an autodidact meets a dilettante…

‘Rise above yourself and grasp the world’ Archimedes – attribution

the shipping industry – a bit of a global warming headache

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Ok, that’s sulphur oxides, nitrogen oxides, carbon dioxide, particulate matter and non-methane volatile organic compounds

I’ve been alerted, by a brief piece on a New Scientist podcast, and then by some passages in Tim Smedley’s book Clearing the air: the beginning and end of air pollution, about some pretty disturbing stats on the polluting and greenhouse impact of the world’s shipping industry – a factor we don’t often consider when we attempt to reduce our personal environmental impact. We tend to focus on the products we consume, the cars we drive, the homes we heat, the plane trips we take and so forth. But once it’s pointed out to us it becomes obvious. We’re the recipients of a vast global trading network involving foodstuffs, appliances and gadgetry of all sorts, as well as bulk supplies of crude oil, iron ore and a host of other raw materials, brought to us by more or less massive marine vessels.According to an article in Chemical & Engineering News (C&EN), goods weighing 11 billion tonnes were shipped across our oceans in 2019, a 3-billion tonne increase from a decade before. And the increase is expected to … increase. So how are these vessels powered? To quote from the C&EN article,

“The shipping industry uses more than 300 million tons of fossil fuels every year, roughly 5% of global oil production,” says Camille Bourgeon, a specialist in air pollution and energy efficiency in the marine environment at the IMO [the International Maritime Organisation – an agency of the UN]. In 2018, global shipping activity emitted roughly 1.05 billion t of carbon dioxide into the atmosphere, accounting for about 2.9% of the total global anthropogenic CO2 emissions for that year, according to the IMO’s 2020 greenhouse gas study.

What’s worse is that for decades the shipping industry has been using the lowest grade, most noxious fuels, ‘the stuff no-one else wants’, as one maritime engineer describes it. This ‘residual fuel’ is also called HFO, for ‘heavy fuel oil’, which the oil industry has been more than happy to provide to the shipping industry rather than having to get rid of it some other, more expensive way. And when you’re out in the middle of the ocean, who’s going to check your emissions? The fuel used has seriously high sulphur content, and once ships come into port, the cargo is offloaded onto diesel trucks and then often onto diesel locomotives. Here are some of Tim Smedley’s opening remarks on the industry:

[Shipping] is easily the transport sector with the worst history. Shipping emissions contribute nearly 15% of NOx [nitrogen oxides including nitric oxide and nitrogen dioxide, some of the worst air pollutants] and 13% of sulphur dioxide emissions globally, and these numbers are increasing. Due to growing populations and consumer spending, more and more supertankers set sail every year. Since 1985 global container shipping has increased by about 10% annually, with only brief dips for each recession.

There seems to be no stopping this growth, and about a quarter of this transport is fuelled by crude oil. As Smedley points out, this ‘gives us the headache-inducing fact that a quarter of all shipping emissions come from shipping the fuel needed to produce the emissions’.

As mentioned, sulphur dioxide is a major constituent of HFO. On the website of Aeroqual, a company that provides air monitoring systems, I found this disturbing claim – the sulphur dioxide of HFO is 2700 times higher than that of road fuel. Sulphur dioxide emissions have been dropping for years in developed countries – a 76% decrease in Europe between 1990 and 2009 – leaving shipping as the primary source.

As also mentioned, ports are some of the most atmospherically noxious places on the planet. Most of them use diesel-powered machinery for off-loading and transportation. Diesel emissions significantly increase cancer risks according to a host of epidemiological studies, and various engine improvements have barely kept up with improvements in emissions monitoring, which have highlighted further dangers. But the diesel issue probably requires a whole new post.

The shipping industry, setting aside all those smelly and sick-making ports, and the sulphur dioxide problem, is a major contributor to greenhouse emissions, releasing over 3% of our carbon dioxide, a percentage that is set to rise in the aftermath of the covid pandemic. A website called ship technology sets out a plan to address the issues, which reminds me of the plans regularly emanating from the IPCC, requiring targets which seem to be seldom met by the major emissions culprits. The plan includes improved ship-to shore data feed technology, exhaust emission technology, behavioural change such as slow steaming (yes, that just means slowing down) and more preventive maintenance, and alternative fuels such as LNG, hydrogen and even solar. LNG is the most touted alternative fuel due to requiring fewer alterations to shipping infrastructure, though it’s surely an interim solution.

The IMO has been rather defensive about its role as the shipping regulator, and the degree of progress made in reducing emissions. Certainly it’s a difficult industry to police, with many nations and companies involved, including military vessels worldwide, which have other priorities, to put it mildly. But it’s clear that shipping officials are feeling the pressure. As one of them put it:

“… can shipping reduce more greenhouse gas emissions? I’m sure it will. But it’s difficult to say how much particularly not knowing the consequences from regional regulations. There seems to be a wish to require unrealistic emission reductions in order to collect money from ships.”

These remarks make me wonder whether money is being collected from land-based greenhouse emitters, and if not, why not? Interestingly, the same official has this to say in the industry’s defence:

“When discussing short-term measures, the figure over the next 10 years will bring the shipping carbon intensity reduction in 2030 to more than 40%, below the year 2008. This is a remarkable achievement by a sector that is, and will remain, the most efficient mode of transportation”.

This appears to be saying that the most efficient form of transport in the shipping sector is, and always will be, shipping. Or maybe I’m reading it wrong. In any case, they’re on the case, which is great. Must remember to have another look in 2030.


Tim Smedley, Clearing the air: the beginning and the end of air pollution, 2019



Written by stewart henderson

July 10, 2022 at 1:29 pm

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