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 to 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.
Diesel Emission Reduction Strategies
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 retired equipment, sometimes in conjunction with retrofit devices or alternative fuels.