Important Acronyms:
BEV - Battery electric vehicle, a vehicle which uses only batteries and one or more motors to provide the force that makes it go.
EV - Electric vehicle, any vehicle that uses electric power to provide some or all of its propulsive force.
FCEV - Fuel cell electric vehicle, an electric vehicle which uses a hydrogen fuel cell as its source of electric power.
HEV - Hybrid electric vehicle, a car or truck that uses both an ICE and an electric motor.
ICE - Internal combustion engine, the powerplant of choice for the dirty, inefficient vehicles of the 20th Century.
PHEV - Plug-in hybrid vehicle, a hybrid vehicle with a battery pack that can be charged from a wall socket.
Have you just developed an interest in electric vehicles? Are you looking to learn some EV fundamentals? You've come to the right place! Read on, and you will start your education on the wonders of EVs. In this article, I will introduce readers to some of the various different types of EVs and explaing some of the advantages and issues associated with each type. Note that this article is only an introduction. I will go into more depth on different aspects of the subject matter in future installments of the "EV Basics" series.
There are several different power trains available which use electric motors. The simplest of these vehicles is the battery electric vehicle or BEV. This is a pure electric vehicle which uses only a battery pack and an electric motor to store energy and create the power necessary to make the car or truck move. BEVs have been around for a long time. In 1835, Thomas Davenport built a railway operated by a small electric motor. In the early years of the 20th Century, BEVs competed quite successfully with ICE-powered vehicles. It was not until Henry Ford started building the Model T that gasoline-powered cars that BEVs faded from public view.
In the 1960s, BEVs began to make a comeback. Interest in electric vehicles has grown steadily since then as concerns about pollution and dependence on foreign oil have permeated mainstream consciousness. Currently, BEVs are being designed and built in a wide variety of styles and layouts, from electric scooters, to low-speed electric cars such as those produced by Zenn Motor Company, to high-power freeway burners such as the two-seat Tesla Roadster or the family-friendly, five-passenger eBox by AC Propulsion.
BEVs must face a few hurdles if they are to replace ICE-only cars as our primary method of transportation. Historically, they have had limited driving range, significantly less than the range of a gasoline-powered car. Additionally, BEV have generally taken several hours to recharge the battery pack. In a world in which people have gotten used to instant gratification, this poses a real problem. The good news is that many people are working on these issues, and dramatic improvements are being made in both range and recharging time. Current EV designs have achieved ranges of more than 300 miles and charging times have been brought down to two hours or less in some models charged with high-powered "smart" chargers.
In the 1990s, Honda and Toyota introduced the American driving public to the hybrid electric vehicle or HEV. These vehicles use both an ICE and an electric motor. There are different types of HEVs which layout the engine and the motor in either a parallel or a series configuration. In a series configuration, the ICE acts only as an electrical generator. In a parallel configuration the ICE again acts as a generator, but it also drives the vehicle's wheels just as the engine would do in an ICE-only vehicle.
HEVs provide significant benefits over ICE-only cars in two distinct areas. Firstly, the electric motor allows engineers to operate the ICE more efficiently because an HEV can rely heavily on the electric motor at points in which the ICE would be operating very inefficiently. Secondly, the battery pack in an HEV can be used to recapture the energy used while braking. To accomplish this, engineers create regenerative braking systems which used the electrical resistance of a generator to slow the car down long before they mechanical brakes come into play. The energy from the generator is then stored in the battery pack for future use. In a car without regenerative braking, all this energy is wasted by creating heat and wearing down the brake pads.
HEVs also have some problems. Unlike BEVs, they require some gasoline or other liquid fuel to operate. Also, they are more complicated then either a BEV or an ICE-only vehicle because they require both types of drivetrain components under one hood. However, they eliminate the range and recharging issues associated with BEVs, so HEVs can be viewed as a good transition step to the vehicles of the future.
Recently, much attention has been paid to plug-in hybrids or PHEVs. In essence, a PHEV is an HEV with a larger battery pack, a plug which allows the battery pack to be charged from a wall socket, and a control system which allows the vehicle to be operated in electric-only mode. The wall-charging feature allows a PHEV to get some of its power from the utility grid (or from a local power source such as a photovoltaic array or wind turbine) and some of its power from gasoline. Recently, several companies and individuals have been working on creating plug-in versions of the Toyota Prius. These conversions allow the Prius to run in all-electric mode until it reaches roughly 35mph. They give varying traveling ranges in all-electric mode, depending on which type of batteries are used and how many extra batteries are installed.
While these plug-in Priuses are a good start, PHEVs as a genre have even more potential. General Motors recently introduced the Chevrolet Volt E-Flex concept car, a PHEV which can travel up to 40 miles in electric only mode. It has a large electric motor and a one liter, three cylinder ICE. PHEVs of the future could follow this trend even further, maximizing the electric elements of the drivetrain while reducing the ICE to a tiny power plant which gets used only as a last resort.
In the last few years, fuel cell electric vehicles or FCEVs have grabbed many headlines. These are electric vehicles which use a hydrogen fuel cell to provide power, eliminating the need for a battery pack. Proponents point out that hydrogen is the most abundant of the chemical elements and that the only gas emitted from an FCEV is steam made from pure water. Detractors point out that nearly all hydrogen currently available is made from natural gas, a petroleum product. Hydrogen is also difficult to store in quantities sufficient to give FCEVs adequate range and it can present safety hazards when pressurized in tanks. Finally, FCEVs currently require complex, bulky support systems which take up excessive space and result in power delivery systems which are far less efficient than those present in BEVs.
Fuel cells have some potential to become part of the overall energy scenario in the future. However, many feel that FCEVs have been used primarily as a distraction and a stalling device. Companies and politicians keep telling us, "We'll have FCEVs in the near future, but until then keep driving your Hummers!" These tactics keep people from demanding BEVs as soon as possible. As one saying puts it, "Practical, viable fuel cells are ten to twenty years away, and they always will be."
One other type of electric vehicle is the human-assist hybrid. The most common example of this vehicle type is the electric bicycle. These are commonly-available, inexpensive, and they give people the health benefits associated with exercise while providing an additional boost when needed. Legally, they must be limited to 20 mph in electric assist mode, and the electric-only range of electric bikes now available is almost always less than twenty miles.
However, readers should ponder the fact that a small, aerodynamic vehicle can cruise at 65 mph on a flat road while using only five horsepower. Imagine the roads covered with small, efficient vehicles that use tiny electric motors and human power to achieve freeway speeds without putting a significant burden on the utility grid. While no major corporations are working on vehicles like this, small groups of dedicated individuals are working to make this type of vehicle available to the general public. These low-power vehicles could become the ultimate transportation solution for an energy-conscious society.
So there you have it! You now have enough information to join EV-related conversations at your next social gathering. You can talk about the different types of EVs, letting people know what is available now and what is coming in the near future. If you are still curious for more details on the benefits of electric vehicles and the advances which are being made in the field, please see the other articles in this "EV Basics" series.
Forbes Bagatelle-Black
West Coast Contributing Editor, EVWorld.com
http://www.evworld.com
