Center for American Progress

Climate Change Threatens Electric Grid Reliability in the Southwest

Climate Change Threatens Electric Grid Reliability in the Southwest

Opponents of the Clean Power Plan claim that it will undermine grid reliability, but climate change is a far greater threat to power in the Southwest.

Lightning strikes over Lake Mead in Arizona. The West remains in a historic drought, and Lake Mead is currently just 38 percent full. (AP/John Locher)
Lightning strikes over Lake Mead in Arizona. The West remains in a historic drought, and Lake Mead is currently just 38 percent full. (AP/John Locher)

The Southwest United States is known for its hot, dry land and the occasional wildfire. Over recent years, however, the region has witnessed more frequent and destructive wildfires, longer heat waves and droughts, and lower-than-ever water levels. Each of these extreme weather events is a symptom of climate change and can cause significant damage to the electricity grid, which relies on steady water levels and occasional heat relief to produce and reliably distribute electricity to consumers.

On August 3, 2015, the Environmental Protection Agency, or EPA, finalized the Clean Power Plan, which will cut carbon pollution from the power sector by 32 percent below 2005 levels by 2030. Since the EPA proposed the rule, opponents have attempted to paint it—inaccurately—as a threat to the reliability of the nation’s electricity grid.

To provide concerned stakeholders with additional assurances, the EPA included new provisions in the final Clean Power Plan that give states greater flexibility to develop an implementation plan that cleans up power plants while keeping the lights on. Moreover, Clean Power Plan critics refuse to acknowledge that the rule serves to fight the actual greatest threat to grid reliability: climate change.

According to the U.S. Department of Energy, or DOE, extreme weather is “a leading environmental risk” to electricity transmission, storage, and distribution systems. In its most recent Quadrennial Energy Review, the DOE noted that transmission, storage, and distribution infrastructure “is vulnerable to many natural phenomena,” including “hurricanes, earthquakes, drought, wildfires, flooding, and extreme temperatures.” As the climate continues to warm, these events are likely to become more frequent and intense. The Southwest United States is already feeling many of the effects of unmitigated climate change, which could strain the electricity grid in several ways.

Heat waves

The 2000s was the hottest decade on record in 110 years, with rising average temperatures accompanied by fewer cold air spells and more heat waves. In the Quadrennial Energy Review, the DOE concluded that climate change poses “particular challenges” for the Southwest because the region is expected to experience population growth while getting hotter and drier. The higher demand for cooling during peak hours will put added pressure on the electricity transmission and distribution infrastructure.

The recent Texas heat wave—which lasted for much of July and August—demonstrates how high energy demand can trigger grid reliability concerns. Demand surged during the more than 30-day streak of temperature highs that stretched from 94 degrees into the triple digits, and energy prices noticeably spiked. In the span of just one day—from Thursday, August 6, to Friday, August 7—energy prices across Texas nearly tripled from $66 to $175 per megawatt-hour.

In September 2014, an intense heat wave with triple-digit temperatures rolled through Los Angeles, pushing electricity demand to record highs. The grid could not handle the increased load. The five-day heat wave led to infrastructure damage, including multiple transformer burnouts and power line failures. More than 3,000 customers were left without service, and the city of Los Angeles had to dispatch additional work crews to address damaged equipment.

Heat waves pose a major health risk to vulnerable groups such as young children, elderly people, and those suffering from asthma. For those who are vulnerable to poor air quality and rely on air conditioning, electricity is potentially lifesaving—especially during heat waves. Grid failures due to heat waves or excessive demand increase public health risks.


The Southwest is already prone to drought, but scientists expect that climate change will increase droughts’ frequency, intensity, and duration. Already, 95 percent of California and 76 percent of Nevada are experiencing severe, extreme, or exceptional drought. Moreover, researchers from NASA, Cornell University, and Columbia University have warned that unmitigated climate change could cause unprecedented “megadroughts” throughout the region.

Prolonged drought threatens the reliability of electricity generation and distribution across the region. The combination of lower stream levels and higher temperatures prevents coal-fired power plants from operating fully, as less water is available for cooling. Drought also can strain the electricity grid by limiting the efficacy of hydroelectric power facilities. One study found that certain power plants could experience as much as an 8.8 percent reduction in generating capacity during summer months.

The ongoing drought in the Southwest is testing the grid’s resilience to climate-related stress. During summer 2012, minimal precipitation and low snowpack levels in the Sierra Nevada Mountains reduced California’s hydroelectric power generation to only 62 percent of the previous summer’s levels. This trend has continued: In June 2014, the state’s generation from hydroelectric power stations was 59 percent of the June average for the preceding 10 years.

In June 2015, water levels in Lake Mead—a key water supply and hydroelectric source for California, Arizona, and Nevada—fell to record lows in the midst of a 15-year drought. In 2014, Lake Mead generators operated at rates 23 percent below average; the generators experienced similar capacity drops in 2010. If the lake’s water level dips below a certain point, the generators cannot operate at all.


Higher temperatures combined with more intense drought conditions increase the risk of wildfires. In the Quadrennial Energy Review, the DOE concluded that more frequent and severe wildfires “are expected to have significant impacts on electricity transmission and distribution in the Southwest.” Wildfires can damage electricity transmission and distribution infrastructure such as utility poles, lines, transformers, and substations.

In summer 2011, for example, the Las Conchas wildfire spread through 78 miles of New Mexico, threatening two major transmission lines that carry power to 400,000 customers. In 2007, a wildfire in Southern California damaged 35 miles of wire in the Southwest Powerlink system, downing more than two dozen transmission lines. Almost 80,000 customers in San Diego County lost power as a result—some for multiple weeks. Some transmission lines in California are particularly vulnerable to wildfire damage. The Union of Concerned Scientists estimates that by 2100, some major lines in the state will be 40 percent more likely to be exposed to wildfires.


Climate change—not its mitigation—is the real threat to grid reliability. In a warmer world, the Southwest will experience additional drought, extreme heat, and wildfires—all of which pose a significant threat to the supply and distribution of electricity, as well as public health and safety. The finalized Clean Power Plan not only provides steps to reduce carbon emissions and address the root causes of climate change but also contains provisions to ensure that the lights stay on.

Myriam Alexander-Kearns is the Research Associate for the Energy Policy team at the Center for American Progress.

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Myriam Alexander-Kearns

Policy Analyst

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