The use of electric vehicles is severely restricted by current battery life of the vehicles in use. The batteries can only store a limited amount of power and must be recharged or replaced regularly, just as a petrol car must be refilled.

Here we will consider the costs of a vehicle that is only run by electricity compared to a vehicle run by petrol or diesel. All comparisons are made excluding tax.

**Cost of electricity**

Link [1] shows the cost of new electric production.

As an average the spot price is around the same as the price of new electric production that is 0.40 SEK/kWh. This price excludes the cost of transmission, distribution and taxes. Let us compare this base price and to what petrol fuel costs without taxes.

**Cost of fuel**

The costs of petrol and fuel has increased eaqually in recent years.

**Energy relation petrol/electricity**

In order to compare the operation costs of petrol cars and electric cars, we need to understand the efficiency ratio of the two vehicles.

Fossil fuels have a net energy content of 33 MJ/litre for petrol and 35 MJ/l for diesel. A petrol motor has an efficiency of around 30% at maximum load, link [2]. A diesel motor has an efficiency of around 40% whereas, an electric motor has an efficiency of around 90%. However, allowing for reduction in the electric motor efficiency for the drive and loss of power in the batteries, we can estimate the net efficiency to be around 85%.

**Calculations and Conclutions**

**Petrol car costs**

Assume that the average petrol car consumes 0.8 litres per 10 km. The motor, therefore, requires an energy output of 0.8 * 33 MJ * 30 % = 7.9 MJ

The cost to operate a petrol car excluding tax is 6 SEK * 0.8 = 4.8 SEK per 10 km.

**Electric Car Costs**

Corresponding car that is run by electricity need 7.9 MJ / 85 % = 9.3 MJ, that is 2.6 kWh.

The cost of electricity without tax is 2.6 kWh * 0.4 SEK = 1.0 SEK

The saving excluding tax is 4.8 – 1.0 = 3.8 SEK per 10 km.

If we consider the effect of current tax rates, the difference becomes even more pronounced. Including tax the cost of petrol is 4.8 SEK *100 / (100-55) =10.7 SEK while the cost of electricity is 1.0 SEK *100/(100- 47) = 1.9 SEK. This is a difference of 8.8 SEK/10 km.

**Conclusion**

The cost benefit to the user of an electric vehicle at current petrol and electricity prices is significant. The analysis of electric cars is based not only on the cost saving, but also the environmental impact.

[1] http://www.aktiefokus.se/wp-content/uploads/2011/08/image022.png

[2] http://sv.wikipedia.org/wiki/Ottomotor