Stefan eefting is, as he puts it, “a long-lasting guy” in the shipping industry. He started as an apprentice engineer in a German shipyard in 1984, and now he's a senior vice president at MAN Energy Solutions, a firm whose engines power every second vessel on the deep seas. Over the course of Eefting's career, he's watched ship engines grow from massive steel contraptions to epically huge ones: The 100,000-horsepower monsters in today's cargo ships are five or six times the size of a house. And for decades, the vast majority of them have ingested heavy fuel oil—the leftover dregs of petroleum distillation, a product so viscous it's practically a solid at room temperature. “Like chewing gum,” Eefting says. “You have to heat it to 140 or 150 degrees Celsius to even load it into the engine.”

Heavy fuel oil burns thick and dirty, throwing off oxides of nitrogen and sulfur and producing more carbon emissions than almost any other fossil fuel. But it's cheaper than anything else on the market. When fuel is your industry's greatest cost—and when your industry guzzles 300 million metric tons of it a year—heavy oil is practically the only choice on the menu.

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That calculation changed, however, on January 1, when a new international regulation mandating low-sulfur fuel kicked in. Ship owners must now either install devices to scrub sulfur out of their heavy fuel oil exhaust or buy cleaner, more expensive fuel—at $600 or $700 a ton, compared to $400 a ton for heavy fuel oil. And that rule is just a foretaste of a massive transformation that is bearing down on Eefting's industry.

Since the 1990s, ship owners have come under intense pressure to pollute the planet less. Container ships are indispensable to trade, and there's no greener mode of transport to move a freshly riveted pair of jeans from China to the US. But the world's 90,000 or so cargo ships contribute between 2 percent and 3 percent of all greenhouse gas emissions—more than the share contributed by Canada or Germany.

While the sulfur cap is hitting shippers now, the far more daunting and impressive target is 30 years away. By 2050, the United Nations' International Maritime Organization (IMO) has stipulated, the shipping industry's total emissions must be at least half of what they were in 2008. That goal is even more ambitious than it might sound. Trade will continue to grow even as 2050 approaches, says Johannah Christensen, the managing director of the nonprofit Global Maritime Forum. There will be many more ships at sea, making many more journeys, than there were in 2008. “What that translates to is actually an 85 percent reduction in emissions intensity per ship.”

Meeting the deadline will require the industry to spend as much as $1.4 trillion on new fuel research and production, rejigged supply chains, and a revamped fleet—and no one even knows which solutions will work. The ambition, Christensen says, is “like a moon shot.”

In some ways, it's easier to decarbonize shipping than, say, automobiles or cement. The number of cargo ships in the world is small enough for them to be individually tracked, and they live so much of their lives in public—being inspected in one international port or another—that they can't slyly break rules the way a cement plant in a corrupt country might. Further, the ships are already regulated by a central authority: the IMO. The nature of this industry—in which ship owners routinely register their vessels under the flags of small countries with lax regulations—also means that the IMO is the rare forum where island nations threatened by rising seas hold significant sway. “Depending on the day you look at it, the Marshall Islands is the second- or third-largest flag register in the world,” says Bryan Comer, a senior researcher at the International Council on Clean Transportation. “And they were instrumental in making the moral argument for reducing emissions at the IMO. If they'd had their way, in fact, they'd have wanted a 100 percent cut, and much before 2050.”

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Even so, it's an unusual challenge for an industry to adopt an emissions target while having no clear notion of the technologies that will get it there. Borrowing ideas from other sectors isn't practical. Batteries are out. A container ship crossing the Atlantic would need so many batteries that it would have no room left for containers. Nuclear power, too, is dead in the water—“for political reasons,” says Simon Bennett, the deputy secretary general of the International Chamber of Shipping. “The idea of foreign ships coming into your port with a nuclear reactor on board—that just won't be acceptable.”

The solution most immediately at hand, liquefied natural gas, emits less carbon dioxide than fuel oil, and ship engines can be retrofitted fairly easily to burn it. But carbon emissions from liquefied natural gas are only about 30 percent less than from heavy fuel oil. What's more, the primary component of liquefied natural gas, methane, is highly prone to “slip,” or leak. Atmospheric methane traps 86 times more heat than carbon dioxide over a 20-year period. At best, says Eefting, liquid natural gas is only a temporary answer—an intermediate station on a zero-carbon pathway.

The fuels with more long-term promise are ammonia and hydrogen, which, when burned, release no carbon emissions at all. MAN plans to deliver its first ammonia engine in 2024. But there's still plenty to be figured out: To be truly green, these fuels will themselves have to be manufactured with no carbon footprint—something the IMO can't regulate. Ammonia production is one of the most carbon-intensive processes in industrial chemistry and is the subject of its own slogging race for sustainable modifications. Meanwhile, ships and ports will have to devise new ways of handling and storing ammonia, given how toxic it is to humans. “Plus, you have to remember,” Eefting says, “ammonia stinks very much.” Hydrogen, for its part, is highly flammable and would require huge, special tanks. “Its molecules are so small that they can leak out of virtually anything,” Eefting adds. “And you need to compress it or cool it to minus-253 degrees Celsius to have a decent energy density.”

Source: Wired

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