clean diesel or alternative fuel school buses. School districts nationwide are imple-
‘Houston, We’re Go W
Seventh largest school district in the nation embraces environmentally-sound practices with alt fuels, GPS and shop innovations
hile vital in helping to reduce the carbon footprint, green student transportation operations have come to mean more than just
menting a wider variety of innovations to make their complete student transporta- tion operations environmentally friendly. Tis extends to maintenance practices in the shop and how GPS is being used to control idling to increase efficiencies. With more and more school districts
“going green,” we turned to Houston In- dependent School District to learn how the seventh largest school district in the county is going about this. Houston ISD is comprised of 300
schools servicing more than 200,000 stu- dents. HISD’s transportation department navigates the greater Houston area, which encompasses 305 square miles. About 1,000 school buses operate out of four motor pools to transport 29,000 students daily. Te fleet records more than 13 mil- lion miles annually and provides more than 15,000 field trips each year in addi- tion to regular route and special needs transportation. Te district also has a large non-school bus fleet comprised of gas, diesel and hybrid vehicles that rack up 8 million miles annually. Te district uses about 1.9 million gallons of diesel and 600,000 gallons of gasoline each year.
diesel
GREEN FUEL AND EMISSIONS Last summer, all HISD school buses and light-fleet vehicles were convert-
ed to biodiesel derived from renewable sources such as soybeans. After studying the use of biodiesel,
Mark Swackhamer, senior manager of fleet operations, found that the conver- sion would be seamless to the end user and would reduce harmful emission gases by up to 5 percent while extending the life of engine parts. Biodiesel adds a lu- bricating property, which reduces wear and can extend engine life. Te change will reduce the district’s use of petroleum diesel by about 95,000 gallons in the first year alone. To help with the price of the biodiesel, HISD entered into a contract with its fuel vendor that includes wording that the price of the biodiesel will never increase higher than Ultra Low Sulfur Die- sel (ULSD) but can be lower depending on the feed stock cost. To change from ULSD to a blended
mix of ULSD and B100, all the fuel tanks were cleaned, tested and inspected. Once cleaning was completed, the tanks were then filled with the new blended mix of fuel. Tis change was performed a month before school started. Notification of the change in fuel type was not announced to the shops or drivers to prevent ghost problems from appearing. Vehicle and bus maintenance and road call records
66 School Transportation News Magazine July 2011
were closely monitored for any problems. After a few months of using biodiesel with no problems and no increase in mainte- nance repairs, the use of the new fuel type was announced. “Te use of biodiesel in our fleet has
been smooth and seamless. Also, by using biodiesel, we have been able to reduce our hydrocarbon emissions by up to 5 per- cent, carbon monoxide emissions by three percent and particulate matter, or smog, by up to 2.5 percent,” Swackhamer said. In addition to the use of biodiesel, HISD
received $2.2 million in grant funding to- ward purchasing 25 propane-powered buses and installing an 18,000-gallon fuel- ing station that will allow for the expansion of the propane fleet at that location. Te fueling station was being installed at the Barnett facility that currently houses 248 buses. By moving the school bus fleet to propane, HISD estimated it will save more than $3,000 per year per bus in both fuel and maintenance costs. Te operational cost of a propane bus is about 70 percent of a conventional diesel engine bus. Te propane-powered buses will reduce par- ticulate matter by 99.99 percent over 1989 model-year diesel buses. HISD is also adding 50 additional par-
ticulate trap filters to its current fleet of 1,002 school buses. Out of the cur- rent fleet, Swackhamer said the district has added both particulate traps and
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