Green fleet options are conventional vehicles with high miles per gallon (mpg) ratings, hybrid electric vehicles (HEVs), diesel vehicles that run on a significant portion of biodiesel, flexible fuel vehicles (FFVs) that run on ethanol (E85) a significant portion of the time, natural gas vehicles (NGVs) or electric vehicles (EVs).  Brief descriptions of each type of vehicle, with pro’s and con’s, are provided below.

Options for high-efficiency replacement vehicles include

• High mileage conventional vehicles
• Hybrid electric vehicles (HEVs)
• Diesel vehicles, if using biodiesel
• Flexible fuel vehicles (FFVs), if running on ethanol (E85)
• Natural gas vehicles (NGVs)
• Electric vehicles (EVs)
• Future technologies
• Other alternatives
• Personal mobility vehicles, i.e. Segways
• Bus
• Carpool
• Car sharing, i.e. Flexcar
• Bicycle

Hybrid Electric Vehicles

Today’s light-duty HEVs rely on gasoline and electricity from batteries for power.  Rather than go through all of the technical features of different types of HEVs, visit this link as well as this one to read how HEVs work.  Basically, an HEV relies on a gasoline engine (usually smaller than in a conventional vehicle) to provide power and also relies on rechargeable batteries (either solely or in combination with the engine).  When and how the engine and electrical system work separately and together determines the type of hybrid.  Most hybrids turn the engine off when idling and use the electric motor to restart the vehicle.  Most HEVs also recharge the batteries via regenerative braking and/or using the engine directly. Some HEVs feature electric-only propulsion at low speeds and for short distances.  How many of these features a hybrid includes and how they are designed to work determine the amount of fuel savings realized by the HEV. Recently, performance hybrids, i.e. the Lexus LS 450h, have appeared that use the electrical system as much to provide a performance boost as a fuel economy boost.

There are other types of hybrids in various stages of development.  Diesel electric hybrids and hydraulic hybrids are two examples and are generally focused on the medium- and heavy-duty sectors. Another example are plug-in hybrids (PHEVs). These vehicles can be recharged via an electrical outlet but also have the functionality of a regular hybrid. In one manner of construction, the first distance you drive is done solely using electricity. After that first period of driving, the vehicle switches to operate like a regular HEV. The all-electric initial range may vary from just a few to 40 or 60 miles depending on the size and type of battery used. Right now, PHEVs are only available as aftermarket conversions of regular HEVs. Major auto manufacturers, including GM and Toyota, have announced efforts to research, design and build PHEVs. The earliest an OEM version is expected to be available is 2010. Stay tuned to see what happens with this exciting new type of vehicle.

Diesel Vehicles

Diesel vehicles could be considered an alternative  fuel vehicles if they use biodiesel.  They can also run on petroleum diesel, which means they have the flexibility to switch back and forth between a renewable fuel and a non-renewable fuel.  The main advantage of the diesel engine is that it is more efficient than a gasoline engine.  Diesel exhaust can be a significant health risk; but modern diesel engines are able to overcome the emission issues and have much better performance than early versions.  As EPA’s emission standards are tightened, diesel vehicles are being redesigned and having additional emission control equipment installed to meet the standards.  While these changes are being made, however, the market for vehicles is in flux.  Expect these issues to be worked out in the near future and diesel vehicles to be reintroduced in increasing numbers in the US market.  In fact, virtually all automakers have made recent announcements of upcoming diesel models or plans to add them in the near future.  The automotive research firm J.D. Power recently predicted that diesel vehicles will make up more than 10% of the US market by 2015.

Flex Fuel Vehicles

FFVs are designed to run on straight gasoline, the gasoline-ethanol mix known as E85 or any combination of the two.  Basically, FFVs are the same as conventional vehicles with a few modifications made to the fuel system to handle the increased corrosiveness of ethanol.  There is also a sensor in the fuel delivery system that detects the amount of ethanol in the fuel and makes adjustments to the engine.  Because ethanol has less energy per unit volume than gasoline, FFVs get less miles per gallon (mpg) of E85 than conventional vehicles running on gasoline.  Estimates range from 5-25% difference in mpg using E85.  Keep in mind, however, that there are still petroleum reductions when using E85 even with the mpg loss because ethanol makes up most of the liquid fuel. (Read more about the realities and misconceptions of E85 in Section 5.2 below.)

Natural Gas Vehicles

NGVs are attractive because natural gas is cheaper than gasoline or diesel and is a very clean burning fuel, which may mean lower emissions and maintenance costs over the life of the vehicle.  Vehicle availability is limited, however; the Honda Civic is the only light-duty NGV available at the time this was written.  Upfitters are beginning to try to replace the void left by the departure of the original equipment manufacturers from the NGV market.  Watch the Puget Sound Clean Cities website for the latest information on upfitters in our area.  Another drawback is that the range of an NGV is often lower than a comparable conventional vehicle because of natural gas’s lower energy density and fuel storage constraints.  More natural gas options exist for heavy-duty applications as can be seen by natural gas use in bus and refuse truck markets.  The natural gas may or may not be from renewable sources, such as landfills or wastewater treatment plants.  This form of natural gas is often called bio-methane.  Infrastructure for NGVs is limited and expensive although efforts are being made to increase the availability of the fuel in our region.

Electric Vehicles

Electric vehicles (EVs) are poised to make a comeback given recent and continuing advances in battery technology. Most of the exciting new EVs are either still in development or are just beginning to hit the market. In addition, the new EVs are most concentrated in California so it may take some time to get them up here in this region. That said, EVs are worth keeping an eye on as they may develop into a much more widely useful alternative vehicle than what is available currently.

A specific sub-class of EVs that are available today are the neighborhood electric vehicles (NEVs), which run solely on electricity, are designed to carry 2-4 passengers on short trips on slow roads.  The vehicles are street legal in Washington on roads with speed limits of 35 mph or less and have maximum speeds of 25 mph.  NEVs have zero tailpipe emissions and operation and maintenance costs are low.  NEVs are recharged in standard wall outlets and recharging time varies by model.  Universities, large shop facilities, office campuses, and parks are applications where NEVs may make sense.  There are also a variety of electric work trucks on the market that may be a good option for a fleet to reduce its emissions. Another category of vehicles in Washington is the low-speed electric vehicles. These are similar to NEVs but are allowed to go up to 35 mph.