Fuel cells: The science, study and promise of the newest player in materials handling
This cross section illustrates a proton exchange membrane, one of several fuel cell configurations and the one best suited to the materials handling industry.
How it works in the lab
Gus Block, a former fuel cell systems engineer, is the director of marketing for Nuvera Fuel Cells, a manufacturer of fuel cell systems and hydrogen generation equipment. Block says fuel cells are energy conversion devices, like standard engines, as opposed to energy storage devices like batteries. There are a few versions of the technology, says Block, but the one best suited to materials handling applications is based on a proton exchange membrane. Hydrogen provided to the anode side of the membrane combines with oxygen from the air on the cathode side. The reaction produces electricity and water vapor as exhaust.
Over time, the membrane will age, with a slight decay rate over years of use, says Block. Nuvera estimates an up to 12,000-hour or higher lifespan for its fuel cell stack. Over 10 years of service in a materials handling application, says Block, the stack may be rebuilt once or twice. The capability to remanufacture (rather than replace) stacks is a feature unique to Nuvera’s proprietary technology, he says.
Several factors must be considered when engineering a fuel cell pack to replace the battery of an electric lift truck, according to Block. In addition to an exhaust-fed humidity system, water filter and air pump, the pack must meet the minimum weight requirement specified by the truck supplier. Fuel cell packs therefore contain an appropriate amount of ballast.
Then there is the hydrogen, which is stored at 5,000 psi in fuel tanks enclosed in the power pack tray. There are a number of ways to get hydrogen on-site, says Block, each of which will impact the carbon footprint of a fuel cell operation. It can be trucked in as a liquid or gas, or can be generated on-site from an electrolyzer, or from a steam methane reformer (SMR). The scale of the need will partly determine the best option. From a carbon emissions standpoint, on-site generation from natural gas is typically the best option.
“If you’re concerned about fossil fuel, then a battery is about your worst choice, because about half of the nation’s electricity comes from coal,” says Block. “Not only is natural gas clean, it’s widely available, there are tremendous reserves, and the prices are good.”
Hydrogen supplied by on-site SMR generators will produce about 33% fewer emissions than electricity from the grid, says Block, citing a recent study by Argonne National Lab. A near zero-emissions fuel cell fleet can be achieved if renewable sources are used for the energy feedstocks.
How it works in the warehouse
Until fully integrated lift trucks are offered, hydrogen fuel cells replace the battery used by electric lift trucks. The hydrogen fuel cell remains in the lift truck and is refueled at a refueling station that can be installed at any location in a warehouse and connected to the outdoor hydrogen generation station. The freedom to position multiple refueling stations inside a facility is a key component of efficiency and productivity gains afforded by a fuel cell system. As compared to batteries, says Simon, fuel cells require less travel distance to a central battery station, they need fewer refueling events, and the time for each fueling could be cut from 18 minutes for a battery swap as little as 2 minutes to fully fill a hydrogen reserve.
Once the fuel tank is full, it will perform at a consistent power output until the hydrogen is depleted, much like an internal combustion lift truck. It will not gradually lose performance like batteries do as the charge weakens. But unlike any IC truck, a fuel cell will not release any toxic emissions.
“It really does change the game for air quality,” says Devlin. “With fuel cells, you’re greener and you’re cleaner.” Devlin goes on to suggest that although the initial outlay is significant, the maintenance and repair costs for fuel cell systems could be quite a bit less than an IC engine.
Hydrogen is sold by the kilogram, for about 8 to 12 dollars, and a kilogram will last 6 to 12 hours depending on whether you’re using a reach truck or a pallet jack, says Devlin.
Who wants fuel cells
Current fuel cell offerings are suited to aggressive, multi-shift fleets of 15 or more trucks. The infrastructure costs will be better justified in a full-building installation as opposed to a partial fleet approach, says Devlin. At this point, cost is a key obstacle to more widespread adoption of fuel cell systems, and the technology seems stuck in a Catch 22; it needs wider adoption to lower the cost, but it needs to lower the cost to stimulate adoption.
“Fuel cells have a couple of percent of the lift truck market share, and will probably never completely supplant the [battery] electric market until there are more affordable options for smaller operations,” says Devlin. “As we go forward, fuel cell solutions will be less customized and more off-the-shelf, but that could take five to seven years.”
Aside from fluctuations in electricity prices and potential improvements to the cost of hydrogen capturing, federal incentives will be key to fully realizing the potential of fuel cells.
“The government is a huge part of the equation at this point,” says Kenro Okamoto, electric product planning specialist for Toyota Material Handling. “Fuel cell infrastructure is much less attractive without those incentives.”
However, even with sufficient federal support, the future of fuel cells is unclear. Okamoto says the limitations of batteries were a key driver in the movement of fuel cell technology from the labs to the field.
“Our customers have been looking for a way around those limitations,” says Kenro. “Fuel cell technology is an answer.”
But Okamoto says it is equally likely that advances in battery technology could make fuel cells obsolete. “Who knows?” says Okamoto. “It’s kind of a wait and see situation.”
Cesar Jimenez, national product planning manager for Toyota, says the uncertainty puts companies like his in a tough place. “It’s difficult for an equipment manufacturer to make a solution for a market that hasn’t really taken off yet,” he says. “The technology is essentially in a beta test.”
Although fuel cells only make up 1% or 2% of the lift truck market, some of those customers include big players. Walmart, FedEx and Coca-Cola have begun dabbling in fuel cell lift trucks, says Jensen. Just a few years ago, there were only one or two fleets of more than 30 lift trucks that had installed hydrogen fuel cells. Now, he says, there are more than 10.
“Some of it’s just traditional,” he says. “You’ve got a paradigm and you’re not ready to shift it. But for those customers who have come off the fence, to them it’s very real and to us it’s very real.”
Fuel cell round up from ProMat
Educated customers explore reality of hydrogen fuel cell at ProMat 2011