Tanker degassing is the process of removing residual vapors and gases from a vessel’s cargo tanks before taking on a new cargo or carrying out maintenance work. This process primarily releases hydrocarbon vapors, including benzene, volatile organic compounds (VOCs), and methane, which are both hazardous to human health and harmful to the environment. This article answers the most frequently asked questions about tanker degassing: what emissions are released, why it is mandatory, how harmful those emissions are, and what regulations apply in Europe.
What gases are released during tanker degassing?
During tanker degassing, volatile organic compounds (VOCs) are the primary emissions released, including benzene, toluene, xylene, and ethylbenzene. Depending on the cargo previously carried, methane, propane, butane, and other light hydrocarbons may also be released. The exact composition of the emissions depends directly on the type of product that was stored in the tank.
For tankers that have carried crude oil or petroleum products, the vapors released are particularly complex. Benzene is one of the most concerning components, as it is a proven carcinogen. VOC emissions during tanker degassing can also contain sulfur compounds, such as hydrogen sulfide (H₂S), which are toxic even at low concentrations.
For vessels that have carried chemicals, the gas composition varies considerably. Some chemical cargoes produce halogenated compounds or other hazardous industrial emissions during degassing that require specific treatment techniques. This makes tanker degassing technically one of the most challenging sources of industrial emissions to manage.
Why is tanker degassing mandatory for vessels?
Tanker degassing is mandatory because residual gases in cargo tanks pose a serious risk of explosion and fire. Before a vessel can take on a different cargo, undergo maintenance, or enter a dry dock, the tanks must be free of flammable or explosive vapor concentrations. Safety on board and in port is the primary reason for this requirement.
Beyond safety considerations, degassing is also necessary for operational continuity. A tank containing residual vapors from a previous cargo can contaminate that cargo or react chemically with a new one. For the chemical and petrochemical industries, cross-contamination is an unacceptable risk that can cause significant economic damage.
The requirement applies to both ocean-going tankers and inland waterway tankers. Ports and terminals impose strict requirements on the gas-free status of tanks before loading and unloading operations may begin. In practice, this means that degassing is a fixed part of every operational cycle of a tanker.
How harmful are degassing emissions to people and the environment?
Degassing emissions are significantly harmful to both human health and the environment. Benzene, one of the most common components in tanker degassing, is a proven carcinogen that increases the risk of leukemia with prolonged exposure. VOC emissions also contribute to the formation of tropospheric ozone, a secondary air pollutant that causes respiratory complaints.
Health risks for people
Direct exposure to degassing emissions can cause headaches, dizziness, and respiratory irritation in port workers, crew members, and nearby residents. At higher concentrations, benzene and other aromatic hydrocarbons can affect the nervous system. Prolonged exposure to even low concentrations of these hazardous substances increases the risk of chronic respiratory conditions and certain forms of cancer.
Environmental impact of tanker cleaning emissions
From an environmental perspective, untreated VOC emissions contribute to the formation of fine particulate matter and smog in urban and port areas. Methane, which is also released during degassing of natural gas- and LNG-related cargoes, is a potent greenhouse gas with a short-term warming potential significantly higher than that of CO₂. Uncontrolled emissions from tanker degassing therefore represent not only a local health risk, but also a contribution to climate change on a global scale.
What are the current methods for treating degassing emissions?
The most widely used methods for treating degassing emissions are vapor recovery units, activated carbon filtration, thermal oxidation, and flameless oxidation. Each method has a different range of applications, cost structure, and degree of emission reduction. The choice depends on the type of gas, the flow rate, and the operational context.
Vapor recovery units capture the hydrocarbon vapors released and return them to the loading installation or store them for reuse. This is an effective method for ports and terminals with high cargo volumes, but requires fixed infrastructure and is less suitable for mobile or temporary applications.
Thermal oxidation burns the vapors at high temperatures, but produces nitrogen oxides (NOx) as a byproduct, creating its own emission problem. Flameless oxidation technology bypasses this issue by allowing combustion to occur without a flame and at lower temperatures. This results in a reduction of up to 98% of harmful emissions, including NOx and CO₂, without requiring additional energy sources or support gases. The technology holds ATEX Zone 0 certification, meaning it can be safely deployed in the most explosive environments, including the tanks and cargo holds of tankers.
What regulations apply to tanker degassing in Europe?
In Europe, tanker degassing is regulated through a combination of international treaties, EU directives, and national legislation. The most relevant international frameworks are the MARPOL convention for ocean-going vessels and the CDNI convention (Convention on the Collection, Deposit and Reception of Waste Generated during Navigation on the Rhine and Inland Waterways) for inland waterway transport. Both conventions set requirements for the treatment of tanker degassing emissions in ports and on the water.
At the European level, the Industrial Emissions Directive requires large industrial installations, including ports and terminals, to apply the best available techniques for emission reduction. For inland waterway transport, the EU has made the use of certified degassing technology on class tankers mandatory from October 2024 onward, marking an important step in tightening European emission standards.
The Corporate Sustainability Reporting Directive (CSRD), which comes into force for an increasingly large group of companies in 2026, requires businesses to report in detail on their direct emissions, including emissions from tanker degassing. This increases pressure on shipping companies, terminals, and chemical businesses to take demonstrable steps toward reducing tanker cleaning emissions. Companies that invest now in certified treatment technology not only position themselves more favorably with regulators, but also strengthen their standing with ESG-focused investors and business partners.
How SuperFlox supports safe and compliant tanker degassing
Meeting the increasingly stringent regulations surrounding tanker degassing requires a reliable, certified solution that demonstrably improves both safety and environmental performance. SuperFlox offers exactly that: a flameless oxidation system specifically developed for the treatment of hazardous degassing emissions on board tankers and in ports.
What sets SuperFlox apart:
- Up to 98% emission reduction of VOCs, benzene, NOx, and CO₂, without the use of support fuels or external energy sources.
- ATEX Zone 0 certified, allowing the system to be safely deployed in the most explosive environments, including the cargo tanks of tankers.
- Mobile and flexible deployment, suitable for both ocean-going tankers and inland waterway tankers, including outside fixed port infrastructure.
- Verifiable CSRD reporting: the systems deliver measurable emissions data that can be used directly for sustainability reporting and ESG accountability.
- Compliant with MARPOL, CDNI, and the EU Industrial Emissions Directive, ensuring shipping companies and terminals meet all applicable obligations.
Want to find out how SuperFlox can make your degassing operations safer, cleaner, and regulation-ready? Contact our team for a no-obligation consultation.