Electric Bikes in the People's Republic of China

Impact on the Environment and Prospects for Growth

• Editorial: Asian Development Bank
• Año: 2009
• ISBN:
  9789292547097
• Edición: 1
• Categoría: Tecnología e ingeniería
• Categoría: Bicicletas y motocicletas

Electric bikes (e-bikes) provide low-cost, convenient, and relatively energy-efficient transportation to an estimated 40 million-50 million people in the People's Republic of China (PRC), quickly becoming one of the dominant travel modes in the country. As e-bike use grows, concerns are rising about lead pollution from their batteries and emissions from their use of grid electricity, primarily generated by coal power plants. This report analyzes the environmental performance of e-bikes relative to other competing modes, their market potential, and the viability of alternative battery technologies. It also frames the role of e-bikes in the PRC's transportation system and recommends policy for decision makers in the PRC's central and municipal governments.

SECTION 1

Energy Use and Emissions of Electric Bike Life Cycle

Most of the environmental impacts of electric bikes (e-bikes) can be divided into two categories: those that occur while they are being produced, and those that occur when they are being used. There are also some significant emissions when they are disposed of, although these are difficult to quantify given the infancy of this mode and little information on disposal practices. One notable disposal emission is that of lead from batteries.

Production Processes

There are hundreds of e-bike manufacturing companies in the People’s Republic of China (PRC), including large factories producing components such as motors, controllers, and frames, as well as small and large plants where the bikes are assembled. To understand the production processes, five e-bike factories in Shanghai and in the provinces of Jiangsu and Zhejiang were visited. Their annual output ranged from 12,000 e-bikes to over 150,000 e-bikes in 2005. Assembly of an e-bike typically requires one main assembly line where the frame is passed through various stages. Generally, e-bike assembly lines have the capacity to produce one e-bike every 5 minutes. Individual components and processes of the e-bike—such as assembling wiring systems, brake systems, and painting—are produced and performed off-line.

Interviews with factory owners and publicly reported statistics on energy use and emissions from the manufacture of raw materials were used to estimate the environmental implications of the production process of e-bikes. Other estimates of energy use and emissions were made using the weight of raw materials required to produce an e-bike and the energy and pollution intensities of producing those materials in the PRC. In some cases, data were not available or were not collected because those factors were estimated to have a relatively small impact.

One of the larger e-bike manufacturers in the PRC reported that in 2005,² it produced 180,000 e-bikes and used 1,278,545 kilowatt-hours (kWh) of electricity, or 7.1 kWh per bike. The processes included in this calculation were frame welding and bending, painting, assembly, assembly of controllers, vehicle inspection and testing, packaging, and general electricity use of the factory.

Another energy-intensive process is the manufacture of lead acid batteries. A large scale e-bike battery manufacturer reported that total energy consumption per 12-volt (V) e-bike battery was approximately 2 kWh. A 36 V battery would require 6 kWh, and a 48 V battery would require 8 kWh.³

The energy required by the assembly process is very small compared with the energy requirements of the raw material manufacturing, such as steel, lead, plastic, and rubber. Moreover, different styles of e-bikes are composed of different materials. E-bikes are generally classified into two styles: bicycle-style (BSEB), and scooter-style (SSEB). The former look and operate much like bicycles, with functioning pedals. The scooter types in many cases have footboards, turn signals, headlights, brake lights, and mirrors. Table 1.1 is an inventory of e-bike components, the material they are composed of, their weight, and the energy required to produce them, calculated from national statistics and literature on the PRC’s steel and lead industries (Price, Phylipsen, et al. 2001; National Bureau of Statistics 2003; Lawrence Berkeley National Laboratory 2004; National Bureau of Statistics 2004; National Bureau of Statistics 2005; China Data Online 2006; Mao, Lu, et al. 2006).

Several assumptions and omissions were made to develop Table 1.1. This table includes energy and environmental impacts due to the mining and production of ferrous and nonferrous metals, and the production of plastic and rubber. It does not include the impacts of battery electrolyte production or fillers in rubber production (particularly carbon black). It also does not include transport logistics impacts. The values presented in Table 1.1 should be considered lower bounds. The values also include the manufacture of replacement parts, specifically five sets of batteries, three sets of tires, and two motors over the life span of the e-bike.⁴

Table 1.1: Material Inventory, Emissions, and Energy Use of Electric Bike

Weight of Electric Bike Materials (kg/bike)
	BSEB	SSEB
Total Steel	18.15	26.18
Total Plastic	5.67	15.22
Total Lead	10.28	14.70
Total Fluid	2.94	4.20
Total Copper	2.55	3.46
Total Rubber	1.14	1.22
Total Aluminum	0.52	0.58
Total Glass	0.00	0.16
Total Weight	41.25	65.73
Associated Energy and Emissions of Manufacturing Processes
	BSEB	SSEB
Energy Use (ton SCE)	0.179	0.261
Energy Use (kWh)	1,456	2,127
Air Pollution (SO2) (kg)	1.563	2.198
Air Pollution (PM) (kg)	5.824	8.173
Greenhouse Gas (ton CO2 equivalent)	0.603	0.875
Wastewater (kg)	1,488	2,092
Solid Waste (kg)	4.463	7.139

BSEB = bicycle-style e-bike, CO₂ = carbon dioxide, kg = kilogram, kWh = kilowatt-hour, PM = particulate matter, SCE = standard coal equivalent, SO₂ = sulfur dioxide, SSEB = scooter-style e-bike.

Source: Authors, from representative electric two-wheeler manufacturers.

End-of-Life

Because of the relatively recent appearance of e-bikes in the transportation system, little is known about the fate of e-bikes that have become obsolete or nonoperational. Many of the earliest e-bike models were simply modified bicycles, so if components failed the e-bike could still operate as a standard bicycle. More recent models would be inoperable if vital components failed. The most notable end-of-life pollution comes from lead, a toxic metal.

Lead Acid Batteries

Lead acid battery pollution is often cited as a reason to regulate e-bikes. Approximately 95% of e-bikes in the PRC are powered by lead acid batteries (Jamerson and Benjamin 2007), although this number is dropping because of more advanced battery technologies. Based on interviews with manufacturers and service facilities, the life span of an e-bike battery is considered to be 1–2 years or up to 10,000 kilometers (km). Bicycle-style e-bikes typically use 36 V battery systems, on average weighing 14 kilograms (kg). The scooter style typically uses 48 V battery systems weighing 18 kilograms. The lead content of electric batteries is 70% of the total weight, so BSEB batteries contain 10.3 kilograms of lead, compared with 14.7 kg for SSEB batteries.

This is perhaps the most problematic issue for e-bikes and is the same problem that influenced the demise of electric car development in the United States (US) in the early 1990s (Lave, Hendrickson, et al. 1995). Because of the relatively short life span of deep-discharge e-bike lead acid batteries, an e-bike could use five batteries in its life, emitting lead into the environment with every battery. Lead is emitted into the environment during four processes: mining and smelting of the lead ore, manufacturing of the battery, recycling of the used lead, and disposal of the nonrecycled lead into the waste stream. Loss rates can be expressed in terms of unit weight of lead lost per unit weight of battery produced for each process. Lave, Hendrickson, et al. (1995) cite that, in the US, 4% (0.04 tons lost per ton of battery produced) of the lead produced is lost in the virgin production processes, 1% is lost during the battery manufacturing, and 2% is lost in recycling. So, a battery composed of 100% recycled lead emits 3% of its lead mass into the environment. A battery composed of 100% virgin material emits 5% of its lead content into the environment. In most industrialized countries, lead recycling rates exceed 90%.

The PRC’s lead acid battery system is very different from that of more industrialized countries (Roberts 2006). Mao, Lu, et al. (2006) investigated the PRC lead acid battery system. They found that 16.2% of the lead content of a battery is lost during mining and concentrating, 7.2% is lost during primary smelting, 13.6% is lost during secondary (scrap and recycled) smelting and recycling processes, and 4.4% is lost during the battery manufacturing process. These rates reflect loss in terms of final battery production (not initial lead input). For instance, 1 ton of final lead output represents 0.044 tons of lead lost during battery manufacturing. Figure 1.1 is derived from the analysis conducted by Mao, Lu, et al. (2006). These very high loss rates are mostly because of poor ore quality and a high proportion of lead ref...