Ozinga Ready Mix Concrete of Mokena, Ill., will have a 100% CNG-fueled fleet by 2020. Lower-cost energy options for fleets include biodiesel, electricity, natural gas (CNG or LNG) and propane (autogas).
Paul Abelson Ozinga Ready Mix Concrete of Mokena, Ill., will have a 100% CNG-fueled fleet by 2020. Lower-cost energy options for fleets include biodiesel, electricity, natural gas (CNG or LNG) and propane (autogas).

A typical concrete producer’s fleet spends much of its total operating budget on energy/fuel, so fleet managers are always looking for ways to reduce energy costs. There are really only two methods: consuming less of the energy you are currently using, or switching to a lower-cost energy source. Implementation is complex due to the nearly limitless configurations and uses.

First, most fleets have to maintain service during any conversion process. They also may have to figure out how to relocate vehicles on an emergency, short-term or permanent basis. Funding is another important consideration. Depending on how a fleet approaches energy cost reduction, it could require significant capital expenditures, one-time expense payouts, and/or ongoing supplemental maintenance and operating costs. Assuming required funding is available, the fleet manager might need to prove an acceptable return on investment (ROI) within a reasonable payback period.

Here are steps to determine the best ways to maximize fleet energy budgets:

1. Analyze Drive and Duty Cycles

Most of the processes and technologies for reducing fleet energy costs are sensitive to drive and duty cycles. While these terms are often used interchangeably, they are separate measurements of how a fleet operates. A duty cycle defines how much a vehicle is used.

  • Average speed
  • Amount of incidental idling time
  • Power export time (PTO operation, etc.)
  • Number of starts and stops per cycle
  • Longest average continuous running time per cycle.

A duty cycle defines how much a vehicle is used and looks at factors such as:

  • Length of average operating cycle
  • Number of operating cycles per period
  • Total miles driven per measurement period
  • Percentage of loaded vs. empty operation
  • Percentage of on-road vs. off-road operation.

Because the effectiveness of energy reduction technologies is generally closely related to a fleet’s drive cycles, fleet managers can utilize drive cycle data to identify technologies that could reduce their energy budgets. They can then use duty cycle data to determine if the projected savings associated with an alternative are adequate to cover the investment and provide the desired ROI. Remember, a single fleet can have multiple drive and duty cycles, so one approach to energy cost reduction might not work across the board. Also, drive and duty cycles are frequently seasonally dependent, especially in areas with harsh winter weather.

For example, a fleet may have an inner-city drive cycle with low average speeds, multiple stop/start cycles and extended periods of incidental idle time. All of these factors are compatible with use of an electric hybrid powertrain. However, a duty cycle analysis could show annual miles driven are so low that even doubling the current average fuel economy will not produce enough savings to cover the cost of buying the hybrid system. Since the drive cycle also documents an excessive amount of incidental idle time, a better (lower-cost) approach for this fleet may be to implement an idle management strategy.

2. Remember the Basics

Often the simplest and most economical approach is to simply consume less energy. The simplest techniques have been recognized for so long, they are often downplayed, but when implemented properly, they can be very effective. These include:

  • Maintain proper tire inflation
  • Reduce vehicle weight
  • Reduce rolling resistance
  • Passive idle reduction (driver coaching,reminder signs, etc.)
  • Maintain vehicles properly

Going beyond these somewhat passive approaches, fleet managers can take action to make new or existing vehicles more efficient. Since the powertrains of newer vehicles are computer-controlled, fleets can often re-map the engine performance curves and transmission shift points of their trucks to improve overall powertrain efficiency. When ordering new trucks, carefully choosing and matching components to specific drive and duty cycles can produce impressive energy reductions.