Alfa Laval has launched the Hukka-5 exhaust gas steam boiler, using a new downward natural-circulation design to increase waste-heat recovery without requiring more space aboard cruise ships and passenger ferries, according to Alfa Laval.
Unveiled at SMM 2026, the boiler is designed for vessels with four-stroke engines and frequent port calls. Its inverted configuration creates counter-current flow while keeping the exhaust gas boiler footprint compact, with the design intended to limit flow instability when exhaust gas temperatures fluctuate.
The Hukka-5 is available immediately for project orders. By recovering more heat from engine exhaust gases, the system is intended to reduce additional fuel consumption and CO₂ emissions.
“Our previous state-of-the-art WHR boiler, Aalborg XWi, set the standard for natural circulation on cruise vessels. Now, as the need for greater waste heat recovery grows, we are introducing the Hukka-5 and taking energy efficiency to the next level. Since every square meter matter on cruise ships, the new innovative inverted natural circulation design recovers more waste heat without increasing the footprint”, said Matti Takasuo, general manager for BD & Sales for Alfa Laval’s Power, Offshore & Cruise business line.
The Hukka-5 joins Hukka-8 in Alfa Laval’s exhaust gas steam boiler range. The systems are compatible with engines and gas turbines operating on all fuels, including methanol and hydrogen.
The new boiler can also integrate electrical steam generation during port stays when shore power is available, avoiding the need for an additional pressure vessel or auxiliary or fired boiler. Its modular design allows multi-stage heat-recovery configurations and an optional condensing cold-end design. A vertical steam drum is standard.
Alfa Laval has completed more than 1,300 waste-heat recovery boiler installations for cruise ships and passenger ferries since 2000, alongside hundreds of land-based projects in more than 100 countries.
The company says the installed systems reduce CO₂ emissions by more than 10 million tonnes annually.
Alfa Laval is a Swedish industrial technology group founded 140 years ago, with customers in 100 countries and more than 23,670 employees. Its 2025 sales were SEK 69.6bn ($7.21bn) and €6.6bn ($7.64bn).
Alfa Laval Aalborg Oy is the Finland-based subsidiary within Alfa Laval’s Ocean division that houses the Power, Offshore & Cruise business line. It designs and supplies waste-heat recovery and fired boiler systems for marine, offshore, power-generation and process-industry applications, with its main operations in Rauma, Finland, and Singapore.