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California ARB releases technology assessment of heavy-duty hybrid and fuel cell vehicles, cargo handling equipment

19 November 2015

The California Air Resources Board (ARB) released three new draft technology and fuel assessment reports: (1) Heavy-Duty Hybrid Vehicles, (2) Medium- and Heavy-Duty Fuel Cell Electric Vehicles and (3) Mobile Cargo Handling Equipment. The reports provide an overview of the current status and the five to ten year outlook for the respective vehicle and equipment technologies, in the context of the ARB’s long-term objective to transform the on- and off-road mobile source fleet into one utilizing zero- and near-zero-emission technologies to meet the state’s air quality and climate change goals. The cargo handling equipment report makes a reference to a possible next round of more stringent, Tier 5 emission standards for nonroad engines.

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Heavy-Duty Hybrid Vehicles. The report covers heavy-duty vehicles with GVWR > 8,500 lbs, including electric hybrids and hybrids utilizing other alternative power sources such as hydraulic hybrids, flywheel-based systems or ultra-capacitors. There are about 2,500 hybrid trucks and buses on the road today in California. These are mostly electric hybrids, however, hydraulic hybrid technology is rapidly developing and is proving itself in select vocations, according to the report.

Hybrid vehicles are available in class 2b and 3 (commercial pickups and vans) mainly as gasoline hybrid electric conversions. Hybrid vehicles are also available for the larger vehicle categories (class 3 to 8) such as urban work trucks including package and linen delivery, transit and shuttle buses, refuse haulers, and beverage and food delivery. Over half the total heavy-duty hybrids on the road in California today are parcel delivery or beverage delivery trucks. The ARB anticipates that the heavier classes of vehicles that are engaging in Class 3 to 8 rural/intracity and regional delivery, including drayage trucks, can be the next group of vehicles that will be hybridized in greater number.

Hybrid technologies reduce fuel consumption from heavy-duty vehicles significantly. Fuel economy improvements for heavy-duty hybrid vehicles have been reported to range from about 10% to 50-70%, depending on the level of hybridization, hybrid architecture and duty cycles.

However, NOx emission benefits from heavy-duty hybrids are less clear, especially for heavy-duty hybrid diesel vehicles. If the hybrid system is well designed and integrated, NOx emissions from a heavy-duty hybrid vehicle can be lower compared to a conventional vehicle. However, if the hybrid system was not properly matched and integrated to the vehicle’s engine and emission aftertreatment systems, hybrid vehicles can have higher NOx emissions compared to conventional vehicles.

Heavy-duty hybrid vehicles are currently not required to be certified for criteria emissions compliance, although the engines that are used in these vehicles have to be certified, and the vehicles must be certified for on-board diagnostics (OBD) compliance and must meet warranty requirements. The ARB is working towards a mandatory certification program for heavy-duty hybrid vehicles by participating in the Phase 2 federal GHG standards rulemaking effort with the US Environmental Protection Agency (EPA). As part of this effort, ARB is recommending that the EPA include a mandatory supplemental NOx emissions check for hybrids that mirrors ARB’s existing voluntary interim certification procedures.

Fuel Cell Electric Vehicles (FCEV). The FCEV report covers the same vehicle categories, including the medium-duty (8,501-14,000 lbs GVWR) and heavy-duty (≥ 14,001 lbs GVWR) truck and bus market.

FCEVs have the capability to completely eliminate tailpipe emissions of criteria and toxic pollutants and reduce overall GHG emissions compared to a conventional fossil-fueled truck or bus. In the assessment, the ARB staff examines current fuel cell vehicle status, as well as the status of hydrogen fueling infrastructure. Overall, the assessment finds that medium- and heavy-duty FCEVs are primarily in demonstration stages, although early commercial models are available for transit buses from two manufacturers.

Recent demonstrations for FCEVs include transit buses, shuttle buses, delivery vehicles, refuse trucks and drayage trucks. Fuel cells have also successfully penetrated the forklift category, and the lessons learned there should be transferrable to the on-road market. Overall, fuel cells are a promising approach to enable zero and near-zero emissions from the heaviest vehicle classes, including line haul trucks. Based on this assessment, ARB believes that fuel cell technology will assist California in reaching its climate change, air quality, and petroleum dependence reduction goals.

Mobile Cargo Handling Equipment (CHE). Mobile CHE is any mobile equipment used at ports, rail yards, and warehouse distribution centers to handle freight and perform other on-site activities. Equipment that handles cargo containers includes yard trucks, top handlers, side handlers, reach stackers, forklifts, and gantry cranes. Equipment that is used to handle bulk material includes dozers, excavators, and loaders. Forklifts can be used in either container or bulk handling operations, and are the primary type of CHE used at warehouse distribution centers.

CHE at California ports and rail yards already employs the cleanest diesel-fueled technology available, due to compliance with the CHE Regulation adopted in 2005, which requires best available control technology (BACT) for both new and existing diesel-fueled CHE at California ports and intermodal rail yards.

The main challenges to reducing emissions for CHE are assuring adequate investment recovery time associated with actions taken to comply with current CHE regulation—notes the report—and the availability of cost-effective next generation technologies. An additional challenge is adequately demonstrating that alternative technology will provide the same durability, reliability, and quick shift to shift turn around that diesel-fueled equipment has provided. The report provides an assessment of a variety of technologies for further CHE emission reductions including:

The lower emission, Tier 5 off-road diesel engine technology would meet more stringent emissions standards than the current US EPA Tier 4 nonroad engine standards—notes the report, making an early reference to the next round of more stringent nonroad emission standards in the United States. The Tier 5 nonroad engines would adopt the low-NOx heavy-duty truck engine technology, currently under development under an ARB/SwRI demonstration program (a progress update on the program was recently presented at the Integer conference in Chicago). A NOx emission standard of 0.02 g/bhp-hr is the current target of the ARB/SwRI joint effort. The ARB anticipates that the transfer of technology to nonroad engines could follow within three to five years after being adopted for on-road applications.

Source: California ARB