going green
Make the garage fuel flexible
Metro Atlanta Regional Transit Authority is fuel flexible. Shown is the Perry CNG refueling station.
By Robert R. Adams Edited by David Hubbard [NOTE: This is a condensed overview of only a few considerations addressed in a white paper by Robert R. Adams, executive vice president, Marathon Technical Services, Heidelberg, OT, Canada, at the request of the Clean Vehicle Education Foundation, Acworth, GA. His white paper in its entirety is available at www.cleanvehicle.org/technology.] Over the past 10 years approximately 25 to 35 percent of transit and shuttle bus orders have been for CNG, LNG and hydrogen powered vehicles. One of the most significant costs in implementing gaseousfueled vehicles can be the cost to retrofit maintenance garages initially designed for diesel and gasoline vehicles. The extra cost to design and construct fuel-flexible facilities at the outset are relatively small and incremental, and give owners the freedom and flexibility to operate a fleet with varying fuel sources. Many features of a fuel-flexible facility do not repre-
18 May 2012
sent additional cost items; they are simply rather adaptations of existing equipment or systems. Marathon Technical Services offers this brief overview of the special considerations required to make bus garages safe for use with lighter-than-air, gaseous-fueled vehicles. Many of these recommendations also provide additional benefits including improved indoor air quality and enhanced personnel comfort and safety. Conversely, several transit agencies have discovered that retrofitting a facility designed as diesel-only can be extremely expensive. In more than a few cases some determined beforehand a diesel garage retrofit to be cost prohibitive. Some older systems are not acceptable for gaseous fuels, such as a conventional ventilation system. A retrofit may require the complete replacement of the system including all ventilation units and ducting, which would be both costly and disruptive to normal operations. A fuel-flexible garage offers a number of personnel safety and comfort advantages including improved air quality and heating capability.
The prudent approach for the long term for facilities expected to last up to 50 years would be to follow the example set by one large transit agency that operated two functioning CNG garages. Unsure of its future CNG strategy, this agency hedged its bets by designing and constructing its next maintenance facility with fuel-flexible heating, ventilation and electrical systems, while deferring the actual CNG station and indoor fueling component for later construction until they were needed. By keeping its fuel options open the agency paid a small premium up front that would save time and money at a later date. Another client of Marathon Technical Services recently completed a similar fuelflexible design. This agency recently took delivery on an order for hybrid buses while protecting its CNG option from a future cost prohibitive retrofit and operational delays. Marathon Technical Services strongly encourages any design consultant for a transit agency to work with someone with experience with gaseous-bus maintenance facilities to ensure that the plant and equipment are consistent with established precedents.
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