbon footprint.

The progress was recognised last month with the classification society DNV GL giving its first design type approval certificate for an auxiliary wind propulsion system: Norsepower’s 30m by 5m Rotor Sail, two of which have been installed
onboard the 109,640 dwt oil LR2 product tanker Maersk Pelican in a trial backed by the UK government.

The Norsepower Rotor Sail is a modernised version of the Flettner rotor, a spinning cylinder that uses the Magnus effect to generate an aerodynamic force to propel ships. First trialled on a ship in the 1920s, the system can deliver fuel and emissions savings ranging between 7% and 20%. The system has also been installed on the 57,565gt Finnish-flagged ferry Viking Grace.
There are now six vessels with commercial rotor installations, including the 63,233dwt geared bulker Afros, with four moveable Anemoi rotors, the ro-ro Estraden retrofitted with two rotors and in regular operation between Rotterdam and Hull, and the general cargoship Fehn Pollux, with a single bow-mounted rotor.

These five vessels follow in the footsteps of the first modern Flettner rotor-fitted vessel, Enercon's E-ship 1, which has been in operation since 2009.
The Rotor Sail, or Fletter rotor, is just one of an increasingly wide range of systems coming onto the market. Other technologies include:

  • soft sail – both traditional sail and new designs, such as DynaRig, originally developed in the 1960s
  • hard sail – wingsails and foils. Some rigs have solar panels for added ancillary power generation
  • suction wings (Ventifoil, Turbosail) – non-rotating wing with vents and internal fan (or other device) that use boundary layer suction for maximum effect kites – dynamic or passive kites off the bow of the vessel to assist propulsion or to generate a mixture of thrust and electrical energy
    turbines – using marine adapted wind turbines to either generate electrical energy or a combination of electrical energy and thrust
  • hull form – the redesign of ship’s hulls to capture the power of the wind to generate thrust

The technological advances, coupled with the environmental, economic and regulatory pressures, are leading a growing number of shipping operators to consider their use.

The International Windship Association (IWSA) says there is the potential for more than 10,000 wind-assisted vessels to be operating within the next decade. 'The way forward is full of exciting opportunities,' says IWSA secretary general Gavin Allwright. 'These activities follow some of the recommendations made in the EU report on wind propulsion market development, which forecast up to 10,700 wind propulsion installations on bulkers and tankers by 2030 if the facilitation framework is in place.'

Last year, he adds, was a very significant one for wind propulsion. 'We could say that a perfect storm is brewing for the uptake of primary [wind, etc] and secondary renewable energy [alternative fuels/energy storage] in shipping,' he
points out. 'Policy, price, perception, providers and people are all starting to align.'

The world fleet accounts for more than 2% of global carbon dioxide emissions, and the industry will have to cut this by at least half over the next 30 years. Next year will see the sulphur cap come into place, and the IWSA reckons the
pressure for change will intensify as conventional marine fuel costs increase. Retrofitting vessels with wind propulsion technology could deliver cost savings of between 10% to 30%, and for newbuilds fuel bills could be halved.
What do such systems mean for seafarers – extra workload, for instance?

'Most of the systems are fully automated on the larger vessels and will be fully integrated into the ship energy management systems in the future,' Mr Allwright says. 'They have weather stations onboard that help optimise the operations and weather routing software for voyage optimisation in the future. The installation and maintenance of the systems are fairly straightforward.'

Shipping industry perceptions of the technology are shifting, Mr Allwright adds, but he warns that the recent report by the UN Intergovernmental Panel on Climate Change on the impact of a 1.5C temperature change should serve as 'a wake-up call to all of us, indicating we have only 12 years until we reach that seriously challenging and potentially catastrophic benchmark'. The study argues that a minimum of 45% CO2 reduction will be required by 2030, he points out, 'so action is needed – deeper and faster'.

As well as the trials being undertaken on a growing number of ships, the past few years have seen detailed proposals being put together for wind-powered vessels. One, which has attracted the attention of the European Commission, is the Ecoliner project developed by the Dutch naval architects Dykstra. Intended as a multipurpose cargoship, the 11,850gt vessel would build on the company’s successful use of the DynaRig technology on the superyachts Maltese Falcon and Black Pearl.

In the Netherlands, the Wijnne Barends general cargoship Lady Christina has reported positive results from trials of an eConoWind unit that uses the VentiFoil system, with savings of up to 800 litres of fuel a day during early tests.

In the UK, Windship Technology is promoting its plans for the Windship Auxiliary Sail Propulsion System (WASP) – claiming the use of its fixed wing technology could cut fuel consumption and emissions from bulkers and tankers by up to 30%, and result in savings of as much as US$3m a year on fuel costs.

Also in the UK, the Smart Green Shipping Alliance is involved in a 12-month feasibility study to test Fastrig sail technology on a Danish-owned bulk carrier that imports biomass to British power stations.

These are just a few of the projects now under way, and Mr Allwright notes: 'The movement in wind propulsion tech and project solutions is picking up pace. Our industry is a broad church and shipping has always had highly talented people in sometimes difficult positions, but there is increasingly a shift to a new generation of decision-makers that are focused on the triple bottom line, engineers and designers producing ever more innovative designs and customers demanding more action on emissions from shipping. Wind propulsion is a credible, viable and increasingly profitable option, and the industry is taking notice.'