Fueling up under pressure
Lake Jackson, Texas, has begun replacing its light-duty and heavy-duty diesel trucks with vehicles powered by compressed natural gas (CNG). The city is making the switch to alternative fuel vehicles to reduce its dependence on foreign oil and to reduce its fleet emissions.
For several years, Lake Jackson officials have been following the development of alternative fuel vehicles and their potential for improving air quality and reducing dependency on overseas energy sources. That included an investigation of a variety of alternative fuels, including biodiesel, liquid petroleum gas (LPG) and CNG with the resulting determination that CNG would best satisfy the city’s needs. “We had looked at some other fuels, but we thought compressed natural gas was the best from a clean air standpoint and from an energy independent standpoint,” Public Works Director Craig Nisbett says. “There were some that were good from an energy-independence standpoint, such as LPG, but we didn’t think it was quite as good on the clean air side.”
Four years ago, Lake Jackson started testing alternative fuel when it purchased five dedicated CNG half-ton pickup trucks to replace some aging diesel trucks. Nisbett waited to begin using the alternative fuel vehicles until CNG engines were available from the manufacturers. He chose not to convert existing diesel trucks to bi-fuel vehicles that could use both CNG and diesel because he wanted maintenance to be as simple as possible for the in-house fleet maintenance staff.
After receiving positive feedback about the CNG trucks from drivers, maintenance staff and city leaders, Nisbett began expanding the CNG fleet. As trucks needed to be replaced, the city replaced them with CNG vehicles. Currently, the city has 15 light-duty pickup trucks by Dearborn, Mich.-based Ford, two rear-loader refuse trucks for residential garbage collection by Hagerstown, Ind.-based Autocar and one roll-off refuse truck by Allentown, Pa.-based Mack Trucks for commercial garbage collection that are powered by CNG. The city even has a CNG forklift by Korea-based Daewoo. Nisbett has ordered two more CNG refuse trucks, and the Public Works Department has the funds for three more in next year’s budget.
For the light-duty trucks, the city pays approximately $4,000 more than it would for diesel trucks, and it has received some small rebates from the Department of Energy to help cover those costs for a few of them. The city pays an incremental cost of $55,000 to $60,000 for new CNG vs. new diesel heavy-duty refuse trucks. A federal Congestion Mitigation and Air Quality Improvement (CMAQ) grant covers 20 percent of the incremental cost.
Each new CNG truck emits 0.075 tons per year less nitrous oxide (NOx) than the equivalent new diesel truck. In addition to reducing emissions, the CNG refuse trucks are quieter for drivers and residents.
Lake Jackson built a CNG fueling station last summer to support the expanding fleet of CNG vehicles. The $250,000 station includes two quick-fill hoses for light-duty trucks and eight slow-fill hoses for heavy-duty trucks. The quick-fill pumps allow drivers to fill up as quickly as they would with regular diesel gasoline, and the slow-fill pumps fill the heavy-duty trucks overnight. “If you’re not going to use the vehicle at night anyhow, and it’s going to be parked on site, it’s cheaper on your station end to let it just slow fill,” Nisbett says.