Nissan says its new electric vehicle, the Nissan Leaf, can provide emergency power to your home during a power failure or brownout (shortage). The charging system that takes power from the wall outlet can, with modifications, run in the opposite direction and provide power back to your house. In Japan, Nissan says there’s enough power to run the average Japanese home for up to two days. In the United States with our higher demands for power, like the beer fridge in the garage, we calculate that you’d fully drain the battery within 20 hours.

Nissan last week said it has a prototype running in Japan and will bring it to market by spring 2012. Systems for other markets would follow later, once Nissan can adapt them for those markets. The system was unveiled at the Kankankyo environmentally friendly model house at Nissan headquarters in Yokohama. The power connection runs from a 200 volt, single phase three-wire connection at the house’s electrical distribution panel to a power control system in the garage to the car’s standard quick charge connector. Normally the switching panel sends current to the car. By flipping a switch, the house can draw power from the car.