What final assessment for FULL of cars?
In the transition from the stinky and polluting petroleum vehicle to the electric vehicle which is the friend of butterflies, one last point of detail remains to be seen: what additional capacity of electric production should be provided to electrify the current fleet of land vehicles which are not already (those that already are trains, trams and trolleys, for the most part). For this we will do a little calculation for France:
Current transport consumption is 54 million tonnes of oil equivalent (1 tonne of oil equivalent = 11.600 kWh; see definitions here), i.e., at constant final energy, around 600 TWh (1 Twh = 1 billion kWh).
In this set, around 5 Mtoe go to air and sea transport, so land transport consumes around 50 Mtoe, or about 550 TWh. In this set, private vehicles represent a large half (utilities and trucks the other half).
A car heat engine has an efficiency of around 20% on average on fuel consumed (it is rather 40% for heavy goods vehicles), which means that the mechanical energy that comes out of the engine is equal to 20% of the energy released by the combustion of the fuel, the rest leaving in the form of heat. The electric motor, it has an efficiency of 80% on electricity used (it's the same meaning), but ...
Storage loses around 20% of the electricity produced, while gasoline storage consumes zero as a first approximation,
electricity distribution losses are 8% (from the power station to the low-voltage outlet) for electricity, but rather of the order of 2% to 3% for fuels,
and for an electric vehicle it is necessary to use the battery to supply the auxiliaries (heating in winter, headlights, windshield wipers and defoggers, etc.) whereas for a thermal engine it is given almost free of charge (in particular the heating, which on a vehicle electric in winter can almost double consumption),
in short, the efficiency of the electric chain is 0,8 (motor efficiency) * 0,8 (storage efficiency) * 0,92 (distribution efficiency) * 0,8 (use of auxiliaries) ≈ 50% in total , against 0,2 (engine efficiency) * 1 (storage efficiency) * 0,98 (distribution efficiency) = 0,2 for the heat engine as a first approximation.
the electric chain is therefore 2,5 times more efficient than the "fuel" chain, so it would take a little more 200 TWh electric to electrify all current road vehicles with identical performance (same masses, same powers, same distances traveled). This is roughly half of French electricity consumption (which is around 450 TWh).
If we intend to produce this electricity with nuclear, it is necessary - without taking into account the possible optimization of existing reactors, in particular with the night load, of which I do not know what that can represent - add about 18 EPR (based on 8000 annual hours of production at full power per year and 1,6 GW of installed power per EPR), for an investment cost of around 110 billion (in 2012) and a lifespan of around 60 years. To this must be added the "strengthening of the network", because going from 550 TWh transported to 750 TWh is not done with a constant network. To give a basis for comparison, French GDP is around 2000 billion euros in 2014, and, on the basis of 100 dollars per barrel and 1,3 dollars per euro, the import of oil for fuels truck costs us around 30 billion euros per year,
If we intend to produce this electricity with wind turbines, you have to install about 110 GW of power (based on 2000 annual production hours at full power per year), at a cost of around 150 billion (in 2014) on land, and a lifespan of 20 to 30 years. To this must also be added the "strengthening of the network", and inter-seasonal storage capacities because wind power produces more in winter than in summer. In practice, this cost must be increased by a factor of 3 for the part of the electricity that needs to be stored elsewhere than in car batteries. For example, installing a kW of pumping station, a kind of double dam that serves as a storage system, costs 5000 or 6000 euros per kW installed in France, much more than the wind turbine itself.
If we intend to produce this electricity with photovoltaic solar panels, it is necessary to install approximately 220 GW of power (on the basis of 1000 annual hours of production at full power per year), at a cost of around 400 billion euros (in 2016), and a lifespan of 20 to 30 years. To this must also be added “network strengthening” and intermediate storage capacities, as above.
If we intend to produce this electricity with gas power stations, knowing that the efficiency of these installations is around 50%, then we must import 450 TWh of gas for these power stations, which is just 20% less ... than oil saved !! (and an import cost of around half the cost of imported oil). These plants will emit CO2, certainly less than with oil, but the discount will be "only" by 40%, which will not be enough to divide the emissions by 4 to 5. In addition, 30 GW of plants would have to be installed gas (based on 8000 hours of production per year), at a cost of around 15 billion euros (and a lifespan of 40 years).
Recall that European gas comes 60% from the North Sea, which has passed its peak in production, and 20% from Russia, which should not significantly increase its exports to Europe (the "growth reserves" in Russia are located in eastern Siberia, and they will probably go ... to the Chinese).
If we intend to produce this electricity with coal plants, knowing that the efficiency of these installations is around 40%, then we would have to import 550 TWh of coal - around 70 million tonnes of coal - per year for these plants , and an import cost of around 6 billion euros per year. It would then be necessary to install 30 GW of coal-fired power plants (on the basis of 8000 hours of production per year), at a cost of around 45 billion euros (and a lifespan of 40 years). And in such cases the CO2 emissions due to mobility would increase by 50%!