Aug 4, 2016 · News

Fostering fuel efficiency

Conserving water in guest bathrooms on Royal Caribbean ships plays an important part in the efficient onboard use of electricity.

To understand the connection, it’s necessary to know something about the almost symbiotic relationship between many disparate shipboard processes, especially on the line’s newer vessels.

First, electricity powers virtually everything on the ship. While it might be assumed that the enormous diesels in the ship’s engine room turn drive shafts that spin propellers to move the ship, that’s actually old technology. Today’s ships use diesels to create electricity for, among other uses, powering electric motors that drive the propellers.

“We produce 100 percent of the power that we consume, and we do that by burning fuel,” says Nick Rose, RCL environmental regulatory lead for environmental stewardship. “So anything we can do to reduce the amount of power needed means we ultimately reduce the amount of fuel we consume,” fuel being by far the biggest expense of operating a cruise ship.

Some savings seem obvious, such as switching to LED or fluorescent lights. Most consumers know that LEDs use less power without losing brightness. But they also throw off less heat, Rose says, “therefore the less heat you have to cool” to keep guest areas comfortable. All newbuilds since Quantum of the Seas use only LED or fluorescent lights, and retrofits are planned for older ships, Rose says.

Motion sensors in hallways and other shipboard areas control dimmers that automatically turn lights down or off when no one is using the space.

As for those low-flow water fixtures in staterooms, reducing the amount of water that pours from the showerhead or tap saves electricity because all potable water is either produced onboard or bunkered in port. Using less reduces the electricity needed to produce the water with evaporators or reverse osmosis, as well as the electricity consumed in treating the resulting wastewater.

RCL ships maintain water pressure in low-flow fixtures by impelling it with compressed air. “You still have the same force or pressure,” Rose says, “but you consume less water and you don’t have to make as much.”

High-efficiency appliances are used for any new installation or replacement in the ships’ galleys. Example: The fleet’s newest icemakers use 65 percent less water than older machines, helping to conserve electricity.

And shipboard pumps now also offer their own electrical efficiencies.

“We have pumps that control water flow, pumps that control air flow, pumps that control fuel flow – there’s thousands of pumps all over the ship,” Rose says. Until recently all these marine pumps had only two settings – on and off.

“However, nowadays we’ve converted most if not all of them over to VFD,” or Variable Frequency Drive, Rose continues. This device feeds only as much power to the pump as it needs to accomplish the task at hand.

“You just try to look at every single way that the electricity consumed by the vessel is most appropriate,” Rose says. “Our number one goal is to minimize the amount of energy we use. Period.”