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Shipping industry coasts towards decarbonised future

image credit: In the past ten years, Maersk has reduced average carbon dioxide emissions per kilometre travelled by each of its containers by 41% through efficiency measures, but actual emissions from shipping have not fallen because of continued growth in global trade

Denmark has a long and proud seafaring history and is one of the world’s biggest shipping nations with the fifth largest merchant fleet. But the sector’s massive carbon footprint sits uneasily with the country’s goal to slash greenhouse gas emissions by 70% by 2030. To try to marry shipping prowess with climate ambition, Maersk, the Danish container group, is leading efforts to find cleaner fuels, but admits a “complete revolution” is needed


Some 80% of world trade travels by sea, accounting for almost 3% of global carbon dioxide (CO2) emissions. Heavy fuel oil, a cheap, highly toxic and viscous residual from crude oil refineries, has traditionally been the main way to power ships. When burned, it emits high levels of black carbon, a substance that is 3200 times more powerful a climate forcer than CO2 a tonne. Distillate fuel, the other main fuel, produces significant amounts of sulphur dioxide.

“With the climate challenge, an entirely new method of propulsion is needed. Full stop,” says John Kornerup, head of sustainability and chief climate change advisor at Maersk. “We are not talking about a bit more efficiency, a bit more of this and that, but a complete revolution in the way shipping is powered. It is a completely different game.”

Since Maersk introduced efficiency measures more than ten years ago, the group has reduced average CO2 emissions per kilometre travelled by each of its containers by 41% compared with 2008. “We are almost twice as efficient today when moving a container from one place to another,” Kornerup says. More efficient use of energy is a trend across companies, which, like Maersk, are part of the Clean Cargo Working Group, a buyer-supplier sustainability forum. Since the group began publicly reporting data in 2009, emissions per container per kilometre have declined by 37.1% on average. But Kornerup admits this fall is only half the story. “The other half is that actual emissions have not fallen during that period. We emit as much CO2 now as we did in 2008 because the world economy and world trade, is growing.”

To try to live up to the commitments of the Paris climate agreement, Maersk set a goal in December 2018 to reach carbon neutrality in its own operations by 2050, with a reduction of 60% by 2030 through further efficiency measures. The 60% target is feasible, but to get emissions towards zero will require new technologies, says Kornerup. “Further streamlining of existing technology will not do it. We know because we have tried everything. We have had hundreds of engineers working on this over the past 11 or 12 years, and so we know how far you can get with efficiency measures.”

Anders Ivarsson, associate professor in the mechanical engineering department at the Technical University of Denmark (DTU), also cites the recent decision by the International Marine Organisation to limit the use of sulphur in fuel oil to 0.50% mass by mass (m/m), compared to the current 3.5% m/m, from January 1, 2020 as providing further impetus for change. “Suddenly, it may be attractive to switch to a fuel which can potentially be 100% green,” Ivarsson says.


New fuels

The list of green fuels that could potentially help decarbonise the shipping industry is long. Hydrogen fuel cells are considered promising. They can convert the chemical energy inside hydrogen to electricity to power a ship’s engine, as in a hydrogen car, explains Faig Abbasov from NGO Transport & Environment (T&E). “The problem is that no one has ever built fuel cells big enough for ships.” Fuel cell research and development is still at an early stage. Given the technological and cost constraints, without a legal requirement incentivising ship owners to switch to new technologies, little will change, he adds. “It is complicated, but not impossible,” says Abbasov. Kornerup agrees there is lots to do if fuel cells are to be used to decarbonise shipping and that costs will be massive. “We need to understand the degree of this challenge,” he says. “We need to go to zero emissions in 2050, which means the first commercially viable ship must be ready in about ten years’ time.” The lifetime of a vessel is 20 to 25 years.

An important step forward would be for the shipping industry to send a very clear signal to those developing new fuels that it intends to move away from fossil-based technologies, says Kornerup. “We are talking about suppliers of a product that does not exist today. They have to invest in its development and so it is important that we, the customers of the future, send a clear signal that this is what we want.”

Maersk is prepared to test new fuels on its vessels, adds Kornerup, explaining this is already happening through a joint project with Lloyd’s Register, a maritime classification society, looking at the costs of various carbon-neutral fuels and how they would work for different types of ships. “We want to get a clear picture of where we should start to focus and what our working hypotheses should be,” says Kornerup. He expects to communicate the results of these tests in autumn 2019. “We do the testing, Lloyd’s will develop the fuels and refine them,” Kornerup says.

Cross-industry cooperation between shipping companies, researchers and technical developers, energy companies and regulators, is vital, says Kornerup. “The year 2030 is not far away, but we are not looking to change the entire fleet by then, just new vessels. Technically, we are very confident. The challenge is to ensure framework conditions that makes it financially viable,” he states. Regulators could facilitate this by agreeing an incentive structure that makes the new fuels competitive with fossil fuels, he says. “There are three important elements in this equation: regulatory framework conditions, R&D and industry cooperation, and the customers who will move the market. All three are equally important and all three must move forward now,” says Kornerup.

“Hydrogen and green fuels will be six, seven times more expensive than the marine fuels used today,” says Abbasov, though he expects costs to come down as hydrogen is produced from ever cheaper renewable electricity. “At the beginning of the twentieth century, people were feeling the same about [the costs of] diesel,” he adds. One kilowatt of power in an internal combustion engine costs around €400, but the same amount of power in the form of fuel cells may be €2000-€3000. Hydrogen fuel cells are not the only option, says Abbasov, suggesting that modifying conventional internal combustion engines to run off hydrogen gas may be a better and cheaper short-term plan for eliminating emissions, though still more expensive than fossil fuels. “Hydrogen is burned directly inside the engine and because hydrogen does not contain carbon, there are no greenhouse gases,” says Abbasov. The solution is being tested in a small passenger service vessel for offshore wind farms in Belgium.


We are talking about suppliers of a product that does not exist today. They have to invest in its development and so it is important that we, the customers of the future, send a clear signal that this is what we want


Testing green DME

Another idea being explored via a joint project between DTU, Maersk and China, is to find out whether dimethyl ether (DME), an aerosol propellant used in many everyday products such as hairspray, can be synthetically manufactured using renewable sources and then used to power large container ships. “In the research community, DME is viewed as a really good alternative to diesel for the transportation sector. The problem right now is the lack of infrastructure such as production capacity and storage,” Ivarsson says.

DTU has a demonstration facility for green DME production at its Risø Campus in Denmark. “But it will require a lot of investment to get this up and running on large scale,” says Ivarsson. “It is important to get a strong business case in place so shipping companies can see the benefits of DME compared with other fuel technologies.” This is where China comes in — the place where most large container vessels sail to and from and the world’s largest producer of DME. China’s interest in reducing its coal consumption and deploying renewable sources also helps build a realistic and strong business case for green DME-based fuel, says Ivarsson.

But he admits there are still significant hurdles, including building large enough electrolysis plants, creating significant amounts of DME and finding the requisite amount of biomass to power the process. Today energy from coal and natural gas is converted to synthesis gas to produce DME. There are large quantities of agricultural waste in China that could be turned into biomass, but it is spread all over the country, says Ivarsson. The Chinese authorities are developing a biomass policy. “We will try to influence it towards replacing coal for DME production rather than for electricity and heat production,” he says.

Other potentially green alternatives to diesel such as ammonia, methanol, ethanol and methane are difficult to ignite — the fuel must ignite when injected into compressed hot air to fire the engine. DME requires a slightly more advanced injection system with a separate lubrication system than diesel, but ignites more easily than the finest, high-quality diesels, Ivarsson says. “Such a system is already on the market,” he adds. Moreover, DME does not produce soot, can be stored at low pressure, is not a greenhouse gas and is non-toxic, he explains.

“Technically, DME is ideal, but it is difficult to get projects off the ground because it is not used as a fuel today,” says Ivarsson. “It is easier to convince investors that liquified natural gas (LNG) is the right thing to fuel ships because fossil LNG is so cheap. But green LNG will not be cheap and it has many technical and environmental disadvantages,” he states. Meanwhile, green drop-in fuels with identical properties to traditional fuels such as diesel do not really exist, says Ivarsson. Food waste is used in some instances, but this is not an infinite source and there is competition from road transport for biodiesel, he adds. “Biofuels from food waste are not the way forward.”

Ivarsson believes it is realistic to see the first ships powered by renewable DME fuel within a few years, but that companies such as Maersk will need to be totally convinced before making any decisions. “A container vessel costs DKK 1 billion (€0.13 billion) and so firms need to know there is enough fuel for the next 25 years, they can have easy access to it and that prices are stable,” he says.

Another company heavily involved in the development of new zero-emission solutions is ABB Marine & Ports, a major technology supplier to the shipping industry globally. “Ideally, we will see a number of different alternative fuels, their use depending on the size of a vessel, its use and the region where it is operating,” says the company’s Klaus Vanska. Billions of euros and plenty of time will be needed to ramp-up production of renewable hydrogen and build a distribution chain, he adds. “After a transition period, I believe there is no big difference in a ship’s total price made with new technology compared with old technology.”

TEXT Karin Jensen

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Matt Chester's picture
Matt Chester on Nov 14, 2019 1:14 pm GMT

Shipping always seems like it's going to be one of the most challenging parts of the global economy to decarbonize, but this great overview shows there's reason for optimism. 

Bob Meinetz's picture
Bob Meinetz on Nov 14, 2019 11:06 pm GMT

“'With the climate challenge, an entirely new method of propulsion is needed. Full stop,' says John Kornerup, head of sustainability and chief climate change advisor at Maersk. 'We are not talking about a bit more efficiency, a bit more of this and that, but a complete revolution in the way shipping is powered. It is a completely different game.'

Nonsense, John. The U.S. Navy, per tonnage afloat, is the greenest in the world thanks to nuclear technology established more than six decades ago..

Five U.S. nuclear aircraft carriers and over 70 nuclear submarines patrol the seas day and night, for months at a time, without emitting an ounce of CO2 or stopping to refuel. The technology is already here to make container ships carbon-free. Implementing it over the objections of multinational oil interests is the only challenge, but a significant one.

Matt Chester's picture
Matt Chester on Nov 15, 2019 1:28 pm GMT

I'm curious, Bob-- are there commercial ships that utilize nuclear technology today or are there policies restricting that?

Nathan Wilson's picture
Nathan Wilson on Nov 16, 2019 6:43 pm GMT

Sure, renewable DME would be a great fuel; the problem is that it contains carbon.  So it must be made from biomass to be carbon neutral.  Biomass has the highest environmental footprint of any sustainable energy source, so we should choose alternate solutions whenever possible (much of the automobile fleet will be resistant to electrification).

As mentioned in the article, ammonia fuel is another option, and it is advancing toward demonstrations of prototype marine engines.  As a carbon-free fuel, it can be made from any primary energy source (e.g. clean electricity or fossil fuel with CC&S), with water and air as the only feedstock.  In small tanks it has triple the energy density of 5000 psi hydrogen gas and can be stored at low pressure (like DME or propane).  For large tanks, it has about the same energy density as liquid hydrogen, but unlike hydrogen, does not produce explosive vapors.

Ammonia can be burned in specially optimized internal combustion engines (it burns cleaner than any other fuel, with zero emission of SO2, soot, or CO2) or it can be used in solid oxide fuel cells (the kind made for fossil gas).

Ammonia is generally less appealing than batteries for regular cars, but is a good fit for nearly every diesel application (i.e. long haul trucks, ships, buses, trains, construction equipment, farm equipment, stationary generators, and even jet aircraft for regional travel - it lacks the weight efficiency for inter-continental flights).


Marine ammonia fuel transition

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