An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. There are three main types of EVs, classed by the degree that electricity is used as their energy source - Battery Electric Vehicles (BEVs) which run completely on electricity stored in onboard batteries, Plug-in Hybrid Electric Vehicles (PHEVs) which utilize both batteries that can be recharged from external sources and a gasoline engine, and Hybrid Electric Vehicles (HEVs) which also have battery storage and a gasoline engine, but utilize regenerative braking and the internal combustion engine to charge. In the early days of motor vehicles, EVs were the preferred method travel, but soon lost the technological race with internal combustion engine (ICE) vehicles, and sales of EVs peaked in the early 1910s. More recently, driven by improvements in battery storage and concern over emissions and the contribution to global warming from burning fossil fuels for transportation, EVs have enjoyed a resurgence, and some experts believe that they are likely to become the future of transportation. (See OWOE: Are all-electric cars likely to become the future of transportation?
The electric motors in an EV may be powered from a variety of sources, including battery storage, regenerative braking that takes advantage of some of the energy normally converted to heat by the process of braking, on-board collector systems such as photovoltaic cells, or generators that convert different forms of fuel into electricity. EVs include road and rail vehicles, surface and underwater vessels, electric aircraft and electric spacecraft. Video 1 describes the technology that combines to make an EV work.
The first EVs were developed in the early 19th century and became the preferred method for motor vehicle travel with the invention of the rechargeable lead-acid battery in 1859 that provided a viable on-board means for storing electricity. Figure 1 shows an EV being charged in Detroit in 1919. EVs did not have the vibration, smell, and noise associated with ICEs, did not require gear changes, and did not require a hand crank to manually start the engines as was required for gasoline powered cars of the day. However, EVs were limited by their slow speed (max 15-20 mph) and low range (30-40 miles). With advancements in ICE technology, including the invention of the muffler in 1897 that helped address the sound issue, the electric starter 1912 which eliminated the need of a hand crank for starting the engine, and the introduction of mass production by Henry Ford which dramatically reduced their price, ICEs became the dominant propulsion method for cars, busses, and trucks. At the turn of the century, 40 percent of American automobiles were powered by steam, 38 percent by electricity, and 22 percent by gasoline. Sales of electric cars peaked in the early 1910s. Other vehicle types, including small vehicle and trains, have remained electric powered. Video 2 includes an interesting history of EVs and postulates on reasons why ICEs won the early battle over EVs to dominate the market.
More recently, driven by improvements in battery storage and concern over emissions and the contribution to global warming from burning fossil fuels for transportation, EVs have enjoyed a resurgence. EVs are considered zero emissions vehicles since there are no emissions from their tailpipes; however, depending on the mix of fuels used to generate the electricity that powers the vehicle, an EV does contribute indirectly to pollution and global warming. For more information on this issue, see OWOE: How much more environmentally friendly is an all-electric car than a gas powered car?
. While environmental concerns were important to many of the early adopters of EVs, more recently Tesla Motors has captured the imagination of the driving public. By building high-end, high-performance EVs they have demonstrated that an EV can be stylish and fun to drive (see Figure 2). In fact, in August 2015 the product testing agency, Consumer Reports, gave the high-performance P85D version of Tesla's Model S a rating of 100, a perfect score, calling it "the best-performing car that Consumer Reports has ever tested". Tesla's Model 3 and General Motors' Bolt, which are intended as mass-market vehicles that can compete on price with similar gasoline powered cars, are due to start delivery in 2017. If these two models can live up to their expectations, they could be the turning point that once again makes EVs the preferred vehicle for motorists, ending the ICE's century long domination of the transportation market.
There are three main types of EVs, classed by the degree that electricity is used as their energy source.
- Battery Electric Vehicles (BEVs) - all-electric vehicles that use batteries solely to power the electric motor are sometimes referred to as battery electric vehicles (BEVs) or plug-in electric vehicles (PEVs). BEV batteries are charged by plugging the vehicle into an electric power source. Traditionally, BEVs have suffered from a shorter driving range than most conventional vehicles, typically less than 100 miles on a fully charged battery. However, with improvements in battery technology, that range has increased dramatically over the past several years. In particular, the Tesla Model S 90D achieved a 303.2-mile range per the EPA's 2016 Green Vehicle Guide, breaking the 300-mile ceiling for a BEV for the first time ever.
- Plug-in Hybrid Electric Vehicles (PHEVs) - similar to HEVs, PHEVs have both an internal combustion engine and an electric motor, which uses energy stored in batteries. PHEVs generally have larger battery packs than HEVs, which makes it possible to drive moderate distances using electricity alone (about 10 to 40-plus miles in current models), commonly referred to as the "all-electric range" of the vehicle. The ICE powers the vehicle when the battery is mostly depleted, during rapid acceleration, or when intensive heating or air conditioning is required. PHEV batteries can be charged by an outside electric power source, by the ICE, or through regenerative braking.
- Hybrid Electric Vehicles (HEVs) - HEVs are powered by both an internal combustion engine than can run on conventional or alternative fuel and an electric motor that uses energy stored in a battery. An HEV does not plug into off-board sources of electricity to charge the battery. Instead, the vehicle uses regenerative braking and the internal combustion engine to charge. The vehicle captures energy normally lost during braking by using the electric motor as a generator and storing the electricity generated in the battery. The energy from the battery provides extra power during acceleration and powers auxiliary loads such as sound systems and headlights. HEVs combine the benefits of high fuel economy and low emissions with the power and range of conventional vehicles. The Toyota Prius, introduced in worldwide in 2000, was the first mass-produced HEV.
Video 3 from Transport Canada describes some of the differences between types of EVs as well as providing general information on why EVs make sense today on Canada's roadways.
Electric motors are mechanically very simple and often achieve 90% energy conversion efficiency over the full range of speeds and power output. They can be precisely controlled and, unlike ICEs, provide high torque from rest and do not need multiple gears to match power curves. This removes the need for gearboxes and torque converters and allows the vehicle to achieve acceleration rates normally found only in high performance sports cars. BEVs provide quiet and smooth operation, with less noise and vibration than ICEs.