Lift Truck Series: Fuel for thought

As materials handling grows from a cost of doing business into a competitive differentiator, lift truck fleets have proven rich with savings and improvement opportunities. With productivity and uptime as the overriding goals, advancements in lift truck electronics, efficiency and ergonomics have helped reduce fleets’ burden on day-to-day operations and the bottom line.

A solutions-based approach to fleet management closely pairs each lift truck’s capabilities with an application. Over time, this precision has helped better define the roles of emerging fuel sources, whose business cases can be more clearly calculated. Absent a new facility, large expansion or other large-scale project, few lift truck users are inclined to switch fuel platforms.

But, it’s not just a question of whether to standardize around internal combustion (IC) or electric. Because each lift truck is ideally tailored to the application, the numbers might point to a mix of power types, including lithium-ion, fuel cells, compressed natural gas (CNG), or opportunity and fast-charging technologies.

To help survey the current lift truck power landscape, Modern rounded up an assortment of experts, including representatives from battery providers, equipment manufacturers and education councils. Here’s a comprehensive look at the benefits and the potential pitfalls of established and nascent power options available today.

Troublesome, or tried and true?
Electric lift trucks now account for as much as 65% of the lift truck market after having spent the last decade capturing share from IC equipment. Mark Faiman, product manager of IC, AWP and GSE products for Toyota Material Handling USA, says about 2,000, 80-volt electric/pneumatic units are now sold each year.

“For capacities up to 10,000 to 12,000 pounds, 80-volt electrics are a realistic consideration for an IC alternative,” Faiman says. “It’s still a pretty small market, but it has been growing over the past six years.”

Sustainability goals have also driven some organizations to evaluate electric as a potentially “greener” power source. “Many electric lift trucks now feature regenerative braking, fewer serviceable parts, and a better balance between the battery, the application, and energy consumption and performance similar to IC equipment,” says Mick McCormick, vice president of warehouse solutions for Yale Materials Handling Corp. “However, one of the central benefits of IC equipment is its ability to offer peak performance as long as there is fuel in the tank. If there isn’t, productivity is just a tank swap away. Batteries, on the other hand, require more precision to optimize.”

“If you don’t have good operator training and good discipline for battery maintenance, the whole ROI calculation turns nasty real fast,” says Wayne Seaman, director of product development for UniCarriers. “Watering the battery and allowing for ample cool down after charging is the responsibility of the battery changer or technician. However, operator discipline needs to be enforced to prevent operators from continuing to use the equipment while the low battery alarm keeps beeping.”

Modern lift trucks with AC motors face a different version of this challenge. Unlike their DC predecessors, AC motors are not characterized by significant drops in performance toward the end of a battery’s charge. According to Steve Spaar, director of marketing for EnerSys, AC motors keep travel and lift speeds more consistent. The length of the charge, however, might shorten. Since performance comes from the combination of volt and current, he says, a decrease in voltage means the current draw has to go up proportionally.

“Even though you’re getting more work done in a shorter amount of time, the battery might not last as long through the shift,” Spaar says. “This means an operator wants to obey the low battery warning since when it dies, it will die quickly.”

One sure way to kill a battery before its time is to poorly manage it. Spaar says many fleet owners don’t right-size their fleets or battery inventory, especially those who change batteries. “A proper battery selection system is not ‘first in, first out,’ but ‘first in, first ready,’” he says. “If that practice is not in place, they’ll select the closest one, which will fail early while three other batteries are never used.”

Even if those unused batteries are better managed and utilized, they are often still not enough to meet the fleet’s needs, according to Brian Faust, general manager at Douglas Battery.

“Very rarely do we see a customer with more batteries than they need,” Faust says. “Upwards of 99% of our customers need more batteries. The battery is the second most expensive asset after the forklift, so they’re typically looking for any excuse not to buy one. However, they end up buying more batteries over time since they burn through them too quickly. It’s very shortsighted.”

Whether batteries are conventionally or opportunity charged, without enough batteries, the fleet will struggle to achieve the runtime needed. As soon as one is over- or under-charged, or improperly cooled, the fleet will lean more heavily on the remaining batteries and the problem is likely to cascade.

Burning bright
Electrics often struggle with rapid changes in business activity, McCormick says. For operations that run one shift, if disruptions suddenly double or triple equipment needs for a short time, it can be hard for electric fleets to react. They might need additional rental batteries or chargers or units, whereas IC equipment is ready to go.

Advances in IC technology are also incrementally increasing productivity, McCormick says. Manufacturers are right-sizing engines to match the available power to the application instead of “one size fits all,” where there’s often high power and fuel consumption.
“Then, there’s the other extreme of maximizing economy at the expense of productivity,” he says. “You need to balance the two. We now offer tunable engines and transmissions that can be adjusted by on-site fleet managers. This approach can save 25% on fuel consumption as compared to a ‘one size fits all’ option.”

California’s Tier 4 emissions standards have had a massive impact on IC efficiency, and it’s a particularly difficult challenge for diesel lift trucks. Electric fleet owners seeking to abandon the cost of a battery room have to decide between propane and diesel. Right now, Faiman estimates that among IC equipment with capacities below 17,500 pounds about 25% are diesel and 75% propane.

Jeremy Wishart, deputy director of business development for the Propane Education and Research Council (PERC), says the council is working with several companies to develop a propane engine suited to a traditionally diesel application. The next-generation propane engine—which could be released as early as 2017—will be more efficient and include larger sizes, from the conventional 2-liter propane engine to 8 liters or larger.

“Right now, the 2- to 4.3-liter applications with capacities of 3 to 6 tons are propane’s bread and butter,” Wishart says. “We want to expand that to get into 8- to 10-ton trucks and heavy-duty applications, since that’s where Tier 4 emissions became the law of the land this calendar year.”

In the meantime, Unicarriers’ Seaman notes a heightened awareness of the need to improve the accuracy of propane trucks’ gauges. To measure the actual fuel tank contents, some technologies read the fuel pressure from the tank to the engine, but since propane pressure is affected by temperature, readings differ on cold and hot days. Some equipment uses a dual-sensing device that checks pressure and temperature and uses embedded algorithms to calculate actual fuel levels.

Hydrogen highlights
Hydrogen fuel cell battery replacement units for electric lift trucks continue to chip away at their reputation as the technology that’s always just around the corner. Sandra Curtin, research and communications manager for the Fuel Cell and Hydrogen Energy Association, says more than 9,000 lift trucks currently use the technology at more than 60 sites globally and have logged more than 1 million refuelings.

Companies including Lowe’s, Procter & Gamble and BMW have been early proponents of fuel cell technology, Curtin says, and Walmart uses more than 2,600 hydrogen-powered lift trucks. Curtin adds that BMW’s South Carolina facility reports fuel cell units last twice as long as batteries and conserve more than 1.8 million kWh per year of electricity consumption for battery charging.
Andy Marsh, CEO at Plug Power, says the value proposition remains clear for existing facilities that have more than 50 lift trucks working more than one shift. For new construction, fleets of 30 or more are viable.

Fuel cells offer the consistent performance characteristics and refueling ease of IC, but rely on a supply of liquid hydrogen that is not yet as established as electricity and propane. On-site hydrogen generation technologies are also poised to piggyback on abundant domestic natural gas reserves.

“Natural gas prices are at historic lows, its use is becoming more widespread, and this is good news for hydrogen fuel cell users,” says Gus Block, director of marketing and corporate development for Nuvera, which was acquired by Hyster-Yale Group in late 2014.

Nuvera offers on-site hydrogen generation units, each capable of producing 50 kg of hydrogen per day from natural gas and water. The unit can be stacked to address the approximately 20% of fuel cell lift truck applications that use more than 100 kg per day. On the lower end, Block says a fleet of around 15 heavily used lift trucks could make economic use of on-site hydrogen production. A facility with such a system might also offer refuelings to public over-the-road fuel cell vehicles to further offset costs.

“Looking ahead, the groundwork is being laid to integrate fuel cells into lift trucks at the manufacturer, not just as battery replacement units,” Block says. “This could open possibilities like narrower electric lift trucks if you can redesign around the fuel cell instead of a battery compartment.”

Toyota’s Faiman says government incentives are a big factor in conversions to power alternatives like fuel cells, CNG or even electric. “If you use IC and are comfortable, then even if you’re opening a new facility it’s a pretty big hurdle to make a change,” he says. “An additional $3 million to participate in a research project could be a big incentive.”

Lithium ion and CNG
Lithium-ion (Li-ion) technologies for lift trucks have also benefited from advancements in automotive applications. In a car, Li-ion makes sense because it is lighter than conventional batteries and able to produce the same amount of energy in about a third of the weight of lead-acid technology. However, lightness is not always an advantage in materials handling equipment that relies on battery weight for balance. Still, McCormick says Li-ion “has a tremendous future” as a power source for materials handling.

“It offers shorter charge times, extended unit life, minimal maintenance, but of course higher initial costs,” McCormick says. “We see the possibilities of Li-ion growing.”

For now, Li-ion lift trucks primarily consist of smaller walkie models. The compact battery housings allow precious inches and pounds to be removed from equipment commonly used for store delivery.

Flux Power launched a Li-ion walkie battery three years ago that has since been approved by lift truck manufacturers including Toyota, Raymond and Crown. The Li-ion value proposition requires fleet owners take a long view, says Ron Dutt, CEO of Flux Power, as over a five-year period the costs are estimated to be half that of a conventional lead-acid alternative.

Li-ion batteries last for 1,000 cycles, and offer the additional advantage of compressing those cycles. A lead-acid battery requires 24 hours to discharge, charge and cool, Li-ion needs only two to six hours to charge and does not need to cool. Therefore a single Li-ion battery has no trouble serving a two-shift application, Dutt says.

Faiman also expects Li-ion will become much more marketable in the near term.

“People are figuring out how to make it work for direct battery replacements as opposed to requiring modifications to make Li-ion work,” Faiman says. “With bigger trucks, you could potentially fit two full Li-ion batteries in the compartment instead of one lead-acid battery and ballast.” 

Companies mentioned in this article
• Douglas Battery
• EnerSys
• Flux Power
• Fuel Cell and Hydrogen Energy Association (FCHEA)
• Nuvera
• Plug Power
• Propane Education and Research Council (PERC)
• Toyota Material Handling USA
• UniCarriers Americas
• Yale Materials Handling Corporation