Some industries are taking action to reduce their CO2 footprint coming up with several ingenious technologies. The primary industries releasing the most CO2 are:
- Industry energy 24.2%
- Energy in buildings 17.5%
- Road transportation 12%
Like all modes of transportation that use fossil fuels, ships also produce CO2 emissions. Maritime shipping generates an estimated 2.2% of the global CO2 emission. The majority is coming from container ships, which after all carry 90% of the world’s trade. You probably think, there are millions of cargo ships hauling our needed commodities around the world. But that is not the case.
Maersk is the largest container shipper in the world, and it is estimated that the company provides for 17.6% of the world’s market share of container shipping. Yet, the company does not possess thousands of ships, but “only” has 786 ships given a lifetime of around 20-30 years.
The truth is that ships have a significant CO2 impact, condemning them as gigantic pollution machines. According to Maersk, the company’s greenhouse gas emissions amounted to almost 36.5 million tonnes of CO2 in 2019, equivalent to a small country’s emissions, like Ireland.
However, one must understand that cargo shipping is the most efficient mode of transportation of goods. In one year, a single large containership can carry over 200,000 containers loads of cargo. Given the amount of CO2 emissions from the maritime shipping industry, sea transport is relatively CO2 friendly compared to air and truck transport.
The illustration shows the amount of CO2 in grams emitted per metric ton of freight per km of transportation. Certainly, compared to the other means of transportation, the Maersk Triple-E released 3 g CO2 per km, but older and smaller ships will not show such low CO2 emissions.
The question is, what did Maersk Triple-E do to get this figure? They did not invent some revolutionary technology or implemented some ingenious know-how to achieve this, they simply made a change of speed and slowed down.
On the basis of major factors affecting a ship’s fuel consumption, there are namely the ship’s size, weight, and speed. The fuel consumption is relative to the ship’s speed and the cargo capacities, and it is typically exponential with each knot of speed added. Therefore, the heavier the ship the more fuel consumption. Let’s take an example:
Reducing speeds across shipping fleets has shown to make a significant contribution to reduce greenhouse gas emissions, however the practice of it began due the rising fuel prices in 2007. The biggest operational cost of vessels for the shipowners is fuel cost, to survive the financial crisis and to lower the costs, shipping companies reduced their speed to save costs. As climate change has come into focus, the trend is more relevant than ever before.
As a result of speed reduction and other activities, Maersk has achieved a 42% reduction in CO2 emissions. Now they are aiming for a 60% reduction by 2030 and an ambitious target of net-zero emissions by 2050. By setting the ambitious target, Maersk hopes to inspire researchers, developers, and legislators to develop sustainable solutions in the maritime industry.
100% CO2 reduction, possible or not?
Alongside operational action to cut emissions, new technologies are being developed to reach net zero CO2 emissions. With the revival of wind power, engineers and ship designers are harnessing a century-old sail technology into a modernized high-tech version, the Flettner rotors. In the simplest form, these are rotating giant tubes made of light composite materials arranged vertically on the ship’s deck using a smaller surface area. The Flettner rotor sail concept works by harnessing the Magnus effect which provides a forward thrust to the ship.
According to Norsepower, the vertical rotors can be retrofitted to many different types of ships and be mounted on trolleys so they can be moved during loading and unloading of containers, they are even controlled by a software requiring minimal input from the ship’s crew. However, like conventional sails, it depends on the direction of the wind, so is best used as a supplementary propulsion system. But imagine if ships could take advantage of modern global positioning and weather forecasting technology to plan their routes to maximize the wind? How much greater an advantage could that be?
However, wind assisted vessel propulsion is not going to power these ships by itself. The biggest challenge the shipping industry faces is fuel. Since the 1960s, heavy fuel oil (HFO) has been the king of marine fuel, cheap and available but very dirty and releasing heavily polluting sulfur and nitrous oxides into air.
These are the driving forces behind the International Maritime Organization’s (IMO) mandate, to limit the sulfur content of ship fuel from 1. January 2020. The shipping industry has responded by turning into cleaner methods such as low-sulfur fuel, while other turn to liquified natural gas (LNG).
The world’s largest container ship powered by LNG launched in September 2020. When burned, natural gas emits less carbon dioxide, sulfur oxides and nitrogen oxides than HFO, resulting in almost 20% less CO2 emissions. Yet, they emit a large amount of methane into the atmosphere, which is 30 times more potent as a greenhouse gas tan CO2.
Another idea is to switch to biofuels like biogas or biodiesel, both fuels derived from biomass. However, there is a lot of controversy surrounding their ability to eliminate carbon emissions. Some methods help reduce the carbon dioxide output and others are worse for the environment than fossil fuels.
Hydrogen is also an option and it has been praised to be the key to a sustainable shipping sector. But as everything else it comes with disadvantages, as being very expensive and with undetermined storage options. Nonetheless, countries like Norway or Japan have been very involved in new technologies concerning hydrogen within the maritime transport. However, this solution poses a problem in the longer routes.
The transpacific route connecting two of the largest economies, China and USA, makes Japan one of the main refueling stops. The length of this route poses certain logistic challenges in the transition to hydrogen, since it has high gravimetric energy density, its volumetric energy density is quite low. As result ships would need to sacrifice some cargo space for fuel storage or to make an additional stop. A presented idea could be if demand allows it, a floating refueling station, with its own hydrogen generation powered by offshore wind between China and USA.
It takes investment, cutting profit and government action to eliminate our CO2 emissions. Companies must be pressured not to only polish their technology, but to be ready for the next step. These big machines will be floating on our oceans for decades, making a bad move now and betting for fuel that isn’t better for the environment is a problem. We need to be future focused and to make the right decision today.