Choosing the Right Low-No Type of Vehicle

  • Date: February 10, 2023

Low-emission vehicles (LEV) produce fewer emissions than the average internal combustion engine vehicle, whereas zero-emission vehicles (ZEB) produce no tailpipe emissions. Low-emission vehicles include hybrid vehicles and those powered by compressed natural gas (CNG) and propane. ZEB vehicles are electric vehicles powered by hydrogen fuel cells or batteries. LEV and ZEB projects (vehicles and infrastructure) are both eligible for funding under the FTA 5339(c) Low or No Emission Vehicle (i.e., “Low-No”) Program

Low-No Vehicle Types

Fuel Cell

A fuel cell vehicle uses hydrogen fuel cells as its power source to convert the energy produced by the reaction between hydrogen and oxygen into usable energy that powers the motor (often called an electric drive train).


Battery-electric buses (BEB) are powered by an electric motor fueled by energy stored in a battery located on the vehicle.

Conventional Hybrid

Conventional diesel-electric hybrid vehicles have a diesel engine that recharges onboard batteries through regenerative braking to power an electric motor for at least a portion of the vehicle propulsion. This type of vehicle uses less fuel than that of a conventional engine, and is therefore considered low-emission.

Compressed Natural Gas (CNG)

CNG is methane stored at high pressure and used as fuel in traditional gas-powered engines, with fuel tanks stored on the roof of the vehicle.


Propane vehicle engines operate similar to that of diesel engines but are not widely used to power heavy-duty vehicles.

Questions to ask before choosing an alternative fuel


  • What goal are you trying to achieve with deploying an alternative fuel?
  • How many miles per day do I need the bus to travel?
  • What size bus am I trying to replace?
  • How often will my bus need to be charged/fueled? At what time of day? How long will it take?
  • What is the availability of power infrastructure?
  • What type of space constraints do I have at my facility?
  • What facility upgrades will I need?
  • Do we run the HVAC system a lot on vehicles?
  • What type of climate and terrain do I operate in?
  • Is there a fuel source nearby?

Pros and Cons of Alternative Fuels

Technology Pros Cons
Conventional Hybrid
  • No infrastructure investments
  • Long driving range
  • Proven technology
  • Lower maintenance cost per mile than conventional diesel
  • Vehicle cost is often 1.33 times greater than conventional diesel
  • Moderately fewer GHG emissions than conventional diesel
Fuel Cell
  • No greenhouse gas (GHG) emissions
  • Longest ZEB driving range
  • Lighter than battery electric
  • Safer fuel source in event of fire
  • No fuel spills
  • Major infrastructure investments
  • Vehicle cost is often 2 times greater than conventional diesel
  • Highest fuel costs per mile
  • Concern over fuel availability
  • Fuel cells must be replaced at 7 years
  • Highest life cycle cost
  • Highest maintenance cost per mile
  • No GHG emissions
  • Less noise produced by motor
  • Lowest maintenance cost per mile for heavy duty vehicles
  • No fuel spills
  • Lowest ZEB vehicle cost
  • Fuel is not shipped in, or stored in on-site tanks
  • Lowest fuel cost per mile
  • Facility solar panels can aid in producing own fuel
  • Higher vehicle cost than internal combustion engines
  • Major infrastructure investments
  • Utility coordination
  • Range anxiety
  • Winter heating concerns
  • Larger parking footprint
  • Long fuelling (charging) times
  • Reliability concerns
  • Variable electric rates significantly impact costs
  • Batteries are replaced after 7 years
  • Slightly higher vehicle cost than diesel
  • Long driving range
  • Major infrastructure investments
  • Largest GHG and CAP emissions of all alternative fuels with combustible engine
  • Better suited for warmer climates
  • Pipeline constraints result in moratoriums on new hook ups
  • No maintenance cost savings compared to diesel
  • Performance does not decrease in cold climates
  • Lowest maintenance cost per mile
  • Long driving range
  • Lowest fuelling infrastructure cost
  • Facility upgrades needed
  • Not available in heavy duty vehicles
  • GHG are comparable to conventional diesel


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U.S. Department of Energy. “Clean Cities Alternative Fuel Report” (July 2021)

TCRP Research Report 219. “Guidebook for Deploying Zero-Emissions Transit Buses” (2021)

Connecticut Center for Advanced Technology, “Fuel Cell Electric Buses: A business Case for Clean Transportation in Connecticut” (January 2018)

Carnegie Mellon University, Scott Institute for Energy innovation. “Which Alternative Fuel Technology is Best for Transit Buses?” (January 2017)

Greater New Haven Clean Cities Coalition. “How can I compare the energy content of alternative fuels and gasoline or diesel?” (April 2017)

Tong, F. Et al. Transportation Research Part D: Transport and the Environment. “Life cycle ownership cost and environmental externality of alternative fuel options for Transit Buses” (Dec 2017)

National Renewable Energy Laboratory. “Fuel Cell Buses in U.S. Transit Fleets: Current Status 2017” (November 2017)

National Renewable Energy Laboratory. “AFLEET Tool 2020” (April 2021)

Energy for Everyone Propane. “Propane Autogas Refueling Options”. Website accessed 5/31/2022

NC Clean Energy Technology Center. “Financing Models: Propane Autogas Vehicles and Infrastructure” (June 2018)