This article is based is on a writeup by Mr Elon Musk, founder on Tesla Motors (link here). We have presented this with new calculations based on Indian conditions and also have documented multiple use cases.

**Use Cases**

Here are some use cases, where we calculate the well-to-wheel efficiency and compare the results in terms of efficiency and CO2 emissions.

- Small petrol car vs Small electric car
- Diesel SUV vs Electric SUV
- Petrol scooter vs electric scooter

## Small petrol car vs Small electric car

**Well-to-Wheel efficiency of a small Indian petrol car**

Petrol has a calorific value of 34.3 MJ/liter. (34300000 Joules or 9528 Wh or 9.5 kWh)/liter

The fully considered well-to-wheel efficiency of a petrol powered car is equal to

- The energy content of petrol (34.3 MJ/liter) minus the refinement & transportation losses (about 33% in India), multiplied by the km per liter.

In other words, to travel a distance of 1 km, a small petrol car must expend

**3.45 MJ or 955 Wh**of energy.

**Well-to-Wheel efficiency of a small Indian electric car**

After observing data from users of the Mahindra e2o electric car, we find that on an average, an electric car in Indian road conditions consumes 90 Wh/km

We know that 1 Wh = 3600 J, so 90 Wh = 324,000 J. And the power plant efficiency, conversion and transmission losses in electricity in India are 70% or more.

So an Indian electric car @ 90 Wh/km has an efficiency of 1/(3600 divided by (100% minus 70%)) x 10^6 x (1/90) km/Wh = 0.93 km/MJ.

We then multiply this by the "The full cycle charge and discharge efficiency of the electric car". Let us take this factor as 80% for the e2o.

Then the final efficiency is 0.93 x 80% = 0.74 km/MJ or 0.74 km/277 Wh

In other words, to travel a distance of 1 km, a small electric car must expend

**1.35 MJ or**

**375**

**Wh**of energy.

**Verdict**

An small electric car is more than 2.5 times efficient than an equivalent petrol car.

## Diesel SUV vs Electric SUV

**Well-to-Wheel efficiency of a diesel SUV**

Diesel has a calorific value of 38.4 MJ/liter. (38400000 Joules or 10666 Wh or 10.6 kWh)/liter

The fully considered well-to-wheel efficiency of a diesel powered SUV is equal to

- The energy content of diesel (38.4 MJ/liter) minus the refinement & transportation losses (about 33% in India), multiplied by the km per liter.

In other words, to travel a distance of 1 km, a diesel SUV must expend

**5.88 MJ or 1633 Wh**of energy.

**Well-to-Wheel efficiency of an electric SUV**

After from the official EPA data of the Tesla Model X electric SUV, we know that that it has an efficiency of 237.5 Wh/km

We know that 1 Wh = 3600 J, so 237.5 Wh = 855,000 J. And the power plant efficiency, conversion and transmission losses in electricity in India are 70% or more.

So a Tesla Model X electric SUV @ 237.5 Wh/km has an efficiency of 1/(3600 divided by (100% minus 70%)) x 10^6 x (1/237.5) km/Wh = 0.35 km/MJ.

We then multiply this by the "The full cycle charge and discharge efficiency of the electric car". Let us take this factor as 90% for the Tesla.

Then the final efficiency is 0.35 x 90% = 0.32 km/MJ or 0.32 km/277 Wh

In other words, to travel a distance of 1 km, an electric SUV must expend

**3.12 MJ or**

**867**

**Wh**of energy.

**Verdict**

An electric SUV is more than 1.8 times efficient than an equivalent diesel SUV.

## Petrol scooter vs Electric scooter

**Well-to-Wheel efficiency of a petrol scooter**

Petrol has a calorific value of 34.3 MJ/liter. (34300000 Joules or 9528 Wh or 9.5 kWh)/liter

The fully considered well-to-wheel efficiency of a petrol powered scooter is equal to

- The energy content of petrol (34.3 MJ/liter) minus the refinement & transportation losses (about 33% in India), multiplied by the km per liter.

In other words, to travel a distance of 1 km, a petrol scooter must expend

**1.03 MJ or 286 Wh**of energy.

**Well-to-Wheel efficiency of an 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/MJ or 2.26 km/277 Wh

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

**0.44 MJ or 122**

**Wh**of energy.

**Verdict**

An electric scooter is more than 2 times efficient than an equivalent petrol scooter.

**Note**

Power plant efficiency

*is*bundled with T&D losses. My figure of "70% losses" was a loose surrogate for BOTH generation loss and transmission/distribution loss.

After further research, I discover that:

- 33% is the efficiency of coal conversion (i.e., power plant efficiency),one of the lowest among major coal -based power producing countries, so I can peg the overall fuel to power generation as 40% because not all fuel is coal.
- According to WRI, Indian T&D losses are 27%. The highest in the world.

Therefore the power produced and delivered from 100 units of fuel in India is 40% x (1-27%) = 29.2 units. Therefore the overall losses are 100 - 29.2 = 70.8% just a bit more than my loose estimate.

**CO2 Emissions**

Applying those carbon content levels to the vehicle efficiencies.

For 1 km of driving,

- Carbon footprint of a small petrol car = 3.45 MJ/km x 19.9 g/MJ = 68.66 g/km
- Carbon footprint of a small electric car = 1.35 MJ/km x 23.8 g/MJ = 32.13 g/km
- Carbon footprint of a diesel SUV = 5.88 MJ/km x 19.9 g/MJ = 117.01 g/km
- Carbon footprint of an electric SUV = 3.12 MJ/km x 23.8 g/MJ = 74.25 g/km
- Carbon footprint of a petrol scooter = 1.03 MJ/km x 19.9 g/MJ = 20.47 g/km
- Carbon footprint of an electric scooter = 0.44 MJ/km x 23.8 g/MJ = 10.47 g/km

The higher CO2 content of coal is offset by the negligible CO2 content of hydro, nuclear, geothermal, wind, solar, etc. The exact power production mixture varies from one part of the country to another and is changing over time. When you consider that, electric vehicles get even greener over time.

**Watch our videos on the PluginIndia Youtube channel**