Calif. leads way in tackling instability tied to renewables

Source: Hannah Northey, E&E reporter • Posted: Friday, November 15, 2013

California is leading what could become a nationwide charge to manage instability in the aging U.S. electric grid brought on by large penetrations of wind and solar power as it combats climate change.

The Golden State’s grid operator, the California Independent System Operator (ISO), in a report laid out solutions for challenges that could crop up during the integration of an anticipated 11,000 megawatts of new wind and solar — equal to the amount of 22 midsized coal plants — during the next eight years.

The North American Electric Reliability Corp., the national grid overseer, released the report using the most recent information from California’s experience, noting the state could serve as a test bed for similar challenges developing in other parts of the country.

The ISO plans to use a host of tools and techniques — more incremental forecasting for weather-dependent solar and wind generators, scheduling, dispatch, and coordinating power use across a larger geographic footprint — to stabilize the grid when there is an unpredictable surplus or dearth of wind and solar power caused by nature.

“Frankly, we’re seeing similar kinds of conditions beginning to emerge in other parts of North America,” Tom Burgess, NERC’s vice president and director of reliability assessment and performance analysis, told reporters on a call yesterday.

California is at the forefront of the issue as its green energy economy blooms and officials implement an ambitious timetable to comply with a renewable portfolio standard requiring that a third of the state’s power come from renewables by 2020. California’s demand for renewables accounts for two-thirds of the need for clean energy in the Western Interconnection, which spans 11 states and portions of Texas, Canada and Mexico.


One problem is that fast-acting gas units needed to support wind and solar generators could see more wear and tear as they’re quickly scaled up and down. Areas with large amounts of renewables may also need extra backup power sources to stabilize system frequency following a grid disturbance.

Those concerns have prompted a closer look at market enhancements such as an “energy imbalance market,” which the ISO’s board of governors signed off on earlier this month (Greenwire, Nov. 8).

The market would allow California to share energy resources in a real-time market — where energy is dispatched every five to 15 minutes — in parts of Oregon, Washington, Utah, Wyoming and Idaho. The grid operator also operates in Nevada and is looking for further links there.

Mark Rothleder, the ISO’s vice president of market quality and renewable integration, told reporters yesterday that California could sell off excess power to adjacent entities or curtail generators. Overall, regional cooperation and diversity over the regional area would provide the benefit of being able to absorb and balance the system, he said.

“Not everybody’s going to be building out with solar resources across the interconnection, but if California is high on solar at given times, perhaps there’s not as much wind production in other parts of the interconnection and they could be able to absorb it at certain times,” Rothleder said.

The ISO is also actively pursuing different products to help generators ramp up and down quickly to match changing solar and wind patterns and mechanisms that would allow energy storage and demand response to bid into the ISO’s auctions more efficiently. And it is proposing a requirement for wind and solar generators to install equipment to help regulate voltage on the system.

“You have to stay one step [ahead] of Mother Nature, one step of demand,” said Stephanie McCorkle, a spokeswoman for the ISO. “We don’t have a crystal ball, but we have a good track record for planning ahead.”

Nadav Enbar, a senior project manager at the Electric Power Research Institute, said states like California, Hawaii and Arizona, where solar penetration is increasing, and windy states like Texas are at the forefront for crafting adaptive strategies, and there’s a growing recognition that increasingly cheaper renewables “aren’t going away.”

Ultimately, the system can be run reliably with high penetrations of wind and solar, he said.

“Technically speaking, reliability can be ensured,” Enbar said. “The cost of ensuring that reliability is now being discussed and approaches that would be fair for multiple parties.”