Retrofitting School Buses
Article originally from American Chemistry magazine
In September, the Texas Commission on Environmental Quality (TCEQ) encouraged school districts across the state to participate in a program that cuts down on diesel emissions from school buses. TCEQ announced an expansion of grants to help the districts invest in emission-reduction technology.
The program is one of a growing number across the country. The U.S. Environmental Protection Agency (EPA) says American children spend three billion hours each year on school buses—and while they are the safest way for children to get to school, exposure to particulates from their diesel engine exhaust needs to be limited for health reasons.
Some 99 percent of school buses are diesel-powered. Current regulations help reduce emissions from new vehicles, but since diesel engines can last 20 to 30 years, emissions from older engines must also be addressed, which is where retrofits are needed.
Of the approximately 450,000 school buses on American roads, some 50 percent can be retrofitted with new emission control equipment. Retrofitting these vehicles can significantly reduce passengers’ and drivers’ exposure to potentially dangerous particulates.
|
|
|
A diesel particulate filter collects particulate matter in the exhaust stream of a school bus or other vehicle. The high temperature of the exhaust heats the filter’s structure and helps the particles inside break down or oxidize into less harmful components. |
BASF’s catalytic diesel particulate filters first trap the particulates, then use catalytic technology to continually burn them at normal operating exhaust temperatures. Referred to as On-filter Passive Regeneration technology, this has allowed BASF to design shorter filters for easier installation. No special maintenance or operational assistance is required.
Diesel particulate filters can be installed on both old and new buses in conjunction with the use of ultra-low-sulfur diesel (ULSD),a fuel with less sulfur content than 15 parts per million. The combination of the filter and the fuel can reduce emissions of hazardous particulates, smog-causing hydrocarbons, and poisonous carbon monoxide by 60 to 90 percent—or even slightly more.
EPA verifies retrofit devices and certifies cleaner fuels to ensure they produce their promised reductions in emissions. With such approval in the U.S. and similar scenarios in other countries, these technologies are already in use today on thousands of buses and trucks around the world, whether they are paid for publicly or privately.
The Clean Buses for Kids Program, for example, provided funds to school districts and other eligible public entities in the U.S. for purchasing and installing emission control equipment on school buses. The program’s funding offset the cost of diesel particulate filters, as well as the ULSD fuel required by the filters. Filtration system provider Donaldson has installed BASF DPX™ filters on more than 1,700 school buses throughout the country under this program.
“The retrofits have proven very cost-effective and are working well,” says Fred Schmidt, who heads Donaldson’s retrofit business in the U.S. “This experience has resulted in significant increases in funding for schools.”
With files from BASF, EPA, and Donaldson. For more information, visit www.basf.com, www.epa.gov, and www.donaldson.com.