Waste Management Inc. is adding four hydraulic hybrid garbage trucks to its Fort Worth fleet, according to the Dallas Morning News. The move is part of the Houston company's plan to test technologies to cut fuel consumption 15 percent. And cutting fuel consumption can improve Fort Worth's air quality as North Texas tries to meet federal clean air standards.

Waste Management picks up garbage and recyclables for residents in Fort Worth and a number of other North Texas cities. The diesel truck's hydraulic system can store energy used during braking and transfer the energy to accelerate the vehicle. Because garbage trucks stop so often, the hydraulic system can cut fuel use by as much as 30 percent, according to William Jackson, vice president of Peterbilt Motors Co., which made the vehicles. He said the technology also cuts emissions by 40 percent.

The trucks are prototypes that Waste Management is testing for Peterbilt, which is working to qualify for a federal program that would provide $12,000 per hydraulic hybrid truck.

In addition to hydraulic hybrids, Waste Management is considering trucks that run on natural gas and on methane produced by landfills.