The vision of hundreds of thousands of electric cars buzzing along American highways and byways makes most utility companies downright giddy. It’s not just the opportunity sell a lot more electricity that gets them excited. “We think there’s a fundamental game-changer here. And that’s energy storage,” said Ed Kjaer, director of electric transportation at Southern California Edison. “For the first time in 120 years in our industry, the commodity we make we may no longer have to make and consume simultaneously.”

Because the grid is currently unable to store energy, utilities are forced to build and maintain base load stations—to provide the majority of power—as well as facilities to handle peak loads during period of high energy demand. These “peakers,” which run during summer months when our air conditioners are blasting for example, are inefficient, expensive, go unused 90 percent of the time, put a strain on transmission and distribution systems, and have less ability to utilize renewable energies. But what if we take the base load energy, and fill up mobile energy storage devices—more commonly known as hybrid or electric car batteries—during off-peak hours? We could then put that energy to good use: transporting people from Point A to Point B in their cars. The practice of using more energy when it’s available but not usually in high-demand is called “valley-filling.”

Researchers at the Department of Energy’s Pacific Northwest National Laboratory have been studying the ramifications of valley-filling and gas-electric hybrids that come equipped to take a charge via a plug. “We set out to study how much power the United States power grid could supply vehicles today,” said Robert Pratt, manager of the Lab’s GridWise Program. Pratt puts that number at about 70 percent of U.S. cars with the energy we can generate and deliver today. “That’s half of our foreign oil. That’s a number that rocks you back in your chair.”

The Car as Electric Device

Electric utility managers go from giddy to euphoric when this idea is taken to the next stage: the creation of two-way energy system between cars and the grid. Pratt and his fellow researchers estimate that all the energy needs for the entire United States could be run for five hours from a nationwide fleet of plug-in hybrids, if those vehicles held enough battery energy to run a vehicle in all-electric mode for 33 miles. More importantly, the ability to pull energy from vehicles during high usage periods could greatly reduce (or “shave”) the peaks. Pratt refers to the ability to store energy and to stop running peaking plants as “the holy grail for the grid.”

In this utopian vision of cars and the electric grid, the electric vehicle or plug-in hybrid becomes like another appliance in the home. Your home’s energy management system doesn’t just manage your car, but your dishwasher, your washing machine, your air conditioning system, and your home energy storage system. “As part of the whole system, the car will be just one component,” said Efrain Ornelas, environmental technical supervisor at Pacific Gas and Electric’s Clean Air Transportation Department. Ornelas looks to a day in the near future when customers will be able to program a home energy system to charge your car from the grid only when it makes sense for you. “Maybe at a point when the price of grid electricity is competitive with gasoline, you may not want to necessarily charge the vehicle. It all comes down to customer choice.”

Back to Earth

If the opportunity represented by the merger of cars and the electric grid into a single energy system is profound, the challenges are just as vast. “There’s a lot of talk about vehicle-to-grid,” said Kjaer. “We get all spun up about how exciting this is. Vehicle to grid is kind of like hydrogen and fuel cells. It’s not just around the corner.” Kjaer can easily rattle off a laundry list of problems to be solved before the car-grid utopia becomes a reality, most notably the current lack of plug-in hybrids or electric vehicles on the market; the lack of next-generation car batteries; the lack of a smart grid that can move energy back and forth; and the lack of common codes and standards for all of these things. He said, “Today, every single battery in every single car from every single automaker and every single driver is different.” On top of that, there are at least six different lithium ion battery technologies competing for prominence in the hybrid market.

Then, add all the IT and communications complexities of exchanging and pricing a two-way energy system throughout the daily cycle. “The utility will want to turn some cars on as soon as they get home on a day that’s not too hot,” said Pratt. “As the evening wears on, and the normal electric load from buildings drops, you’re turning more and more cars on. This is a very nuanced thing. And the current time of use block rate doesn’t communicate with any nuance.” The system will need to facilitate communication “handshakes” between cars and the grid, while balancing the relative state-of-charge of each car, and how urgently the owner of that car wants the juice.

None of this has been worked out yet. PGE’s Ornelas said, “The biggest area we need to focus on is codes and standards. We need to work with the automobile companies on how their vehicles are going to interconnect with the grid, and how those vehicles are going to connect with a smart metering systems that we’re implementing.”

First Things First

Given these challenges, attempts to create a car battery swapping systems, like the one being attempted by Israel’s Project Better Place, seem quixotic. “With battery swap-outs, you’re dealing with 300 pounds of batteries and every one is different,” said Kjaer. “You’ve got liability issues. You have issues around how that battery has been consumed by the previous driver. It’s not there today because the technology is not mature and we don’t have standardization.”

Kjaer believes the first priority is to simply put plug-in hybrids and electric vehicles on the road in enough volume to reduce cost and spawn successive generations of technology innovation, while establishing standardization along the way. Industry observers expect the first plug-in hybrids around 2011 or 2012, and it’s hard to predict if they will take as long as today’s gasoline hybrid to penetrate the market. After eight years in the U.S. market, hybrids comprise a little more than two percent of new car sales. “The big mystery here is how fast these vehicles going to penetrate,” said Robert Pratt of the Pacific Northwest National Laboratory. “The answer is nobody knows.” said Pratt.

Ed Kjaer, Robert Pratt, and Efrain Ornelas participated in a panel discussion at Auto FutureTech, March 2008, in Vancouver, British Columbia. The panel was moderated by Donna LeClair, chief technology officer, BC Hydro.