Distribution networks, V2G

V2G, Vehicle to Grid, is the technology that enables electricity storing during off-peak hours and electricity recovering from electric vehicle batteries into the network during peak hours. V2G technology allows batteries to charge during off-peak hours, when kWh is cheaper, and selling it to the network during peak hours, when the kWh is more expensive. Everyone wins with V2G: vehicle owners, electricity supply companies, society and the planet, although an appropriate infrastructure (currently inexistent) should be created first. Even without V2G, transport electrification has important benefits for all.

China and India, due to a lack of the classic transport infrastructure based on hydrocarbon, are expected to be the first countries to implement major transport electrification. This technological leap is very similar to that from developing countries, which implemented cellular phones without the fixed telephone intermediate step. China is the major lithium battery manufacturer and has BYD Motors and other leading companies which collaborate in the development of electric vehicles. A similar situation is to be found in India with manufacturers Reva and Tata. In both countries a huge growth of the vehicle fleet is expected together with the emergence of a new middle class, which will be able to own a vehicle for the first time.

Vehicle recharging may be conductive or inductive. The conductive system is a direct plug-in to network, as simple as plugging in the vehicle through special high capacity wires with connectors that protect drivers from high voltage. Inductive connection has the advantage to prevent electrocution. However, it is more expensive and less efficient than the first one.

Network electricity is supplied to the vehicle in alternating current. The charger usually converts it into direct current and supplies it to the battery at the appropriate voltage, from where it is subsequently supplied to engine and wheels. Some engines work with alternating current, so a reverser must convert the direct current of the battery.




Given that in Spain, like in most countries, the night or off-peak fee is lower than the normal fee, it would be advisable to recharge batteries at night. An intelligent network of thousands of charging stations in streets and parking lots with appropriate software would advise the car user on the right time for recharging, stopping or even deliver electricity into the network. It must be taken into account that a vast majority of the car fleet is parked during most of the time, and generally it is only used around one or two hours per day. On average, 95 % of all vehicles are parked at some point and are used half an hour per day.



Electric vehicles might therefore play a crucial role in the better management of the network, flattening the charge curve, profiting from the so-called active reserve, which usually is wasted (the amount of electricity available to ensure immediate availability in case of need due to an unexpected increase of the demand) and enabling the rise of wind energy and other renewable sources contribution. It might also involve a reconversion of the electricity supply and transport sectors, promoting the creation of new specialized companies, following a similar model to that in the cellular phones sector.

The active reserve might supply the electricity consumed by a third part of the car fleet in most countries, as long as the appropriate network exists. Besides, it would also prevent having to create a highly expensive generation capacity that it would only be used a few hours a year, those 30-40 hours coinciding with a cold or heat wave. An average electric vehicle covering 17,000 km a year and performing an 80% of the recharge with night fees would spend about 800 € a year in electricity. Taking into consideration the average driving patterns, covering the same distance with gasoline or diesel would involve spending between 2,000 and 2,500 € in fuel.

For electricity supplying companies, transport electrification would not only mean the opening of a new market for their product, electricity, but also the possibility to optimize the generation park and the electric network, flattening the charging curve by promoting a new demand during off-peak hours. This could be achieved by means of an intelligent battery recharging system managed by computer, which would advise on the right moment to charge, stop or deliver electricity into network during peak hours. This system is ideal to manage the growing contribution of wind energy and take a huge leap towards electricity generation sustainability.