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Emission Reduction Strategies by Application

Construction Equipment
Dockside and Cargo Handling Equipment
Marine Vessels
Rail/Locomotives
Trucks
EPA Verified Technology List

Construction

View National Clean Diesel Construction Page

Retrofit Reduction Strategy	Description	Pollutants Reduced	Additional Information
Diesel particulate filters (DPFs)	Diesel particulate filters (DPFs) are honeycomb or mesh devices placed within the exhaust stream that physically trap and oxidize PM.	HC, CO, PM (85% or more reduction)	DPFs must be paired with ultra low sulfur fuels. DPFs use either passive or active regeneration systems to oxidize the PM in the filters. Passive filters require higher operating temperatures to work properly. Filters require some maintenance. Costs can range from $5,000-$8,000 per unit on highway equipment.
Diesel Oxidation Catalysts (DOCs)	DOCs are devices that oxidize pollutants in the exhaust stream and can be packaged with mufflers.	PM (10-50%), HC (50% or more) and CO	DOCs have an established record in the highway sector and are gaining in nonroad applications. Sulfur in fuel can impede the effectiveness of DOCs; therefore, the devices require fuels with sulfur levels of 500ppm or lower. DOCs can be coupled with closed crankcase filtration technologies (see below). In highway applications, DOC costs typically range from $1,000-$4,000 per vehicle and require no continual maintenance.
Closed Crankcase Ventilation (CCV)	In many diesel engines, crankcase emissions-or "blow-by"-- are released directly from the engine through the "road draft tube." Closed Crankcase Ventilation (CCV) devices provide a cleaner engine environment by capturing and returning oil in blow-by gasses to the crankcase. CCV devices direct NOx, HC and toxics to the intake system for re-combustion instead of polluting the environment. PM is collected in a filter and removed from the crankcase vapors.	PM reductions of about 10%, depending on a number of factors. The emissions reductions will be increased if paired with a DOC.	CCV devices have the following benefits: Improved vehicle/equipment reliability and maintenance Keeps engine compartment and components clean Reduces oil usage and operating costs CCV devices may be used on newer equipment as a way to meet upcoming engine emissions standards. EPA's 2007 Highway Heavy Duty Diesel rule requires that engine manufacturers consider crankcase emissions as a part of overall emissions that must be reduced.
Selective Catalytic Reduction (SCR)	Selective Catalytic Reduction (SCR) Systems inject urea (or some form of ammonia) into the exhaust stream and react over a catalyst to reduce NOx emissions.	PM (about a 25% reduction) and NOx (80% reduction)	Commonly used in stationary applications, such as power plants. CARB has verified a SCR system for certain nonroad applications. SCR systems require periodic refilling of an ammonia or urea tank. Often used in conjunction with a DOC or catalyzed DPF to reduce PM emissions.
Exhaust Gas Recirculation (EGR)	Exhaust Gas Recirculation (EGR) devices reticulate a portion of engine exhaust back into the engine to cool peak combustion temperatures and thus reduce NOx.	NOx (40-50%) , PM if paired with a DPF	EGR technology is being considered by some original equipment manufacturers as a way to meet upcoming engine emissions standards.
Replacing older diesel equipment with newer diesel equipment.	Replacing older vessels, equipment, trucks and switchers with ones that are newer and cleaner.	Typically, NOx, PM, HC, CO.	Most cost effective when uncontrolled engines are replaced such as pre-1984 trucks or pre-1996 nonroad equipment. Typically there are benefits in fuel efficiency, reliability, warranty and maintenance costs.
Replacing diesel equipment with electric, hybrid or alternative fuel equipment (LNG, CNG, propane).	Can replace diesels with those with utilizing hybrid technology or alternative fuels.	Typically, NOx, PM, HC, CO.	Examples include hybrid switcher locomotives, electric cranes, LNG or LPG yard tractors, forklifts or loaders. Natural gas replacements may require fueling infrastructure.
Low sulfur fuels: Ultra low sulfur diesel (ULSD) - 15 ppm EPA on-highway diesel - 500ppm CARB on-road diesel - 150ppm	Switching to fuels that contain lower levels of sulfur reduces PM and enhances retrofit technologies.	SO and ambient PM	Current marine fuel can have sulfur contents as high as 50,000 ppm and bunker fuel can average 27,000 ppm. Low sulfur fuels also enable many retrofit technologies such as DPFs, because sulfur will poison many catalysts (see below). EPA's LSD is mandated for non-road, C1 and C2 marine and locomotive use beginning in 2007. ULSD is required for non-road use beginning in 2010 and locomotive and marine use beginning in 2012.
Emulsified Diesel	Water and additives mixed with fuel to lower combustion temperatures. Additives prevent water from contacting engine.	NOx (9-20%), PM (16-58%)	Good for centrally fueled fleets using equipment that does not sit for more than 30 days. May affect peak horsepower in some applications. Costs approximately $0.01-0.20 more per gallon than standard diesel fuel.
Liquefied Petroleum Gas (LPG or propane)	Propane is a byproduct of natural gas processing and petroleum refining.	Can reduce NOx, CO	Propane requires a dedicated engine. LPG forklifts and loaders are common. Propane is primarily produced domestically.

Dockside

Retrofit Reduction Strategy	Description	Pollutants Reduced	Additional Information
Diesel particulate filters (DPFs)	Diesel particulate filters (DPFs) are honeycomb or mesh devices placed within the exhaust stream that physically trap and oxidize PM.	HC, CO, PM (85% or more reduction)	DPFs must be paired with ultra low sulfur fuels. DPFs use either passive or active regeneration systems to oxidize the PM in the filters. Passive filters require higher operating temperatures to work properly. Filters require some maintenance. Costs can range from $5,000-$8,000 per unit on highway equipment.
Diesel Oxidation Catalysts (DOCs)	DOCs are devices that oxidize pollutants in the exhaust stream and can be packaged with mufflers.	PM (10-50%), HC (50% or more) and CO	DOCs have an established record in the highway sector and are gaining in nonroad applications. Sulfur in fuel can impede the effectiveness of DOCs; therefore, the devices require fuels with sulfur levels of 500ppm or lower. DOCs can be coupled with closed crankcase filtration technologies (see below). In highway applications, DOC costs typically range from $1,000-$4,000 per vehicle and require no continual maintenance.
Selective Catalytic Reduction (SCR)	Selective Catalytic Reduction (SCR) Systems inject urea (or some form of ammonia) into the exhaust stream and react over a catalyst to reduce NOx emissions.	PM (about a 25% reduction) and NOx (80% reduction)	Commonly used in stationary applications, such as power plants. CARB has verified a SCR system for certain nonroad applications. SCR systems require periodic refilling of an ammonia or urea tank. Often used in conjunction with a DOC or catalyzed DPF to reduce PM emissions.
Exhaust Gas Recirculation (EGR)	Exhaust Gas Recirculation (EGR) devices reticulate a portion of engine exhaust back into the engine to cool peak combustion temperatures and thus reduce NOx.	NOx (40-50%) , PM if paired with a DPF	EGR technology is being considered by some original equipment manufacturers as a way to meet upcoming engine emissions standards.
Replacing older diesel equipment with newer diesel equipment.	Replacing older vessels, equipment, trucks and switchers with ones that are newer and cleaner.	Typically, NOx, PM, HC, CO.	Most cost effective when uncontrolled engines are replaced such as pre-1984 trucks or pre-1996 nonroad equipment. Typically there are benefits in fuel efficiency, reliability, warranty and maintenance costs.
Replacing diesel equipment with electric, hybrid or alternative fuel equipment (LNG, CNG, propane).	Can replace diesels with those with utilizing hybrid technology or alternative fuels.	Typically, NOx, PM, HC, CO.	Examples include hybrid switcher locomotives, electric cranes, LNG or LPG yard tractors, forklifts or loaders. Natural gas replacements may require fueling infrastructure.
Replacing nonroad equipment with certified highway equipment built to stricter emissions standards	Highway equipment is cleaner than nonroad equipment in comparable model years. Therefore specifying highway engines in yard trucks and applicable landside equipment reduces emissions.	Typically, NOx, PM, HC, CO.	Specifying that replacement equipment utilize highway engines, where possible can save money through fuel savings and come with additional safety features. [Dockside equipment such as yard tractors that have duty cycles similar to highway engines]
Low sulfur fuels: Ultra low sulfur diesel (ULSD) - 15 ppm EPA on-highway diesel - 500ppm CARB on-road diesel - 150ppm	Switching to fuels that contain lower levels of sulfur reduces PM and enhances retrofit technologies.	SO and ambient PM	Current marine fuel can have sulfur contents as high as 50,000 ppm and bunker fuel can average 27,000 ppm. Low sulfur fuels also enable many retrofit technologies such as DPFs, because sulfur will poison many catalysts (see below). EPA's LSD is mandated for non-road, C1 and C2 marine and locomotive use beginning in 2007. ULSD is required for non-road use beginning in 2010 and locomotive and marine use beginning in 2012.
Emulsified Diesel	Water and additives mixed with fuel to lower combustion temperatures. Additives prevent water from contacting engine.	NOx (9-20%), PM (16-58%)	Good for centrally fueled fleets using equipment that does not sit for more than 30 days. May affect peak horsepower in some applications. Costs approximately $0.01-0.20 more per gallon than standard diesel fuel.
Natural Gas	CNG consists mainly of methane (CH4) and is drawn from gas wells or in conjunction with crude oil production. LNG is compressed natural gas that is cooled to -260F degrees.	Natural gas is an inherently cleaner fuel. When paired with catalysts or filters, CNG and LNG emissions are comparable to diesels outfitted with DPFs (see below). CNG and LNG can result in increased methane emissions.	CNG and LNG require dedicated engines and a fueling infrastructure. Storage can be an issue with CNG and LNG because CNG is less dense than regular fuel and LNG requires low temperatures. Natural gas is ubiquitous in the US and can be produced domestically.
Liquefied Petroleum Gas (LPG or propane)	Propane is a byproduct of natural gas processing and petroleum refining.	Can reduce NOx, CO	Propane requires a dedicated engine. LPG forklifts and loaders are common. Propane is primarily produced domestically.

Marine Vessels

Retrofit Reduction Strategy	Description	Pollutants Reduced	Additional Information
Replacing older diesel equipment with newer diesel equipment.	Replacing older vessels, equipment, trucks and switchers with ones that are newer and cleaner.	Typically, NOx, PM, HC, CO.	Most cost effective when uncontrolled engines are replaced such as pre-1984 trucks or pre-1996 nonroad equipment. Typically there are benefits in fuel efficiency, reliability, warranty and maintenance costs.
Replacing diesel equipment with electric, hybrid or alternative fuel equipment (LNG, CNG, propane).	Can replace diesels with those with utilizing hybrid technology or alternative fuels.	Typically, NOx, PM, HC, CO.	Examples include hybrid switcher locomotives, electric cranes, LNG or LPG yard tractors, forklifts or loaders. Natural gas replacements may require fueling infrastructure.
Natural Gas	CNG consists mainly of methane (CH4) and is drawn from gas wells or in conjunction with crude oil production. LNG is compressed natural gas that is cooled to -260F degrees.	Natural gas is an inherently cleaner fuel. When paired with catalysts or filters, CNG and LNG emissions are comparable to diesels outfitted with DPFs (see below). CNG and LNG can result in increased methane emissions.	CNG and LNG require dedicated engines and a fueling infrastructure. Storage can be an issue with CNG and LNG because CNG is less dense than regular fuel and LNG requires low temperatures. Natural gas is ubiquitous in the US and can be produced domestically.
Selective Catalytic Reduction (SCR)	Selective Catalytic Reduction (SCR) Systems inject urea (or some form of ammonia) into the exhaust stream and react over a catalyst to reduce NOx emissions.	PM (about a 25% reduction) and NOx (80% reduction)	Commonly used in stationary applications, such as power plants. CARB has verified a SCR system for certain nonroad applications. SCR systems require periodic refilling of an ammonia or urea tank. Often used in conjunction with a DOC or catalyzed DPF to reduce PM emissions.
Low sulfur fuels: Ultra low sulfur diesel (ULSD) - 15 ppm EPA on-highway diesel - 500ppm CARB on-road diesel - 150ppm	Switching to fuels that contain lower levels of sulfur reduces PM and enhances retrofit technologies.	SO and ambient PM	Current marine fuel can have sulfur contents as high as 50,000 ppm and bunker fuel can average 27,000 ppm. Low sulfur fuels also enable many retrofit technologies such as DPFs, because sulfur will poison many catalysts (see below). EPA's LSD is mandated for non-road, C1 and C2 marine and locomotive use beginning in 2007. ULSD is required for non-road use beginning in 2010 and locomotive and marine use beginning in 2012.

Rail / Locomotives

Retrofit Reduction Strategy	Description	Pollutants Reduced	Additional Information
Idle Reduction	Devices that prevent operators from idling for long periods. Examples include shut-off devices and auxiliary power units which are portable, mounted systems that can provide climate control and power without idling.	NOx, PM, CO and HC	Some of these technologies pay for themselves in a short time through fuel savings. Idle reduction also can save wear and tear on engines which reduces maintenance costs. Can be especially effective for switcher locomotives.
Replacing older diesel equipment with newer diesel equipment.	Replacing older vessels, equipment, trucks and switchers with ones that are newer and cleaner.	Typically, NOx, PM, HC, CO.	Most cost effective when uncontrolled engines are replaced such as pre-1984 trucks or pre-1996 nonroad equipment. Typically there are benefits in fuel efficiency, reliability, warranty and maintenance costs.
Replacing diesel equipment with electric, hybrid or alternative fuel equipment (LNG, CNG, propane).	Can replace diesels with those with utilizing hybrid technology or alternative fuels.	Typically, NOx, PM, HC, CO.	Examples include hybrid switcher locomotives, electric cranes, LNG or LPG yard tractors, forklifts or loaders. Natural gas replacements may require fueling infrastructure.
Natural Gas	CNG consists mainly of methane (CH4) and is drawn from gas wells or in conjunction with crude oil production. LNG is compressed natural gas that is cooled to -260F degrees.	Natural gas is an inherently cleaner fuel. When paired with catalysts or filters, CNG and LNG emissions are comparable to diesels outfitted with DPFs (see below). CNG and LNG can result in increased methane emissions.	CNG and LNG require dedicated engines and a fueling infrastructure. Storage can be an issue with CNG and LNG because CNG is less dense than regular fuel and LNG requires low temperatures. Natural gas is ubiquitous in the US and can be produced domestically.
Liquefied Petroleum Gas (LPG or propane)	Propane is a byproduct of natural gas processing and petroleum refining.	Can reduce NOx, CO	Propane requires a dedicated engine. LPG forklifts and loaders are common. Propane is primarily produced domestically.

Trucks

Retrofit Reduction Strategy	Description	Pollutants Reduced	Additional Information
Diesel particulate filters (DPFs)	Diesel particulate filters (DPFs) are honeycomb or mesh devices placed within the exhaust stream that physically trap and oxidize PM.	HC, CO, PM (85% or more reduction)	DPFs must be paired with ultra low sulfur fuels. DPFs use either passive or active regeneration systems to oxidize the PM in the filters. Passive filters require higher operating temperatures to work properly. Filters require some maintenance. Costs can range from $5,000-$8,000 per unit on highway equipment.
Diesel Oxidation Catalysts (DOCs)	DOCs are devices that oxidize pollutants in the exhaust stream and can be packaged with mufflers.	PM (10-50%), HC (50% or more) and CO	DOCs have an established record in the highway sector and are gaining in nonroad applications. Sulfur in fuel can impede the effectiveness of DOCs; therefore, the devices require fuels with sulfur levels of 500ppm or lower. DOCs can be coupled with closed crankcase filtration technologies (see below). In highway applications, DOC costs typically range from $1,000-$4,000 per vehicle and require no continual maintenance.
In many diesel engines, crankcase emissions-or "blow-by"-- are released directly from the engine through the "road draft tube." Closed Crankcase Ventilation (CCV) devices provide a cleaner engine environment by capturing and returning oil in blow-by gasses to the crankcase. CCV devices direct NOx, HC and toxics to the intake system for re-combustion instead of polluting the environment. PM is collected in a filter and removed from the crankcase vapors.	PM reductions of about 10%, depending on a number of factors. The emissions reductions will be increased if paired with a DOC.	CCV devices have the following benefits: Improved vehicle/equipment reliability and maintenance Keeps engine compartment and components clean Reduces oil usage and operating costs	CCV devices may be used on newer equipment as a way to meet upcoming engine emissions standards. EPA's 2007 Highway Heavy Duty Diesel rule requires that engine manufacturers consider crankcase emissions as a part of overall emissions that must be reduced.
Lean NOx Catalyst (LNC)	Similar to a SCR system except the LNC injects diesel fuel into the exhaust stream and then catalyzes the reaction to reduce pollution.	NOx (5-40%) and PM	Verified LNCs are paired with either a DPF which requires ultra low sulfur fuel or a DOC. LNCs can increase fuel usage by 5-7%.
Idle Reduction	Devices that prevent operators from idling for long periods. Examples include shut-off devices and auxiliary power units which are portable, mounted systems that can provide climate control and power without idling.	NOx, PM, CO and HC	Some of these technologies pay for themselves in a short time through fuel savings. Idle reduction also can save wear and tear on engines which reduces maintenance costs. Can be especially effective for switcher locomotives.
Replacing older diesel equipment with newer diesel equipment.	Replacing older vessels, equipment, trucks and switchers with ones that are newer and cleaner.	Typically, NOx, PM, HC, CO.	Most cost effective when uncontrolled engines are replaced such as pre-1984 trucks or pre-1996 nonroad equipment. Typically there are benefits in fuel efficiency, reliability, warranty and maintenance costs.
Replacing diesel equipment with electric, hybrid or alternative fuel equipment (LNG, CNG, propane).	Can replace diesels with those with utilizing hybrid technology or alternative fuels.	Typically, NOx, PM, HC, CO.	Examples include hybrid switcher locomotives, electric cranes, LNG or LPG yard tractors, forklifts or loaders. Natural gas replacements may require fueling infrastructure.
Low sulfur fuels: Ultra low sulfur diesel (ULSD) - 15 ppm EPA on-highway diesel - 500ppm CARB on-road diesel - 150ppm	Switching to fuels that contain lower levels of sulfur reduces PM and enhances retrofit technologies.	SO and ambient PM	Current marine fuel can have sulfur contents as high as 50,000 ppm and bunker fuel can average 27,000 ppm. Low sulfur fuels also enable many retrofit technologies such as DPFs, because sulfur will poison many catalysts (see below). EPA's LSD is mandated for non-road, C1 and C2 marine and locomotive use beginning in 2007. ULSD is required for non-road use beginning in 2010 and locomotive and marine use beginning in 2012.
Emulsified Diesel	Water and additives mixed with fuel to lower combustion temperatures. Additives prevent water from contacting engine.	NOx (9-20%), PM (16-58%)	Good for centrally fueled fleets using equipment that does not sit for more than 30 days. May affect peak horsepower in some applications. Costs approximately $0.01-0.20 more per gallon than standard diesel fuel.
Biodiesel	Renewable fuel (meeting ASTM spec 6751) that can be manufactured from vegetable oils or animal fats.	PM, CO, HC. Can increase NOx 2-10%	Can have various blends of biodiesel. For example, B20 is 20% biodiesel and 80% diesel. B100 is not recommended for cold weather operation. B20 can cost $0.10-$0.50 more per gallon than standard diesel fuel.
Natural Gas	CNG consists mainly of methane (CH4) and is drawn from gas wells or in conjunction with crude oil production. LNG is compressed natural gas that is cooled to -260F degrees.	Natural gas is an inherently cleaner fuel. When paired with catalysts or filters, CNG and LNG emissions are comparable to diesels outfitted with DPFs (see below). CNG and LNG can result in increased methane emissions.	CNG and LNG require dedicated engines and a fueling infrastructure. Storage can be an issue with CNG and LNG because CNG is less dense than regular fuel and LNG requires low temperatures. Natural gas is ubiquitous in the US and can be produced domestically.
Liquefied Petroleum Gas (LPG or propane)	Propane is a byproduct of natural gas processing and petroleum refining.	Can reduce NOx, CO	Propane requires a dedicated engine. LPG forklifts and loaders are common. Propane is primarily produced domestically.
Closed Crankcase Ventilation (CCV)	In many diesel engines, crankcase emissions-or "blow-by"-- are released directly from the engine through the "road draft tube." Closed Crankcase Ventilation (CCV) devices provide a cleaner engine environment by capturing and returning oil in blow-by gasses to the crankcase. CCV devices direct NOx, HC and toxics to the intake system for re-combustion instead of polluting the environment. PM is collected in a filter and removed from the crankcase vapors.	PM reductions of about 10%, depending on a number of factors. The emissions reductions will be increased if paired with a DOC.	CCV devices have the following benefits: Improved vehicle/equipment reliability and maintenance Keeps engine compartment and components clean Reduces oil usage and operating costs CCV devices may be used on newer equipment as a way to meet upcoming engine emissions standards. EPA's 2007 Highway Heavy Duty Diesel rule requires that engine manufacturers consider crankcase emissions as a part of overall emissions that must be reduced.
Exhaust Gas Recirculation (EGR)	Exhaust Gas Recirculation (EGR) devices reticulate a portion of engine exhaust back into the engine to cool peak combustion temperatures and thus reduce NOx.	NOx (40-50%) , PM if paired with a DPF	EGR technology is being considered by some original equipment manufacturers as a way to meet upcoming engine emissions standards.

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