g/bhp-hr – Grams per Brake
PM – Particulate Matter
NOx – Nitrogen Oxide
NMHC – Non-Methane Hydro Carbon
When EPA 2010 standards go into effect, no heavy-duty diesel engine can be emitting levels of nitrogen oxides (NOx) higher than .2 g/bhp-hr (grams per brake horsepower-hour), a standard more stringent than any place in Europe.
Specific to heavy-duty commercial vehicles, the new regulations introduce very stringent emission standards, as follows:
The PM emissions standard took full effect in the 2007 heavy-duty engine model year. The NOx and NMHC standards will be phased in for diesel engines between 2007 and 2010.
For more information on EPA emissions standards, click here.
Emissions Reduction History
Progress on emissions controls have been encouraged by more than a decade of policy and oversight by the Environmental Protection Agency (EPA). Over the years, these emissions control mandates have brought vehicle emissions to near-zero levels. While the mandates were spaced out to provide time for the development and commercialization of emissions control improvements, they have created unique and complex challenges to communications, research and development cycle and purchase planning.
To encourage early adoption of the technologies by customers, particularly in the Class 8 heavy duty industry, and to offset some of the research and development strain, emissions control oversight agencies developed a family credit system whereby companies could earn credits based on sales of vehicles in their product portfolios that produce less than mandated emissions. These credits can be used to offset the company’s sale of higher emissions emitting vehicles for a period of time prior to the company’s development and delivery of technologies that would meet the emissions criteria.
At this time, it could be argued that using those credits meets the letter of the law but not the spirit of the law. Additionally, it is foreseeable that when nitrogen oxides (NOx) emissions credits run out, and barring any revolutionary combustion and/or alternate NOx emissions control technology breakthroughs, SCR remains the only long-term viable solution. For this reason, the leading truck and engine manufacturers in the Class 8 heavy duty trucking industry, representing more than 80 percent of the new trucks and engines to be sold, have chosen SCR as their emissions technology of choice for meeting EPA 2010 standards.