One container ship can emit almost the same amount of pollution as 50 million cars, and yet, shipping emissions are often overlooked. Here’s how researchers plan on curbing this serious source of global pollution.

Sulphur dioxide and nitrogen oxides (NOx) are some of the nastiest pollutants found in emissions from ships. Global shipping contributes about 15 percent of all human-caused nitrogen oxide emissions, contributing to acid rain that affects everything from vegetation to humans.

And research has now recently found that a single container ship can emit almost the same amount of chemicals that are associated with cancer and asthma risk as 50 million cars.

“If you’re producing nitrogen oxides close to a populated place, then people will have breathing issues,” says Dr Vikram Garaniya, Associate Head of Research and Global at the University of Tasmania’s Australian Maritime College (AMC).

To combat this oft-ignored source of air pollution, Dr Garaniya and his colleagues at the AMC have been working with the Australian Maritime Safety Authority (AMSA) to determine how best to introduce new, cleaner air standards for ships.

In Emission Control Areas (called ECAs), it’s estimated that these new NOx standards, which go into effect in 2021, will result in an 80 percent reduction of NOx emissions by ships below year 2000 levels.

In addition, in 2020, new world standards will reduce the maximum allowed level of sulphur in fuel from 3.5 to 0.5 percent, which alone could prevent more than 570,000 premature deaths by 2025.

These major changes cannot be achieved merely by tweaking or tuning engines, but require revolutionary changes on-board ships, costing millions of dollars and requiring the vessels to be out of action for considerable periods.

“This is a big change, but we are ensuring that it is carefully managed,” says Dr Garaniya.

“AMSA regularly contracts the Australian Maritime College to get research done in order to get specific answers. We are the national institute for maritime research, education, and training, so we are able to guide AMSA on what’s best for Australia. We are proactive in bringing emissions down, but at the same time we are providing technical inputs as to what’s right and appropriate for Australia.”

Change takes time

At times, Dr Garaniya’s research has resulted in him recommending a particularly cautious approach – even extending the deadline for some of these new emission targets by up to five years.

For example, he recommended delaying the introduction of the new NOx standards in ECAs from 2016 to 2021, because his studies indicated that an earlier date would have resulted in the detention of many ships, crippling Australia’s export and import industries.

“We don’t like to tighten the screws for companies that are not ready,” he says. “In the shipping industry, change takes time. Ships need time to travel and organise downtime, their schedules are at least a year in advance.”

Dr Garaniya says fuel used in shipping is often ‘dirtier’ than other regular fuels.

“After extracting crude from the earth, refineries strip things like diesel and petrol out of it – whatever is in demand – and what’s left goes into shipping,” he explains.

“That’s why it’s not the best in terms of its combustion characteristics. It even contains heavy substances like bitumen (asphaltenes). Often they have to keep it warm all the time or it will jam the pipes – it’s really sticky.”

Yet, per tonne moved, shipping is more economical and produces far fewer emissions than moving cargo by road or air, so it’s important that the industry survives into the future.

“You can move a big load of cargo in an economical way, so the amount of pollution is very low,” says Dr Garaniya.

“Ships are getting bigger too. The largest ship we have now can take 21,000 containers, with each 20-foot (609-cm) container holding 15 to 20 tonnes, and the demand for shipping is increasing every day.”

Taking the smarter approach

Sulphur emissions can be reduced by changing to low-sulphur fuels, but Dr Garaniya’s research showed that Australia does not have an adequate supply of these fuels.

“We only have small number of refineries in Australia, so when we have to implement these changes, we will mainly be relying on overseas suppliers,” he says.

To reduce sulphur dioxide emissions, ships can use cleaner fuels such as LNG (liquefied natural gas), but many Australian LNG bunkering infrastructures are still under construction.

NOx emissions, on the other hand, aren’t generally caused by problems in the fuel, but by high temperatures in the combustion process. As a result, there are various technological methods that ships can introduce to meet the new, improved standards for NOx emissions.

“There are seven different technologies that they can use, but each ship has to work out what’s best for them,” says Dr Garaniya.

One method is selective catalytic reduction, in which urea or ammonia can be injected in the exhaust gas, causing a chemical reaction that reduces the NOx levels. Another method is called scavenging air moisturising, in which the intake air is preheated at 70°C with a high humidity, which can also reduce NOx production.

Dr Garaniya says the AMC will continue helping the shipping industry in finding other ways of reducing emissions, such as relying on shore power when in port, rather than keeping the marine fuel generators going.

It’s a ‘slowly but surely’ approach to the future, but for an industry based on that philosophy, it’s looking like a perfect fit.

Key facts:

  • Global shipping contributes 15 per cent of all human-caused nitrogen oxide emissions. 
  • In 2020, new world standards will reduce the maximum allowed level of sulphur in shipping fuel from 3.5–0.5 per cent, which could prevent more than 570,000 premature deaths by 2025. 
  • New standards for NOx emissions will result in an 80 per cent reduction of NOx emissions by ships below year 2000 levels. 
  • The largest ships in world can take 21,000 containers, with each 20-foot (609-cm) container holding 15 to 20 tonnes.

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About Dr Vikram Garaniya

Dr Vikram Garaniya is a Course Coordinator for the BEng (Marine and Offshore Engineering) program. His main area of research is in marine fuels and ship emissions. Vikram has published over 25 papers in scholarly journals and conferences. Recently he led a team which received a $60,000 USD grant from the International Association of Maritime Universities. Vikram's research interests include chemical and thermal engineering related areas, such as combustion science, computational fluid dynamics, modelling of engines, mathematical modelling, evaporation, pyrolysis, thermal cracking, coke formation, soot burnout, heavy fuel oil and continuous thermodynamics are his most areas of interest. He also has a very keen interest in chemical process optimisation, and safety and reliability of such systems.

View Dr Vikram Garaniya's full researcher profile