All new engines have been certified to comply with emission standards in place at the time of certification. Retrofit technologies may be added to further reduce emissions from certified engine configurations.The most common retrofit technologies are retrofit devices for engine exhaust after-treatment. These devices are installed in the exhaust system to reduce emissions and should not impact engine or vehicle operation. Examples of retrofit devices include diesel particulate filters (DPFs) and diesel oxidation catalysts (DOCs). They are designed and evaluated to reduce emissions from certified engine configurations and should be added only to properly maintained engines.
Diesel engines are important power systems for on road and off road vehicles. These reliable, fuel-efficient, high torque engines power many of the world's heavy-duty trucks, buses, and non-road vehicles. While diesel engines have many advantages, they have the disadvantage of emitting significant amounts of particulate matter (PM) and the oxides of nitrogen (NOx) into the atmosphere. Diesel engines also emit toxic air pollutants. Health experts have concluded that pollutants emitted by diesel engines adversely affect human health and contribute to acid rain, ground-level ozone and reduced visibility. Studies have shown that exposure to diesel exhaust causes lung damage and respiratory problems and there is increasing evidence that diesel emissions may cause cancer in humans.
Companies that manufacture emission controls have responded to the challenge of reducing the air pollution from diesel engines. Through their efforts, cost-effective retrofit technologies have been developed to reduce harmful emissions. Within the various mobile source sectors, diesel retrofit technologies have demonstrated their ability to significantly reduce unwanted emissions at reasonable costs without jeopardizing vehicle performance.
An engine with a malfunctioning or damaged component should be repaired quickly to avoid additional damage to the engine, vehicle and emission control system.
Diesel engines often can be rebuilt and continue to operate in the same capacity. An engine in need of rebuilding may have low power, increased emissions and increased fuel consumption. In some cases an engine can be rebuilt to comply with cleaner emission standards.
Replacing an older engine with a new one which has been certified to cleaner emission standards is another option for some equipment and vehicles. Repowering with a new engine may extended the life of the machine, reduce fuel consumption, and significantly reduce emissions.
A variety of alternative fuels can be used in diesel engines. Some require little or no modification to the engine while others require engine conversion or replacement. Some of the alternative fuels include emulsified diesel, biodiesel, natural gas, propane and ethanol. In addition to these fuels, use of diesel fuel with lower sulfur content can help to reduce emissions.
Replacement involves retiring higher polluting equipment from service before it would otherwise be retired. Newer equipment that meets more stringent emission standards is purchased to replace the retire equipment, sometimes in conjunction with retrofit devices or alternative fuels.
While diesel engines have many advantages, they have the disadvantage of emitting significant amounts of toxic particulate matter (PM) and nitrogen oxides (NOx) into the atmosphere. Health experts have concluded that those pollutants adversely affect human health and contribute to acid rain, ground-level ozone and reduced visibility. Studies have shown that exposure to diesel exhaust causes lung damage and respiratory problems and there is increasing evidence that diesel emissions may cause cancer in humans.
The information below provides estimated emission reductions which may be used in the selection of appropriate technologies for air quality programs. It may not be used to support formal emission reduction claims for State Implementation Plans (SIPs), compliance programs, or consent decree projects.
Technology
Typical Emission Reductions (percent)
Typical Costs ($)
Diesel Oxidation Catalyst (DOC)
Diesel Particulate Filter (DPF) Active or Passive
Partial Diesel Particulate Filter (pDPF) Partial or Flow-through
Selective Catalytic Reduction (SCR) *
Closed Crankcase Ventilation (CCV) *
Exhaust Gas Recirculation (EGR) *
Lean NOx Catalyst (LNC) *
*May be combined with DOC or DPF systems to reduce PM, HC and CO emissions.
(Source: EPA)
Note: Actual emissions reductions and costs will depend on specific manufacturers, technologies and applications. EPA and the California Air Resources Board (CARB) verify the emissions performance of retrofit devices through specific testing protocols and statistical analysis.
Note: In India the cost would be lower with domestic manufacturing
EGR and Lean NOx technologies are also used for Diesel Retrofitment. Combined systems to reduce both PM and NOx simultaneously are also available. Fuel economy and CO2 emissions should not be negatively impacted by the use of a retrofit emissions control device provided the system is properly designed for the particular applications. Biofuels can affect engine-out emissions and performance; therefore, their impact should be evaluated before fitting a retrofit emissions control system on an existing vehicle.
The key technical considerations for successful Retrofit projects are matching the right technology to the vehicle or equipment, Vehicle should be well maintained before considering retrofit, Proper Professional Installation, Maintenance – vehicle/equipment and retrofit device may require frequent inspection and maintenance, On-Vehicle Monitors – provide important user feedback on performance. Further, Successful Retrofits Require a Cooperative Effort between Fleet Owners, Operators and Technology Providers
Currently the challenges for Retrofits in India Packaging constraints (Integration of Retrofit package in existing vehicle configuration), Availability of clean fuel (Un-adulterated fuel with appropriate sulfur content for better emission and PM control), Need for good preventive maintenance practices (Air filters, injectors, and turbochargers), Basic inspection and maintenance of installations and Must be mindful of not taking short-cuts to get equipment retrofitted quickly.
Recommendation of the Auto Fuel Policy 2025 related to Retrofits
Auto fuel policy 2025 report under consideration of the Govt. has stated that we should by law enforce retro-fitment of emission control devices on BS III diesel vehicles within 2 years of BS IV fuel availability.
“It is recommended, that once geography is fully converted to BS IV grade fuel, commercial vehicles are required by law to get the retro-fitting of catalytic converters and particulate filters done within a period of two years for the extension of their operating license under the Motor Vehicles rules.”
The continuation of BS III along with BS IV in India up to April 2017 will delay the implementation of BS IV particularly on commercial vehicles as most of the heavy commercial vehicles are registered in BS III areas. BS IV will expand to only 30 cities in addition to initial 13 cities by end of this year while 50 were planned up-to 2015. The entire country will go to BS IV only by April 2017.
Large number of LCVs and HCVs would have been registered as BS III. Such LCVs, and heavy vehicles, buses and trucks will also get BS IV fuel from April 2017. Several of the off highway engines designed for lower norms will also continue in use and will also get BS IV fuel without realizing any benefits to environment. Retrofits on these vehicles and engines have potential to cut on PM and NOx emissions when BS IV fuel will be available.
US EPA and CARB have established mandatory and voluntary retrofit program for most in-use Diesel powered vehicles. Both agencies conducted rigorous verification program to ensure that the devices need strict performance and durability requirements.
Over 300,000 on road and off road heavy duty engines worldwide had been retrofitted with DOC and over 250,000 on road and off road heavy duty engines with DPFs during 2000-2009.The total number of DPFs sold by MECA members in California in first six months of 2014 was 5,780, a 65% increase over the same period in 2013. CARB estimate that around 36,000 trucks would need to take steps to comply with regulation by end 2014, mostly by installing DPF retrofit.
In UK, the most polluting of vehicles are encouraged to retrospectively install technologies to reduce its emissions. The aim is to reduce the emissions of more polluting vehicles being used in a particular area by setting particular emission standards or criteria encouraging them to retrofit abatement equipment, with the aim of improving local air quality. A range of systems exist for vehicles that could abate particulate matter (PM 10) and nitrogen oxides (NOx) emissions. Where emission criteria are expressed in technology-neutral terms (i.e. a given Euro-standard must be achieved) then retrofit is most significant viable route to compliance on older vehicles.
Schemes are operating in several UK and overseas cities. London Low Emission Zone scheme from July 2008 requires that all heavy duty vehicles achieve at least a Euro III emission standard for PM10. Many operators comply with the scheme restrictions via retrofitting particulate filters.
In Europe, the first Environmental Zones regulation—which became effective on July 1, 1996 in Stockholm, Gothenburg, and Malmoe—introduced emission control requirements for diesel PM and HC. The regulation was then modified, effective January 1, 2002, by adding a NOx control option. The Environmental Zones program applied to trucks and buses powered by a diesel engine and with a gross vehicle weight of more than 3.5 metric tons. The basic requirement for entering the Environmental Zones was that all heavy-duty diesel vehicles must not be more than 8 years old. Vehicles aged between 9 and 15 years had to be retrofitted with an approved emission control device in order to receive an exemption and to be allowed to travel in Environmental Zones. All vehicles older than 15 years were banned.
Different after treatment devices and their combinations provided different extensions of the traveling period in the Zones, depending on the vehicle model year. As an example, a model year 1993 vehicle was allowed to enter the Zones until 2005 if retrofitted with a Level B system, or until 2007 if retrofitted with a Level B+C system. Special exemptions could be granted for engines meeting Euro IV or better emission standards.
Fuel economy and CO2 emissions should not be negatively impacted by the use of a retrofit emissions control device provided the system is properly designed for the particular applications."Biofuels can affect engine-out emissions and performance; therefore, their impact should be evaluated before fitting a retrofit emissions control system on an existing vehicle.
On 7th June 2013 the French Order on Retrofits was published in the Official Journal of France.
The Order defines emissions requirements for the retrofit of Euro II, III, and IV base engines up to Euro III, IV, V, or EEV levels. In addition, retrofits to Euro III and IV levels require a minimum performance of 50% on PM and/or NOx reduction. Retrofits to Euro V and EEV require also a PM reduction >90% and/or NOx reduction >70%, according to the type of retrofit device installed. These efficiencies are to be measured on the European Transient Cycle (ETC).
The Order also includes requirements on NO2 emissions. When the base engine NO2 emissions measured on the ETC exceed 0.8 g/kWh, the retrofit device should not increase this level. Otherwise, an NO2 limit of 0.8 g/kWh applies after retrofitting. Also ammonia emissions, in the case of a DeNOx retrofit, need to comply with maximum levels allowed in appropriate Euro legislation.
On 25th June 2014 the new UN Regulation concerning the approval of Retrofit Emission Control devices (REC) for heavy-duty, agricultural and forestry tractors, and non-road mobile machinery equipped with compression ignition engines was published as UN Regulation No 132.A series of amendment to this Regulation, introducing more stringent requirements on the level of emissions reduction, will be published in the next months.
A few projects have been done by few Indian agencies like ARAI, TERI and IOC in India together with ECMA members. US-EPA had also done a program in Pune. These programs have established the feasibility of retrofit devices being installed on the vehicles/engines with environmental benefits but have not been followed up for implementation on commercial scale.