Wave of interest in blue sky thinking

SkySails, a recent winner of the Greenship Technology Award, has won orders from European shortsea shipowners for its kite system.
This provides thrust, which in turn means less engine power is needed for specific speeds.
Similarly, UK-based Greenwave is developing the wind rotor concept as part of a stable of projects.
Wind rotors are nothing new; similar systems were trialled in the last century but failed to catch on. The concept is surprisingly simple: by making use of the Magnus effect, wind energy is converted directly to forward thrust – a phenomenon that is also responsible for footballers being able to bend their free kicks.
On a ship, a spinning 17 metre-high tube creates a whirl of air around itself and a force perpendicular to the line of motion and away from the direction of spin.
Thrust is therefore created, similar to an aerofoil or a sail, and when in use means the ship’s engines can be slowed down while the speed is maintained.
Greenwave, set up as a charitable organisation whose board of trustees all come from the shipping industry, has trialled the concept on large-scale models at Warsash College’s test lake in Southampton.
The charity is now building a full-scale model that will be tested with the help of the Royal Air Force to iron out problems before it undertakes a full trial with four rotors on board a 55,000 dwt bulk carrier later this year.
Project director Nick Dearden believes the simple aspect of this once forgotten design will prove popular as fuel prices climb and emissions limits are lowered.
Kite concept
“The rotor is 10 times more efficient than a sail, both in terms of scalability and manageability” he said.
The system provides direct thrust for a vessel in the same way as a sail, rather than creating electricity from the wind to supplement a diesel electric drive as a wind turbine might.
The thrust calculations were easy to perform, according to Mr Dearden, although he realises that the system, which is somewhat like the kite concept, has some limitations.
“It works best when a vessel has a wind on the beam, as the perpendicular force created is greatest. But when operating it means the engines can be reduced significantly,” he said, claiming that savings are in the range of 13%-30% depending on the route and prevailing conditions.
The system may not be suitable for all ship types. Larger container vessels on fast liner routes, with boxes stacked nine high and with normal speeds of over 25 knots are unlikely to find the rotor useful.
However, bulk vessels with slow-speed diesel engines and a normal sailing speed of under 15 knots are the target group, as are smaller vessels such as trawlers and fishing boats which Greenwave will target with a scaled-down version of the rotor.
The charity is looking at a number of projects aimed at reducing the environmental impact of vessels. It has created a community interest company. This will be used to sell the licences for the rotor concept when it has been fully tried, tested and approved by Lloyd’s Register, which is collaborating on the project.
Greenwave will also continue to look for other concepts to develop into full-scale solutions.
“There is a lot of fantastic work being done, especially in universities,” Mr Dearden said.
Greenwave sees its role as helping to get some of these ideas off the university shelves and into development workshops.