Smart and Smarter Synchronizing the Smart Grid with Electric Cars and Hybrids

Coupled with a growing fleet of hybrid electric, and eventually fully electric, vehicles, the smart grid could save massive amounts of power, enable alternative energy and be a potent weapon in the fight against climate change. But the question of how best to integrate alternative energy options is tricky. Wind and solar are intermittent. Electric cars rely on an expensive battery and need time to power up. Maximizing alternative energy requires a new kind of intelligence and flexibility.

Fortunately, that dynamic mix should soon be available in the form of a smart grid that’s able to deliver electricity with pinpoint efficiency. Electric vehicles will take in electricity when the rates are lowest. Even better is the possibility that such vehicles will then return electricity to the grid when it’s most needed. A smart grid would essentially “let the grid reach down and optimize delivery,” says Allen Hefner, a scientist on the Smart Grid Team at the National Institute of Standards and Technology.

Charge by Night

In one likely scenario, plug-in vehicles would power their batteries late at night when demand is low. Then, when demand is high, hundreds of thousands of vehicles would return energy to the grid as needed. Institute of Electrical and Electronics Engineers (IEEE) Fellow Alan Mantooth describes “a nine-story garage full of electric vehicles’ that he says will function “as one big battery.”

Storage has long been a problem for alternative energy, given that solar power can be disrupted by clouds and is unavailable at night, and wind might die down when most needed. The use of plug-in vehicles as storage units, regulated by a smart grid, would thus provide tremendous flexibility, squeezing more out of alternative energy.

“If everyone plugs in their vehicles at 5 p.m., the grid can’t take it.”

Such a scenario “demands a certain level of study,” says Mantooth, “to come up with charging/discharge algorithms.” Because a battery pack for an electric car costs upwards of $10,000, the possibility that recurrent charging and discharging would wear out the battery remains a problem. The hope is for a resilient battery capable of performing long-term under a variety of conditions. While studies are not complete, anecdotal data on the hybrid electric Toyota Prius shows that “batteries have been holding up nicely,” says Mantooth. Another factor is how slowly or quickly batteries charge and discharge energy, with a quick-charge battery the most flexible option to date.

Smart grid users would have control over when their car takes in energy, for instance setting it to charge only at times of minimum costs, if they know their vehicle is to be parked for a long time, or to charge quickly despite cost if they’ll need it soon. “If everyone plugs in their vehicles at 5 p.m., the grid can’t take it,” says Hefner. Instead, charging can be “staggered over a long period of time.”

The Plug-Ins

Two kinds of plug-in vehicles are now or will shortly be available. Hybrid electric cars that depend on a gasoline engine for extended range will include the Fisker Karma, the Chevy Volt and a new version of the Toyota Prius. Fully electric cars include the already-available Tesla Roadster and the Nissan Leaf.

Hybrid and electric cars are only a real environmental step up if coupled with greater use of alternative energy. Mantooth points out that the possibility of switching to 100 million electric cars in the U.S., if tied to an electric system based largely on coal, as we have today, would be “trading one problem for another.” Renewable energy dispatched through a smart grid, conversely, would be “a big net plus for electrical efficiency and reduction of greenhouse gases.”

Two experimental projects are already combining electric vehicles and the smart grid. Toyota, in partnership with Xcel Energy, is supplying about 20 hybrid electric Priuses to SmartGridCity, a working prototype of the future located in Boulder, Colorado (see “A City Gone Smart,” page 26). While SmartGridCity was launched in 2008, the electric car part of the program is set to begin by July of this year.

Beyond technology, the program is testing “a lot of other social and behavioral questions,” says Jaycie Chitwood, future fuels and environmental strategy manager at Toyota. “One of the goals has been to incentivize customers to balance the load between charges, peaks and valleys.”Infrastructure Issues

But SmartGridCity still has a problem—car batteries will be charged primarily from homes. “There aren’t any public stations yet, say in hotels or underground parking,” says Chitwood. “Right now there’s not a lot of that in Boulder or anywhere.” Furthermore, interaction is one-way, with cars taking power from the grid but not able to return it, and to act as storage batteries.

To begin to put a broader infrastructure into place, the Electric Transportation Engineering Corporation, eTec, is working on the EV Project, funded by a $100 million grant from the U.S. Department of Energy, to bring charging stations to five states: Arizona, California, Oregon, Tennessee and Washington. Some 11,000 charging stations are projected. While most will rely on the grid, 125 will be equipped with solar panels to provide energy from the sun directly to cars. According to Burak Ozpineci, leader of the Power and Energy Systems Group at Oak Ridge National Laboratory (ORNL), “these charging stations will be like gas stations’ for electric cars.

As part of this effort, a pilot project with 100 charging stations is to be installed in December 2010 on the Tennessee campus of ORNL. Participants will drive the Nissan Leaf, a 100% electric vehicle. Twenty-five of the charging stations will be solar, allowing a driving experience free of gasoline, coal or other fossil fuels. Nevertheless, as with SmartGridCity, the project will not allow cars to put electricity back into the grid. No vehicles near production have that capability, according to Ozpineci.

The project will also study how to implement electric cars in a smart grid setting as used by actual human beings. “It hasn’t been done,” says Ozpineci. “We’re trying to come up with best practices,” he adds, including such mundane details as keeping people from tripping over power cords. The project will closely monitor habits, such as how often, at what times and at what levels consumers charge their vehicles. Another option being studied is whether consumers might have an extra battery at home to be charged while the vehicle is on the road.

The Gas Factor

Hefner believes that everything is in place to begin the evolution toward hybrid electric, and then fully electric cars coupled to a smart grid. Businesses are taking the initiatives that could build into a complete system. “The infrastructure can evolve,” he says. “We don’t need to replace every gasoline station now.” Hybrid electrics could at first charge up only at home, then at select parking lots and eventually at roadside stations.

But the viability of converting to a combination of electric cars and a smart grid depends largely on the cost of the alternative: today’s gasoline. If the “price of gas is at $2 a gall

on, this ain’t gonna happen,” says Mantooth. “But at $4.50 a gallon, this will happen.”

Of course, the price of gas could be artificially increased if a carbon tax is instituted. As Hefner points out, “the cost of delivering service can include social costs such as carbon dioxide emissions.”