By Paul Abelson, senior technical editor
Any good competitor finds a way to beat the competition. In baseball it may be buying the lightest weight cleats for extra speed on the bases or buying the latest, greatest bat on the market. Finding an edge, any edge, may at times come down to the equipment.
And in the idling game, it’s no different. Even though key-off life has been around since the early 1970s, the technological advances are pushing the envelope and finding new advantages that will help you win the game.
This isn’t science fiction. Rather, it’s an evaluation of where current technology can take us.
Idle-reduction technology started in the 1970s. Some truckers realized that idling for driver comfort and to ensure a running engine was costing about a dollar an hour. Not only did high idle burn a gallon of diesel an hour, it contributed to wear and tear in an era when engines needed rebuilding at only 250,000 to 300,000 miles. Back then, emissions were not a consideration.
Some may remember owners putting frames on the deck to hold lightweight Chevy Vega and Ford Pinto engines. Their air conditioners cooled the cab, and their coolant warmed the big diesel. These “pony engines” gave way to the early auxiliary power units that evolved into today’s modern units.
In the past few years, the newest idle-reduction technology development has centered on electricity. The advent of absorbed glass mat batteries coupled with cost reductions and efficiency improvements in inverters (the devices that convert 12-volt direct current to 110-120 volt alternating current) have made electric APUs practical and affordable.
Early models used flooded lead-acid batteries, but unless dedicated deep-cycle, marine-type batteries were used, 12-volt systems lacked capability and endurance. Absorbed glass mat batteries have the endurance of a deep-cycle coupled with the power density of a flooded cell starting battery.
Through the use of inverters, system makers have a choice of 12-volt or household current air conditioners. Using 12-volt systems for air conditioners and refrigerators, smaller and less expensive inverters are needed for flat panel TV and other entertainment systems. As efficient as modern inverters are, they still lose 10 to 20 percent or more input amps to internal heat and inefficiency.
Diesel fuel is still the most energy-efficient source of heat, which is why most battery-based APUs are coupled with either Espar or Webasto cab heaters. The alternative is to run an inexpensive ceramic heater off the inverter. But at 1,500 watts output, the input to the inverter is 180 amps. With that load, it doesn’t take long to run down even AGM batteries, especially at freezing ambient temperature when the heat is needed.
The trade-off, if you operate in the frozen North, would be to add a few more AGM batteries to power your $100 (or less) ceramic heater – if you have the space for the batteries and can afford the weight. That can save you well over $1,000 compared to the fuel burners.
Truck stop electrification, or shorepower, may be in its infancy but is getting a significant boost from government grants that are helping to wire truck stops, rest areas and terminal yards. After some initial failures (Park ‘N View and the first IdleAire), shorepower is showing some commercial viability. It could depend in large part on how fast power providers want to recoup their investment in infrastructure and how much they charge per unit of use. Competition isn’t necessarily with the cost of idling, but with the cost and portability of alternative idle-reduction systems.
Another technology under development and getting a great deal of attention is natural gas power. The major truck stop chains have announced plans to add fueling facilities for liquefied natural gas (LNG). Within the next few years, there will be 400 or more across almost all Interstate highway routes.
But you can’t just fuel APUs with LNG any more than you can switch big diesels to natural gas without a great deal of re-engineering. Differences are in the fuel delivery and ignition systems. Compression ignition, or diesel ignition, won’t work with gas.
Cummins Westport engines are currently dominant in the market. They are spark ignited with a unique gas delivery system. Others are developing diesel pilot ignition systems, in which a small quantity of diesel is ignited by the heat of compression. The gas is then sprayed over the diesel flame, eliminating the need for spark ignition but requiring two fuel delivery systems.
Most engines builders, including Cummins, have announced natural gas engines using one or both systems. And, of course, Westport engines will still be an option. But no APU maker has announced plans for a small-bore natural gas-fueled engine.
Some small diesel manufacturers, however, have gaseous-fueled engines. Many are for propane or compressed natural gas fuel and weigh more than current diesel-fueled APU engines.
Current APU equipment will work with trucks using diesel pilot ignition. But many drivers object to refueling with both diesel and natural gas. So most of the development in alternative fuel APUs seems to involve single fuel spark-ignited engines.
What will the future of idle reduction hold? The market place will ultimately decide, and for now the contenders are clearly battery power, plug-in electricity, traditional APUs and natural gas-fueled APUs. Heavy hitters all. LL