It’s not always easy to understand the technology and situational requirements dictating the design and deployment of advanced technology on fire apparatus.

Case in point, a question the team at Pierce Manufacturing hears a lot—why does an electric fire truck still need a diesel engine?

This blog post seeks to dispel the myths and misconceptions about zero-emission electric fire trucks.

Q: Why Does an Electric Fire Truck Still Need a Diesel Engine?

The simple answer—to protect civilians, structures and communities should a fire event require prolonged emergency response support.

Fire trucks respond to all types of calls, some lasting only a few minutes and others hours or even days. The Pierce® Volterra™ electric fire truck is custom-designed to surpass the energy requirements for the average call volume and call duration for the fire station it serves on battery energy alone—but there are unforeseen events which must also be taken into consideration.

The primary reason the Pierce Volterra electric fire truck incorporates a diesel engine is to provide a failsafe for uninterrupted power. 

In emergency situations, fire trucks must operate for extended periods, perhaps in locations where recharging stations may not be readily available. Diesel engines serve as a backup power source, ensuring the fire truck can continue to operate even if the battery’s charge depletes during critical moments. This redundancy is crucial to maintain continuous operation until the emergency is fully resolved.

Even with depleted batteries, the diesel engine on the Pierce Volterra electric fire truck is designed to maintain uninterrupted, continuous operational capabilities.

Q: Does an Electric Fire Truck with a Diesel Engine Reduce Emissions?

Yes, electric fire trucks contribute to a substantial reduction in emissions over the vehicle's lifetime. But, to complicate things a little, it depends on the design structure of the electric fire truck.

• A range-extended series-electric drivetrain vehicle runs on battery power and utilizes a generator or engine as backup power and to charge the batteries. Once the batteries’ state of charge drops below a specified threshold, the range extender begins to charge the batteries while the batteries continue to power all operations.
  This type of truck will produce CO2 emissions whenever the range extender is employed and may emit higher criteria pollutants if an off-highway engine is used.

• A parallel-electric drivetrain fire apparatus, like the Pierce Volterra EV, operates in either all-electric mode or internal combustion engine mode. In other words, the fire truck operates under electric power in normal situations and uses an internal combustion engine (ICE) for backup power during prolonged emergency operations.
  This type of electric fire truck can operate 100% emission-free most of the time while retaining full operational capability under all circumstances.

Pierce Volterra electric fire trucks currently in service have operated on nearly 100-percent electric power outside of testing and multiple alarm fires.

To further clarify, a range-extended series-electric drivetrain fire apparatus has an ICE to recharge the batteries and manage prolonged fire events as long as the event does not exceed the range extenders rating, while a parallel-electric drivetrain fire apparatus can operate at full performance directly from the ICE to manage prolonged fire events.

Therefore, a parallel-electric drivetrain fire apparatus, like the Pierce Volterra EV, can be a zero-emission vehicle, emit no exhaust gases and contribute significantly to cleaner air and a reduction in greenhouse gas emissions.

You can learn more about the distinction between pump operations for a series-electric drivetrain vehicle versus a parallel-electric drivetrain vehicle in our blog here.

Although the presence of a diesel engine might seem contradictory on a zero-emission vehicle, its limited use ensures the overall emission levels from the electric fire truck is still far below those of traditional fire apparatus.

 In fact, one Pierce customer, the City of Madison in Wisconsin, calculated the impact an electric pumper fire truck would have on carbon dioxide emissions.

“Through reduced diesel fuel usage, the pumper is expected to eliminate over 31.8 metric tons of carbon dioxide from being emitted into the environment every year,” said City of Madison Mayor Satya Rhodes-Conway.

Q: Are Electric Fire Trucks Really Safer than Traditional Fire Apparatus?

The shift towards electric fire trucks has highlighted several safety advantages that directly benefit firefighters.  

The two key benefits are:

• Reduction in firefighter exposure to harmful emissions. Diesel exhaust, a known carcinogen, poses a substantial health risk, particularly in the confined spaces of a fire station where traditional internal combustion engine vehicles may be started frequently—up to 12-15 times daily. Starting diesel engines frequently in close quarters can lead to high levels of exposure to toxic fumes.

By transitioning to battery-powered vehicles, fire departments can drastically reduce diesel exhaust, providing a cleaner, healthier work environment for their crews.

• Lower noise levels compared to traditional ICE vehicles. The quieter operation of electric trucks offers significant operational benefits. Lower engine noise enhances communication among crew members during an emergency response and while operating equipment. Effective communication is crucial in emergency situations—it reduces misunderstandings and improves the coordination of firefighting teams, which can directly enhance the safety and efficiency of response efforts.

Reduced noise on scene means firefighters can communicate more effectively, which enhances firefighter and civilian safety.

Electric fire trucks offer substantial safety advantages over traditional fire apparatus by reducing exposure to harmful emissions and enhancing on-scene communication. These benefits contribute to a healthier work environment and safer, more effective emergency response operations, making electric fire trucks a compelling choice for modern fire services.

For departments considering the adoption of electric fire trucks, understanding the balance between electric efficiency and the reliability of traditional diesel power is crucial.

To learn more about how the Pierce Volterra electric fire truck with an integrated diesel backup engine can enhance your fleet's capabilities while aligning with sustainability goals, contact a Pierce dealer today. Together, we can discuss how our innovative solutions meet your specific needs and help keep your firefighters and community safe.