Engine designer WinGD has published a white paper outlining the use of variable compression ratio (VCR) technology as a retrofit option for LNG dual-fuel engines already in service, positioning the system as a near-term emissions reduction measure.

The paper, titled 'LNG-Fuelled Fleets Reducing Emissions: VCR retrofitting as a ready solution,' examines how VCR can be applied to existing engines to support compliance with the International Maritime Organization’s 2030 emissions targets.

According to WinGD, VCR technology is fitted as standard on its X-DF2.0 engines. It can also be retrofitted to earlier X-DF LNG dual-fuel engines currently operating in the global fleet. The company said the system is additionally available for RT-flex50DF engines, with around 50 engines identified as technically suitable for retrofitting.

VCR works by adjusting the engine’s compression ratio in real time to optimise combustion across different operating conditions. WinGD said this enables lower fuel consumption in both gas and diesel modes, while reducing methane slip, particularly at partial loads.

Rene Baart, Head of Retrofit Solutions at WinGD, said the technology represents a pragmatic approach to decarbonisation. "It does not rely on unproven infrastructure or future regulation; it delivers measurable improvements using technology that is available now," he stated.

WinGD said the retrofit can be installed during planned dry-dockings, allowing operators to combine maintenance schedules with performance upgrades. The system is fully integrated into the engine control system and does not require crew operational input, according to the company.

Since the commercial launch of VCR in 2023, more than 170 systems have been ordered, WinGD said. While early uptake has been most substantial among LNG carriers, the company said demand is expanding to other vessel segments, including pure car and truck carriers, bulk carriers and container ships.

The company added that while the technology is currently optimised for LNG operation, it is designed to be compatible with future fuels, allowing shipowners to adapt existing engines as fuel strategies evolve.

The white paper is available for download from the WinGD website.