Introduction

Electric vehicles (EVs) first appeared in the late 19th century at about the same time that internal combustion (IC) engine-powered vehicles were introduced. Electric motor and steam technologies were actually more advanced and more reliable than the early gasoline engine [1]. William Morrison of Des Moines, Iowa, built the first successful electric car produced in America in 1890 [2], and by 1900, 38 percent of U.S. automobiles were electric. Almost 34,000 electric cars were registered in the U.S. in 1912, the year of their peak acceptance [3]. Quiet operation, reliability, and easy starting and operation were their major selling points. Nevertheless, the limited range and speed of electrics combined with the lower purchase price and low fuel cost for cars powered by gasoline led to a rapid decline in use of electric cars, particularly as the IC engine was improved. By the 1930s, gasoline-powered vehicles dominated the market.

With the oil crisis of the 1970s, interest in alternative fuels for vehicles, including electricity, experienced resurgence and serious development efforts resumed. However, these efforts were difficult to sustain during a period of fluctuating oil prices, and only small numbers of EVs that were conversions of IC-powered cars were produced. In the early 1990s, regulatory requirements emerged for the first time as a major factor with the establishment of the California Zero Emission Vehicle (ZEV) initiative. The United States Advanced Battery Consortium (USABC) and more recently the Partnership for a New Generation of Vehicles (PNGV) were formed to address technical challenges to the commercialization of viable electric and hybrid electric vehicle (HEV) power sources and systems. The active participants in these groups have included the major U.S. automobile manufacturers, the U.S. Department of Energy (DOE), and the Electric Power Research Institute (EPRI). As a result of these and other efforts, small numbers of advanced, purpose-built EVs have been offered to consumers in certain areas (e.g., under manufacturer memoranda of agreement in California). The limited range of pure EVs, particularly with lead-acid batteries (the only option available at first), and their high capital cost continue to be the major impediments to wide-scale commercialization. Therefore, much research has been and continues to be directed toward advanced batteries, fuel cells, and other energy storage devices (capacitors, flywheels, etc.), as well as hybrid power plant designs. Advanced batteries include those technologies that were not commercialized by about 1990 (e.g., nickel/metal hydride, lithium-ion).

The U.S. DOE, as a major participant in the USABC and PNGV programs, has been working to address infrastructure barriers to the commercial acceptance of EVs since the early 1990s. As an outgrowth of a workshop held in 1991 on sodium-beta batteries [4], a Working Group was established to identify and recommend solutions to commercialization barriers in the areas of battery shipping, battery reclamation and recycling, and in-vehicle safety [5]. The Advanced Battery Readiness Ad Hoc Working Group, as it is now known, continues to provide a forum for discussion of these issues.

The purpose of this chapter is to review the current state of recycling technologies for EV and HEV battery power sources. We will use the term recycling to include materials that are reclaimed for use in different products as well as the materials that are reclaimed and transformed into new batteries. A practical method for recycling batteries and other energy storage components from EVs is viewed as essential for the successful implementation of this transportation technology. Toxic materials are found in many battery technologies (e.g., lead, cadmium, nickel). Disposal of EV batteries may be allowable by regulations in some cases, but is likely to be costly and detracts from the environmental benefits of a zero-emission vehicle. The battery is a major cost component for EVs, and therefore disposal is doubly expensive, especially if the waste contains valuable materials. Recycling provides an opportunity to reduce life cycle costs through recovery of high-value materials and avoidance of the cost of hazardous waste disposal. Most developers of power sources for EVs therefore have a goal of recycling as much material as possible at the end of life. Less demanding, secondary uses for the energy storage device may extend its term of operation, or in some cases refurbishment could also be considered. Eventually, however, the battery must be processed in such a way that all the valuable and/or hazardous components and materials can be recycled.

ELECTRIC VEHICLE/HYBRID ELECTRIC VEHICLE BATTERIES

EVs depend entirely on the battery system for their power, while HEVs combine a battery system with some other power source (e.g., internal combustion engine, fuel cell) in order to maximize efficiency and increase range. Batteries for EVs and HEVs are much different in scale than those commonly used in portable consumer electronics such as cell phones or laptop computers. EV battery packs typically generate 300 to 350 volts, with 10 to 30 kWh of stored energy for EVs and 1 to 5 kWh for HEV applications. The power to energy ratio is 2 to 4 times greater for the HEV-battery design than that for EVs. The batteries are usually made up of multi-cell modules connected in series/parallel arrangements, although the number of individual cells, battery mass, and battery volume vary somewhat with the design and the type of battery chemistry used. Relatively few consumers would be expected to perform their own battery maintenance, and almost none could replace one of these large batteries themselves. The problem of handling is compounded by the fact that large numbers of EVs and HEVs may come into widespread use.

Nominal characteristics for several recent types of EV/HEV battery packs and then-associated vehicles are shown in Table 1. Originally, most of the battery packs were of the valve-regulated lead-acid (VRLA) type, which suffers from the disadvantage of a relatively low specific energy (Wh/kg). VRLA-powered vehicles therefore usually exhibit more limited range and payload capacity than those using advanced battery systems. As shown in Table 1, more than a 40% improvement in battery pack energy can be realized by substituting a nickel/metal hydride (Ni/MH) battery for VRLA in the same vehicle. This can be achieved with no increase in battery weight or volume. For most four-passenger family size EVs, the battery weighs about 500 kg and occupies a 200-L volume. HEV batteries only need to be about 10 to 20% of this size and weight because of their lower energy storage needs and the exclusive use of advanced battery chemistries.

The configuration of the battery also varies widely with the vehicle design. In some instances (e.g., the EV1 battery shown in Figure 1), the battery fits in a T-shaped tunnel within the vehicle. In other vehicles (trucks and vans), a flat battery pack is placed beneath the floor so as not to take up so much of the internal cargo space. Typical configurations of some of the current or proposed battery packs are shown in Figures 1 through 7.

Table 1

Typical EV/HEV Battery Pack Characteristics

Table 1

Typical EV/HEV Battery Pack Characteristics

Vehicle

Battery Type

EV/HEV

Pack Power (kW)

Pack Energy (kWh)

Pack Voltage (V)

Pack Capacity (Ah)

Pack Volume (L)

Total Pack Mass (kg)

Project Earth Conservation

Project Earth Conservation

Get All The Support And Guidance You Need To Be A Success At Helping Save The Earth. This Book Is One Of The Most Valuable Resources In The World When It Comes To How To Recycle to Create a Better Future for Our Children.

Get My Free Ebook


Post a comment