Power system experts agree: wind energy can help reliably meet EPA’s Clean Power Plan

New studies by some of the nation’s leading power system experts confirm that electric reliability will not be negatively affected as wind energy and other clean resources continue their growth to help the nation reduce carbon pollution. This conclusion builds on the findings of the non-partisan Energy Information Administration, which last month forecast that wind energy will account for more than half of the generation additions in the lowest-cost portfolio of Clean Power Plan compliance solutions thanks to wind’s recent cost reductions. This week’s results confirm that wind energy is not only poised to help meet the Clean Power Plan cost-effectively, but also reliably.

Yesterday, well-known utility consultants the Brattle Group released their report, “Integrating Renewable Energy into the Electricity Grid: Case studies showing how system operators are maintaining reliability.” The Brattle report documented how grid operators are already reliably integrating large amounts of wind energy and how far larger amounts of wind can be reliably integrated using the resources we already have on the power system today, providing independent expert validation of the points AWEA made earlier this year in our report, “Wind energy helps build a more reliable and balanced electricity portfolio.” Yesterday’s report also builds on broader work the Brattle Group released earlier this year explaining that electric reliability will not be harmed by the Clean Power Plan.

The Brattle report consists primarily of case studies of two power systems that are reliably integrating large amounts of wind energy today: the main power systems in Texas and Colorado. Last year, the Texas power system (ERCOT) obtained 10.6 percent of its electricity from wind energy, a percentage that should grow to the high teens within the next two years as planned and under construction wind projects come online. At times, ERCOT has already reliably obtained more than 40 percent of its electricity from wind energy. Xcel Energy’s Colorado power system reliably obtained 18.7 percent of its electricity from wind energy in 2013, a figure that also continues to grow.

These levels of wind energy use are much higher than those envisioned by EPA in its proposed state emissions targets under the Clean Power Plan, indicating that EPA could significantly strengthen those targets without any electric reliability concerns. In its June 2014 draft of the Clean Power Plan, EPA proposed that the U.S. only reach 12 percent non-hydro renewable energy use by the year 2030. The U.S. is already at approximately 7 percent non-hydro renewable energy use, and new wind and solar planned for next two years alone will add several percentage points to that. As shown in the chart below, the U.S. has already reached EPA’s 2020 target for renewable energy, and even under a conservative trajectory for future growth, renewable energy will greatly exceed EPA’s proposed target.


Brattle notes that these and significantly higher levels of wind and solar use could be reliably achieved, based on the experience of Texas, Colorado, and other regions. Moreover, Brattle notes that even higher levels are achievable with cost-saving grid operating reforms and new technologies that are expanding the reliability services contributions of renewable generation. The report notes how Texas grid operators have been able to reliably integrate more wind power than any other state with only minor changes to power system operations. Brattle also presents ERCOT data showing that the cost of holding additional power system reserves to accommodate incremental electricity supply and demand variability introduced by wind energy is trivially small, supporting AWEA’s analysis of ERCOT data demonstrating that integration costs for wind in Texas are significantly lower than the integration cost of holding reserves to accommodate abrupt failures at large conventional power plants.

Brattle also describes how Xcel Energy’s Colorado power system has been able to reach nearly 20 percent wind energy use due to a combination of advances in wind energy forecasting and Xcel’s innovative use of wind plants’ ability to make exceptionally fast changes to their output in response to dispatch signals. This capability has enabled Xcel’s Colorado power system to at times obtain more than 60 percent of its electricity from wind energy, with wind plants at times providing a significant share of the total Colorado power system need for dispatchable generation.

Xcel has also been a leader in pushing for the grid operating changes that will enable far higher levels of wind use. Brattle notes how coordinating grid operations across a large area and moving to more frequent updates of generation schedules drastically reduces the cost of operating the power system, providing benefits even in the absence of renewable energy. The fact that Xcel Colorado was able to obtain 18.7 percent of its electricity from wind in a region without those practices demonstrates that utilities can still reliably and cost-effectively integrate large amounts of wind energy even if they are forced to work with less favorable grid operating procedures.

The Brattle report notes howtechnological improvements, mostly from the use of advanced power electronics and fast controls in wind turbines, allow wind plants to provide essential reliability services as well as or better than conventional power plants. The report notes how wind plants now meet a more stringent requirement for remaining online when the power system experiences fluctuations in voltage or frequency, which incidentally are often caused by the unexpected failure of large conventional power plants. Wind’s superior capability in this regard is extremely valuable, as a failure of conventional power plants to ride-through grid disturbances has been a contributing factor in many recent large-scale blackouts.

As NERC experts and others have noted, wind plants are capable of providing all reliability services currently provided by conventional power plants, in some cases better than conventional power plants provide them. For example, wind plants offer excellent voltage and reactive power control, again thanks to their sophisticated power electronics. Through the use of advanced wind forecasting, fast and accurate wind plant power control, and efficient market practices, wind plants are now fully incorporated into power system markets and operations in regions like Texas and the Midwest, a move that has been beneficial both for grid operators and wind plant owners.

Brattle’s primary conclusion is that “To date, these [renewable] integration efforts have been largely relying on well-established technologies, indicating that lack of technology cannot be considered a major barrier to being able to integrate amounts of variable renewable generation significantly in excess of current average U.S. levels. Though new technologies are being explored and becoming more promising, particularly storage, it is not necessary to have large amounts of such new resources to incorporate meaningful quantities of renewables onto a system and preserve its security and reliability.”

Other expert analysis released this week supports the finding that established power system planning, market, and operating practices are up to the task of reliably meeting the Clean Power Plan. The respected Analysis Group released a study concluding that the MidContinent Independent System Operator (MISO), the grid operator for much of the Midwest, is well-positioned to reliably achieve the Clean Power Plan. Like the Analysis Group’s previous analysis of the Mid-Atlantic and Great Lakes regional grid operator, PJM, this week’s study found MISO’s markets and planning practices are designed to accommodate precisely the kind of energy mix change the Clean Power Plan is expected to bring about, including greatly expanded use of renewable energy. As explained by Rob Gramlich, AWEA’s Senior Vice President for Government and Public Affairs, at a February 2015 Federal Energy Regulatory Commission hearing about the Clean Power Plan, “Reliability can be maintained because our country’s electricity markets and regulatory structures work.”

With EIA’s economic analysis several weeks ago and this week’s reliability analyses, momentum is building for wind energy to be a primary tool for reliable and cost-effective Clean Power Plan compliance. As EIA noted, “renewables play a critical role under a range of different market conditions and policy assumptions.” States and grid operators should take the results of these studies into account as they begin planning the policies and infrastructure that will be needed to achieve the Clean Power Plan.

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