CNG fleet conversion reduces environmental impacts

For fleet managers seeking to reduce environmental impacts, making the switch to a fleet powered by compressed natural gas is worth a serious look.

The path to successfully converting and operating a CNG fleet has significant operational impacts and requires thinking differently about routing, maintenance, labor, technical assistance and training. Significant up-front investment in infrastructure is a given, as well as incremental vehicle costs and higher operational costs. But for high-fuel-consumption fleets running relatively short routes, a CNG fleet can be a smart alternative and a winning environmental move.

Ninety-six percent of the natural gas used in the United States is domestically produced. It is the cleanest-burning fossil fuel on earth — mostly made up of methane and trace amounts of a few other gases — and it can significantly reduce emissions when compared with gasoline and diesel. Emissions reductions in natural-gas vehicles depend on a number of factors, including drive cycle, engine and vehicle type, but they can offer a 13 percent to 21 percent reduction in greenhouse gases, up to 95 percent reduction in nitrogen oxides (ozone-forming pollutants) and up to 90 percent reduction in particulate matter, which is an even greater health concern than ozone, according to information from Natural Gas Vehicles for America. Cleaner fuel can mean less maintenance and longer engine life as well.

Depending on fleet size and vehicle type, startup costs, infrastructure and incremental vehicle costs can be significant and return-on-investment timeframe can vary widely as well. For all but the smallest fleets, necessary investments are likely to include private fueling stations, retrofits for maintenance-shop safety, storage tanks and fueling “trees.” Operational costs likely will increase as well due to ongoing technical training, certifications, compliance assurance, specialized tools and consulting services. Refueling is a slow process with CNG, which impacts route planning and efficiency. And because CNG fuel tanks have a shorter range than diesel, additional on-vehicle fuel tanks may be required.

For fleets with no margin for downtime, those for whom transportation is their core business, additional consideration should be made in planning for redundancy. Support services taken for granted in the diesel world, such as fuel supply, parts availability, experienced mechanics and technical expertise may not be readily available for their CNG counterparts.

There are natural-gas fleet alternatives for almost any transportation business. CNG engines operate in much the same way that conventional gasoline vehicles do using a spark-ignition, internal combustion engine. Everything from vans and shuttles to transit buses, school buses, waste-disposal trucks, semi-trucks and delivery vehicles can be fueled by CNG. The number and variety of factory-ready CNG vehicles and conversion-eligible CNG vehicles is increasing. Vehicles currently running on traditional gasoline or diesel can convert to natural gas by using qualified retrofitters. CNG conversion (or NGV conversion) kits are available for many types of vehicles, from pickup trucks to transit buses, and a number of them allow for bi-fuel operation, which can be important on long-haul routes.

Given the clear benefit to public health and the environment, programs have been put in place by policy makers to encourage and assist businesses in the switch to natural-gas vehicles. As of this writing, the state of Colorado and the federal government are offering various grants, tax credits and other incentives. However; it is unknown how long they will continue.

At Western Disposal, we log more than 1.3 million miles annually. With nearly 60 percent of our collection fleet converted to CNG thus far, we’re avoiding nearly 800 tons of CO2 annually and have virtually eliminated the nitrogen oxides and particulate matter these vehicles would have produced, keeping us on a path of environmental responsibility, a core value we share with the communities we serve.

Kevin Afflerbaugh is environmental coordinator for Western Disposal Services Inc. He can be reached at 303-448-2332 or


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