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EPA Finalizes Tier 3 and Tier 4 Standards for Locomotive and Marine Diesel Engines

Progression in NOx and PM standards for switch locomotives (one of the regulated categories). Click to enlarge.

The US Environmental Protection Agency (EPA) has finalized its Tier 3 and Tier 4 emissions standards for locomotives and marine diesel engines. Tier 3 emission standards will take effect in 2012, followed by Tier 4 in 2015.

The final requirements will bring earlier and greater emission reductions of NOx and PM from the locomotive and marine sectors than the proposed program envisioned. This is accomplished by finalizing the first-ever national standards for remanufactured large commercial marine diesel engines (above 600kW) and starting Tier 4 NOx requirements for line-haul locomotives and for the largest (2,000-3,700 kW) marine engines two years earlier than initially proposed.

EPA estimates 90% PM reductions and 80% NOx reductions from engines meeting the ultimate Tier 4 standards, compared to engines meeting the current Tier 2 standards. By 2030 this program will reduce annual emissions of NOx by about 800,000 tons and PM emissions by 27,000 tons and those emission reductions continue to grow beyond 2030 as fleet turnover is completed.

Nationwide, this regulation will help prevent 1,400 premature deaths, and 120,000 lost workdays annually in 2030, according to the EPA. The estimated annual health benefits are valued between $8.4 billion and $12 billion. When these older locomotive and marine engines reach the end of their useful life, and new engines enter into the nation’s diesel fleet, the benefits of the new rules will increase.

The rule cuts emissions from all types of diesel locomotives, including line-haul, switch, and passenger rail. The regulations apply to both newly manufactured marine diesel engines and remanufactured commercial marine diesel engines above 600 kw (805 hp) with displacement of less than 30 liters per cylinder installed on vessels flagged or registered in the United States.

These are commonly referred to as marine diesel engines and are divided into three categories for the purposes of EPA’s standards. The cut points for the standards have been revised in the final rule to ensure that the appropriate standards apply to every group of engines.

Category 1 represents engines up to 7 liters per cylinder displacement. Category 2 includes engines from 7 to 30 liters per cylinder. Category 3 engines are those at or above 30 liters per cylinder. Category 3 engines are not included in this rule. They are typically used for propulsion on ocean-going vessels and will be addressed in a separate EPA rulemaking.

Marine diesel engines covered by this proposal are used in a variety of applications. Commercial propulsion applications range from fishing and tug boats to Great Lakes freighters. Recreational propulsion applications range from sailboats to super-yachts. Auxiliary power units range from small generator sets to large auxiliary engines on ocean-going vessels.

For the first time, this rule requires remanufacturing standards for marine engines, reductions in engine idling, and the use of aftertreatment technology that will further reduce diesel emissions. Phasing in tighter long-term standards for PM and NOx will begin in 2014 for marine diesel engines and in 2015 for locomotive engines. Advanced after-treatment technology will apply to both types of engines.

Locomotive and marine diesel engines contribute significantly to air pollution in many cities and towns. EPA anticipates that over the next few decades, these engines may account for an even greater share of overall emissions as other emission control programs take effect for cars and trucks and other nonroad emissions sources. Estimates show that, without the emission reductions from this final action, by 2030 locomotive and marine diesel engines would contribute more than 65% of national mobile source diesel PM2.5, or fine particulate, emissions and 35% of national mobile source NOx emissions, a key precursor to ozone and secondary PM formation.

About 144 million people in the US live in areas that violate air quality standards for ground-level ozone, as of October 2007, and about 88 million people live in areas that violate air quality standards from PM. The locomotive and marine diesel emissions reductions will particularly benefit those who live, work, or recreate in and along our nation’s coastal areas, rivers, ports, and rail lines.

Switch Locomotive Emission Standards (g/bhp-hr)
Year of original mfrTier of standardsNOxPMHCCO
1973-1992 Tier 0 11.8 0.26 2.10 8.0
1993-2004 Tier 1 11.0 0.26 1.20 2.5
2005-2011 Tier 2 8.1 0.13 0.60 2.4
2012-2014 Tier 3 5.0 0.10 0.60 2.4
2015 or later Tier 4 1.3 0.03 0.14 2.4




nice! for all the focus on emissions from passenger cars, a large portion of transportation emissions are from the trucks/trains/boats that move our goods. this is an easy way to reduce emissions without all the whining from tahoe-driving losers who refuse to walk around the corner to buy a pint of milk instead of driving their land-yacht.

John Taylor

Now if the USA threatens to require non-USA flagged shipping to meet these standards while trading involving USA ports, the effect could rapidly become a universal world standard.

If they don't, then much of the USA commercial fleet will simply register to "flags of convenience" and side step the regulations.

@ John Taylor,

You have hit the nail on the head of the big loophole. Your diagnosis and solution is quite correct.

At present most of the world's fleets are not registered in America and fly flags of convenience. Even American owned vessels do so. So a enforcement mechanism that sees the ability to call on American ports, is the only solution with teeth.

The politicians will try to talk of a need for an international organization setting standards and enforcing them but that is pure eyewash delay.

The standards, to do any good, MUST effect any ship on any nation's registry entering US territorial waters to call on a US port.

I am glad this regulation has a re-manufacturing requirement as well; since the lifetime of locomotives and ships can be several decades.

I think once the principal of regulating emissions from these large sources is established, that the standards be rapidly raised commensurate with automotive emissions standards.

Here the cost of compliance is infinitesimal compared to the capital cost of the product. I see no reason that locomotives could not meet T2B5 or better standards for the effluent from their exhaust emissions. Ditto for seagoing vessels.

Of course, any CAFE-type requirements, or disguised CAFE via CO2 emissions per unit distance, are inapplicable and null and void.

The reason for the desire for rapid toughening of the standards is that the technology now exists to clean diesel exhaust, as now forced-developed for the automotive industry.

Implementing equivalent technology even on one-off (re-)implementations for shipping, would only add costs measured in the tens of thousands of dollars per installation. This is an incidental and insignificant cost literally peanuts, compared to the capital cost of these vehicles.

Unfortunately, our Democrat brethren seem intent on retreating into an isolationist mentality and in any case are likely to demagogue the issue, seeking nihilist impossibilities, if it becomes prominent in the news. Republicans are likely to try to stall and delay in behalf of the maritime interests.

Once again the Bush administration has quietly made progress here, isolated the obstructionists, as they did with USABC, ITER, reformed laws regarding plant construction and licensing, cajoling for private-public investment in "standardized designs" for power plants.

The Bush administration gets little credit, with this appraoch, but the progress is cumulatively substantial. They have succeeded by utilizing their low key approach and letting everyone complain but not interfere with the advance of the public interest.


However, if the EPA--and very likely the EU--requires cleaner-burning marine diesel engines for ships operating at ports in the USA and Europe, the whole world will take notice and even newly-built ships registered at "flags of convenience" like the Bahamas, Panama, and Liberia will have to get these engines.

In fact, several diesel engine manufacturers are looking at ways to drastically reduce NOx output on marine engines. One way is essentially a super-scaled version of the plasma gas reactor system Honda recently developed for the new i-DTEC turbodiesel engine.


Going along the same lines of also requiring any vessel that enters US ports to also meet EPA standards, I would also suggest that all motor vehicles entering the states also meet ARB or CARB standards.

Living close to the Mexican border, hardly a single day goes by when I don't get stuck behind a vehicle that would easily qualify as a gross polluter if it was registered here judging from the vast amount of hydrocarbons spewing out their tailpipes.

It's often so bad that you are forced to change lanes or switch to recirculated air.

Performing random emissions tests on out of country vehicles crossing the border would go a long way towards maintain clean air quality on our side of the borer.

Tokyo Joe

I think you will find that this legislation does not affect ocean freighters as it only refers to marine diesel engines. Ships use bunker fuel not diesel. (Correct me if I am wrong.) It doesnt address the issue of CO2 emissions from shipping or offer any solutions to one of the major sources of GHG.

International shipping is increasing rapidly with demand for new vessels outstripping capacity to build them, there is a need to look at alternative fuels for ships.

Bunker fuel surcharges are also forcing the cost of freight to rise substantially. This should be driving innovation in the shipbuilding industry to look at new fuel sources and engine technologies. I wonder if this is the case?


@ Tokyo Joe

They are still diesel engines despite burning bunker fuel.

joe padula

First of all every ship that could go out of US flag did it years ago. The ones that have not have a reason, ie Militaryand government cargo, runs to Guam, Hawaii, Puerto Rico that require US flags.
Didn't anyone read this ? It is for Cat II engines guys. They are all locomotive engines basicly under 6000 HP even though called marine diesels since they are installed on boats and ships . No US company makes a true marine diesel by the way. Only locomotive engines used in small ships, tug boats etc.
Japanese and Europeans make small marine diesels and license them worldwide.
These engines are only the generator diesels on a large ship,under 2500KW electrical, not the prime mover for the propeller. They are the Cat III engines not covered by these rules.

The Cat II engines used as propulsion engines almost all use gas oil (#2 car and truck diesel). A few use MDO, marine diesel ( like home heating oil). The european and japanese designs used on real ships generators use bunker fuels ISO 380 centistoke viscosity or lighter. THe same fuel as in the main engine. They can all also use MDO or gas oil of course.

On a practical note, whenever you switch over most engines leak out ever gasket and O ring since the lighter fuels wash out the crud stopping the bunker from leaking!

Bunker fuel can be 4% sulfur 40,000 PPM not 15 like ULSD. The normal is 2.0% New regs IMO for European waters only will require .5%.
Also most Cat III engines use heavy"Bunker" fuels. The largest ships use one slow speed 2 stroke engines turning 75-125 rpm at full speed, no reduction gear. The engine runs in reverse to back the ship.
Other smaller ship tend to use 4 stroke "medium speed engines" under 600 rpm with a reduction gear. They run in one direction and generally use controllable pitch props to reverse.

The FAA requires All planes flying into the US to follow most US laws so there is precedent for this in international trade. This happened after a Avianca Jet crashed in some movis stars house in long Island after a flight to NY Kennedy from South America.

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