Carnival Corporation hit its 2030 greenhouse gas target five years early. The company then reset the bar, setting a new goal for a 25 percent reduction in emissions intensity by 2029 against a 2019 baseline.

Marcel Goncalves, the company’s vice president of decarbonization, said the more interesting question is what comes next. The answer is heat.

“Of the energy in the fuel, about half of it’s used, half of it’s not, and we’re trying to tap into that piece that’s not, to make the entire ship more efficient,” he told Cruise Industry News.

Waste heat recovery is not new to cruise ships. What has changed is how much of that heat can be recovered and what it can be turned into.

“In the past you would use steam, which is really high temperature heat, to produce electricity. Today, you can use hot water, which is a lower temperature heat, to also produce electricity,” Goncalves explained.

Captured heat can also be converted to cooling, or used for hot water and the spa.

Waste heat joins three areas the company has focused on in recent years: the engines, propulsion and the hotel load, much of it air conditioning.

The single-largest contributor so far has been what Carnival calls Power Saver Packs.

“The biggest win by far, and it doesn’t sound very sexy, is what we call internally Power Saver Packs, and that’s really designed to make the hotel side of the ship more efficient,” Goncalves said. “It’s still the exact same amount of cooling, the same comfort level.”

The gains come from smart systems that respond to actual demand. One example is recirculating cool air in an empty show lounge rather than cooling outside air.

“The physical equipment is already there, but you have to upgrade the brain,” he said.

On the engine side, turbocharger and camshaft upgrades have been folded into planned overhauls. The gain per engine is a few percentage points, but it applies to everything.

“Your engines are the entire thing,” Goncalves said. “If you can get a few percentage points there, it translates directly to a fuel reduction, and then ultimately in greenhouse gas emissions reduction.”

Itinerary design has also played a part, with destinations sequenced to bring down distance and speed. Fuel-efficiency gains are on pace to save roughly $650 million in 2026 versus 2019.

Air lubrication systems are now fitted to 13 ships. They include new Carnival Cruise Line newbuilds, whose hull designs suit the technology despite shorter Caribbean itineraries.

“If you had asked me 15 years ago, ‘Hey, what’s going to happen in hydrodynamics?,’ I would have never mentioned air lubrication systems,” Goncalves said.

LNG Over Methanol

Carnival Corporation operates 11 LNG-powered ships, about 21 percent of fleet capacity, with seven more on order through 2033.

“LNG in fossil form is widely available, and it’s by far the lowest greenhouse gas fossil fuel,” Goncalves said. “With LNG, we see a clear pathway to bio-LNG and to e-LNG, and in fact we’re already operating partially in Europe with bio-LNG.”

Methanol remains under evaluation, but he was blunt about its near-term case.

“Fossil methanol, basically 99.9 percent of the methanol in the world today, is worse than diesel. So if you operate a ship on fossil methanol, you’re actually increasing your emissions,” he said.

Chicken Nuggets

Food waste was down 47 percent per person in 2025 against 2019, close to the 2030 target of 50 percent. Goncalves credited demand forecasting.

“If you have a ship that’s sailing in February, you probably have mostly older adults, and if that same ship is sailing in the middle of summer, you probably have more families, more kids, and I can guarantee you there will be more demand for chicken nuggets in the summer,” he said.

Data Underneath

Underneath nearly all of it is instrumentation, which Goncalves said did not get enough attention.

“You have sensors that are giving you data every three seconds, and then you’re aggregating half a dozen sensors and coming up with a metric that really gives you insights that you didn’t have back then,” he said.

“People associate a cruise ship with a boat moving through water, but the reality is it’s basically a self-sustained city,” Goncalves added. “I intend on working in this space for a long time. We’re not going to run out of ideas.”

Excerpted from the Fall 2026 Cruise Industry News Quarterly Magazine.