Wednesday, September 14, 2011

Can EVs solve wind power puzzle?

Electric vehicles outfitted with a $10 computer chip can help streamline the addition of wind power to the electric grid, according to a study that shows how the two types of technology could piece together the puzzle of our green energy future.
One of the biggest hurdles utilities face with the addition of wind power and other renewable sources of energy to the grid is where and how to store excess generation for use when people actually need it. Until that happens, if the wind blows when nobody needs electricity, for example, the energy is wasted.
"If I could wave my magic wand and have anything, new types of technology that allow you to store large amounts of energy cheaply would be fantastic," Steve Kern, a power supply and environmental affairs officer with Seattle City Light, told me along with a group of reporters this July on a trip sponsored by the Institutes for Journalism and Natural Resources.
Kern was speaking at a hydropower dam in the North Cascades that supplies 17 percent of Seattle's electricity. The utility occasionally lets water spill over the dam instead of through its turbines because there is no place to store the excess generated electricity.
Despite the storage limitations, Renewable Portfolio Standards require utilities to add more sources of energy such as wind to the grid. In the Pacific Northwest, 10 gigawatts of wind power will come online by 2019, for example. The conundrum is how to effectively manage the wind's fickleness.
EVs absorb the wind
The new study put out by the Department of Energy's Pacific Northwest National Laboratory shows that plug-in electric vehicles equipped with so-called Grid Friendly charging technology could help utilities better utilize this additional wind energy.
The technology essentially ramps up and down the rate at which the battery is charged depending on availability of electricity, Michael Kintner-Myer, a staff scientist at the lab and a co-author of the new report, told me on Monday.
The chip, which is added to the vehicle battery or charging station, reads the signal of the voltage and current at the outlet, he explained. Utilities in the United States try to maintain this metric, called frequency, at 60 hertz.
When there's more demand for electricity than is being generated, the frequency drops. When there is more generation than needed, like when the wind blows in the middle of the night, the frequency speeds up.
"We are evaluating what the frequency is … and in the over-generation mode we really ramp up the charging current to its maximum and if it is under generation, we ramp it down," Kintner-Myer explained.
This starting and stopping of the charging cycle allows electric vehicles to absorb the excess wind power when it is generated. Doing so reduces the need for backup power plants to keep the grid in balance, according to PNNL.
This grid-friendly approach contrasts with another, potentially more robust, load management system known as vehicle-to-grid technology, which maintains a two-way communication between the car battery and the electric grid.
In this scenario, the battery is a storage device as well as a generator, providing electricity to the grid when demand rises. This causes more wear and tear on batteries and requires a more complex and expensive integration with the grid, according to Kintner-Myer.
"From a cost-benefit process, I think we have a higher value," he added.
This benefit of the Grid Friendly approach comes if about 13 percent, or 2.1 million vehicles in the Northwest Power Pool, which covers Idaho, Montana, Nevada, Oregon, Utah and Wyoming, are equipped with the technology, according to the PNNL study.
In addition, about 10 percent of the cars would need access to charging stations during the day in order to absorb excess wind energy. "That means for utilizing these vehicles for grid applications, you don't have to have a one-to-one ratio of public-to-private charging stations," Kintner-Myer said, noting that has been a concern within the energy industry.
His team is negotiating with a public utility in the Pacific Northwest to demonstrate the feasibility of the technology, which he said is available today. In fact, similar chips were tested in home appliances on the Olympic Peninsula a few years ago.
No silver bullet
Kern, with Seattle City Light, told me today that the Grid Friendly technology can help, "but it is not going to be the silver bullet" he longs for.
One problem from the utility perspective, he noted, is an obligation to customers to provide power when they want and need it. And, for most owners of electric vehicles, that means when cars are parked in the garage at night.
So, if electric-vehicle owners plug in their cars but the wind's not blowing, "I still have to have the underlying supply to backstop that wind," he noted

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