State Grid Corp of China, the nation's biggest electricity distributor, demonstrates the "vehicle-to-grid" (V2G) technology at the ongoing World Expo 2010 Shanghai, Nikkei reported today.

This technology enables electricity exchange between an electric vehicle (EV) and a charging stand. However, the full-fledged introduction of the V2G technology will depend on the wide use of EVs.

"Using the rechargeable batteries of electric vehicles will help stable operation of the electricity grid," said an official of Shanghai Municipal Electric Power Co, an affiliate of the State Grid, at the Expo 2010 Shanghai.

For example, when the output from renewable energy sources such as solar power drastically drops, electricity can be supplied from several tens or hundreds of EVs to the grid to reduce the number of electric outages.

State Grid has developed an EV rapid charger to support the V2G technology. When an EV is connected to this charger, it will switch between charging and discharging according to the supply of the grid.

Besides the rapid charger, State Grid also shows a normal charger, which supports a single-phase alternating current and has a maximum output of 5kW.

The demonstration uses the EV version of SAIC Motor's self-developed Roewe 350. Equipped with a 35kWh lithium-ion rechargeable battery, it runs 310km per charge.