Deficiencies in the Brazilian PROCONVE P-7 and the case for P-8 standards
To B10 or not to B10: Reference fuel debates should not delay adoption of world-class heavy-duty vehicle emission standards in Brazil
With the publication of the final rule for China VI emission standards on June 28, 2018, Brazil has the ignominious honor of being the last major automotive market without Euro VI-equivalent emission standards in place for heavy-duty trucks and buses. The benefits of Euro VI standards are well documented, and the adoption of equivalent regulation in Brazil would significantly improve the environmental performance of new heavy-duty vehicles sold in the country, leading to better air quality and improved public health.
Brazilian regulators are now developing the next phase of their program for controlling harmful air pollutant emissions from heavy-duty vehicles, PROCONVE P-8. A proposal for P-8 standards has been developed by IBAMA, the agency under Brazil’s Ministry of Environment responsible for regulating vehicle emissions. Following a public comment period, discussions are underway to submit a revised proposal to CONAMA, the National Environment Council of Brazil.
To protect public health, it is important that P-8 standards be adopted and implemented as soon as possible, and that these standards follow, to the greatest extent possible, the Euro VI regulation. In Europe, Euro VI standards have proven very effective in controlling harmful pollutant emissions from trucks and buses, thanks to stringent emission limits and other provisions that encourage better real-world control of emissions. In order to fully realize this level of emissions control in Brazil, emission limits, certification test procedures, in-service conformity testing requirements, and other provisions patterned closely on the Euro VI standards should be adopted in the development of the P-8 phase of PROCONVE.
One point that has been raised for discussion in response to the initial P-8 proposal relates to the specifications for diesel fuel used during certification testing, in particular the biodiesel content of this reference fuel. Specifications for reference fuels in Brazil are set by the Agência Nacional do Petróleo, Gás Natural e Biocombustíveis (ANP), and currently do not include requirements for biodiesel blending in reference diesel fuels. This does not match requirements for commercial diesel fuels sold in the country, which now call for 10% biodiesel blending (B10). Furthermore, the current reference diesel specifications do not match those included in the Euro VI standards, which call for 7% biodiesel blending (B7).
There are now open questions related to the timing of the introduction of new reference fuel specifications by ANP and the biodiesel content requirement which will be adopted in the new diesel fuel specification. Discussions over biodiesel content concern whether B10 will be selected to match commercial diesel fuel sold in Brazil or B7 to match reference fuel specifications included in the Euro VI standard. Ideally, reference fuel specifications should match those of commercial fuels. However, current Brazilian law requires 3 years to specify a new reference fuel to be used for certification purposes. That timeline for new specifications for reference diesel fuels, whether B7 or B10, could delay the implementation of P-8 standards.
That outcome should be avoided. Biodiesel blends at the levels being discussed here, between 0% and 10%, will have a relatively minor impact on emissions, if any. Researchers have generally found that higher biodiesel blend levels tend to decrease emissions of particulate matter, hydrocarbons, and carbon monoxide and modestly increase emissions of nitrogen oxides (NOx), relative to petroleum diesel fuels. However, these effects are fairly small at the low blend levels under consideration.
For example, recent research commissioned by the California Air Resources Board (CARB) on B5 and B10 fuels found that biodiesel blending at these levels had relatively small effects on NOx emissions. The plot below shows results from the CARB test program. In general, B5 and B10 fuels were found to increase NOx emissions, but the relative change was only on the order of a few percent, with some variability according to blend level, feedstock, and engine duty cycle.
Effect of biodiesel blend level on NOx emissions from a model year 2006 diesel engine. Each marker shows the change in emissions measured for a given biodiesel blend level relative to B0 diesel fuel for a given engine duty cycle. The test engine was not equipped with aftertreatment emission control technologies which are required to meet Euro VI emission standards, such as a selective catalytic reduction system or diesel particulate filter. The use of these technologies can nearly eliminate fuel effects on emissions. Data sourced from the California Air Resources Board.
These tests were carried out on an engine that was not equipped with the aftertreatment control technologies which are needed to meet Euro VI emission standards, such as selective catalytic reduction systems and diesel particulate filters. The use of these advanced control technologies greatly reduces emissions from diesel engines and nearly eliminates any fuel effects on emissions.
*Similar tests and studies were conducted in Brazil to validate the use of different biodiesel blends (B10, B15, and B20), involving several ministries, ANP, IBAMA, vehicle and auto parts manufacturers, biodiesel producers, fuel distributors and academia. The results for different B10 samples showed no issues reported by the companies, and those blends were approved. In these tests, compliance with regulatory emission limits was evaluated by several manufacturers. These assessments involved not only emissions analysis but also possible effects on emission control systems, such as particulate filters. In all tests, it was concluded that B10 does not impact gaseous and soot emissions, nor the proper functioning of aftertreatment systems.
Brazilian regulators need not wait for new reference diesel specifications from ANP to implement P-8 emission standards. In light of the small effect of low-level biodiesel blends on emissions from diesel engines equipped with advanced control technologies, there is no reason why homologation of P-8 engines could not begin with current reference diesel fuel specifications. In this case, B0 reference diesel could be used for P-8 certification testing until the new reference diesel specification comes online.
In developing new reference diesel specifications, ANP will need to determine whether to set the biodiesel blend level at 7% (B7) or 10% (B10). While this may seem like a relatively minor difference, any changes to the fuel specifications included in the Euro VI regulation may provide a window for engine manufacturers to argue for weakening of provisions that make the standard effective. Because biodiesel has different chemical and physical properties than petroleum diesel fuels, biodiesel blends can affect the performance and durability of diesel engines. Engine manufacturers are generally resistant to higher level biodiesel blends. While it would make sense for Brazil to adopt B10 as the reference fuel specification in order to match commercial diesel fuel sold in the country, this should not come at the cost of watering down the P-8 regulation.
With the development of PROCONVE P-8 standards, Brazil has the opportunity to catch up with other major vehicle markets in controlling harmful air pollutant emissions from heavy-duty trucks and buses. In order to achieve the greatest benefits from this step, Brazilian regulators should strive to implement P-8 standards as soon as possible, while maintaining consistency with the Euro VI regulation. Unresolved questions about the schedule for new reference diesel specifications and biodiesel blending levels should not impede or delay these objectives.
*Updated 2018.08.03 to note that similar tests were conducted in Brazil.