ZIGBEE® AND THE ELECTRIC CAR
“The Volt provides enough all-electric range to meet the daily transportation needs of 75 percent of Americans without using a drop of petrol.”
At its recent centennial birthday party, General Motors unveiled the Chevy Volt, a plug-in electric car designed to travel about 64 km on a single charge and then use a petrol-powered charger to replenish the batteries on longer trips. According to GM, the Volt provides enough all-electric range to meet the daily transportation needs of 75 percent of Americans without using a drop of petrol. The cost of recharging the Volt from a standard outlet will cost “less than purchasing a cup of your favourite coffee” and will use less energy than a refrigerator in a year. Ford has also announced their plans for plug-in cars while Toyota and Nissan are planning to have their models available in 2010.
With plug-in cars becoming a reality for consumers during the next decade, consumers will be looking for smart energy solutions to optimise their electric consumption. Plug-in cars will need to communicate with the grid to optimise charging and potential discharging for the benefit of both drivers and utilities.
ZigBee wireless networking and the ZigBee Smart Energy profile are a logical choice for vehicle-to-grid communications. Although ZigBee is not currently included in any of the announced vehicles or plans to date, ZigBee Smart Energy is able to offer additional intelligence to plug-in cars.
The Volt might equal a refrigerator in annual electricity consumption, but your local utility may not want 100,000 more households adding a second fridge, especially one that runs continually from 8pm to 8am every night. Life isn’t always orderly enough to be able to maintain a consistent charging schedule either. Plug-in cars can use the features of the ZigBee Smart Energy profile for simple metering and pricing clusters to monitor the price of electricity and charge according to preferences set by drivers.
A battery that’s big enough to charge a car is also big enough to provide energy back to the garage and house to which it’s attached. Residential energy storage systems have been discussed for their wide range of benefits: including acting as resources for peak shaving; reservoirs for power created by distributed generation such as solar panels; and back-up power during outages. As with charging, plug-in cars can use ZigBee Smart Energy to monitor the price and status of power to know when to discharge.
Consumers and utilities have expressed concern over handling billing for a large and highly mobile electric device like a plug-in car. If a consumer recharges their Volt in a parking garage in another city, how does that get reflected on their electricity bill? One school of thought says it doesn’t need to show up on the consumer’s electricity bill. Think of the outlet in a petrol pump: consumers would “pay at the pump” for electricity, like the current system for petrol. With ZigBee Smart Energy, the parking garage has the potential for sub metering and to resolve charges to consumers’ credit cards or their monthly parking account.
GIANT URBAN CAPACITORS
Imagine it’s a hot day at a large downtown parking garage full of plug-in cars – each equipped with ZigBee Smart Energy. Many of the cars are plugged in after the morning commute, out of habit, and are close to fully charged. The local utility calls a demand response event for 1-3pm that day. The cars in the garage can receive the signal and respond by discharging some energy according to their owner’s preferences. Cars that put energy onto the grid will generate a credit for their owners. On this hot day, the parking garage acts as a giant urban capacitor to keep the grid reliable and prices steady. Once the demand response event ends, cars that need to can recharge and be ready for the commute home at 5pm. Downtown workers can climb into their Chevy Volts and other plug-in cars for the quiet, nonpolluting commute home. The announcement of the Chevy Volt is an exciting milestone for the automotive and energy industries. Getting a large number of plug-in cars on the road is just part of our energy challenge. Connecting these cars intelligently to the electricity grid, potentially with ZigBee Smart Energy, will make them truly a part of the Smart Grid.