Despite being the most efficient mode of transporting cargo, shipping globally has a significant carbon footprint. The sector today represents approximately 3% of global CO2 emissions. The impact of other harmful emissions from shipping, such as particulate matter and sulfur oxides (which are detrimental for human lungs), is believed to be even greater.
Authorities are seeking to address the issue through various means. In 2020 the International Maritime Organization (IMO) introduced rules to cap sulfur emissions and is now aiming to further reduce CO2 emissions. Decarbonization of shipping will not be instantaneous nor easy. The global fleet currently almost completely relies on fossil fuels. That said, there are new fuels and technologies emerging in the sector. For example, ships are being electrified, sails are making a comeback as an assisting means of propulsion, and new promising fuels such as hydrogen, methanol and ammonia (NH3) are being tested.
Ammonia made with renewable energy is a very promising fuel for several shipping segments. It is carbon free, a widely traded commodity, and has a high energy density. Ammonia will however generate some emissions like all other promising fuels when combusted. To tackle this, the AMAZEMENT (AMmoniA Zero Emission abateMENT) project focuses on developing technological solutions to minimize such emissions from the use of ammonia as a maritime fuel.
This will be achieved by targeting the following emissions that are produced by an engine burning ammonia:
- Un-combusted ammonia (NH3) – Risk to human health
- Nitrogen oxides (NOx) – Contributes to acid rain
- Nitrous oxide (N2O) – Greenhouse gas, 300 times more harmful than CO2
The technology will convert these emissions found in the engines exhaust gas into harmless nitrogen gas and water, allowing the cleaned gas to be safely released into the air by the ship. This process is essential for the use of ammonia as an environmentally friendly marine fuel.
The AMAZEMENT (AMmoniA Zero Emission abateMENT) project aims to develop a new abatement system for the removal of nitrous oxide (N2O), nitrogen oxides (NOX) and ammonia slip (NH3) from the exhaust gas of an ammonia fuelled engine used for maritime propulsion and power generation. It is comprised of fundamental changes to the abatement system technology used for removal of atmospheric pollutants from marine engine exhaust gas. The project will enable the use of ammonia as a carbon free marine fuel with zero or extremely low pollutant emissions and it will demonstrate the multi-stage abatement system capable of removing the exhaust gas’s polluting components.
Stricter emissions regulations are an imminent challenge for the maritime industry. To mitigate the environmental threat imposed by greenhouse gases (GHG) and other pollutants, the International Maritime Organisation (IMO) has set the target of a reduction in CO2 emissions by 40% by 2030 and an overall reduction in greenhouse gas (GHG) emissions by 2050. To achieve zero emission vessel operation shipowners are looking to ammonia as a fuel due to its high energy density, existing and mature production and storage, and ability to be produced from renewable energy. When combusted in-engine, the exhaust gas will contain nitrogen oxides (NOX), un-combusted ammonia (NH3), and nitrous oxide (N2O).
The most challenging component to abate is N2O, a potent ozone depleting GHG and it has approximately 300 times higher global warming potential than CO2. Land-based methods utilise specialised catalysts and the high temperature of the gas for efficient abatement. Ammonia fuelled engine exhaust gas will be significantly lower resulting in zero to very-low conversion using existing methods. The AMAZEMENT project aims to develop a N2O catalyst with a high conversion rate at sufficiently low temperatures as part of a system treating N2O, NOX and NH3 present in the exhaust gas from an ammonia engine.