Want to improve your bottom line and cut emissions today? Upgrade your turbocharger efficiency
While enginebuilders, equipment manufacturers and systems suppliers are toiling away to commercialise next-generation technologies that will slash greenhouse gas emissions tomorrow, shipowners need practical solutions today to improve their fleet’s environmental performance and save on fuel costs. This is particularly essential with the implementation of the Energy Efficiency Index for Existing Ships (EEXI) and Carbon Intensity Indicator (CII) right around the corner and very-low sulphur fuel oil (VLSFO) eclipsing US$1,000 per tonne in Rotterdam.
A big driver of specific fuel oil consumption is turbocharger efficiency. In the case of an ultra-large container vessel, Dirk Balthasar, head of global service sales at Accelleron (formerly ABB Turbocharging) told Marine Propulsion: “If you have a turbocharger with higher efficiency, you can save several hundred tonnes of fuel and also CO2 on an annual basis.” Discussing turbocharger developments during a podcast, Mr Balthasar observed: “This is a technology that is already available.”
And while the turbocharger has been around for more than 100 years, it has benefitted from constant refinement.
During the discussion, Mr Balthasar noted several trends in the marine market, including two-stage turbocharging. Over the last decade or so, Mr Balthasar said two-stage turbocharging has become increasingly popular in the marine market for four-stroke, high- and medium-speed engines. “It’s a big step from single-stage turbocharging,” he said, allowing “enginebuilders to increase the power density of engines and reduce fuel consumption.” Compared to single-stage turbocharging, two-stage turbocharging, in combination with Miller timing, offers significant improvements in engine performance.
“A turbocharger can save several hundred tonnes of fuel and also CO2”
Two-stage turbocharging uses two turbochargers, a low-pressure-stage and high-pressure-stage unit, as a means to overcome the need to reduce NOx emissions to comply with stricter IMO Tier III emissions regulations, without increasing fuel consumption.
Mr Balthasar also highlighted opportunities to increase an engine’s performance by swapping out a legacy turbocharger. “You’re exchanging an older turbocharger with low efficiency with a modern turbocharger. You can increase efficiency and reduce fuel consumption with a newly tuned engine,” he said.
With an eye on decarbonisation, turbocharger designers are collaborating with enginebuilders on developing prime movers that will burn low- and zero-carbon fuels such as methanol, ammonia and hydrogen. Dual-fuel engines capable of operating on methanol have been in service for years and the first hydrogen-fuelled engines have just been released in the marine market. Two-stroke and four-stroke marine engines will be released over the next three years.
Mr Bathasar said turbochargers are operating on engines in service and on testbeds running on methanol, ammonia and hydrogen. This involves adjusting the turbocharger design and product materials to the different power densities and characteristics of the fuel. Ammonia, for example, has a low combustion rate, is highly corrosive and highly toxic. It’s energy density, however, is higher than liquid hydrogen.
Looking further towards the future, Mr Bathasar foresees turbocharger technology continuing to play an important role in shipping’s decarbonisation, underpinning a new generation of “supercharged fuel cells” for ships.
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