Cruise Lines International Association (CLIA) has released its annual Environmental Technologies and Practices (ETP) report.
The report gave a profile of the CLIA-member oceangoing cruise fleet and highlighted environmental technologies in use by member oceangoing cruise lines, which comprise more than 90% of the cruise sector.
This year’s report showed continuous and measurable progress by CLIA member cruise lines, as they advance an ambitious environmental agenda—from testing and piloting biofuels, to investing in fuel-flexible engines, to the increasing use of lower emissions fuels, and maximising energy-efficiency measures.
“Cruise lines are early adopters and innovators of maritime technology — examples include advanced wastewater systems, onshore power supply, air lubrication systems, and the newest generation of dual- fuel engines—from which other sectors of maritime also benefit,” said Bud Darr, CLIA President and CEO (pictured).
“Cruise lines are investing tens of billions of dollars to build the fleet of the future, including more than 80 new ships on order worldwide that feature these and other innovations.
“These orders represent tangible steps that are significantly enhancing the operational capability and efficiency of the collective global cruise ship fleet of our members,” he added.
Fleet profile:
- CLIA-member Cruise Lines: As of August 2025, 45 cruise lines, representing 90% of global oceangoing capacity, were members of CLIA.
Combined, these cruise line members operate 310 ships at 637,847 lower berths, compared to 303 ships at 645,034 lower berths last year.
- Fleet Profile: Analysis of the current CLIA member cruise line fleet indicated that the majority of oceangoing ships—73% — are small to mid-size ships (about 3,000 lower berths), with the percentage of ships by size remaining relatively balanced through at least 2036 (based on the orderbook, which runs through December, 2036):
Pursuit of net-zero emissions and operational efficiency:
- Multi-fuel capable ships: Multi-fuel engine technology provides the fuel flexibility needed to utilise zero – and near-zero emission fuels, as they become available, at scale, with little to no engine modifications.
- The number of ships operating with multi-fuel engines that can switch from conventional fuels to zero- and near zero emission fuels both in port and at sea has increased from just one ship in 2018 to 19 ships today, which are all dual-fuel.
- By year-end 2025, 23 ships with fuel-flexible engines are forecast to be in service, including the first cruise ship with a tri-fuel capability.
- Through 2036, 32 dual-fuel ships are forecast to be introduced, including seven capable of using methanol and 25 capable of using LNG.
- Uptake of alternative, zero- and near-zero emissions fuel pathways: Cruise lines continue to increase their use alternatives to heavy fuel oil (HFO) as options begin to emerge, including biofuels, LNG, and others, as exemplified by the delivery of one ship in 2024 specified for methanol use by 2026, and another due for delivery by the end of this year.
- Onshore power supply (OPS) connectivity: Also referred to as shoreside electricity (SSE) capability, this allows ships to turn off their engines while in port for emissions reductions of up to 98% (with all emissions covered) depending on the mix of energy sources, according to studies conducted by a number of the world’s ports and the US Environmental Protection Agency (EPA).
- The number of CLIA-member cruise line ships with the ability to utilise OPS has nearly doubled since 2018, when 55 ships, representing 25% of the fleet and 28% of capacity, had OPS capability. Today, 166 ships are able to plug in at port, a 12% increase from the previous year. These ships represent 58% of the fleet and 65% of capacity.
- By 2036, 273 ships that can connect to OPS are expected to be in service (based on the number of ships scheduled to be retrofitted and new ships on the order book specified for OPS connectivity).
- This includes 166 currently with OPS, plus 59 currently in service scheduled for retrofit and each of the 48 CLIA-member cruise ships on the 2025/2036 orderbook.
- Currently 41 of the ports worldwide where cruise ships call (fewer than 3%) have a cruise berth with OPS, an increase of eight ports since last year.
- Europe has led the expansion over the last 12 to 18 months—with OPS being launched in six additional cruise ports, and the UK and North America each added one new cruise port with OPS.
- There are 19 ports that have secured funding for OPS and 26 more with plans to do so.
As part of the EU’s Fit for 55 de-carbonisation regulations, by 2030 major ports in Europe will be required to have shoreside power, which will further accelerate port infrastructure investment in that region.
*Selective catalytic reduction technology (SCR): SCR reduces particulate matter and nitrogen oxide emissions, thus helping ships to meet IMO Tier III classification standards for nitrogen oxide emissions (NOx).
- The number of CLIA-member cruise line ships with SCR systems has increased tenfold, from seven ships in 2018, representing 3% of the fleet and 3.2% of capacity, to 81 ships, representing 28.5% of the fleet and 22.3% of capacity.
Shipboard water production:
- Freshwater Production: Systems that enable most CLIA-member cruise lines to produce the majority of their water needs on board rather than drawing from ports and destinations where resources may be limited.
- This is made possible by a range of environmental practices that include steam evaporation, reverse osmosis, aeration, and other systems that enable cruise lines to conserve water.
- Today, 279 ships, representing more than 98.2% of the fleet and 99.9% of global capacity, are able to do so.
Wastewater treatment:
- Advanced wastewater treatment systems (AWTS): The majority of CLIA member ships sailing today utilise advanced wastewater treatment systems (AWTS), which are capable of exceeding MARPOL Annex IV requirements.
- In addition, as part of their overarching sustainability focus, cruise lines have committed to not releasing untreated sewage anywhere in the world during normal operations.
- Across the CLIA cruise line member fleet, 234 ships, representing 82.4% of the fleet and 85.4% of global passenger capacity, are equipped with AWTS, a 4% increase in the number of ships and passenger capacity year-on-year, and a 72% and 71% increase, respectively, since 2018.
- Today, more than one-third of the ships equipped with AWTS are capable of meeting the more stringent wastewater standards of the Baltic Sea Special Area.
- By 2036, 273 ships and 685,000 lower berths’ capacity are specified to have AWTS.
Waste Management:
- Waste Management: Alongside the uptake of lower-emissions fuels and increasingly energy efficient fleets, cruise lines are beginning to deploy a new generation of shipboard waste management technologies—with some ships able to recycle or repurpose nearly all waste generated on board.
- Some of the systems currently used on cruise ships include:
- Waste-to-energy gasification systems: Currently in use on eight cruise ships, these systems convert waste into usable energy to support the ship’s operations, thus reducing waste sent to landfills and decreasing the ship’s energy demand.
- Microbial digesters for food waste: Currently in use on 128 cruise ships, representing 45% of member ships and 52% of capacity, to significantly reduce food waste, few of these types of waste management systems were present on cruise ships five years ago.
