Freight Ship Deploys Spinning Sails to Cut Fuel Use

Shipping giant Maersk has long been working on innovative solutions to shipping's carbon footprint. While much of the effort lies in super-giant, ultra-efficient new ships, it seems reasonable to assume that fleets will still run older, more polluting models for many years to come. And given shipping's reliance on highly polluting, low grade bunker fuel, that's a serious problem.

So, what hope is there for retrofit solutions?

We've already seen that simply operating cargo ships at lower speed can dramatically reduce emissions, and there have been trials of interesting add-ons like kite-powered ships—although we haven't head many updates on that particular innovation in the last few years.

Now another contender is making a splash (sorry!). The Guardian reports that Maersk is installing "spinning" or rotor sails on one of its ocean-going freighters, with the hope of testing this technology for fuel savings. The "sails"—made by Finnish company Norsepower—are basically 100ft (30-meter) columns which are rotated using electricity. As wind passes across the column, it slows down on one side and speeds up on the other, generating a thrust perpendicular to the direction of the wind. (The rotation can be reversed if wind speed changes.)

The projected fuel savings are significant, if not mind blowing. Horsepower CEO Tuomas Riski told The Guardian he is confident they'll see 7-10% cuts in fuel use, amounting to about 1,000 tonnes of fuel a year. I suppose the question will be whether rotor sails can be used in combination with other retrofit and/or operational solutions such as slower speeds, heat recovery systems from the ship's motor and/or solar to deliver deeper cuts than any single technology could deliver alone.

The sails are going to be fitted in 2018, and tested through 2019, so we should have a better idea by the end of the decade whether this solution can scale to deliver meaningful savings.