Indirect Emission Myths Revisited

Electric vehicles (EVs)  produce indirect emissions through the production of electricity to charge the batteries.

This is true, but when calculating the “well to wheels” efficiency of conventional scooters, we discover that they are less than half as efficient as electric scooters, even after taking into account the production of electricity to power the batteries.

Petrol scooter:

  • Petrol has a calorific value of  9.5 kWh)/liter
  • The fully considered well-to-wheel efficiency of a petrol powered scooter is equal to the energy content of petrol (9.5kWh) minus the refinement & transportation losses (about 33% in India), multiplied by the km per liter.
  • So a regular petrol scooter giving 50 km/liter has an efficiency of 1/(9.5kWh divided by (100% minus 33%)) x 50 km/l =  0.97 km/277 Wh

In other words, to travel a distance of 1 km, a petrol scooter must expend  286Wh of energy.

Electric scooter

  • After observing data from users of electric bikes like Hero electric, Morello Yamasaki and also getting test data from upcoming e-bikes like Ather S340, we find that on an average, an electric scooter in Indian road conditions consumes 33 Wh/km
  • And the power plant efficiency , conversion and transmission losses in electricity in India are 70% or more.
  • So an Indian electric scooter @ 33 Wh/km has an efficiency of 1/(3600 divided by (100% minus 70%)) x 10^6 x (1/33) km/Wh = 2.52 km/MJ.
  • We then multiply this by the “The full cycle charge efficiency of the electric bike”. Let us take this factor as 90% for ebikes.
  • Then the final efficiency is 2.52 x 90% = 2.26 km/277 Wh

In other words, to travel a distance of 1 km, an electric scooter must expend 122 Wh of energy.

Conclusion: An electric scooter is more than twice as efficient as an equivalent petrol scooter.