Understanding the Bharat Stage (BS) Emission Standards
Bharat Stage (BS) Emission Standards are environmental regulations enacted by the Indian government to control the output of air pollutants from internal combustion engine equipment, including motorcycles.
These stages, notably BS4 and BS6, denote the severity of the regulations in terms of which pollutants and how much of these pollutants motor vehicles can emit.
BS4: An Introduction
BS4, or Bharat Stage 4, is the fourth iteration of these emission standards and was implemented across the country in April 2017.
Technical Aspects of BS4
Under BS4 norms, two-wheelers were required to have a carbon monoxide emission limit of 1.0 g/km, hydrocarbon emissions were set at 1.0 g/km, and Nitrogen Oxides were limited to 0.18 g/km.
Another critical aspect of BS4 was the onboard diagnostics (OBD) that became mandatory for all vehicles. OBD is a system that detects malfunctions or abnormalities in the vehicle and alerts the owner through warning signals on the dashboard.
Real-World Impact of BS4
Manufacturers had to make changes in their manufacturing process to meet these requirements. These alterations included modifications in engine calibration, the introduction of new technologies, and changes in hardware design, such as the installation of catalytic converters, to meet the BS4 emission norms.
Transition to BS6 from BS4
The Indian Government decided to leapfrog from BS4 to BS6, completely skipping over BS5, in an attempt to adhere to global NOx emission norms. This swift change required significant upgrades in engine technology, fuel, and overall bike design.
A Close Look at BS6
BS6 or Bharat Stage 6, currently the most stringent emission norm in India, was implemented across the country in April 2020.
Technical Aspects of BS6 Standards
The BS6 emission standards are significantly stricter than the BS4. For two-wheelers, the carbon monoxide emission limit is the same at 1.0 g/km. Still, the combined limit for hydrocarbons + nitrogen oxides has been capped at 0.50 g/km. This new limit means a reduction of over 70% in NOx emissions compared to BS4.
Moreover, BS6 standards mandate the use of OBD II (On-Board Diagnostics level II), an advancement over the OBD in BS4. This system is capable of diagnosing and reporting even more advanced issues, essentially ensuring better emission control.
Real-World Impact of BS6 Standards
The implementation of BS6 called for significant upgrades from bike manufacturers. To meet the rigid emission standards, motorcycles needed to incorporate new technologies like fuel injection, enhanced Exhaust Gas Recirculation (EGR), and advanced catalytic converters.
Many manufacturers also included technologies to enhance combustion efficiency and reduce fuel wastage. This move has meant increased manufacturing costs, making BS6 bikes slightly more expensive than their BS4 counterparts.
The Fuel Factor
One of the most important factors considered in the BS6 transformation is the fuel quality. BS6 engines require cleaner fuels, specifically petrol with substantially less sulfur content (nearly five times lower than before). The low sulfur content ensures reduced emission of sulfur oxides and also protects the more efficient but vulnerable BS6 technology components, such as advanced particulate filters.