Seattle CNG Fleet Analysis Highlights Fuel Advantage

| USA, Seattle WA

45 Chevy Impala hire-cabs achieve CO2 emissions reduction of approximately 28% annually, or over 500 tons, compared with similar conventional-fuel taxis.

Taking the concept of green cabs literally, new Seattle taxi company CNG for Hire has launched a fleet of green and blue coloured compressed natural gas (CNG) cabs. The first vehicles brought into service are 45 Chevy Impalas. World CNG, based in Kent, Washington, outfitted these vehicles with approximately 11 GGE (gasoline gallon equivalent) of CNG storage, providing a range of approximately 200 miles.

Sarah Roberts, Director of Environmental Business Strategy for World CNG explained to NGV Global News: “Taxi vehicles in this area cover approximately 100,000 miles per year. Given the average mileage of these vehicles and the current average regional price differential between gasoline and CNG ($3.60 – $1.89 = $1.71), each CNG for Hire vehicle stands to save approximately $10,000 per annum on fuel costs ($450,000 across the fleet).

CNG for Hire was awarded $460,000 in stimulus grants under a $300 million U. S. Department of Energy program to help commercial fleets, including taxis, convert to cleaner fuels. The conversion cost per vehicle was around $10,000.

World CNG carried out a small fleet-wide analysis for the City of Seattle shortly after CNG for Hire’s kick-off event some weeks ago. “I compared the annual CO2 emissions from the 45-vehicle CNG for Hire fleet with that of a fleet of 45 Ford Crown Victorias (the the most common conventionally fueled taxi vehicle in Seattle). The reduction in CO2 afforded by this CNG fleet is impressive,” said Roberts.

The analysis compared annual emissions of carbon dioxide (CO2) from a 45-vehicle fleet of 2009 Chevrolet Impalas operating on compressed natural gas (CNG) to a 45-vehicle fleet of 2009 Ford Crown Victorias operating on conventional gasoline, as a function of percent city driving. For both fleet scenarios, 100,000 miles driven annually is assumed. Fuel economy and emissions data were derived from U.S. Department of Energy Alternative Fuels and Advanced Vehicles Data Center and U.S. Environmental Protection Agency Office of Transportation and Air Quality sources.

Gasoline (red) and CNG (blue) clearly depict CNG advantage (Source: World CNG)

The bottom (green) line shows that over the course of one year, replacing a fleet of 45 Ford Crown Victorias operating on conventional gasoline with 45 Chevrolet Impalas running on CNG results in CO2 emissions reduction of approximately 28%, or over 500 tons.

It should be noted that in addition to producing lower emissions of the principle greenhouse gas carbon dioxide, CNG-powered vehicles produce significantly lower harmful emissions, including nitrogen oxides, particulate matter, and toxic and carcinogenic pollutants, than gasoline and diesel vehicles. “Particularly in urban environments CNG vehicles are a proven solution for meeting EPA non-attainment measures and improving local air quality,” Roberts added.

CNG for Hire vehicles do not carry fare meters; drivers are also prohibited from picking up customers trying to hail a cab on the street.

(This article primarily compiled using information supplied by World CNG)


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