Texas, Colo. show how to integrate renewables as carbon plan looms — report

Source: Edward Klump, E&E reporter • Posted: Thursday, June 11, 2015

Electric systems in Texas and Colorado are demonstrating that a range of actions can be used to successfully and reliably integrate large amounts of renewable energy, according to a new report completed for the Advanced Energy Economy Institute.

TheĀ study, which is being made public today, was conducted with a focus on two entities — the Electric Reliability Council of Texas (ERCOT), that state’s main grid operator, and certain Xcel Energy Inc. operations in Colorado. Both states have seen increasing amounts of wind energy and both have kept electricity flowing.

“What we’re trying to portray or say is not that this is all incredibly easy, but that utilities and system operators — when faced with higher shares of renewables — have worked hard to figure out how to integrate them and are managing to do so,” said Jurgen Weiss, co-author of the new report put together by the Brattle Group.

The discussion is of particular relevance as U.S. EPA prepares to release a final rule this summer for its proposed Clean Power Plan, which seeks to cut carbon dioxide emissions from power plants 30 percent by 2030 compared with 2005 levels. Renewables are among the factors states will be examining to meet potential carbon reductions.

Brattle, a consulting firm, weighed in via the new report to say increasing renewable holdings shouldn’t derail efforts to comply on carbon.

“Specifically, integration of variable renewable energy at levels of penetration as high as those reliably managed by ERCOT and Xcel Energy Colorado, if not higher, should not be seen as a significant technical obstacle to compliance with EPA’s proposed Clean Power Plan,” Brattle said.

Rather, the firm said, examining lessons from states such as Texas and Colorado should help independent system operators and utilities “ensure that significantly larger amounts of variable renewable energy can be integrated at small to modest costs while maintaining high levels of reliability.”

The new report recounted a number of ways to integrate renewables, including changes in ancillary services that can manage short-term mismatches in demand and supply; improved forecasts for wind production; and more flexibility with power plants that use fossil fuels.

Brattle said changing capabilities of renewable generation also can aid reliability. Other factors mentioned included expanding transmission infrastructure and emerging approaches such as large-scale storage, dynamic management of transmission line capacity and securing a bigger role for demand response in helping with variability.

Seeking to ‘shine a light’ on success

The potential for changes in U.S. power systems is being watched by Advanced Energy Economy (AEE), an association of businesses, and the research entity known as the Advanced Energy Economy Institute.

Matt Stanberry, vice president of market development at AEE, said this week’s report was commissioned amid a period of change in energy, including increasing penetration of renewable technologies.

A number of people are used to thinking about renewables “the way they did 10 years ago,” Stanberry said, when the resources weren’t as well-understood. The idea with the report was to explore the techniques used in certain areas with substantial renewables.

“It’s pretty easy to see that the integration has been successful in these places,” Stanberry said. “It’s really to shine a light on how the grid operators are doing that.”

Brattle’s report began by noting the rise of wind and solar energy production in the United States, which brings variability amid a need to ensure total electricity generation equals demand in real time. The firm said grid operators, utilities and regulators will need to consider further investments in transmission and distribution systems.

Brattle noted that the North American Electric Reliability Corp. has raised concerns about possible levels of renewable energy amid potential greenhouse gas emissions cuts. Brattle said it previously found such concerns likely were overstated (EnergyWire, Feb. 12). This latest report served as a follow-up assessment as it zeroed in on Texas and Colorado.

In ERCOT’s region, according to data cited by Brattle, the operator estimated the cost of integrating the first 10,000 megawatts of wind was about 50 cents per megawatt-hour of wind generation.

The experiences in Texas and Colorado show integrating variable renewables at 10 to 20 percent average penetration levels, and sometimes more than 50 percent, is possible, according to Brattle.

Brattle noted ERCOT’s relative isolation from other grids, adding that the Xcel operations in Colorado have vertical integration but aren’t part of an independent system operator or regional transmission organization.

In its ERCOT section, Brattle said Texas leads the country in installed wind energy capacity, with the wind contributing more than 10 percent of the power to meet ERCOT demand in 2014.

Looking at a ‘whole host of options’

Texas wind has seen a major benefit from a roughly $7 billion program to boost transmission infrastructure through the Competitive Renewable Energy Zone (CREZ) program in recent years. ERCOT also has been helped by items such as different prices in various locations and improved calculations of wind’s contribution, Brattle said. The cost of CREZ lines is on top of smaller integration costs cited earlier, Brattle said, and there have been questions about whether renewable resources should shoulder some costs for added transmission.

Stanberry pointed to the role of demand response, which lets customers on a system be aggregated and called upon to reduce power consumption at certain times to help manage peak demand.

“You’ve seen this use of demand response to help with renewables integration,” he said.

ERCOT also is using changes in ancillary services markets and seeking more flexible resources, Stanberry said. He said he’s excited to see how technological and operational changes continue to evolve.

In reviewing Colorado, Brattle discussed wind and solar production for the Xcel Energy territory. It noted the role of ancillary services, advanced wind forecasts and better operations, such as improved startup time for certain gas units. The study noted work in other regions that follow some of the same trends found in Texas and Colorado.

Stanberry said AEE views the Clean Power Plan “as a chance for our electric system to continue to modernize.” Given the flexible structure in EPA’s carbon plan, he said a basket of technologies could be considered. Some avenues help with emissions cuts even if that’s not their primary goal, he said.

“We do believe that if state regulators really step back and look at the whole host of options available to them that they can design compliance plans that could in fact help them achieve multiple goals at once,” Stanberry said.

As for the Clean Power Plan, he said AEE is in favor of seeing it implemented in a “logical, forward-thinking manner.”

Weiss, co-author of the new Brattle report, said high levels of reliability can exist with larger shares of renewables than are seen on average in the country today.

“It doesn’t take some kind of miracle science to make this happen,” Weiss said. “Once people put their minds to it, then solutions emerge. And solutions have emerged or are emerging.”