Sunday, December 30, 2012

Electric Car Charging Stations & Grid Storage

Conventional cars need to visit a petrol station to refuel which can often be a time consuming task. In some cases, filling up at a petrol station can add even more miles to a journey depending on its location.

One advantage with electric cars is that they can be plugged in to a normal power socket at home allowing the battery to be changed whenever it is convenient. The task of queuing and paying at a petrol station will be a thing of the past.

For some people, however, it will not be possible to change their cars from their own homes as it would result in power cables running across the pavement. To solve this, additional charging points could be installed outside private homes, workplaces and public locations.
Another advantage with cars being plugged in to charging points is that energy stored in the battery can be borrowed when we need extra electricity for powering our homes and offices. It is better to take this extra electricity from the cars’ batteries than generate it using dirty fossil fuels. These smart chargers would be aware both of the value of electricity, and of the car user’s requirements (for example, “my car must be fully charged by 7am on Monday morning”). The charger would sensibly satisfy the user’s requirements by guzzling electricity whenever renewable energy is available, and switching off when the renewables drops. These smart chargers would provide a useful service in balancing to the electricity grid, a service which could be rewarded financially.

If a car driver needed to make an unplanned long journey and didn’t have time to wait for the car’s batteries to fully charge, the car could be driven to a nearby charging station for a complete battery swap.  In the USA, Better Place have designed a battery switch station to achieve this.

At a Better Place switch station, the driver enters a lane and proceeds along a switch-lane conveyor. The automated switch platform below the vehicle will align under the battery, initiate the battery release process and lower the battery from the vehicle. It will then replace the depleted battery with a fully-charged battery. The depleted battery is placed in a storage room and recharged to be available to other drivers.  The process is completed in just a few minutes, while the driver remains in the car, providing a fast and convenient range-extension solution.

This solution would probably require a number of standards to be developed to swap batteries from different types of vehicles.

For more details on electric vehicles and charging see
For more details about how cars can be used as a storage system for intermittent renewables then see page 195 in Chapter 26 at

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