The California Air Resources Board (ARB) has relaxed the requirements facing operators of off-highway vehicles with certain large-spark-ignition (LSI) engines to comply with the fleet-average emission-level (FAEL) standard.

Principally, the gasoline and liquefied petroleum gas engines power forklifts, sweeper/scrubbers, industrial tow tractors and airport ground support equipment.

The ARB relaxed the requirements in recognition of decreased economic activity and an associated decrease in emissions as well as the unavailability of retrofit kits verified to suitably clean engines with a displacement greater than three litres, says Mark Williams, air pollution specialist with ARB's zero-emission vehicle implementation section.

ARB commits to exclude greater-than-three-litre-displacement LSI engines from the LSI fleet average calculations until 16 April 2012 instead of that date in 2011. "To the extent that sufficiently clean retrofit kits are not available by that time, operators will have to achieve the FAEL standard through repower, replacement or retirement," ARB says.

Further, ARB has commited to exclude fleets comprised solely of fully OEM-controlled late model year LSI engines from the LSI-fleet-average requirements with the same one-year extension. "ARB has determined that there are still no retrofit kits for OEM-controlled engines, and this lack of availability may impact an operator's ability to comply with the FAEL standard," the agency notes.

In addition, ARB will exclude limited-hour-of-use (LHU) equipment from LSI engine fleet average requirements under certain circumstances. In December, ARB adopted a proposal to reinstitute an LHU provision, but it has not become law yet. In the interim period preceding the provision becoming law, ARB will allow operators to exclude LSI equipment used less than the LHU threshold.

The LHU threshold was 251 hours for the 2010 calendar year and is 200 hours for 2011 and subsequent calendar years.

Two key manufacturers of the retrofit kits and other engine emission-control equipment are based in the Canadian province of Ontario. The businesses are Nett Technologies Inc in Mississauga and Catalytic Solutions Inc's Engine Control Systems business unit (ECS) in Thornhill.

ARB needs to verify the emission-standard compliance of Nett or ECS systems, but these manufacturers must be the ones to determine if the potential sales market warrants the investment in research and development. In other words, ARB cannot force manufacturers to market a kit for a given engine/equipment combination.

Operators of forklift fleets can opt for equipment retrofit, replacement or retirement to meet the averages, Williams notes, but in some cases there may be less incentive to retrofit. In general, retrofits are most effective if the age and condition of the piece of equipment warrant it being retrofitted.

The age of a forklift may go beyond its usual service life and, in most cases, replacement becomes mandatory for an operator.

Nett, for instance, began a 2,500-hour durability test of a greater-than-three-litre-displacement retrofit kit in late 2009 at a plywood plant, but the down economy and lower utilization rate have resulted in the trial reaching about 1,600 hours now, according to Wayne Moffat, senior technical representative for Nett sales on the West Coast of the US and Canada.

ARB expects Nett to complete the test protocols by the end of 2011 so ARB can begin the verification process, Williams says.

As for the next steps in emission controls, "there is nothing in the future to indicate it would be worthwhile investing another CAD50,000 on testing" of retrofit kits, Moffat says.

"Engines with less-than-three-litre displacement are cleaned up," Moffat notes. Sales of Nett's ARB-verified BlueCat 300 retrofit kits for engines with less-than-three-litre displacement went on sale in 2008 with operators completing the installation process "pretty much by the end of 2010".

Sacramento-based ARB, a department of the California Environmental Protection Agency, gave notice of the changes through recent guidance documents.