Pollution due to shipping

What is the carbon footprint of the maritime transportation industry?

In the past few decades, there has been a rapid surge in the release of greenhouse gases (GHG) into the atmosphere, primarily caused by the escalated use of fossil fuels and intensified industrial activities. Although there was a temporary decline in emissions during 2020 as a result of the COVID-19 pandemic’s restrictions, global emissions have since bounced back and hit all-time highs. In 2021, global GHG emissions reached 54.6 billion metric tons of carbon dioxide equivalent (GtCO₂e).

Transportation-related CO₂ emissions worldwide have witnessed remarkable growth, starting at 2.84 billion GtCO₂ in 1970 and escalating to 7.64 billion GtCO₂ by the year 2021, because of the expansion of both global populations and economies. The primary source of these emissions is the combustion of petroleum-based fuels (coal, crude oil, diesel, natural/derived gas, petrol…), predominantly within internal combustion engine vehicles (ICEVs). As of now, the transportation sector contributes a substantial 20.2 percent of the world’s total CO₂ emissions, firmly establishing itself as the second-largest contributor to carbon pollution on a global scale.

Within the transportation sector, shipping claims the third position in terms of carbon dioxide emissions, comprising 11% of the total, trailing closely behind passenger vehicles at 39% and medium to heavy trucks at 23%. Due to the increase in global trade and the demand for maritime carriage of goods, the sector’s carbon footprint, primarily because of CO2, is poised to potentially surge by 50% to 250% by the year 2050 if proactive measures are not taken.

Ships require energy to operate. While cleaner fuels are gradually gaining traction, shipping companies continue to depend on fossil fuels like marine gas oil and heavy fuel oil. The combustion of Heavy Fuel Oil (HFO) results in the release of harmful gases, including carbon dioxide (CO2), methane (CH₄), and nitrous oxide (N₂O), all of which contribute to the problem of climate change. In addition, ships produce sulfur oxide (SOx) emissions, which, although not directly affecting the climate, pose significant environmental and health risks.

The specific emission levels can vary based on multiple factors, including the size and type of ships, their dead weight capacity, energy efficiency, the type of fuel used, and the distances they cover on an annual basis.

As an illustration, cargo ships are reported to produce 16.14 grams of CO2 per kilometer for each metric ton of cargo they carry. Yet, while container ships release an annual average of 140 million metric tons of carbon dioxide, bulk carriers contribute a total of 440 million metric tons of carbon dioxide emissions each year.

A benchmark created by CarbonChain, the carbon accounting platform for the world’s supply chains, provides an overview of cargo ships’ AER* (Annual Efficiency Ratio) depending on their dead weight capacity:

Less than 5,000 gross tonnage: 15.4 gCO2/dwt.nm
From 5,000 to 9,999 gross tonnage: 14.7 gCO2/dwt.nm
As from 10,000 gross tonnage: 11.2 gCO2/dwt.nm

*The AER quantifies a ship’s carbon dioxide emissions per unit of nominal transport work. This metric is calculated as the product of a ship’s dead weight capacity and the total distance it travels in nautical miles, expressed as grams of CO2 per deadweight ton per nautical mile (gCO2/dwt.nm).

What are the environmental initiatives to lower the GHG emissions in shipping?

Recognizing the imperative to mitigate the environmental impact of freight transportation by sea, the International Maritime Organization (IMO) has revised its sights on achieving net-zero emissions for the sector by around 2050. As a recall, it initially set a target to cut emissions by 40% in 2030 and 70% in 2050compared to the levels recorded in 2008.

To reach this ambitious goal, member nations have agreed on “benchmark milestones”: a 20% reduction by 2030 (with a goal of 30%) and a 70% reduction by 2040 (with a goal of 80%).

The IMO’s GHG strategy, which was set to enhance the sustainability of the industry, encompasses a range of initiatives:

Harness renewable energy sources to power oceangoing vessels: wind power, including sails and rotor sails, can assist in propulsion, while the installation of solar panels on ships can generate clean electricity.

Switch from traditional marine fuels to cleaner alternativesthat emit fewer pollutants and greenhouse gases: This includes options such as liquefied natural gas (LNG), hydrogen, and biofuels like methanol and ammonia. Battery-electric or hybrid systems can be used for energy storage, especially on short sea routes. Additionally, hydrogen fuel cells can be employed for electric propulsion.

Promote the development of more energy-efficient vesselsby optimizing their design and equipment. This involves modifying hull shapes to enhance propulsion efficiency and reduce energy consumption. Applying specialized hullcoatings can decrease friction and improve fuel efficiency. Upgrading engines to more energy-efficient models is also crucial.

Utilizing slow steaming to reduce the speed of cargo shipscompared to their maximum capabilities enables the reduction of fuel consumption and greenhouse gas emissions.

Leverage technological innovations to enhance fuel efficiency: Employ data analytics to optimize ship routes, speeds, and operations. Install advanced onboard systems for improved energy management.

Provide shore power at ports to enable ships to turn off their engines while docked, thus reducing emissions.

Implement supportive policy measures to facilitate the transition toward eco-friendly practices: Encourage companies and organizations to invest in carbon offset projects as a means to compensate for their emissions. Governments can provide financial incentives such as subsidies or tax incentives to companies adopting cleaner technologies and fuels. Additionally, pricing carbon emissions can incentivize emissions reductions.

DMU Timestamp: February 26, 2025 22:37