WinGD chief executive Klaus Heim details why the Swiss engine designer’s low-pressure two-stroke, dual-fuel engines have been such a success, how it is tackling methane slip and where its X-DF portfolio fits in the energy transition
Since the first unit was installed six years ago, WinGD’s X-DF, low-pressure, Otto-cycle, two-stroke, dual-fuel engine has created a sea change in the propulsion market, emerging as the dominant choice for LNG carrier newbuilds and a strong contender in the container ship market.
“The advantage of the Otto-cycle engine, in a nutshell, is the simplicity of the entire system,” explained WinGD chief executive Klaus Heim. Speaking to Marine Propulsion during a recent interview at SMM 2022 in Hamburg, Mr Heim said: “A low-pressure gas supply system operating at 20 or 30 bar is a different story from one running at 200, 300 or 400 bar. It’s a lot about the safety system and safety requirements that make the low-pressure, Otto-cycle engines simpler, easier and more cost efficient. Also, the capex costs are lower for an Otto-cycle gas engine. There is no need for an expensive compressor or high-pressure system that you need for a Diesel-cycle, dual-fuel engine.”
At the time the X-DF engine was introduced in 2013, LNG shipowners saw four-stroke, dual-fuel engines and steam turbines as acceptable power choices. “This was the solution the industry was waiting for,” Mr Heim said, “Simple, high fuel efficiency and very competitive capex.”
Overcoming methane slip
As Marine Propulsion reported in August, the International Gas Union (IGU) pointed out in its annual report that “the emergence of more efficient containment systems with lower boil-off gas (BOG) rates in combination with short-term and spot trading of LNG have spawned demand for more flexible and efficient propulsion systems to adapt to varied sailing speeds and conditions.” IGU said as a result of these factors, “a new wave of dual-fuel propulsion systems that also burn boil-off gas with a small amount of pilot fuel or diesel” have been introduced into the market.
However, one of the technical hurdles to overcome with low-pressure, dual-fuel, Otto-cycle engines is methane slip — unburnt fuel that escapes into the atmosphere from the exhaust. Methane is a powerful greenhouse gas with a global warming potential of between 27 and 30, according to the US EPA.
“This was the solution the industry was waiting for”
“With the strong refocus of the whole industry on decarbonisation, methane slip has become a very important and challenging topic when we talk with customers about new LNG carrier projects,” said Mr Heim. “That’s why we developed a competitive solution based on EGR technology. It’s a smart way of recirculating exhaust gas back into the engine that provides a two-fold advantage; first, it improves efficiency and second, it reduces methane slip.”
In 2020, the Swiss engine designer unveiled iCER — short for Intelligent Control Exhaust Recycling — in its second generation WinGD X-DF 2.0 platform to cut methane slip by 50%. The added benefit of the iCER aftertreatment technology was fuel savings, yielding improved fuel consumption of around 8% in gas mode and 6% in diesel mode, as well as satisfying Tier III NOx emissions limits in both modes.
Now, WinGD is taking the next step and rolling out the first versions of its integrated, on-engine iCER technology, minimising the engine’s footprint.
“This is the way we are lowering methane slip and keeping the low-pressure, dual-fuel engine competitive,” said Mr Heim.
The first of these units, WinGD’s X-DF2.1 engine with iCER technology, passed factory acceptance tests in July at Hyundai Heavy Industries, Engine & Machinery Division in South Korea.
Getting ready for methanol
Of course, LNG is not the only fuel shipowners want to use on their journey to decarbonisation. Ammonia, methanol and hydrogen are also being considered as viable paths to net zero. Engine designers must respond to market demands and WinGD has its nose to the grindstone getting its engine lineup fit for the future.
This is particularly challenging given that each of these alternative fuels has its own unique combustion, gas supply, carriage, lubricity, health and safety challenges. While ammonia is a carbon-free fuel, for example, it is highly toxic, corrosive, has low flammability and is less energy dense. To rise to the occasion, engine designers such as WinGD are pouring millions of dollars into R&D and forming new alliances.
WinGD and HSD Engine have initiated a joint development project (JDP) to advance the development of WinGD’s methanol, dual-fuel, two-stroke engines.
“We are lowering methane slip and keeping the low-pressure, dual-fuel engine competitive”
The aim of the JDP between the Swiss engine designer and the South Korean enginebuilder is to deliver a big-bore dual-fuel engine capable of running on methanol (or biomethanol or green methanol when available) by 2024.
The JDP will focus on some of the largest engines in the WinGD portfolio, the X92 and X82. These engines will be suitable for the larger and ultra-large container ships, sectors where WinGD sees rapidly growing interest in green methanol.
Getting ready for ammonia
As for ammonia, WinGD will supply two of its most powerful engines in its X-DF2.0 portfolio for two different classes of LNG ammonia-ready dual-fuelled container ships ordered by Pacific International Lines (PIL). The forward-leaning Singaporean shipowner has ordered four 14,000-TEU box ships with X92DF engines and four 8,000-TEU vessels with X82DF engines. These vessels will each be equipped with an ammonia intermediate ready fuel tank.
Mr Heim noted that PIL’s newbuilds were the first for X82DF with new iCER technology. “That’s why this order is of particular importance to us and enables us to get our ICER technology into the market,” he said. These newbuilds are just part of the “strong demand” for ammonia-ready and methanol-ready vessels, said Mr Heim.
“We will have to pass a transition period where there will be pilots running on ammonia and methanol. Most of these ships, however, will continue to operate on traditional liquid fuels or LNG. Doing this transition phase, [operators] will want to run the vessels on a fuel that is available globally with the ability to convert in the future,” he said.
With the company’s X-DF engine platform, Mr Heim sees a distinct advantage for the clean energy transition: “With our Otto-cycle engine, the low-pressure and high-pressure cycle are already built into the engine. When it runs on diesel or heavy fuel it runs according to the high-pressure, Diesel principle. When it operates on LNG, it runs on the low-pressure, Otto cycle.”
Since both cycles are built into the engine, he believes it will be easier to retrofit them for ammonia. Retrofit packages to convert LNG dual-fuel engines to ammonia, which are still under development, will be offered in the future.
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