Wärtsilä engines and fuel gas systems to help reduce greenhouse emissions


Wärtsilä is developing an unprecedented range of engine and fuel gas supply systems to help ship owners navigate the route to reduced greenhouse gas emissions – whatever fuels they choose.

While shipping tries to significantly reduce emissions, it is far from clear which fuels it will be using to do so. Marine fuel market has been almost entirely dominated by oil for 100 years. A large array of potential clean fuel is now emerging.

In the next 10 to 20 years, the viability of many new fuels depends on overcoming many challenges. But the urgency of the shipping’s determination to decarbonize – especially the goal of the International Maritime Organization to reduce gross greenhouse gas emissions by at least half by 2050 –means that there is no time to wait for the perfect solution.

“There are uncertainties around every prospective fuel, including when and where they will be available and at what price. Building fuel flexibility into new vessels – and, where appropriate, retrofitting flexible powerplant in older vessels – offers a hedge against these risks.”

Mikael Wideskog, general manager, technology strategy & innovation, Wärtsilä Marine.

With a limited component exchange, today’s marine engines can burn any of the clean fuels that are expected to become available in the years ahead.

Given the properties of new fuels, storage , handling and fuel supply can be more complicated, but the challenges are manageable, especially if vessels are constructed with future conversions in mind.

Wärtsilä is investigating all new fuels-including bio-and synthetic methane , ammonia, methanol, hydrogen and biofuels to power shipping regardless of fuel choices.

Its research draws on the experience it has already gained building engines, supply and storage systems for a wide range of fuels including LNG, LPG, biodiesel, methanol and volatile organic compounds.

“We will continue to be a provider of complete fuel supply and engine solutions for all future fuels. Given the market demand, in the next decade we will commercialize engine technology and fuel gas supply systems that will allow ship owners to be prepared to make use of all fuels currently under discussion. Given the modularity of modern engines this means that, as long as ship owners consider storage requirements, they can already be planning to use new fuels on vessels being built today.”

Mikael Wideskog, general manager, technology strategy & innovation, Wärtsilä Marine.

Bio-& synthetic LNG

For those vessels powered by liquefied natural gas ( LNG), Wärtsilä claims the transition to clean fuels would be the easiest, most cost-effective and quickest.

Developing methane from biomass and synthetic sources means that there is a clear road to LNG carbon-neutral energy that already provides reductions in greenhouse gas emissions by 5 – 21 percent compared to heavy fuel oil.

Initially, bio-and synthetic LNG can be used as drop-in fuels alongside traditional LNG to reduce its fossil carbon content, and eventually, as supply rises, to fully substitute it.

Today this path is technologically and logistically feasible. LNG-designed engines and fuel-supply systems do not need adjustments to use bio-or synthetic LNG.

And in addition to being compatible with current LNG engines, the future carbon-neutral varieties can also be used in the bunkering infrastructure already set up for LNG.

Compared to other fuels that will need supply infrastructure to be built from scratch, this offers a dramatic head start (both in terms of time and financial).

“There are already vessels running on a mix of bio-LNG and fossil LNG, and small trials are planned using synthetic LNG. The prospect of large-scale supply compares favorably to other clean fuels that may be a decade or more away from commercial availability.”

Mikael Wideskog, general manager, technology strategy & innovation, Wärtsilä Marine.

A problem with the LNG process is methane emission, a potent greenhouse gas that affects LNG output, supply, and incomplete combustion. It can to some degree offset the reduced carbon dioxide emissions from the use of LNG.

However, engine developments in the next two to three years will restore the benefits, and as biomass and synthetic sources emerge, the main source of methane emissions – producing, storing and transporting fossil LNG –will be considerably reduced.

For these reasons, Wärtsilä claims that even with the challenge of methane slip, LNG provides the quickest and most cost-effective decarbonization route to shipping.


LNG is not the only way to make shipping clean. Hydrogen based fuels can provide a greenhouse gas-free energy source if they are generated using renewable energy. Methanol and ammonia are the two most common.

Ammonia exploration as a fuel is also advancing very rapidly. Many countries are strongly supporting ammonia as a potential fuel. It has many benefits over hydrogen: it has a higher energy density, for example, and it does not need to be stored under compression or at very low temperatures.

Ammonia is still difficult to handle, as it is toxic and highly corrosive, particularly for passenger vessels.

Wärtsilä is not start from scratch though. For several years, it has developed cargo handling systems that can handle ammonia, for use on LPG carriers.

On the fuel storage and supply side, Wärtsilä is participating in an EU project ShipFC by designing systems that will supply ammonia to fuel cells that will be mounted on Eidesvik Offshore’s Viking Energy supply vessel by 2023.

The basic fuel supply principle is identical to that for LNG, and ammonia fuel can be treated in a stainless steel version of Wärtsilä’s fuel gas supply system LNGPac.

In March, Wärtsilä conducted ammonia combustion tests. The research on both dual-fuel and spark-ignited gas engines will be continued based on initial results.

This will be followed by field experiments from 2022 in cooperation with shipowners.

In the meantime, Wärtsilä will work with shipowners, shipbuilders, classification societies and fuel suppliers to learn more about system and safety specifications, as well as fuel quality, emissions and performance.

Ammonia has many other properties that require further study. Compared to other fuels, it ignites and burns poorly and combustion may result in higher NOx emissions unless regulated either by post-treatment or by optimizing the engine process. A regulatory framework and class rules will also need to be developed for its use as a marine fuel.


Methanol wasn’t commonly used as a marine fuel until now. The industrial alcohol that is easily and cheaply manufactured is today primarily made from natural gas, but the use of hydrogen from renewable electricity and recaptured carbon to make green methanol will make it carbon neutral.

And with better combustion and simpler storage and handling than ammonia, methanol could be a dark horse in shipping’s race towards decarbonization.

Only a few marine engine builders have methanol engine experience. In 2015 a project started to convert a Wärtsilä Z40 engine to burn methanol on ro-pax vessel Stena Germanica. The engine now mostly runs on methanol fuel, and the installation’s performance has inspired Wärtsilä to look into the fuel more.

“The real benefit of methanol is the ease of storage. For Stena Germanica it was a simple conversion of a ballast water tank. But the engines converted are quite old and we now want to examine the performance of methanol on a more modern engine. In the coming months we will begin testing methanol on our Wärtsilä 32 engine and will be looking at other concepts for burning methanol.”

Mikael Wideskog, general manager, technology strategy & innovation, Wärtsilä Marine.


Biomass-derived fuels have much potential as a carbon-neutral source of energy. They can be produced in a range of ways that can be used in diesel engines as well as gas engines, either as a drop-in fuel or on its own.

Since biofuels can be used in existing engines, fuel supply and storage technologies can provide easy and capital-efficient shipping decarbonization, depending on the ability to raise supply at a reasonable price.

More recently, Wärtsilä has been working with bunker supplier Boskalis and biofuels company Goodfuels to develop and test suitable biofuels for shipping use. Wärtsilä tested a series of new biofuels under the partnership starting in late 2015 and had optimized fuel and engine performance by April 2016, dramatically reducing particle emissions and eliminating sulphur content.


Wärtsilä dual-fuel engines and spark-ignited gas engines can already run on a fuel mix of up to 15-25% hydrogen, further emphasizing the flexibility of dual-fuel engines.

“Onboard storage in the quantities needed for deep-sea shipping is more feasible for ammonia and methanol than for hydrogen. We see some niche applications for hydrogen as there are some national interests pushing this fuel, and strict local regulations may make it feasible for some short-sea shipping. But the main role of hydrogen in shipping will be as a building block for other fuels.”

Mikael Wideskog, general manager, technology strategy & innovation, Wärtsilä Marine.

In 2015, Wärtsilä first attempted to use hydrogen in its gas engines, and is now continuing to develop towards a pure hydrogen engine.

But fuel storage and supply remain a problem for hydrogen due to its low volumetric energy density–liquefied hydrogen has about a third of LNG energy per cubic metre, meaning tanks need to be nearly twice the size–as well as its explosive and corrosive nature.


Marine fuel market’s future is far from certain but ship investment can not stop. It is essential that shipowners prepare to build flexibility in their vessels to manage this risk.

“Our aim is to ensure that the global fleet can be powered cleanly and reliably, whichever fuels ultimately help shipping reach its emission ambitions.”

Mikael Wideskog, general manager, technology strategy & innovation, Wärtsilä Marine.
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