The Environmental Impact of Electric Bicycles: A Life Cycle Assessment of Transport Options for Commuters

Summary

This study compares the relative environmental impact of the following modes of transportation: foot (walking), bicycle, electric bicycle, automobile, bus, train, and airplane. It was conducted by a graduate student at MIT under standard academic practices for Life Cycle inventory calculations.

Life Cycle Assessment allows the comparison of each stage of energy input and greenhouse gas emission. Any mode of transportation requires a certain input of energy to manufacture, assemble, and operate. In addition, energy is required to construct and maintain the infrastructure required for operation and there is an end-of-life environmental impact to disposal of the vehicle. Every form of energy input, from electricity to gasoline to human calories is associated with some release of greenhouse gas emission. Greenhouse gases have been identified as a significant driver of climate change and environmentally responsible choices require full assessment of a product’s life cycle impacts.

Findings

The results from this study will enable commuters to make informed choices about their modes of transportation. It is apparent that electric bicycles rank in the top three forms of transportation when it comes to minimizing environmental impact. In fact, 

An electric bicycle is:

• about 18 times more energy efficient than a SUV
• about 13 times more energy efficient than a sedan
• about 6 times more energy efficient than rail transit
• and, of about equal impact to the environment as a conventional bicycle. 

Furthermore, both bicycles and electric bicycles are often not used to their end-of-life. In other words, the more miles that a bicycle travels, the less of an environmental impact it has per mile. The same is true for electric bicycles because the majority of the impact is in the manufacture of the product, rather than the operation.

Beyond these findings, the role that society plays in the efficiency of vehicles is very interesting to consider. There is, for each mile traveled by a passenger, less of an environmental impact from traveling by Boeing 737 than from taking a standard bus for the same distance. This can be attributed to the fact that it is incredibly expensive to operate an airplane that is not to a certain capacity. More people on a flight means that there is less of an impact per person. Buses, by contrast, operate as a public service, running at regular intervals and as a result, may run with very few passengers at certain hours. On average, the impact per person-mile-traveled is higher.

Below is a graph that represents greenhouse gas emissions per passenger-mile-traveled for each mode of transportation analyzed. Clearly, walking, bicycling and electric bicycling have the least impact environmentally.

Figure 1: Greenhouse gas emissions per passenger-mile-traveled.

In summary, both technology and habit influence the energy and environmental impact of transportation options. It is important to recognize that what ultimately matters environmentally is the cumulative impact. For an automobile, the tipping point may be, that increasing the number of miles it travels will reduce the impact per mile – until energy required for the operation phase of the vehicle exceeds the energy input of manufacturing – but cumulatively, increasing energy input increases the greenhouse gas emissions. Therefore, for each additional mile one may travel, choosing the appropriate mode of transport with the lowest emission per PMT is important.

Download the complete research paper:  The Environmental Impact of Electric Bicycles: A Life Cycle Assessment of Transport Options for Commuters