City staff projections for the city fleet were right on target. Growth has come from outside the city through private sales to individuals with CNG vehicles as well as to commercial fleets.
“The message there is we’re seeing a growth in the CNG fleet out there,” O’Leary said.
The city owns 35 CNG vehicles and continues to add those vehicles whenever it can, but staff measures the costs versus benefits in each case. On Tuesday night, the Norman City Council members approved the purchase of a CNG trash truck to replace a damaged truck.
“Trash trucks are a fast payback on the additional cost for the CNG,” O’Leary said. “Every vehicle that is CNG costs more. That difference is coming down. We’re seeing a gradual decrease, but they’re still higher than conventional vehicles.”
The city must justify the additional cost of purchasing CNG vehicles and look at the long-term payoff.
“Trash trucks get about three miles to the gallon,” O’Leary said. “You can do the math pretty quickly there. A trash truck with our kind of mileage and our kind of price will pay for itself in two to three years, and we get seven to 10 years out of an average trash truck. It doesn’t take long to figure out that’s a sound investment.”
But money saved isn’t the only advantage. Vehicles fueled by CNG have less polluting emissions and create much less noise than diesel vehicles. O’Leary said the city has had a “very positive maintenance experience” with CNG vehicles.
“The CNG is such a clean-running fuel, we’re finding we can extend oil changes by several thousand miles,” O’Leary said. “There’s noise reduction of about 90 percent from a diesel vehicle to a CNG.”
That $1.36 charged to the public is higher than the city cost for fuel, in part because the city doesn’t have to pay state and federal fuel taxes on their product.