Research

Hybrid

How hybrids work
Hybrid-electric vehicles (HEVs) combine the benefits of gasoline engines and electric motors and can be configured to obtain different objectives, such as improved fuel economy, increased power, or additional auxiliary power for electronic devices and power tools.

Some of the advanced technologies typically used by hybrids include:

Regenerative braking. The electric motor applies resistance to the drivetrain causing the wheels to slow down. In return, the energy from the wheels turns the motor, which functions as a generator, converting energy normally wasted during coasting and braking into electricity, which is stored in a battery until needed by the electric motor.

Electric motor drive/assist. The electric motor provides additional power to assist the engine in accelerating, passing, or hill climbing. This allows a smaller, more efficient engine to be used. In some vehicles, the motor alone provides power for low-speed driving conditions where internal combustion engines are least efficient.

Automatic start/shutoff. Automatically shuts off the engine when the vehicle comes to a stop and restarts it when the accelerator is pressed. This prevents wasted energy from idling.

How hybrids get such great gas mileage
It is no accident that the most fuel efficient vehicles in some classes for this model year are hybrid-electric vehicles (HEVs). Hybrids combine the best features of the internal combustion engine with an electric motor, and they can be configured to achieve a variety of different objectives, such as improving fuel economy, boosting performance, or providing electrical power to auxiliary loads such as power tools.

HEVs are primarily propelled by an internal combustion engine, just like conventional vehicles. However, they also convert energy normally wasted during coasting and braking into electricity, which is stored in a battery until needed by the electric motor. The electric motor is used to assist the engine when accelerating or hill climbing and in low-speed driving conditions where internal combustion engines are least efficient. Some HEVs also automatically shut off the engine when the vehicle comes to a stop and restart it when the accelerator is pressed. This prevents wasted energy from idling.

Unlike all-electric vehicles, HEVs now being offered do not need to be plugged into an external source of electricity to be recharged; conventional gasoline and regenerative braking provide all the energy the vehicle needs.

Five new hybrids available since 2007

• Lexus GS 450h - Compact car equipped with a 6-cylinder engine and 6-speed automatic transmission
• Toyota Camry Hybrid - Midsize car equipped with a 4-cylinder engine and a continuously variable transmission (CVT)
• Saturn Vue Hybrid - Sport utility vehicle equipped with a 4-cylinder engine and a Hydra-matic 4-speed automatic transmission
• Saturn Aura Hybrid (not yet available) - Midsize car equipped with a 4-cylinder engine and a 4-speed automatic transmission
• Nissan Altima Hybrid (not yet available) - Midsize car

The GS 450h, Camry Hybrid, and Vue Hybrid vehicles are eligible for federal income tax credits. The Aura and Altima are not yet available for sale and have not been certified by IRS as eligible for the credit.

Sources: J.D. Power-LMC; Energy & Environmental Analysis (EEA), Inc.; manufacturer web sites. Updated 9/6/2006.

All figures cited were originally gathered and reported by www.fueleconomy.gov.

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Diesel & biodiesel

Diesel vehicles may be making a comeback. Diesel engines are more powerful and fuel-efficient than similar-sized gasoline engines (about 30-35% more fuel efficient). Plus, today's diesel vehicles are much improved over diesels of the past.

New diesel technologies have improved performance and efficiency, reduced tailpipe emissions, vibrations, and noise of diesel vehicles.

Ultra-low sulfur diesel (ULSD), available beginning in 2006, is cleaner burning and allows diesels to be equipped with more-effective controls for reducing particulates and smog-forming nitrogen oxide (NOx) emissions.

Biodiesel, a non-petroleum fuel produced from renewable sources, reduces tailpipe emissions and dependence on foreign oil.

Better performance
Improved fuel injection and electronic engine control technologies have

• Increased power
• Improved acceleration
• Increased efficiency

New engine designs, along with noise- and vibration-damping technologies, have made them quieter and smoother. Cold-weather starting has been improved also.

Cleaner
Today's diesels must meet the same emissions standards as gasoline vehicles, and advances in engine technologies, ultra-low sulfur diesel fuel, and improved exhaust treatment have made this possible.

Although emissions of particulates and smog-forming nitrogen oxides (NOx) are still relatively high, new "clean" diesel fuels, such as ultra-low sulfur diesel and biodiesel, and advances in emission control technologies will reduce these pollutants also.

Ultra-low sulfur diesel
Ultra-low sulfur diesel (ULSD) replaced conventional diesel fuel starting in 2006. The new fuel will contain 97% less sulfur than conventional diesel—sulfur will be reduced from 500 parts per million (ppm) to 15 ppm.

ULSD is cleaner-burning, producing less particulate emissions in both older and new engines.

It also allows the use of improved exhaust treatment devices to reduce emissions of particulates and smog-forming nitrogen oxides (NOx). These devices can be "poisoned" by the sulfur in conventional diesel fuel.

Biodiesel
Biodiesel is a form of diesel fuel manufactured from vegetable oils, animal fats, or recycled restaurant greases. It is safe, biodegradable, and produces less air pollutants than petroleum-based diesel.

Biodiesel can be used in its pure form (B100) or blended with petroleum diesel. Common blends include B2 (2% biodiesel), B5, and B20. B2 and B5 can be used safely in most diesel engines. However, most vehicle manufacturers do not recommend using blends greater than 5%—using higher blends will void some engine warranties. Check with your owner's manual or vehicle manufacturer to determine the right blend for your vehicle.

Note: You should never fuel your vehicle with clean or used grease or vegetable oil that has not been converted to biodiesel. It will damage your engine.

All figures cited were originally gathered and reported by www.fueleconomy.gov.

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Flex-fuel

Flexible fuel vehicles (FFVs) are designed to run on gasoline or a blend of up to 85% ethanol (E85). Except for a few engine and fuel system modifications, they are identical to gasoline-only models.

FFVs have been produced since the 1980s, and dozens of models are currently available. Since FFVs look just like gasoline-only models, you may have an FFV and not even know it. To determine if your vehicle is an FFV, check the inside of your car's fuel filler door for an identification sticker or consult your owner's manual.

FFVs experience no loss in performance when operating on E85. However, since a gallon of ethanol contains less energy than a gallon of gasoline, FFVs typically get about 20-30% fewer miles per gallon when fueled with E85.

All figures cited were originally gathered and reported by www.fueleconomy.gov.

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Ethanol

Ethanol is an alcohol-based fuel made by fermenting and distilling starch crops, such as corn. It can also be made from "cellulosic biomass" such as trees and grasses. The use of ethanol can reduce our dependence upon foreign oil and reduce greenhouse gas emissions.

E10 (gasohol)
E10 (also called “gasohol”) is a blend of 10% ethanol and 90% gasoline sold in many parts of the country. All auto manufacturers approve the use of blends of 10% ethanol or less in their gasoline vehicles.

E85
E85, a blend of 85% ethanol and 15% gasoline, can be used in flexible fuel vehicles (FFVs), which are specially designed to run on gasoline, E85, or any mixture of the two. FFVs are offered by several vehicle manufacturers. To determine if your vehicle can use E85, consult your owner’s manual or check the inside of your car's fuel filler door for an identification sticker.

Cost
Cost varies regionally. It is cheaper than gasoline in some areas, such as the Midwest, and more expensive in others.

Availability
Several hundred filling stations in the U.S. sell E85, and that number is increasing rapidly. Visit the alternative fuel station locator for locations of service stations selling E85.

Performance
No noticeable difference in vehicle performance when E85 is used.

MPG
FFVs operating on E85 usually experience a 20-30% drop in miles per gallon due to ethanol’s lower energy content.

All figures cited were originally gathered and reported by www.fueleconomy.gov.

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Natural gas

Natural gas, a fossil fuel comprised mostly of ethane, is one of the cleanest burning alternative fuels. It can be used in the form of compressed natural gas (CNG) or liquefied natural gas (LNG) to fuel cars and trucks.

Dedicated natural gas vehicles are designed to run on natural gas only, while dual-fuel or bi-fuel vehicles can also run on gasoline or diesel. Dual-fuel vehicles allow users to take advantage of the wide-spread availability of gasoline or diesel but use a cleaner, more economical alternative when natural gas is available. Since natural gas is stored in high-pressure fuel tanks, dual-fuel vehicles require two separate fueling systems, which take up passenger/cargo space.

Natural gas vehicles are not produced commercially in large numbers—the Honda GX CNG is the only new vehicle available in the U.S. However, conventional gasoline and diesel vehicles can be retrofitted for CNG.

All figures cited were originally gathered and reported by www.fueleconomy.gov.

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Propane

Liquefied petroleum gas (LPG)
Propane or liquefied petroleum gas (LPG) is a clean-burning fossil fuel that can be used to power internal combustion engines. LPG-fueled vehicles produce fewer toxic and smog-forming air pollutants. LPG is usually less expensive than gasoline, and most LPG used in U.S. comes from domestic sources.

No LPG-fueled light-duty passenger cars or trucks have been produced commercially in the U.S. since the 2004 model year, but gasoline and diesel vehicles can be retrofitted to run on LPG in addition to conventional fuel. The LPG is stored in high-pressure fuel tanks, so separate fuel systems are needed in vehicles powered by both LPG and a conventional fuel such as gasoline.

All figures cited were originally gathered and reported by www.fueleconomy.gov.

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Hydrogen

Hydrogen (H2) is being aggressively explored as a fuel for passenger vehicles. It can be used in fuel cells to power electric motors or burned in internal combustion engines (ICEs).

It is an environmentally friendly fuel that has the potential to dramatically reduce our dependence on foreign oil, but several significant challenges must be overcome before it can be widely used.

Benefits
Produced domestically. Hydrogen can be produced domestically from several sources, reducing our dependence on petroleum imports.

Environmentally friendly. Hydrogen produces no air pollutants or greenhouse gases when used in fuel cells; it produces only NOx when burned in ICEs.

Challenges
Fuel cost & availability. Hydrogen is currently expensive to produce and is only available at a handful of locations, mostly in California.

Vehicle cost & availability. Fuel cell vehicles are currently far too expensive for most consumers to afford, and they are only available to a few demonstration fleets.

Onboard fuel storage. Hydrogen contains much less energy than gasoline or diesel on a per-volume basis, so it is difficult to store enough hydrogen onboard a vehicle to travel more than 200 miles.

Other challenges include fuel cell performance, customer acceptance, and hydrogen transport and bulk storage.

All figures cited were originally gathered and reported by www.fueleconomy.gov.

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Electric

Electric vehicles (EVs) are propelled by an electric motor (or motors) powered by rechargeable battery packs. Electric motors have several advantages over internal combustion engines (ICEs):

• Energy efficient. Electric motors convert 75% of the chemical energy from the batteries to power the wheels—internal combustion engines (ICEs) only convert 20% of the energy stored in gasoline.
• Environmentally friendly. EVs emit no tailpipe pollutants, although the power plant producing the electricity may emit them. Electricity from nuclear-, hydro-,
  solar-, or wind-powered plants causes no air pollutants.
• Reduce energy dependence. Electricity is a domestic energy source.
• Performance benefits. Electric motors provide quiet, smooth operation and stronger acceleration and require less maintenance than ICEs.

The down side: batteries
EVs face significant battery-related challenges:

• Driving range. Most EVs can only go 150 miles (or less) before recharging—gasoline vehicles can go over 300 miles before refueling.
• Recharge time. Fully recharging the battery pack can take 4 to 8 hours.
• Battery cost. The large battery packs are expensive and usually must be replaced one or more times.
• Bulk & weight. Battery packs are heavy and take up considerable vehicle space.

Researchers are working on improved battery technologies to increase driving range and decrease recharging time, replacement frequency, weight, and cost. These factors will ultimately determine the future of EVs.

All figures cited were originally gathered and reported by www.fueleconomy.gov.

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Fuel cell

Although they are not expected to reach the mass market before 2010, fuel cell vehicles (FCVs) may someday revolutionize on-road transportation.

This emerging technology has the potential to significantly reduce energy use and harmful emissions, as well as our dependence on foreign oil. FCVs will have other benefits as well.

A radical departure
FCVs represent a radical departure from vehicles with conventional internal combustion engines. Like battery-electric vehicles, FCVs are propelled by electric motors. But while battery electric vehicles use electricity from an external source (and store it in a battery), FCVs create their own electricity. Fuel cells onboard the vehicle create electricity through a chemical process using hydrogen fuel and oxygen from the air.

FCVs can be fueled with pure hydrogen gas stored onboard in high-pressure tanks. They also can be fueled with hydrogen-rich fuels; such as methanol, natural gas, or even gasoline; but these fuels must first be converted into hydrogen gas by an onboard device called a "reformer."

FCVs fueled with pure hydrogen emit no pollutants; only water and heat; while those using hydrogen-rich fuels and a reformer produce only small amounts of air pollutants. In addition, FCVs can be twice as efficient as similarly sized conventional vehicles and may also incorporate other advanced technologies to increase efficiency.

Meeting challenges together
Before FCVs make it to your local auto dealer, significant research and development is required to reduce cost and improve performance. We must also find effective and efficient ways to produce and store hydrogen and other fuels.

Automakers, fuel cell developers, component suppliers, government agencies, and others are working hard to accelerate the introduction of FCVs. Partnerships such as the DOE-led FreedomCAR initiative and the California Fuel Cell Partnership have been formed to encourage private companies and government agencies to work together to move these vehicles toward commercialization.

FreedomCAR
FreedomCAR is a new cooperative research effort between the DOE and the U.S. Council for Automotive Research (Ford, General Motors, and DaimlerChrysler) formed to promote research into advanced automotive technologies, such as FCVs, that may dramatically reduce oil consumption and environmental impacts. FreedomCAR's goal is the development of cars and trucks that are:

• Cheaper to operate
• Pollution-free
• Competitively priced
• Free from imported oil

California Fuel Cell Partnership (CaFCP)
The California Fuel Cell Partnership is a collaboration of auto companies, fuel providers, fuel cell technology companies, and government agencies demonstrating fuel cell electric vehicles in California under day-to-day driving conditions. The goals of the partnership are to test and demonstrate the viability of FCVs and related technology under real-world conditions, move them toward commercialization, and increase public awareness.

All figures cited were originally gathered and reported by www.fueleconomy.gov.

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