Engine emission regulations for marine applications

Let’s start with why the marine industry is unique when it comes to emission regulations.  

“First, there are multiple agencies regulating maritime emissions. The U.S. Environmental Protection Agency (EPA), European Union (EU), International Maritime Organization (IMO) and Ministry of Ecology and Environment of China are the major ones to mention,” says Michael Drew, Marine Certification Manager at Cummins. “Second, since marine vessels often operate across geographies, they need to comply with multiple emission regulations through their operation. Moreover, what makes marine even more unique is the emission regulations sometimes set by local ports,” adds Drew. 

IMO Emission Standards for Marine Applications

IMO’s MARPOL Annex VI

The IMO’s MARPOL Annex VI was first adopted in 2000 with the introduction of IMO Tier I. These regulations limited the emission of air pollutants within ships’ exhaust gases. Initial regulations have specifically targeted nitrous oxides and sulfur oxides.

One reason behind this initial focus on nitrous oxides and sulfur oxides was their impact on the environment and on those that live within the affected coastal environments. You can read more about these on reducing greenhouse gas, sulfur, and nitrous oxide emissions in the maritime industry. 

IMO II and IMO III Emission Regulations

The IMO has continued to set regulations with reduced emission objectives. Each subsequent regulation (IMO Tier II and Tier III) continued to lower nitrous oxide and sulfur oxide emissions. 

IMO Tier II regulations went into effect in 2011. The most recent IMO III emissions regulations specifically apply when ships are operating within NOx Emission Control Area (ECA). Some of the ECAs around the world are the Baltic Sea area, the North Sea area, the North American area, and the U.S. Caribbean Sea area. For North America and U.S. Caribbean Sea NOx ECAs, these IMO III regulations apply to vessels built after January 1, 2016. 

As a result of these regulations, today ships emit 80% less nitrous oxides and 89% less sulfur oxides compared to their counterparts built in 1990s. 

You can learn more about the Cummins IMO III Solutions, and the technologies available to fulfill the needs of your business.

EPA’s Tier 4 Engine Emission Regulations for Marine Applications

The EPA’s Tier 4 exhaust emission regulations have recently replaced the previous Tier 4 transitional, Tier 3 and Tier 2 regulations for engines that produce 600 kW and higher power output. These Tier 4 emission regulations are applicable for a variety of vessels ranging from ferries and tugboats to large ocean-going vessels. For recreational vessels, EPA Tier 3 compliance is still the most current regulation.

The EPA has defined three engine categories to determine the applicability of Tier 4 exhaust emission regulations. These are Category 1, Category 2, and Category 3. A combination of maximum engine power and displacement (L/cylinders) determine which category each engine falls into. 

We will focus on Category 1 engines for the rest of this article. These are the engines most frequently used for tugboats, offshore supply vessels, towboats, passenger ferries, fishing boats, and superyachts. 

Tier 4 regulations have introduced further reduction in emissions of particulate matter, nitrous oxides and hydrocarbons compared to Tier 3 regulations. Engine manufacturers commonly use a separate exhaust aftertreatment technology to accomplish these emission reductions. 

EPA Tier 4 Particulate Matter Emissions

EPA Tier 4 introduced a 63% reduction in particulate matter emissions over Tier 3 regulations for many of the engines above 600 kW power output. For example, Cummins QSK60 engines are Tier 4 compliant for marine applications. These engines emit less than 0.04 g/kW-hr of particulate matter. 

EPA Tier 4 Nitrous Oxides and Hydro-Carbon Emissions

EPA Tier 4 introduced a 64% reduction in nitrous oxides and hydro-carbon emissions over Tier 3 regulations for many of the engines above 600 kW power output. For example, Cummins QSK38 engines are Tier 4 compliant for marine applications. These engines emit less than 1.8 g/kW-hr of nitrous oxides and 0.19 g/kW-hr of hydrocarbons.

You can read more about Cummins EPA Tier 4 engines for marine to find the right solution for your vessel. Please also note that some vessels need to meet both EPA Tier 4 and IMO III standards depending where they are operating.

EU’s Stage V Emission Regulations for Inland Waterways in Europe

European Union’s Non-road Mobile Machinery (NRMM) emissions regulate the diesel engines used in selected marine applications. European Commission’s emission regulations focused on exhaust emission of vessels operating in inland waterways.

The European Union, like the EPA, chose to concentrate on reducing the emission of carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter.

Stage V is the latest tier of these regulations. Here are the key highlights of Stage V emissions for inland waterway vessels:

• A 72% reduction in emission of nitrous oxides and the hydrocarbons compared to Stage IIIa. Nitrous oxides emissions are now set at the extremely low level of 1.8 g/kW-hr. Cummins engines for these applications use selective catalytic reduction (SCR) aftertreatment technology to deliver this extra-low emission. 
• A 93% reduction in emission of particulate matter compared to Stage IIIa. Particulate matter emissions are now set at the extremely low level of 0.015 g/kW-hr. Moreover, the introduction of particulate number (PN) count essentially leads to 99.9% elimination of all PM. Cummins engines for these applications use diesel particulate filter (DPF) to achieve this near-zero level. 

You can read more about how the Cummins X15 is powering boats on the European inland waterways. 

Emission Regulations from Ministry of Ecology and Environment of People’s Republic of China

The focus of non-road mobile machinery emission regulations in China is on five key pollutants: carbon monoxide, hydrocarbons, nitrogen oxides, methane, and particulate matter. In China, Stage 1 emission requirements that impacted selected marine applications went into effect in 2018. Stage 2 emission requirements are going into effect starting 2021. These Stage 2 emissions are applicable for China flagged vessels that are operating within inland waterways and coastal areas. 

With Stage 2 emission regulations in China, there will be a significant emission reduction for the engines used in marine applications. These new Stage 2 emission regulations are very similar to the EPA’s Tier 3 Recreational regulations. 
Similar with the EPA’s Tier regulations, emission regulations in China also look at engines in categories: Category 1 and Category 2. Let’s look at how engines in Category 1 (liters per cylinder between 1.2 and 5) will have reduced emissions with Stage 2 regulations. 

• Hydrocarbons and nitrous oxides (HC + NO_x): Marine engines compliant to Stage 2 emission regulations will emit 19% less HC and NOx compared to their Stage I counterparts. This means limiting HC and NOx emissions at 5.8 g/kWh. 
• Methane (CH₄): Marine engines compliant to Stage 2 emission regulations will emit 33% less methane compared to their Stage I counterparts. This means limiting methane emissions at 1 g/kWh.
• Particulate matters (PM): Marine engines compliant to Stage 2 emission regulations will emit 40% less PM compared to their Stage I counterparts. This means limiting PM emissions at 0.12 g/kWh.

Local emission regulations among ports

In addition to the above emission regulations, specific port authorities around the world have also regulated the emissions of equipment operating within their geography. This equipment includes trucks, trains, and harbor and ocean-going vessels. Nitrous oxide emissions often become the primary focus of these port-oriented regulations when it comes to marine applications.

These variations in emission regulations bring a new challenge to vessel operators: the need to comply with multiple emission regulations. For example, a vessel that is visiting a port could be required to lower its emissions while within the port boundaries. In this scenario, if the vessel features some of the latest Cummins technology, the operator can simply switch between IMO II and III mid-journey. This ability to “pause” SCR functions (where applicable) minimizes DEF use and the associated costs while maintaining the high level of fuel efficiency.

To learn more about marine power solutions Cummins offers, visit our webpage.