a (load) balancing act: the challenge of clean power - battery energy storage system

The third of California's five stories of renewable energy and wind power is booming in California, but sometimes the sun doesn't shine and the wind doesn't blow.
So California utilities are hoping to eliminate these bumps by doing little on the Internet today: storing electricity.
California's independent system operator is the traffic police of the state's power grid.
Its job is to predict how much electricity the country needs. -
Every four seconds. -
And ensure supply.
In an unmarked building on the outskirts of Sacramento, dozens of people were glued to the computer screen, a wall with a display screen drawing a huge red line, real-time display of how much electricity California is currently using.
Dave Hawkins, an engineer at ISO in California, said: "Our grid today, just like we built and managed it, is a huge 'time' delivery system . ".
When we turn on the switch, in order for the lights to light up, the energy supply and demand must be perfectly balanced, says Hawkins.
"If we don't get all the correct numbers, then there will be some serious imbalances and some unhappiness in the system," he said . ".
Today, most of the state's energy comes from gas plants, which produce a stable supply of electricity.
But a record amount of wind and solar power is generated every year.
Since the sun disappears behind the clouds and the wind disappears, renewable energy is variable.
"The curves that have emerged so far are very unstable," Hawkins said . ".
"In a very short time, you will see output changes of 40, 50, 60%.
"Better weather forecasts can help ISO predict volatility, but Hawkins says they need something else to fill the gap.
Outside Los Angeles on Huntington Beach, AES Energy Storage's Praveen Kathpal shows one of the state's largest batteries.
It looks like a simple container from the outside.
"We are working on what we call the Sano project. It's a 2-
"Megawatt energy storage devices," Kathpal said.
"It doesn't look spectacular, it's good ---
If we can avoid it, we don't like the excitement of the power industry.
"Inside, 83,000 of the small lithium is loaded in the container --
Ion battery.
The test battery provides enough power to 1,500 households, and Kathpal says power can be used by grid operators to smooth the secondto-
The second fluctuation on the grid.
Batteries and other energy storage technologies can also be used for long-term storage, especially for wind power generation.
"Unfortunately there is a lot of wind blowing at night and we don't want to blow the wind out," said Dan Rastler of the electric power Institute, a non-profit research and development group sponsored by the national utility.
Rastler said that if wind power at night can be stored in batteries for hours like AES, power grid operators can use it during the day with the highest energy demand.
However, there is a big problem: batteries and other storage technologies are expensive.
In the best case, the cost of battery storage is twice that of conventional power supplies.
This makes it unusable for most utilities.
But Mr. Rastler says federal stimulus money could change that.
"It's huge--
I believe the stimulus is about $0. 25 billion. -[it]really is jump-
"Some key demonstrations have started," he said . "
California's largest utility company is leading several of these demonstrations or pilot projects.
But given the cost, it may take decades to expand energy storage, and California's utilities are on a tight schedule.
They need one-
By 2020, their third electricity came from renewable sources.