Diesel’s demise denied, but doubts raised over future fuels

Paul Gunton

Paul Gunton · 22 February 2019


Diesel engines will face very little competition from alternative propulsion plants, despite IMO’s goal of cutting carbon emissions from shipping by at least 50% by 2050, according to panellists and delegates at ShipInsight’s inaugural conference last week. But doubts emerged over how much carbon-free fuel will be available as that deadline nears.

Its opening session had the provocative title ‘The demise of the diesel engine’ but also questioned whether fuel cells and renewable energy sources will ever make an impact on ship power options. If so, it will take a long time for their potential to be realised, feedback from attendees suggested, although the possibility of nuclear propulsion was not ruled out as a carbon-free option.

Panellists representing two major engine OEMs – René Laursen, mechanical engineer at MAN Energy Solutions and Rolf Stiefel, vice president of sales and marketing at WinGD – both said they were ‘offended’ at the suggestion that the diesel engine faced its demise. “Efficiency is the decisive topic we need to look at,” Mr Laursen said.

In fact, he said, early diesel engines used distillate fuels and it has only been since the late 1950s that engines have been able to burn heavy fuels, “so the heavy fuel oil age is not something that has been carved in stone.” Rudolf Diesel himself ran his engines on ammonia, he later said in discussion.

However, with the advent of new fuels, to call them ‘diesel’ engines is now a misnomer. Although it remains an internal combustion engine, “now we call it an Otto engine,” he said, in recognition of how gas-fuelled engines operate. More important than whether the engine will survive is the question of what fuel will be available from 2030 onwards, he said. IMO has set that date as an interim target in its GHG emissions reduction strategy by when it hopes shipping will have reduced CO2 emissions per unit of work by at least 40%.

In support of the diesel engine’s future, Mr Laursen stressed its flexibility. “If you are able to get a fuel into the combustion chamber, we will be able to burn it,” he said. He said that 55 of MAN Energy Solutions’ dual-fuel engines are in operation with more than 265,000 running hours on gas. Seven ships were in operation on methanol within a year of that engine option being introduced in 2013 and two ships are running on ethane, clocking up 24,000 running hours since its launch in 2014. It now has an order for its first LPG engine, which will be in operation in mid 2021.

Whenever regulation has been introduced, “the two-stroke engine has always been able to meet those goals,” he said, but he conceded that hitting IMO’s CO2 target will be a challenge. That will depend on a carbon-free fuel becoming available, “otherwise we will not be able to meet that.” But MAN Energy Solutions is developing an ammonia-burning engine, he said; reports last month indicated that the plan is that they will burn ammonia produced using electricity generated by windfarms.

Another panellist, technical director of Bureau Veritas Jean-Françoise Segretain, recalled that since their introduction a century ago, diesel engines have consistently gained market share over other options. Even on LNG carriers, many of which have used steam turbines in the past, now use diesel engines, he said. They are easy to operate, they are efficient and they can burn “just about anything.”

But he echoed Mr Laursen’s comments about achieving CO2 reductions, agreeing that new fuels will be needed. He also spoke positively about fuel cells. Because they convert chemical energy directly into electrical energy, “they are not limited by the maximum efficiency of the Carnot cycle,” so if engineers hope to exceed that cycle’s theoretical limit, fuel cells offer one way of doing that, he said.

Although they will not displace diesel engines for a long time, he predicted that fuel cells might initially be used for generating electricity. “You could not replace one established technology with a completely new one with no proven record before about 2030,” he said.

Klaus Vänskä, global business development manager for marine systems at ABB, considered the features that any alternative power source should have, with GHG and CO2 emission reduction targets driving the change. Those goals dictate a search for alternatives to fossil fuels, he suggested, but he also took into account other factors, including the trend towards digitalisation and automation, which would have an effect on engine development. Those developments would need machinery that is less dependent on onboard maintenance, he said.

He also raised the prospect of future legislation imposing emission levies that could affect the competitiveness of investments now being made. “That’s a big question mark,” he said. Because of that, whatever the technology and whatever the fuel, “efficiency will play a very big role” from an economic point of view, he said.

Once the session was opened to discussion via an online discussion platform, one question that was supported by a number of delegates asked whether the main factor affecting future powering options was “less about the demise of the diesel engine and more about the sustainability of the fuel source.”

Mr Vänskä responded by taking hydrogen as an example and wondered if there was enough wind, wave and solar power on Earth that could produce enough hydrogen. But he said that some countries – he named Chile, Uruguay, Saudi Arabia, Australia and some African countries – are looking at how they could increase renewable energy sources to start production of low-cost hydrogen for use by fuel cells. The same energy sources could also be used to produce other carbon-free fuels, such as ammonia, he said.

Another question that prompted significant discussion was about nuclear power: did it offer a practical carbon-free energy source? It is technically feasible, said Mr Segretain, as is shown by its use in naval vessels, but none of the few merchant ships has ever been successful. Despite this, in the long term, “probably we will see some place for nuclear energy production.”

Mr Laursen confirmed that the suggestion was not a hypothetical one. Faced with the need to produce a lot of carbon-free fuel to meet IMO’s 2050 goal, “many believe that the only way we can achieve that is through nuclear,” he said, because there is very little carbon-free fuel available and little incentive to invest in technology to produce it. “If there’s no subsidy to produce carbon-free fuel it will not start by itself [yet by] 2035 half of all ships need to be carbon free to meet the 2050 goal.”

A significant argument against nuclear power was raised by one delegate: who would insure such ships? Mr Laursen believed that governments would have to. “If we cannot scale the production of carbon-free fuels, what other way is there?”

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