Royal Caribbean generates big energy savings on Harmony of the Seas

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There was no fudging or guessing when Xavier Leclercq responded to a question about the number of energy efficiency projects included on Royal Caribbean’s newest, biggest ship, Harmony of the Seas.

“There were exactly 89 initiatives,” said Leclercq, formerly the technical director for STX France shipyard – where Harmony was designed and built – and now Royal Caribbean’s senior vice president for Newbuild and Innovation.

His answer was emblematic of the exacting brain power brought to bear on designing the most modern mega-cruise ship in the world. Among the most important of mandates: to make this vessel even more energy efficient than anything that came before.

“We have a fairly energy efficient class of Oasis ships, and when we started the project we thought that 12 percent (energy savings) would be a really good score,” Leclercq said. “In the end we reached almost 20 percent. We actually increased our output by one-fifth, which is a significant improvement of which we are all extremely proud.”

Environmental-HarmonyAlthough dozens of small projects, such as using a different type of glazing around windows, contributed to the improvement, just a few major undertakings provided the bulk of the benefits.

“One big change is in Harmony’s hydrodynamics. By changing the hull form starting from the bow, our drag coefficient was reduced considerably,” Leclercq explained. Large ships benefit from a bow that protrudes from the front of the ship just under the waterline. A new “bulb” design directs water away from the hull, reducing drag, which means we need less energy to propel the ship.

Though they’ve been used in shipbuilding since World War I, the bulb on Harmony is longer and straighter than usual.

“It’s a very innovative shape,” Leclercq said. “The idea is to minimize the added resistance of waves on the hull.”

Harmony is also equipped with the air-bubble lubrication system first used on Quantum of the Seas in 2014 that blankets the ship’s bottom with micro-bubbles, further reducing drag. Four side thrusters on Harmony were also redesigned for an even greater reduction in drag.

“Another of our biggest improvements is on the pod system,” Leclercq continued, referring to the adjustable Azipods that hold the ship’s propellers, providing both propulsion and maneuverability.

“There has been quite extensive work done on the exact position, the tilting, the angles, the rpms generated, the blade and the pod shape,” boosting efficiency by some 4 percent.

By far, however, the greatest energy savings, half or more of the 20 percent total gain, was achieved inside the ship with a reimagined electrical system.

Virtually all onboard power is electrical, from lighting (now entirely LED) and air conditioning to food prep and storage areas in the galleys. By recovering some of the enormous amount of energy normally lost in the air or the water used to cool the ship’s power plant, Harmony’s designers created a system that is using the energy that is normally lost to drive steam turbines that in turn produce about 1 megawatt per hour of “free” electricity for Royal Caribbean’s hotel operations.

“Overall we constantly set the bar exceptionally high. Our teams systematically to look at every aspect of our ship design to find creative ways to make our ships more energy efficient, so they reduce our costs, and more importantly, shrink our environmental footprint,” Leclercq concluded.