A trucking company's carbon footprint goes beyond its on-road vehicle fleet to include other direct emissions, indirect emissions and the optional "life-cycle" emissions
, according to the American Transportation Research Institute.

ATRI released the findings of its analysis of greenhouse gas reporting tools and emissions models, with the goal of helping carriers quantify potential sources of greenhouse gases within their operations.

'ATRI's study also highlights the need for industry involvement in standardizing approaches for carbon accounting," said Mike Naatz, president of the customer care division and chief customer officer for YRC Worldwide. Naatz is a member of the ATRI Research Advisory Committee, which identified this research priority.

ATRI's research identified both U.S. and international reporting tools and methodologies. Among the key findings were differences in the weighting of model inputs, which in turn impact the reported level of emissions.

The report pointed out that while many carriers rely on the U.S. EPA SmartWay Partnership Truck Model to quantify greenhouse gas emissions, this model does not take into account other classifications of emissions. A fleet's emissions come not only from the combustion of fuel, but also from the use of mobile equipment used at company facilities, such as yard tractors and forklifts; stationary equipment used at company facilities, such as furnaces, generators and other on-site fuel-burning equipment; and air conditioning and/or refrigeration systems.

ATRI said that while emission factors for these fuels and refrigerants are available, the accounting tools differ slightly. The report recommends changes to these methodologies to improve their applicability to trucking.

The SmartWay measurement system also doesn't include the indirect emissions associated with electricity. The issue here is that the greenhouse gas emissions generated from electricity purchased in one part of the country can be twice as high as the same amount of electricity purchased in another part of the country.

The last classification of emissions includes those from business-related activities, such as business travel and employee commuting. Because this area is optional, there is little guidance and consensus on how to account for these emissions, ATRI said.

"The issue of carbon accounting is both technical and complex," the report said. "There are a number of areas where further guidance is needed to better quantify the greenhouse gas emissions generated by motor carriers. However, it should be recognized that precision may be sacrificed when data reporting is done at the energy consumer level, e.g. a motor carrier, as opposed to the energy producer level."