The Propane Education and Research Council (PERC) released the review, which indicated that forklifts, when fitted with approved closed loop controls and exhaust catalysts, had very low emissions that meet and exceed California Air Resource Board Large Spark Ignition (CARB LSI) standards.
The review also found propane delivers the highest energy efficiencies when compared to other fuel production life cycles.
"Eighty percent of class 4 and 5 internal combustion forklifts are fueled by propane," said Roy Willis, PERC president. "Yet the forklift market is plagued by reports that are misleading or contain conflicting data on the relative emissions benefits of various fuels. We believe this review sets the record straight. When forklift emissions data is compared accurately, propane delivers the highest efficiencies and remains one of the cleanest fuels available for industrial lift trucks."
Conducted by two independent alternative fuel vehicle (AFV) experts, the review, "Industrial Truck Emission Data Compared by Fuel," examined research findings from seven forklift emissions studies performed between 1990 and 2002. "Testing conditions are an integral part of research studies," said William McGlinchey, one of the review's authors. "Our review has found that previous research studies often did not use the same fuel delivery system and engine; elements that are crucial for accurate comparative studies."
The authors examined two studies that used a Life Cycle Analysis (LCA) emissions model to assess the emissions impact of "upstream" production of a given fuel. The model estimates upstream and total fuel cycle energy consumption, greenhouse gases, and emissions for both short-and long-term scenarios. The model describes upstream emissions as the emissions emanating from pre-consumer fuel processing from feedstock to the gas station dispenser.
The review found when propane is compared accurately to CNG or gasoline, differences in industrial truck tailpipe emissions are negligible. In addition, the review revealed the most recent substantive comparison of gasoline and propane, a 2002 study conducted by Southwest Research Institute on behalf of CARB, found that emissions results meeting CARB LSI standards for large spark-ignited industrial trucks could be obtained using propane and a properly operating control system and exhaust catalyst.
The review emphasizes the role that regular maintenance plays in fuel control system performance and emissions reduction. "Our next step is to support the training and maintenance needs of propane-powered forklift operators," said Willis. "PERC has funded programs to ensure that propane-powered forklift operators receive the support they need to comply with emissions standards and achieve greater return on their investments."