About Hybrid and Electric Cars

Hybrids

Hybrid cars are fueled with gasoline only. They recapture some energy during braking and store it as electricity which can help power the car. These hybrids cannot be plugged in and charged, but they can be very fuel efficient. Hybrid electric vehicles (HEVs) combine the benefits of gasoline engines and electric motors. They can be designed to meet different goals, such as better fuel economy or more power.

Most hybrids use several advanced technologies:

• Regenerative Braking. Regenerative braking recaptures energy normally lost during coasting or braking. It uses the forward motion of the wheels to turn the motor. This generates electricity and helps slow the vehicle.
• Electric Motor Drive/Assist. The electric motor provides power to assist the engine in accelerating, passing, or hill climbing. This allows a smaller, more-efficient engine to be used. In some hybrids, the electric motor alone propels the vehicle at low speeds, where gasoline engines are least efficient.
• Automatic Start/Stop. Automatically shuts off the engine when the vehicle comes to a stop and restarts it when the accelerator is pressed. This reduces wasted energy from idling.

Plug-in Hybrids

Plug-in hybrids can be fueled with both gasoline and electricity from an outlet or charger. Some can go over 70 miles on electricity alone, and all can operate solely on gasoline—like a regular hybrid—when necessary. Some types of plug-in hybrids are called extended range electric vehicles (EREVs).

Plug-in hybrids, sometimes called Plug-in Hybrid-Electric Vehicles (PHEVs), are hybrids with high-capacity batteries that can be charged by plugging them into an electrical outlet or charging station. They can store enough electricity from the power grid to significantly reduce their petroleum consumption under typical driving conditions.

Different Kinds of Plug-in Hybrids

There are two basic plug-in hybrid configurations:

• Series plug-in hybrids, also called Extended Range Electric Vehicles (EREVs). Only the electric motor turns the wheels; the gasoline engine is only used to generate electricity. Series plug-ins can run solely on electricity until the battery needs to be recharged. The gasoline engine then generates electricity to power the electric motor. For shorter trips, these vehicles might use no gasoline at all.
• Parallel or Blended Plug-in Hybrids. Both the engine and electric motor are mechanically connected to the wheels, and both propel the vehicle under most driving conditions. Electric-only operation usually occurs only at low speeds.

Plug-in hybrids also have different battery capacities, allowing some to travel farther on electricity than others. Their fuel economy, like that of electric vehicles and regular hybrids, can be sensitive to driving style, driving conditions, and accessory use.

Benefits and Challenges

Less Petroleum Use. Plug-in hybrids use roughly 30% to 60% less petroleum than conventional vehicles. Since electricity is produced mostly from domestic resources, plug-in hybrids reduce oil dependence.

Less Greenhouse Gas Emissions. Plug-in hybrids typically emit less greenhouse gas than conventional vehicles, but the amount generated depends partly on the fuel used at electrical power plants—nuclear and hydroelectric plants are cleaner than coal-fired power plants.

Higher Vehicle Costs, Lower Fuel Costs. A plug-in hybrid can cost roughly $4 to $8 thousand more than a comparable non-plug-in hybrid. Using electricity is usually cheaper than using gasoline—sometimes much cheaper—but whether fuel savings will offset the higher vehicle cost depends on the vehicle purchased, the percentage of miles operating on electricity, fuel costs, and ownership length. in USA Federal tax incentives up to $7,500 are currently available for qualifying plug-ins.

Re-charging Takes Time. Re-charging the battery using a 120-volt household outlet can take several hours; re-charging using a 240-volt home or public charger can take roughly 1 to 4 hours; while a “fast charge” to 80% capacity may take as little as 30 minutes. However, these vehicles don’t have to be plugged in. They can be fueled solely with gasoline but will not achieve maximum range or fuel economy without charging.

Estimating Fuel Economy. Since a plug-in can operate on electricity alone, gasoline alone, or a mixture of the two, EPA provides a fuel economy estimate for gasoline-only operation and an estimate for electric-only or gas-and-electric operation—both for combined city-highway driving.

All-Electric Cars

All-electric cars use only electricity and must be plugged in to charge. All-electric vehicles (EVs) run on electricity only. They are propelled by one or more electric motors powered by rechargeable battery packs. EVs have several advantages over vehicles with internal combustion engines (ICEs):

• Energy efficient. Electric vehicles convert about 59%–62% of the electrical energy from the grid to power at the wheels—conventional gasoline vehicles only convert about 17%–21% of the energy stored in gasoline to power at the wheels.^*
• 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.
• Performance benefits. Electric motors provide quiet, smooth operation and stronger acceleration and require less maintenance than ICEs.
• Reduce energy dependence. Electricity is a domestic energy source.

EVs do, however, face significant battery-related challenges:

• Driving range. Range is typically limited to 60 to 120 miles on a full charge, although a few models can go 200 to 300 miles.
• Recharge time. Fully recharging the battery pack can take 4 to 8 hours. Even a “fast charge” to 80% capacity can take 30 min.
• Battery cost: The large battery packs are expensive and may need to be replaced one or more times.
• Bulk & weight: Battery packs are heavy and take up considerable vehicle space.

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