Electric cars: calculations

Was wondering how efficient electric vehicles really are, and made some back of the envelope type of calculations, and here is what I ended up with.

Total installed capacity : 128581.47 MW

Thermal : 84404.84 MW = 65.6%

Efficiency of Thermal (including coal, diesel and gas) :

contribution of Coal – 82.48% at 40% efficiency.

contribution of Gas – 16.09% at 60% efficiency.

contribution of Diesel – 1.5% at 40% efficiency.

Average efficiency = around 43%.

Hydro : 34085.77 MW = 26.5%

Average efficiency = 70%

Rest : Renewables and Nuclear = 7.9%

Average efficiency = 60% (bad for nuclear and good for wind, solar). Since we have no proper values for efficiency of renewables, keeping the value low.

Total efficiency of power generation in India = 51.5%, which is not a very conservative one, probably very optimistic!

All values were taken from the power ministry website.

Transmission and Distribution losses in India = 23% among the worst in the world, TERI. Thus efficiency is 77%.

Conversion from AC to DC for storage = around 95%

Conversion back to AC for driving AC motor = around 95%

Have assumed very good values here for more optimistic values.

Efficiency of AC motor = 90%

Overall efficiency = product of all above efficiencies = 32.2% !!! In comparison, petrol engines have efficiencies of 30% and diesel engines 45% !

Also since coal is the mainstay, and this has a calorific value of round 5000 Kcal/Kg, when compared to petrol and diesel, around 10000 Kcal/Kg, we consume more amounts of fuel to get equivalent performance.

Only saving grace is that one tonne of coal is considerably cheaper than diesel or petrol, almost 10-20 times.


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