2020s: the decade wind assistance for tankers became a reality

All the ingredients for tanker retrofit installation and newbuildings are available off the shelf and owners and operators are keen to reap the benefits.

In Riviera Maritime Media’s Practical application of wind technology on tankers webinar, experts from the fast-emerging wind technology industry reported on developments for the tanker sector and how owners and operators could take advantage of the services and tools available. The webinar was sponsored by Anemoi, a global provider of proven wind technology and giant engineering and maritime services provider Wärtsilä.

International Windship Association (IWSA) secretary general Gavin Allwright opened the proceedings with an overview of the surprisingly large number of wind power technology projects underway in the shipping sector, but first defined wind propulsion: the direct application of wind power, not the conversion of wind into alternative fuels.

Wind assistance is a term used to cover some key elements: zero-emissions energy source, free and delivered to the point of use, no onboard storage, compatible with all fuels, facilitates secondary renewable fuels, uniquely available to shipping. In retrofit installation form, IWSA estimates it can provide between 5% and 20% propulsive force and on a newbuilding with operational changes, the estimates ramp up to 50% to 80%.

The range of direct wind propulsive technologies include kites, hard sails, rotors, turbines, soft sails, suction wings and will include changes in the hull form on newbuildings. Mr Allwright noted “If this is tied in with operational changes, for example speed reduction and weather routing, then rather than the siloed savings, we start to see some interesting combined savings.”

He added that when tied in with vessel optimisation, more integration into the energy management systems and technologies like air lubrication, this creates a “hybrid wave” of savings.

There are currently two tankers with wind propulsion assistance. Timberwolf (ex-Maersk Pelican) is an MR tanker fitted with rotor sails, and New Vitality is the first VLCC newbuilding to be installed with rotors. IWSA estimates there are 15 current installations of all ship types with a research and development pipeline of around 30 technologies and products. An EU report noted that market potential for bulk ship types including tankers was 3,700 to 10,700 installed systems by 2030.

But what did the audience think would be the percentage of wind propulsion assisted tankers in 2050? 1-5 percent 10%; 6-10 percent 19%; 11-25 percent 38%; 26-50 percent 21%; 51-75 percent 8%; 76-100 percent 4%.

MARIN senior project manager ships, team leader transport and shipping Patrick Hooijmans described the development of the free-to-use Blueroute application within the WiSP2 Joint Industry Project, which is an online web application where you can carry out performance estimations for any type of ship and any type of wind device. This was designed to allay one of the barriers to the take up of wind propulsion, which was uncertainty of the cost efficiency and the lack of transparency and information on performance, operability and safety, among others.

In a poll, the audience were asked: What do you consider the main barriers to wind propulsion? 32% felt capex was the main issue and 25% performance validation. Lack of clear class rules and regulations was a concern for 13% and 12% chose potential IMO manoeuvring compliance issues. Technology readiness level 9% and a lack of tools to determine benefits 9% were the other main concerns.

Performance predictions must meet the methods approved for EEDI and EEXI and be made available to the public.

This has led to the development of tier one, which encompass the effect up to 10%. Above this, there are knock-on effects, explained Mr Hooijmans, such as heel and leeway, interaction from the rotors, propeller unloading and subsequent increases in specific fuel consumption. The solution is to conduct voyage simulations using weather statistics and global wind statistics (EEDI/EEXI).

In a poll, the audience were asked: How useful would a global wind probability matrix be for EEDI/EEXI calculations? Half (50%) agreed this would be useful, 24% classed this as ’nice to have’, 23% thought this essential and 3% deemed this a backward step.

In the case of the Blueroute application, the scientific design concepts are the WASP-Ecoliner and MARIN’s own MHTC. These have been verified against real-life operational data from New Vitality (DSIC rotors) and Timberwolf (ex-Maersk Pelican – Norsepower rotors).

The provision of Blueroute by Marin is a useful tool for tanker owners assessing how to tackle EEXI compliance. In a poll, when offered alternative fuels, energy saving technologies, or engine power limitation, 65% said they would use a combination of these technologies. Only 18% choose power limitation alone, 14% energy saving technologies alone and 3% would rely on alternative fuels only.

Wärtsilä director propellers and transmission Elias Boletis explained the integration of wind assisted propulsion into the tanker’s systems. He noted there are significant variations of wind propulsion depending on the direction of the wind on the rotor. There is a 30° area of low forward thrust around the ahead position. In an example, 16 m/s wind speed at 60° to the rotors produced 513 kN of forward thrust for 4 X 175 m² of rotor sail area.

Mr Boletis explained that the wind impacts healing and drift, which in turn creates an angle at which water is approaching the rudder. Therefore, an integrated approach is needed to explain and account for all the aspects of the forces on the rudder and propeller and the impact on the vessel. Mr Boletis felt that when wind propulsion is producing in excess of 15% of the engine thrust, there needs to be special considerations, such as special rudder types, controllable pitch propeller and integration of the thrust assessment systems on the vessel.

Anemoi mechanical engineer Joe Baker was to address these issue head-on later in his presentation (build or retrofit the tanker ’wind ready’) but commenced with an overview of Anemoi products. The Anemoi is a fully integrated system, taking wind speed, direction and other data from instruments installed on the tanker, feeding the data into the processing unit and presenting the information on a dashboard on the bridge. The system is entirely autonomous.

“The data can be transferred from the ship to shore for performance monitoring from various stakeholders. The system monitors the health of the machine and includes safety and alarm features to ensure the reliable operation of the system at all times,” he said.

One frequent question from the webinar delegates concerned the deck of the tanker and the installation of rotors. He said, “The design is class approved and includes installation of the steel foundations for sub deck strengthening and a power supply network for the system. At this point, the vessel is said to be wind ready and can receive the equipment.”

He noted that tankers have hazardous zones such as manifolds and pipework on deck, but generally this presents no problem and in fact the ’clean’ nature of tanker decks lends them to rotor sail installations.