Fuel-saving idle-reduction (IR) systems – technology developed for over-the-road trucks in advance of the U.S. Environmental Protection Agency’s 2010 diesel emissions standard – have found cross-functional application in the fire service.
Called alternate power units (APUs), these on-board systems provide continuous 120-volt (AC) and 12-volt (DC) power for electrical equipment and components through the use of a diesel gen-set when the chassis motor is shut down. Burning roughly 80 percent less fuel per hour than the chassis motor and using the chassis fuel as its source, an APU replaces the power generated by a truck’s engine when not in pump mode with the parking brake set.
By using an APU, concerns over toxic emissions entering the environment when trucks sit at idle with the engine running are addressed. This concept is an integral part of the government’s National Clean Diesel Campaign strategy.
Parallel to this program are measures at the state and local levels that make it illegal for diesel trucks to idle while stationary for even short periods of time. More than a dozen states and over 100 cities in the U.S. have enacted anti-idling regulations to curb diesel emissions in some fashion. Some locations also employ noise pollution ordinances to keep ambient noise to a minimum.
Though fire apparatus and other emergency vehicles are exempt from such regulatory compliance, the fire service has seen enormous growth in recent years for non-fire responses. The days when virtually all fire runs involved suppression activities are disappearing from the landscape. One recent survey reports 76.63 percent of calls for the nation’s 100 busiest fire departments in 2008 were for emergency medical services.
More often than not, fire apparatus at the scene of an emergency simply sit idle while manpower is used for the incident. This is especially prevalent at long incidents where apparatus sit in a staging area.
Rosenbauer recognized this trend and became the first American apparatus manufacturer to embrace APU technology in late 2009 with its introduction of the GreenStar idle-reduction technology system.
The functional properties of an APU on fire apparatus are quite simple. When the parking brake is activated and the pump is not engaged, a relay timer shuts down the chassis motor at a pre-programmed interval designated by the fire department while simultaneously activating the gen-set.
Once running, the APU – through a hard-wired module – produces 120-volt AC electricity, which is converted to 12-volt DC power from the gen-set, to energize critical on-board systems, including the minimum electrical load required by the National Fire Protection Association 1901 fire apparatus standard. With the APU engaged, the chassis HVAC system is equally energized to ensure a climate-controlled environment inside the cab for rehabilitation at a BTU output set by the fire department.
When operating with what can be described as a discrete “hum,” the idle-reduction system addresses noise concerns, since the chassis motor fan never has to be engaged to cool the engine while the truck is stationary. This can prove beneficial to a department’s political standing in the community, as residents whose homes are near an emergency scene in the middle of the night do not hear the noise generated by loud fire apparatus.
Because trucks are more frequently idling without the pump engaged, the APU can serve a dual-operational role, insofar as it can also be used to energize rescue tool power packs, light towers, flood lights and electric cord reels, provided the generator capacity is suitable. Should the on-board electrical system reach a point where the electrical current falls below 12.9 volts DC, the engine is programmed to restart itself without operator intervention until such time as electrical system stability is achieved.
It is no secret that fire apparatus spend a great deal of time sitting idle at emergency scenes without the pump engaged or an aerial device operating while the engine runs simply to maintain power to warning lights, batteries and other critical on-board systems. The time spent idling appears counterproductive as needless carcinogenic emissions are introduced into the environment, especially at medical calls.
Though not a direct result of fire apparatus emissions, the current buzz phrase among municipal politicians is their cities must become environmentally conscious, or “green friendly.” Due in part to what is called the Mayoral Climate Agreement advanced by the U.S. Conference of Mayors, more than 1,110 member cities have agreed to employ “green” technologies in all possible ways in their day-to-day operations.
Idle-reduction technology is one way for cities to meet their “green” commitments. The only time idle-reduction technology cannot be used on a fire apparatus is if it is flowing water and the pump is engaged.
Beyond the environmental benefits, APUs can produce dramatic cost savings for fire departments through fuel savings and reduced maintenance costs. With diesel fuel hovering near $3 per gallon, a fire department using IR technology can expect to save upwards of $2,500 per truck annually in fuel costs based on 1,500 non-fire runs where the truck idles on average for 45 minutes per call.
The greatest savings can be realized through the reduction in maintenance costs associated with cleaning the diesel particulate filter (DPF). The DPF captures unburned soot generated by the motor when the engine operates at cooler temperatures, typically at idle. An idling vehicle has a corresponding increase in unburned emissions captured in the DPF, which must be eventually serviced at a cost of $500 per interval. Should a DPF need to be replaced, that cost can reach as high as $5,000 per vehicle.
When compared against a direct-drive PTO and hydraulic generator, an APU is a relative bargain, insofar as the cost is comparable to PTO-driven generators. When you consider the multi-functional aspect of an APU, the value to including the system on your vehicle becomes obvious.
While state governments and the EPA presently fund grant programs to cover the costs of APU technology for over-the-road trucks, such programs do not exist today for fire apparatus. Efforts, however, are underway in several states to ensure availability of funds to cover IR costs for fire apparatus.
These funding initiatives may accelerate in the coming months as cities become more aware of IR technologies and local officials pressure state legislators for assistance.
As these types of systems gain acceptance in the fire service, it is expected the momentum behind being “green friendly” will take on a more pronounced role in the next update to the NFPA 1901 standard.
Editor’s Note: Sean P. Duffy, a 27-year veteran of the emergency services, including 18 years as a volunteer firefighter, is the technical committee co-chair for the Fire Apparatus Manufacturers’ Association (FAMA) and FAMA’s alternate voting member on the National Fire Protection Association (NFPA) 1901 technical committee.