Check out the ClimateAction Center E-Bike Buyers Guides to learn more about how e-bikes work, and how to buy and take care of one. An increasing number of incentive programs are making e-bikes more affordable.
The US EPA defined the term MPGe (Miles Per Gallon equivalent) to rate energy efficiency of an electric vehicle comparably to how we rate and label gas vehicles for fuel efficiency. It compares the energy in the charging electricity compared to the energy in a gallon of gas.
According to the EPA, one gallon of gas has the energy equivalent of 33.7 kilowatt-hours (kWh) of electricity. To determine the MPGe for an e-bike or other electric vehicle, we measure the miles an electric bike or car goes on a charge, divide it by the number of kilowatt hours of electricity it takes to recharge and multiply by the 33.7 kWh/gallon energy equivalence factor.
We normally record electric charging energy in "kWh per 100 miles" since the amount of kilowatt hours used per mile is very low - usually between 0.01 and 0.02 Hence the formula is:
Miles per Gallon equivalent (MPGe) = 100 miles X 33.7 kWh/gallon gas (EPA MPGe factor) / kWh (of electricity to charge the battery) per 100 miles [1]
Although e-bikes and electric cars have no emissions at the tailpipe, there are still climate gases (and other pollutants) emitted from some of the electric generating stations making the power they use to charge their batteries. Electricity generation is getting to be a steadily more climate friendly way to get energy as more renewable carbon free sources, such as wind and solar are added to the grid each year. But plenty of fossil fuels are still used in the mix.
To calculate the CO2 (carbon dioxide) emitted from generating the electricity used to charge e-bikes and electric cars we divide the state utility CO2 emissions for a year by the total kWh produced to obtain a CO2/kWh factor. [2] For the CO2 from gasoline burned in cars we use a factor of 19.4 lbs CO2/gallon of gas from the U.S. Energy Information Administration. [3]
The carbon dioxide emissions from electricity generation vary widely from one utility to another. In the United States, 2016 CO2/kWh rates ranged from 0.057 in Vermont to 2.026 in Wyoming averaging 0.998 across the United States. Even when charged in Wyoming with the most carbon intensive electricity in the US, an e-bike has only one tenth the carbon emissions per mile of a 30 MPG gas car. [4]
You can view a googlesheet that contains many of the factors and calculations we use in this project here.
One of the challenges of a conversion to all electric transportation is that the batteries require a lot of material. Lithium is strip mined causing significant environmental damage while cobalt and graphite are linked to serious pollution issues and human rights violations. Just as every e-bike trip that replaces a gas car trip dramatically reduces climate change emissions, every e-bike trip that replaces an electric car trip dramatically reduces lithium, cobalt and graphite usage. Our analysis indicates that e-bikes get 30 to 100 times more miles per pound of battery than electric cars. Find out more about the problems with batteries and how we calculated the e-bike differential on the Battery page.
You bet! If 20% of all Americans got out of their cars on to an ebike for just 5 miles a day, it would replace more than the oil that we currently import from Russia.