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What if LNG carriers can run on several alternative fuels?

05 November 2021

It is often said that today's LNG vessels will run on biogas in the future. But why rely on a single carbon-neutral fuel whose availability is uncertain in the future? The possibility of rebuilding and running LNG vessels on ammonia are now studied by different actors.

In the absence of green alternative fuels, the European Commission has determined that LNG is necessary as a transitional fuel. The EU's attitude has been criticized by the environmental movement, which claims that the use of LNG will delay the introduction of zero/carbon-neutral fuels. The Swedish Energy Agency has also questioned the EU's requirements for the expansion of an infrastructure for fossil fuels.

But a sudden switch to electro-fuels and advanced biofuels is unrealistic due to supply issues

“The truth is that we still have very little renewable energy and hydrogen or decarbonized forms of energy available in Europe”, said Joaquim Nunes de Almeida, director for energy-intensive industries and mobility with the European Commission’s DG GROW, at a conference on green innovation in the maritime sector some weeks ago.

Today, less than one percent of the world's ships run on alternative fuels, but there will be more. According to DNV, 12 percent of all orders for new constructions that are made today have alternative fuel systems with LNG leading the way. So which zero/carbon-neutral fuel would dominate the future?

“No one has the exact answer to how this will develop, but my gut feeling is that in the future we will see a combination of different technologies”, said CLIA Europe's Ukko Metsola at the same conference.

Of course, he is not alone in that gut feeling. In its latest Maritime forecast to 2050, DNV GL takes a closer look at how an LNG vessel could be rebuilt into a vessel with a dual-fuel engine that can also run on ammonia. Of course, there are real challenges here. Engines will need to be modified as well as the ship's tanks. Ammonia is only half as energy-dense as LNG. This means that the mileage is reduced for a ship that converts from LNG to ammonia with the help of existing tanks. Compensated measures, such as fuel storage, will be required, writes DNV. Ammonia is also significantly heavier than LNG, which will require strengthening of the fuel tanks. Since ammonia is also more toxic than methane, other requirements will be set for, for example, safety distances, ventilation and fuel preparation rooms.

But a conversion is possible. On the same day as this is written, the news comes that Wärtsilä will join forces with Simon Møkster Shipping to investigate the possibilities of developing a dual-fuel engine that has ammonia as primary fuel and LNG as an alternative. The benefits of this are of course many, not least from an accessibility perspective. Or as DNV writes: “Assume, for illustrative purposes only, a 30% probability that one of the carbon-neutral fuel options being contemplated (e.g. ammonia, biodiesel, methanol) is not available when needed. If the ship can use two of these fuels, the risk of not obtaining the fuel needed to be compliant drops from 30% to 9%. If the vessel can use three fuels, this risk drops to 3%.”

DNVs Maritime forecast to 2050

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