After strong validation from shipowners – particularly LNG carriers – both main engine designers will offer low-pressure, dual-fuel, two-stroke engines from 2022
Do you need low pressure or high pressure to get the job done? The question has concerned engine designers since the advent of dual-fuel technology. Although the low-pressure gas admission (or lean-burn, or Otto-cycle) concept has captured more of the high-speed engine market, dual-fuel two-stroke engines predominantly use high-pressure gas injection (or the Diesel cycle). That may be about to change.
High-pressure engines still dominate the two-stroke sector. MAN Energy Solutions’ ME-GI series has registered around 280 orders to date. But low-pressure engines have taken nearly 90% of dual-fuel two-stroke engine sales over the past year, according to data seen by Marine Propulsion. Winterthur Gas & Diesel, the only designer of low-pressure dual-fuel engines, now has an orderbook of more than 200 units, with 32 ordered in the first quarter of 2019.
MAN has taken action. On 22 May it announced publicly that it had begun developing its own low-pressure engine. But the announcement had been planned for a long time. Rumours had been circulating for nearly a year beforehand and were confirmed a week before the official statement, when enginebuilders attended a licensee conference hosted by MAN in Japan.
In a market update note on 7 June, MAN revealed the name for its new engine design. As opposed to the gas injection of the high-pressure ME-GI engines, the low-pressure series will be known as ME-GA, for gas admission.
The note also succinctly explains MAN’s rationale for the move. It states: “Twin engine LNG carrier vessels currently represent the biggest market for the ME-GI engines. This market segment has shown a strong interest in low-pressure dual-fuel gas engine systems where first cost is prioritised. The main reason is the relatively high first cost of the fuel gas supply system including the high-pressure compressor for boosting up the pressure of the boil-off gas to the 300-bar injection pressure needed for the ME-GI – a compressor and an investment only used for the LNG carrier application.”
The ME-GA engine will initially be available in the 70-cm bore engine size. The first engine could be installed on an LNG carrier in the first half of 2022.
The news is just the latest in a busy roster of gas engine developments from MAN this year. In January the company confirmed its intention to develop an ammonia-fuelled two-stroke engine, potentially using ammonia sourced from renewable electricity generated by windfarms.
“We are making a significant investment and believe that, for the foreseeable future, LNG will play a significant role in the fuel market”
Overseeing both projects will be MAN vice president of research and development, two stroke business Brian Østergaard Sørensen, who joined the company from Maersk Tankers – where he was most recently head of group fleet management – in March.
MAN, as any competitor would, has spent three years highlighting the methane slip problem associated with low-pressure gas admission. But Mr Sørensen rejects the idea that the decision to now invest in the technology represents an about turn.
“Our high-pressure ME-GI concept will continue to be a strong pillar within our engine portfolio and we will continue to develop it,” he says. “We see that there is interest in low-pressure technology. On the methane slip we see there is a penalty which you don’t see on high-pressure technology. But we want to be present in both segments.”
Mr Sørensen believes that high-pressure injection still offers competitive advantages and says it will remain the backbone of MAN’s dual-fuel two-stroke portfolio.
“It has better fuel performance, better fuel consumption, no methane slip and we don’t see knocking [when the air-fuel ratio is too lean -Ed.]. And with high-pressure technology we have a very high degree of fuel flexibility – it’s the concept we are using for other alternative fuels.”
MAN is not entirely starting from scratch with its low-pressure concept. The company has in-house expertise, including in its four-stroke engine business, where it already offers Otto-cycle dual-fuel engines. The company has also taken on additional development resource, Mr Sørensen reports, to cover extra duties in the development of both low-pressure and high-pressure technologies.
“We’re not breaking new ground with the concept, but we need to scale it up. We want to make a high-performing engine: simplifying safety systems, making installation easy for the yards and operation easy for the owners and factoring cost into every decision we take. It’s not quite starting from scratch, but we did use a clean sheet of paper.”
As well as its in-house expertise, MAN is working with Hyundai Heavy Industries Engine Machinery Division to develop the project. It will lend expertise not just as an enginebuilder and licensee of MAN, but also as a major shipyard that will ultimately be responsible for installing the new engines, notes Mr Sørensen.
Shipyards are increasingly willing to take on LNG retrofit projects, but MAN believes that owners who are considering future conversions should opt for high-pressure rather than low-pressure engines.
“Retrofitting is always possible, but the scope of changes will be too big for it to be realistic,” says Mr Sørensen. “We think that’s why we haven’t heard of any retrofits of our competitor’s engine. Our ME-GI technology is well suited for retrofits and we have already completed many of these projects.”
“It’s not quite starting from scratch, but we did use a clean sheet of paper”
Perhaps one of the most interesting facets of MAN’s low-pressure manoeuvre is what it says about the company’s view on LNG as a marine fuel over a relatively long timeframe. These engines will not be on the market until 2022 and many will still be on ships sailing by 2045. Given the contested nature of LNG’s contribution to reducing greenhouse gas emissions, the company must either be confident of selling a lot of engines fast, or that gas engines will be part of the solution even beyond 2050.
“We are making a significant investment and believe that, for the foreseeable future, LNG will play a significant role in the fuel market,” says Mr Sørensen. “[Low-pressure technology] will get us some of the way there and we will be delivering a concept that is competitive on performance and reliability. We also have the high-pressure pillar where we can burn a lot of the new fuels coming – be it methanol, ethane, ammonia or LPG. We will be making a range of technologies available to make sure the road to decarbonisation is possible for the shipowner.”