A demonstration of “shore power” at the National Idling Reduction Planning Conference held in May. Drivers can hook up and run appliances without idling their engines.
Although diesel engines are stuck with poor public perceptions, they will continue to dominate trucking for the foreseeable future. That’s because, by volume, diesel fuel packs more energy than any other liquid or gaseous fuel known to man.
But from an emissions standpoint, the persistence of diesel isn’t really a bad thing. Today’s diesel engines are many times cleaner than those of just a few years ago. And with super-clean, ultra-low-sulfur fuel coming in 2006, and tough new emissions regulations taking effect in 2007, diesels in the near future will emit nearly zero soot, or smog-producing oxides of nitrogen (NOx).
The not-so-good news is that new, clean diesels consume more fuel than those produced prior to 2002, making trucking more dependent on expensive foreign oil. Also, oil is ultimately a non-renewable resource – it won’t be around forever. But as long as there are people, trucks will be needed to deliver the food and goods they need.
Time to start planning ahead.
Michelin uses the term “sustainable mobility” to describe the purpose of its annual Challenge Bibendum (see “Showing the green,” page 56). As it applies to trucking in the near-term, that means the industry will need to gain experience with fuels and devices that conserve resources and reduce pollution. In the long run, fuels and power sources that are renewable or inexhaustible – and clean – must be developed and made practical.
It pays to conserve
There’s little question that the biggest squanderer of fuel is idling. An idling truck gets zero miles per gallon. The Technology & Maintenance Council (TMC) has been trying to stick an accurate price tag on idling for years, and has estimated that the average heavy-duty, long-haul truck idles about 6 hours per day, mainly to heat or cool the interior, or to power onboard appliances.
If the industry-accepted average of idling fuel consumption at about a gallon an hour is even close, that could translate into nearly 2,000 gallons of fuel per truck, per year, wasted. In fact, an estimate found in the report Analysis of Technology Options to Reduce the Fuel Consumption of Idling Trucks, by the Argonne National Laboratory, puts the annual waste figure at about 838 million gallons (20 million barrels) for U.S. long-haul trucks. And this says nothing of the noise, extra wear on engines or the tons of pollutants needlessly dumped into the atmosphere by idling.
While one could argue that fuel burned idling is not totally wasted – it is, after all, providing driver comfort and convenience – there are alternative, more efficient means of performing these functions. Options available today include onboard inverters/chargers; auxiliary direct-fired gasoline; diesel or propane heaters for cab and engine heating; thermal storage units for cab heating and cooling; self-contained, onboard auxiliary power units (APUs); and electrical power supplied at truck stops.
However, onboard devices are not universally embraced by fleet operators, who cite initial cost, weight and maintenance as deterrents to their use. For example, “APUs do it all. But the maintenance interval isn’t the same [as for trucks], and with the additional maintenance, they don’t cost-justify,” notes Michael Beauchamp, manager, tractor engineering, Schneider National. These issues were discussed at the National Idling Reduction Planning Conference held in May. The meeting was sponsored by the Department of Energy, the New York State Energy Research and Development Authority, the Environmental Protection Agency and the U.S. Department of Transportation.
A regulatory question raised is just how much the government can and should do to help truckers finance idling reduction equipment, which can cost thousands of dollars. Actions could include exempting the cost of APUs or other anti-idling equipment from the Federal Excise Tax or, with such devices weighing as much as 400 pounds, exempting users from the 80,000-pound gross combination weight limit. Clearly, some kind of government involvement will be needed to make these devices more popular.
Truck stop electrification or “shore power” appears to be gaining acceptance, as more facilities provide it. But, “You can’t just supply power, you need heat and air conditioning,” insists Tom Badgett, chief information officer, IdleAire Technologies. IdleAire’s system, already installed at many Petro Stopping Centers, allows drivers to access electrical power, heat and air, and communications and entertainment services in their cabs, without idling their engines during federally mandated daily rest breaks. The charge is $1.25 per hour.
Stop & go
Another opportunity to avoid wasteful and emissions-producing idling is to stop a truck’s engine whenever it’s not being used for propulsion. General Motors already has such a system, called Flex Power, available in its Chevrolet Silverado Fleetside and GMC Sierra Wideside pickups. Flex Power automatically stops the engine when the vehicle stops, and instantaneously restarts it when the driver releases the brake or presses the accelerator pedal.
Instead of a conventional starter motor and alternator, Flex Power pickups use an electric starter/generator nestled between the engine and transmission. It provides fast starting and generates electrical current to charge the batteries. Steering assist is provided by an electrohydraulic system that works even when the engine shuts down, and the HVAC system has extra-large capacity to provide warm or cool air when the engine is off. If needed, the engine will restart to keep the cabin comfortable. The system provides a 10- to 15-percent increase in fuel economy, says GM, with an attendant reduction in emissions.
If one motor is good…
Using an electric motor to assist an internal-combustion engine has already proven cost- and emissions-effective in passenger cars like the Toyota Prius. Such a system is called a parallel hybrid, and there’s no reason it can’t be applied to trucks. In fact, Eaton Corp. has already built several parallel hybrid systems, some of which have been installed in a test group of FedEx Express delivery trucks.
The hybrid powertrain combines a diesel engine and electric motor, either or both of which can drive the wheels. A computer determines the most efficient mode, depending on operating conditions and driver demand. During light acceleration, with a fully charged battery pack, the electric motor provides propulsion. Under harder acceleration or when the battery pack is low, the diesel engine pitches in for charging and/or propulsion.
Braking is progressively regenerative; that means that, before the service brakes are activated, light braking causes road speed to be absorbed by the electric motor, which becomes a generator for recharging the drive batteries.
Two FedEx units are operating in California, and the company plans to put more of the trucks in service on the East Coast. “Right now, we’re just trying to determine their reliability,” says Sid Gooch, FedEx Express’ managing director. “So far, we’re pleased.”
The hybrid package, says Don Alles, Eaton’s director of communications, decreases particulate emissions by 90 percent, reduces NOx by 75 percent and increases fuel efficiency by 50 percent. It could be commercially available as early as next year.
Or, how about a little help from a hydraulic motor? Eaton is developing what it calls the hydraulic launch assist (HLA) system, which harnesses energy normally lost as heat during braking, and uses it to help propel a truck during acceleration. HLA consists of a hydraulic pump/motor, mounted axially in the driveline, and two accumulator/storage tanks; one for high-pressure fluid and one for low.
When an HLA-equipped vehicle is braked, the pump/motor becomes a driveshaft-powered pump, forcing low-pressure fluid into a high-pressure accumulator. Since this process absorbs energy, it slows the vehicle, and is a form of regenerative braking, since the pressure is later used.
Upon acceleration, a valve directs high-pressure fluid to the pump/motor, which goes into motor mode, and adds energy to the driveshaft. This helps the vehicle accelerate more quickly, while increasing fuel economy by 25 percent to 35 percent in stop-go driving, and reducing exhaust emissions by a like amount in light trucks, says Alles. In heavier vehicles, when driving cycles involve frequent starts and stops, the percentages are estimated to be higher. HLA should be available within the next two to three years.
Putting ‘bio’ in diesel
One way to extend existing supplies of diesel fuel while curbing emissions is by blending it with refined organic oils, soy oil being the most common. Usually, the blending is done by a fuel distributor and the “biodiesel” is delivered to centrally fueled fleets, but “biodiesel is starting to appear at pumps in certain areas,” according to Gary Haer, sales manager, West Central Soy.
Biodiesel can contain anywhere from 2 percent to 100 percent organic oil. A concentration of 20 percent or “B20” produces a 25 percent reduction in all emissions except NOx, says Haer. Moreover, it has superior lubricity for engine protection, improves diesel’s cetane rating (similar to octane in gasoline) and has better detergency for engine cleanliness.
B20 costs 15 cents to 20 cents a gallon more than straight diesel, but tax incentives can make that a wash. In Illinois, for example, “if you’re running at least a 10 percent mix, you don’t pay sales tax on the fuel,” says Haer.
Trucking can be a gas
Natural gas and liquefied petroleum (LP – mostly propane) gas have long been used as motor fuels, mainly by utility and municipal fleets, which have ready access to the stuff, and whose vehicles typically come “home” every night for refueling. Of the two gases, LP relies on petroleum for production so, while it burns extremely cleanly, it can’t free the U.S. of dependence on fossil fuel. Natural gas, which is mostly methane, burns just as cleanly, and can be generated by the decomposition of organic matter. It’s considered indefinitely renewable.
As a vehicle fuel, natural gas can be either compressed (CNG) or liquefied (LNG). While CNG is compressed like the air in a scuba tank, LNG is stored at a cool -260 degrees Fahrenheit, in super-insulated tanks that resemble large Thermos bottles.
Since LNG must be vaporized prior to combustion, the only real difference between LNG and CNG systems is in the fuel delivery hardware. There’s no such thing as an LNG or a CNG engine. By the time the fuel gets burned, it’s simply natural gas – the engine doesn’t know the difference. In either case, the fuel mixes with air at the throttle body and is ignited by a spark plug at each cylinder (diesel engine conversions require the addition of a spark ignition system).
As manager of vehicle maintenance for the U.S. Postal Service in Oklahoma, Lew Flowers operates about 200 CNG light-duty trucks. “The only problem with natural gas is that you can’t find it everywhere,” he says. “We’ve had to build our own infrastructure, and it’s been expensive.” Operationally, “We don’t see a lot of trouble with the vehicles,” he adds. “But we’ve found that they run best with top-shelf ignition systems.”
LNG has the advantage of much higher density and, therefore, much better range per volume of fuel carried. Gallon for gallon, LNG provides about 70 percent of the fuel economy of gasoline, per unit equivalent. Since CNG is far less dense than LNG, the tanks need to be larger, and there is generally more than one. Range, per volume of fuel carried, is much less.
LP and natural gas packages are offered by most truck manufacturers, and retrofit kits are widely available. There are actually some fueling stations around the country, and there are tax advantages. According to the Natural Gas Vehicle Coalition, the main U.S. federal incentive for the purchase or conversion of individual alternative-fuel vehicles is an income tax deduction of $5,000 for vehicles with gross vehicle weights of 10,000-26,000 pounds, and $50,000 for those more than 26,000 pounds and for buses capable of carrying 20 or more adults.
Cellular fuel
Electric vehicles are limited in range and not practical for many commercial applications, but the fuel cell promises to change that picture. A fuel cell is essentially a high-tech, chemical-reaction electric generator. It’s quiet and efficient, and can provide sufficient power to heat and cool truck interiors, run onboard electrical equipment and eventually power vehicles themselves. Fuel-cell-powered prototype vehicles exist now, but in the near term, fuel cells will start showing up in APU applications.
One fuel cell that’s being aggressively pursued by auto and truck makers is the hydrogen-fueled, proton-exchange membrane (PEM) type. This fuel cell, like a rechargeable battery, is an electrochemical reactor – it uses chemicals that react and produce electricity. The difference is that, while a battery contains the reacting compounds and reaction products, the fuel cell merely produces electricity. It does not store energy or reaction byproducts. When a rechargeable battery runs out of energy, the reactants must be regenerated by recharging. When a PEM fuel cell runs out of fuel, the fuel storage container can be refilled as quickly as a gasoline tank.
Freightliner and Ballard Power Systems have developed a concept fuel cell APU system. It includes one Ballard fuel cell stack and a fuel processing system that extracts hydrogen from methanol (wood alcohol). The exhaust emissions are limited to water vapor and carbon dioxide. The process generates 42 volts and up to 5 kilowatts that are used to recharge the vehicle’s batteries and the fuel cell system batteries, and to provide a power source for cab loads.
Meanwhile, Metallic Power, Carlsbad, Calif., has developed a zinc/air fuel cell which, says the company, is quickly refuelable, is non-polluting, has three times the energy-efficiency of gasoline and has seven times more energy per pound than lead/acid batteries. The system combines tiny zinc pellets with oxygen from air. This forms zinc oxide (a safe, white compound, commonly found in skin-care products) and releases large amounts of electricity. The reaction takes place in the presence of potassium hydroxide (the electrolyte found in alkaline batteries). Water, a reactant in the process, is recycled automatically within the fuel cell.
To refuel the cell, a recycling/refueling unit pumps zinc pellets and electrolyte into the fuel cell, while pumping zinc oxide out and back to the recycler – a process that “takes minutes.” The fuel cell is then ready for more use. Meanwhile, the recycling unit uses household current to recycle the zinc oxide back into fresh zinc pellets and release oxygen back into the air. Nothing added, nothing discarded, claims the company.
Metallic Power is concentrating on short-term development of APUs for telecom, marine, truck and RV markets, and is currently developing a 12-volt unit that will deliver 2,000 watts of continuous power and 4,000 watts peak power.
While trying to establish APU testing programs with truck OEMs and fleet customers, the company also has partnered with Toro on quiet lawn-maintenance equipment and with Textron to adapt fuel-cell technology to that company’s Cushman and E-Z-Go golf carts and small utility vehicles.
Metallic Power has demonstrated a fuel cell-based portable power source. In powering a lighting system, the device provided more than 1,000 watts using a single sealed, quick-change fuel cartridge containing zinc and electrolyte. With this technology, users will be able to refuel by inserting cartridges indefinitely while the system provides continuous power. The cartridges themselves can be recycled over and over with a recycling unit.
What next?
These are just some of the technologies ripe for development. For example, besides being used in a fuel cell, hydrogen, the most plentiful element on the planet, can be directly burned in an internal-combustion engine. And hybrid powerplants can be mixed with fuel cells, gaseous fuels, photovoltaic panels that turn sunlight into electrical power – almost any combination imaginable.
Choices will no doubt be made by careful assessment, based on the specialized needs of each individual fleet. Ultimately, there is no reason the dream of sustainable mobility can’t become a reality.
Showing the green
Michelin’s Challenge Bibendum showcases pro-environment technologies
Each year, Michelin stages Challenge Bibendum, an international event created to further the dialogue on energy and emissions and to showcase advanced-technology vehicles – vehicles that conserve traditional fuels, or run on alternate fuels or power sources, and produce low emissions.
Awards are given, but not as a testament to the virtues of any particular technology. The idea, according to Michelin, is not to pick one superior vehicle, but to compare current performance standards to those afforded by a variety of new technologies. For more information, visit this site.
