KBB Turbochargers: pioneering innovation for the future of marine propulsion

Alternative fuels

As the shipping industry pivots toward alternative fuels, each new energy source presents unique technical challenges for turbocharger design. KBB has demonstrated remarkable agility in adapting its systems to these emerging fuels.

Ammonia is heralded as a carbon-neutral fuel, but its slow combustion rate and the production of nitrous oxide (N2O) emissions present significant hurdles. Furthermore, its interaction with engine oils can lead to material degradation, particularly in copper-bearing systems.

“Corrosion is a significant challenge with ammonia,” noted Dr Risse. “We’ve invested heavily in high-performance materials and have optimised air intake and compression systems to address these issues.” KBB is also exploring ammonia-hydrogen blends, which improve combustion stability and reduce the need for complex exhaust gas treatment systems, like selective catalytic reduction (SCR).

Hydrogen’s rapid combustion and high flame speed necessitate turbochargers capable of handling extreme thermal loads and delivering significantly higher air mass flow. KBB has risen to the challenge by developing turbochargers tailored to these conditions, enabling efficient hydrogen combustion in dual-fuel engines.

“Our work on hydrogen-diesel dual-fuel engines demonstrates how KBB turbochargers can maintain efficiency while accommodating hydrogen’s demanding characteristics,” Dr Risse explained. The company’s innovations in this area highlight its ability to align with emerging energy trends without sacrificing performance​.

Methanol’s combustion properties are closer to conventional marine fuels, making it a more straightforward transition for shipowners. However, its lower calorific value and unique chemical profile still require careful adaptation. KBB has optimised its turbochargers to manage methanol’s characteristics, ensuring efficient combustion with minimal modifications to existing engines.

Dr Risse pointed out that methanol’s high-octane number supports higher compression ratios, which aligns well with KBB’s advanced turbocharger designs. “Methanol is increasingly being used in real-world applications, such as harbour tugs, demonstrating its practicality as a transitional fuel,” he said.

Biofuels, such as hydrotreated vegetable oil (HVO) and fatty acid methyl esters (FAME), are increasingly being adopted as drop-in replacements for traditional fuels. These fuels have lower energy density and higher viscosity, which can affect engine performance. KBB has modified its turbocharger systems to accommodate these properties, enabling efficient combustion, even when using biofuels.

Material science and emissions control

Alternative fuels place immense stress on turbocharger materials, due to high combustion temperatures and corrosive environments. KBB has addressed this challenge through the development of advanced alloys and ceramic coatings. These materials ensure durability and efficiency, even under the extreme conditions associated with hydrogen and ammonia combustion.

To meet emissions regulations, KBB turbochargers integrate seamlessly with advanced exhaust gas after-treatment systems such as SCR and exhaust gas recirculation (EGR). These systems mitigate NOx emissions, a common challenge with hydrogen and ammonia. Dr Risse emphasised the importance of a system-wide approach: “The turbocharger, engine, and after-treatment system must function as a cohesive unit to meet decarbonisation targets.”

“Methanol is increasingly being used in harbour tugs”

The flexibility of dual-fuel engines, which can switch between conventional and alternative fuels, requires turbochargers capable of dynamic adaptability. KBB’s variable geometry turbines (VGTs) and adaptive compressor technologies allow seamless transitions between fuels, ensuring optimised performance regardless of fuel type.

“Pressure ratio demands are increasing, and two-stage turbocharging systems are becoming more prevalent to meet the requirements of alternative fuels,” Dr Risse noted. These systems deliver the higher air pressures needed for efficient combustion of low-energy-density fuels, like ammonia and methanol​.

A vision for sustainability

KBB’s forward-thinking approach ensures its turbochargers are not only efficient but also aligned with the maritime industry’s broader decarbonisation goals. By combining digital innovation, material advancements, and adaptability to alternative fuels, KBB is creating solutions that meet the demands of both shipowners and regulators.

The company’s efforts extend beyond product development. Dr Risse underscored the importance of collaboration with engine manufacturers, academic institutions, and other stakeholders to ensure a holistic approach to sustainability. “Our goal is to support the maritime industry through a balanced focus on future fuels, retrofitting existing vessels, and integrating advanced technologies,” he said.

“Digital twins enable remote diagnostics and troubleshooting”

As the maritime sector navigates a period of unprecedented change, KBB is leading the way with turbochargers that combine innovation, efficiency, and environmental responsibility. By addressing the challenges of alternative fuels, integrating advanced digital tools, and pushing the boundaries of material science, KBB is setting a new standard for marine propulsion.

With a steadfast commitment to research, collaboration, and sustainability, KBB turbochargers will continue to play a pivotal role in shaping the future of global shipping. By embracing the complexities of alternative fuels and leveraging cutting-edge technology, KBB is not just adapting to change — it is driving it.