As the temperature dropped over the past several weeks, shocking Minnesotans into fall, the leaves have begun to turn from their vibrant summer green to shades of crimson, tangerine and nostalgic school-bus yellow. Thwarting nature's change of clothes, Minnesota's yellow school buses seem to be doing just the opposite — running cleaner and greener, thanks to the efforts of many Minnesota organizations.

Minnesota is fortunate to have many entities dedicated to improving air quality and reducing exposure to pollutants, including those found in diesel exhaust. The American Lung Association of Minnesota, for example, is encouraging publicly and privately owned school-bus fleets to consider using higher blends of biodiesel. ("The yellow bus goes green — and could go greener," MinnPost). Over the next several years, all of the diesel fuel in Minnesota will contain a higher percentage of biodiesel, which is a cleaner-burning diesel fuel made from natural, or renewable, sources.

Biodiesel, however, is just one of many ways to reduce the environmental impact of school-bus and other diesel fleet operations. Project Green Fleet (PGF) is a collaborative effort among business, government agencies and nonprofit organizations to improve air quality and protect health by reducing emissions from Minnesota's school buses, heavy-duty trucks and other diesel vehicles. The Minnesota Environmental Initiative, a local nonprofit organization, administers the program, which is co-chaired by the Minnesota Chamber of Commerce and Minnesota Center for Environmental Advocacy.

Retrofitting is free
Project Green Fleet implements a range of strategies to reduce emissions, including installation of pollution-control equipment, idle-reduction technologies, and replacement of older engines with new cleaner-running engines. Installation of pollution-control equipment, or retrofitting, is provided at no cost to participating fleets.

Two pieces of pollution-control equipment are installed on school buses and other diesel vehicles. This equipment includes a diesel oxidation catalyst (DOC) and a closed-crankcase filtration system (CCFS). These low-maintenance retrofit technologies are cost-effective and if combined can reduce diesel exhaust by up to 50 percent.

Project Green Fleet makes retrofitting easy for fleets. Keith Paulson, director of transportation for the Anoka-Hennepin School District, says, "Project Green Fleet allowed the Anoka-Hennepin School District to retrofit close to 200 of the privately owned school buses serving the district. Without this program, school districts could not afford to upgrade buses with pollution-control equipment. The staff makes it easy by evaluating the fleet, ordering the equipment and scheduling the installation. All you have to do is say yes and get out of the way."

Only ongoing cost: filter replacement
Funds from both public and private contributors — including Flint Hills Resources, Blue Cross Blue Shield Foundation of Minnesota, Minnesota Pollution Control Agency, U.S. Environmental Protection Agency and many others — fully fund the cost of retrofit equipment and installation. The only ongoing cost for school districts or privately owned fleets is the periodic replacement of a filter, which can range from $50 to $100 per vehicle per year. Two replacement filters are provided for free with every vehicle retrofitted with the closed crankcase filtration system.

More than 1,400 school buses and 80 heavy-duty diesel vehicles, including snowplows and dump trucks, have been retrofitted in Minnesota since 2005. What is truly remarkable about the efforts of Project Green Fleet is that Minnesota does not currently violate federal air quality standards for particulate matter or ground level ozone. No one in Minnesota is required to do any of this work.

School districts and privately owned school-bus fleets participating in emission reduction efforts through Project Green Fleet are doing so on a voluntary basis. There are an estimated 4,000 school buses in Minnesota that are eligible for retrofit technologies through the project, and funds are available now to those who wish to participate.

Emily Franklin is a project manager with the Minnesota Environmental Initiative in Minnesota. Fleet owners and operators, parents, students and others interested in having their school-bus fleet retrofitted can get started by visiting the Project Green Fleet website.