Berkeley scientists see big drop from 2009 in emissions of black carbon and nitrogen oxides.
Scientists at the Lawrence Berkeley National Laboratory have measured dramatic reductions in diesel emissions from trucks, including drayage trucks moving cargo to and from the Port of Oakland.
Thomas Kirchstetter — who is a staff scientist in the Sustainable Energy Systems Group at the Berkeley Lab and is a professor in the University of California Berkeley Department of Civil and Environmental Engineering — and his collaborators performed detailed measurements of pollutants emitted by thousands of trucks both in the port and at the Caldecott Tunnel, a four-bore tunnel to the northeast of the port that leads Route 24 in and out of Oakland.
With a specially outfitted research van equipped with sophisticated monitors for several types of pollutants, scientists studied emissions levels from diesel trucks to understand and analyze the impact of new air pollution control technologies and California air pollution regulations.
Kirchstetter, Rob Harley, professor of civil and environmental engineering at UC Berkeley, and Phil Martien of the Bay Area Air Quality Management District, found the regulations are having their desired effect.
“At the Port of Oakland, we measured dramatic reductions of nitrogen oxides and black carbon PM, indicating a large degree of success, which should translate into local improvements in air quality, especially as more trucks on the road use these technologies,” said Kirchstetter.
While the U.S. Environmental Protection Agency has set emissions standards for new engines, most trucks and buses run for several decades. So the California Air Resources Board has sought to accelerate emissions reductions with aggressive new regulations in recent years. As a result, growing numbers of heavy-duty diesel trucks in California are using two control technologies — a diesel particle filter, which removes most particulate matter, and selective catalytic reduction, which targets emissions of nitrogen oxides, a precursor to ozone.
A video, which shows how pollutants such as carbon monoxide, particulate matter, carbon black particulate matter and nitrogen oxides can be measured in real time as trucks pass, can be viewed on the Berkeley Lab website.
Between 2009 and 2013, the amount of trucks at the Port of Oakland equipped with a diesel particle filter increased from 2 percent to 99 percent, and the median engine age fell from 11 years to 6 years. During the same period, the emission factor (or average emission rate) decreased by 76 percent for black carbon and by 53 percent for NOx.
The researchers monitored drayage trucks at the Port of Oakland in 2009 before a new emissions rule was implemented; in 2011, during the rule’s phase-in; and in 2013, after the rule was implemented.
The technologies come with some trade-offs that the research team is investigating. Selective catalytic reduction can cause some trucks to have increased emissions of nitrous oxide, a potent greenhouse gas. With diesel particle filters, the catalytic oxidation process leads to increased tailpipe emission of nitrogen dioxide, NO2, which is a toxic air contaminant and is involved in the formation of ozone. While these were known side effects, the research team is measuring the amounts of these increases.
The team plans to return to the Caldecott next summer and again in 2017, when nearly all heavy-duty trucks will have diesel particle filters installed. CARB’s truck and bus regulation applies to approximately 1 million trucks and buses operating statewide.
New regulations help reduce pollution at Port of Oakland
