With the recent reintroduction of mainstream manufactured electric cars, the big question has been about users’ real-world car-charging needs—and how utilities and municipalities can support these needs.
In 2009, Ecotality, an electric transportation and storage technologies company, received a $99.8 million grant from the U.S. Department of Energy (DOE) to study the experiences of EV charging at home, work, and public charging stations. Additional funds that more than doubled the original grant allocation were supplied by project partners—including automakers, local governments, equipment suppliers, and retailers.
“The EV Project,” says Colin Read, Ecotality’s vice president of corporate development, “is really a data collection project. We deploy infrastructure and recruit vehicle owners to help give us that data.”
The EV Project is the largest evaluation of EV infrastructure ever conducted. By November 2012, more than 6,300 drivers—nearly all owners of either the Nissan Leaf or Chevy Volt—had signed up to participate. They all received free home charging equipment and, in most cases, a large enough credit to pay for the installation, which ranges from $1,500 to $2,500.
In exchange, participants agree to give The EV Project access to their charging data. The Blink charging equipment, manufactured by Ecotality, uses wireless technology to transmit charging information to a central database.
“In some locations, it can be three or four weeks to get certified to install a charger,” Read explains. “But in other places, it’s an over-the-counter 24-hour thing.” The EV Project is located in major metropolitan areas across the United States.
| The Blink home charger logs and transmits EV charging data. | In addition to home chargers, Ecotality manufactures the 480 VDC Fast Charger, capable of a full recharge in less than 30 minutes. | With some user programming, home charging equipment (below) allows EV drivers to monitor cost, charging status, and estimated CO2 savings from the equipment’s touchscreen. |
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The EV Project has logged more than 1 million electric car-charging events. Forty million miles of electric driving have been documented, revealing these patterns:
- EV drivers are clocking about the same number of miles on average as the typical American motorist. In the third quarter of 2012 (the latest data available), Nissan Leaf owners drove an average of 30 miles per day. According to the U.S. National Highway Traffic Safety Administration, drivers of gas-powered cars average 28.9 miles per day.
- Owners of the Chevy Volt—which has a gas engine to extend driving range—drive even more miles and charge more frequently than Leaf owners. On average, Volt owners drive 41.2 miles per day and plug in 1.4 times per day, while Leaf owners charged, on average, 1.1 times per day.
- Although Volt owners can fill up at a gas station to extend driving distance, the experience of driving on electrons—and avoiding the use of hydrocarbons—is addictive. More frequent charging, while not absolutely necessary, allows Volt owners to manage nearly all of their driving without using gasoline.
- EV drivers drive longer distances and use public charging stations more often the longer they own their cars. “Either public charging is becoming more ubiquitous, or EV drivers are becoming more familiar with where chargers are located,” says Read.
- Economics matter. The lion’s share of EV charging takes place at home—in the third quarter of 2012, 67% of charging for Nissan Leaf owners took place at home. (That’s down 11% from the 78% of home charging that took place a year earlier.)
Charging patterns at home are greatly affected by the rate plans offered by utilities. In many locations, utilities offer special rates to EV drivers based on time-of-use metering. Under these plans, the cost for a kilowatt-hour of electricity can be two or three times higher during peak hours—mostly during the middle of the day—as opposed to the wee hours of the morning.
Utilities offer the cheaper rates because steady demand helps the power plants run more efficiently, helping mitigate the need for upgrades or repairing overtaxed transformers. “The last thing you want to do is add the equivalent of a household of power load—the EV’s 3.3- to 6.6-kilowatt draw—during the peak periods of the day,” says Read. “If EV users can charge during off-peak hours, there’s a benefit to the grid and to all rate payers.” It also further reduces the cost of electric fuel, which, per mile, is already half the cost or lower compared to gasoline.
In places like Tennessee, where electricity rates are low and there’s no time-of-use rate, people charge around the clock. “In California,” says Read, “where there is a higher average utility price, those time-of-use rates have a large effect [on charging behavior].”
This insight can help utility companies prepare for a time when millions of electric cars roam U.S. roads. The first million plug-in vehicles are expected by about 2017.
The EV Project’s deployment of charging equipment, on both residential and commercial fronts, is about two-thirds complete. The project is slowly working through the reservation queue as it adds the last thousand or so participants.
