How much pollution do cargo ships cause

Floating polluters: container ships have to become greener

On television, in the newspaper or on news websites, the latest economic data is often accompanied by photos and sequences of fully loaded container ships. The illustration is obvious, because a large part of the global flow of goods flows over the Atlantic, Pacific, Mediterranean and Co. To be able to imagine the dimensions that global shipping has now assumed, one can take a look at the Baltic Sea, for example: around 2000 container ships run there within 24 hours. In principle, if the ships have a comparatively good energy balance because they can transport a lot of cargo with comparatively little energy, things look very different when it comes to propulsion technology.

Container ships have a three percent share of global CO2 emissions

The fuel of the vast majority of ships is heavy oil. Heavy oil is an inferior quality leftover from the refinery that is produced during the further processing of petroleum. Heavy oil is characterized by its particularly high proportion of sulfur and other pollutants. Seafaring accounts for three percent of global CO2 emissions. The ships pollute the air, especially on coasts and in port cities, with sulfur oxides, nitrogen oxides, soot and fine dust. Nitrogen oxides are considered to be the cause of respiratory and cardiovascular diseases, and they can also lead to over-fertilization of the sensitive ecosystems in the sea. If the sludge from processing heavy fuel oil is illegally disposed of at sea instead of in port, this can have dramatic consequences for marine life. Soot and fine dust also pose a health risk - despite this, there are still no really effective guidelines for reducing emissions in international shipping.

Climate targets for container ships are not ambitious

The organization that negotiates and decides on such limit values ​​and other environmental protection measures is the International Maritime Organization, or IMO for short. It is a specialized agency of the United Nations and is based in London. It was not until 2016 that the 173 member countries of the IMO decided that the permissible sulfur content in heavy fuel oil should be reduced from a maximum of 3.5 to 0.5 percent; the new limit will apply from 2020. The organization took even longer to achieve a specific climate target: in 2018, the IMO that greenhouse gas emissions from shipping should halve by 2050 compared to 2008. In order to achieve the Paris climate targets, this value is probably not sufficient. So far, this project has hardly been supported with concrete measures.

In May the member states agreed on stricter environmental guidelines, but these are also not very far-reaching. Internationally, new container ships must now “already” meet higher efficiency standards from 2023 instead of 2025. The rules only apply to new ships - with a service life of 20 to 40 years, the environmental protection measures are more likely to have an effect in the long term. With its more ambitious goals, the EU Commission was unable to prevail against the proposal of the World Shipping Council, which in turn represents the shipping companies that offer regular service with container ships.

Slow container ships are more environmentally friendly

Speed ​​limits, as requested by 120 shipowners in the run-up to the meeting, are also not being introduced. Saudi Arabia, the United States and Brazil, among others, had resisted. This easy-to-implement measure has a surprisingly high effect, because slow-moving ships emit around a third less CO2 - and the shipping companies have significantly lower costs. The European umbrella organization, the European NGO Transport and Environment association, has calculated how serious a speed limit would have: the total CO2 saved corresponds to the elimination of 82 coal-fired power plants. At least there is a vague possibility that at the next IMO meeting in autumn there will still be a decision to regulate the speed.

Compared to other technological developments in the transport sector such as e-cars or hydrogen trains, the measures under discussion seem to be very unimaginative and immature. But there are also approaches for the shipping industry that point towards a more sustainable future. A sample comes from Denmark: In order to minimize the harmful emissions of heavy oil combustion, the world's largest shipping company Maersk has recently begun offering its customers the option of adding 20 percent vegetable used cooking oil to the heavy oil and thus transporting goods in a more environmentally friendly way. Since this makes transport more expensive, it remains to be seen how many customers will actually make use of the offer.

There are alternatives to heavy fuel oil for cruise ships

In the cruise industry, which, despite its equally devastating environmental balance, should only be mentioned in passing, liquefied natural gas (LNG for Liquefied Natural Gas) is now regarded as the clean fuel of the future. In fact, LNG reduces the air pollution caused by the floating giants, above all the natural gas, which has been cooled to minus 162 degrees, causes less fine dust and nitrogen oxides when burned. The big problem is that methane escapes when LNG is extracted, transported and used as a fuel. Methane, in turn, is many times more harmful to the climate than CO2. A more promising alternative to LNG and heavy fuel oil would be marine gas oil, which has a significantly lower sulfur content and causes less particulate matter and soot. However, it is also significantly more expensive than heavy fuel oil, which has so far prevented shipping companies from using marine gas oil on a large scale.

The fact that containers will one day even be transported across the oceans with electrical energy or hydrogen is at best a very quiet dream of the future. The world's first fully electric ferry is currently going into operation in Denmark. In Scotland, a hydrogen-powered ferry with fuel cells is also being worked on. However, the energy requirements of a gigantic container ship that carries thousands of tons of cargo instead of a few dozen passengers is much greater.

In the long term, it will be inevitable for shipowners to replace the environmentally harmful heavy fuel oil with other propulsion technologies. When it comes to climate protection, however, speed is of the essence, so that stricter requirements and limit values ​​are urgently required. Where, for example, particle filters and fuel-saving engines have long been part of everyday life in road traffic, shipping with its floating pollutants seems to have fallen out of time. High time for the IMO to change course.