Alternative Fuels Data Center

A CNG-powered Orange County Transportation Authority bus. Source: Matthew Jude Brown, Wikimedia Commons

Introduction

A project of the US Department of Energy, the Alternative Fuels Data Center (AFDC) works to reduce transportation petroleum use in the use. Much of its information is aimed at large fleet operators, including transit operators with buses and vans. The AFDC contains a variety of resources, including interactive tools, maps, and consumption reduction strategies.

Tools

Alternative Fuel Life-Cycle Environmental and Economic Transportation (AFLEET) Tool

Developed by Argonne National Laboratory, AFLEET is an Excel-based tool that allows fleet managers (including transit operators) to estimate petroleum use, GHG emissions, and other variables related to fuel consumption. AFLEET offers three calculators that can show this data in different ways:

• Simple Payback Calculator - This option compares acquisition and operating costs of alternate-fuel vehicles compared conventional vehicles. Estimate petroleum use and emissions numbers are also included.
• Total Cost of Ownership Calculator - This tool also calculates the costs, consumption, and emissions of new and existing vehicles. However, it then evaluates the net present value of these costs over the vehicle’s entire lifecycle.
• Fleet Energy and Emissions Footprint Calculator - The last option similarly calculates fuel consumption and emissions, but looks across a fleet and factors in the varying efficiency of vehicles of different ages.

Vehicle and Infrastructure Cash-Flow Evaluation Model (VICE)

Compressed natural gas (CNG) is a popular energy source because it burns cleaner than gasoline and diesel. However, converting a fleet to CNG is a significant investment. VICE, which also runs in Excel, helps determine the return on investment of moving to CNG. The tool can be used to assess together or independently the costs and benefits of acquiring CNG vehicles and developing the infrastructure to use them.

Fuel Reduction

One section of the AFDC is dedicated to reducing fuel consumption. This is broken down into six categories: idle reduction, parts and equipment, vehicle maintenance, driving behavior, fleet rightsizing, and transportation system efficiency. The first five are particular relevant to transit operators.

• Idle reduction - Engine idling is a major source of fuel consumption. Transit vehicles in particular often spend large amounts of time idling at stops and depots.
• Parts and equipment - There are a variety of technologies on the market to make vehicles more fuel efficient, including low rolling resistance tires, aerodynamic design, and fuel-tracking devices.
• Vehicle Maintenance - Ensuring that vehicles have properly inflated tires and the correct oil and receive regular tune-ups in an easy way to maximize fuel efficiency.
• Driving Behavior - Transit drivers should already be trained thoroughly, but extra emphasis can be placed on the ways that improper shifting, accelerating, and braking can decrease fuel efficiency.
• Fleet rightsizing - Transit agencies often struggle with fleet size. Fuel efficiency is one rationale for reducing fleet size or switching to smaller, lighter vehicles.

Compressed Natural Gas

Many public transportation fleets have reduced petroleum consumption and emissions with the help of AFDC and its sponsor, the US Department of Energy’s Clean Cities program. One of the most common strategies is to move to CNG.

• Arkansas - Central Arkansas’s Rock Region Metro turned to Clean Cities when considering a move to CNG buses. They were able to determine that making the switch would be worth the investment and ended up purchasing 15 CNG buses. This will save an estimated $340,000 in fuel costs per year. The agency is looking to transition to a CNG-only fleet in the next decade.
• Colorado - The city of Fort Collins is a leader in alternative fuel adoption, using hybrid, electric, diesel, and ethanol vehicles. It is converting its entire diesel bus fleet to CNG.
• New Mexico - Santa Fe Trails Transit System uses CNG for its buses and paratransit vans. In addition to being lower-emission, this contributes to the local economy because the agency uses natural gas produced in New Mexico.