The Massachusetts Port Authority Board (Massport) voted on July 15 to spend almost $35 million for a fleet of 50 new alternative fuel buses to replace Boston Logan International Airport's aging fleet of compressed natural gas (CNG) buses and the 94 diesel-powered rental car company buses that currently serve the airport.

The environmentally-friendly unified fleet is part of the $337 million consolidated rental car (CONRAC) facility which will be built in the Southwest Service Area of the airport.

The purchase includes 32 60-foot long articulated buses with diesel-electric hybrid propulsion systems which will replace the rental car buses and 18 42-foot long CNG buses which will replace the existing CNG shuttle buses, which have logged more than 13 million miles.

"This represents an important investment in building a better Logan,'' said Thomas J. Kinton Jr., Massport's CEO and executive director. "Not only will the new unified bus system improve air quality through alternative fuels, it will reduce emissions by cutting congestion and dwell times at the terminal curbs. It also represents a significant improvement in customer service, because departing passengers will be dropped off on the upper level and a separate bus loop will pick up arriving passengers on the lower level.''

Massport expects the new fleet to be in operation for at least 12 years during which time it will reduce carbon dioxide emissions by more than 1,840 tons as compared to the existing rental car company buses. The reduction is equivalent to the amount of carbon sequestered each year by 356 acres of pine forest.

As part of the procurement, Massport applied for a Federal Aviation Administration Voluntary Airport Low Emissions AIP grant to cover 75 percent of the incremental cost of purchasing alternative fuel buses. If the grant application is approved, Massport will be the first New England recipient of the VALE grant.

The new buses will be built by Anniston, Ala.-based North American Bus Industries, Inc. and have a sleeker, more aerodynamic look than the current fleet. The 60-foot long buses will have three sets of doors for easy entrance and exit and storage space for luggage.

They will transport passengers via the CONRAC to the terminals and the Blue Line Airport T station and back to the CONRAC. They may also be used during peak times to transport workers to and from the airport employee parking garage in Chelsea. The smaller buses will shuttle passengers between terminals and workers to various airport locations.