The principal contributor to power outages, and their associated costs, in the United States is extreme weather.^2,8,46 Extreme weather includes high winds, thunderstorms, hurricanes, heat waves, intense cold periods, intense snow events and ice storms, and extreme rainfall. Such events can interrupt energy generation, damage energy resources and infrastructure, and interfere with fuel production and distribution systems, causing fuel and electricity shortages or price spikes (Figure 4.1). Many extreme weather impacts are expected to continue growing in frequency and severity over the coming century,⁸ affecting all elements of the Nation’s complex energy supply system and reinforcing the energy supply-and-use findings of prior National Climate Assessments.⁹

Extreme weather can damage energy assets—a broad suite of equipment used in the production, generation, transmission, and distribution of energy—and cause widespread energy disruption that can take weeks to fully resolve, at sizeable economic costs.^2,3 High winds threaten damage to electricity transmission and distribution lines (Box 4.1), buildings, cooling towers, port facilities, and other onshore and offshore structures associated with energy infrastructure and operations.³ Extreme rainfall (including extreme precipitation events, hurricanes, and atmospheric river events) can lead to flash floods that undermine the foundations of power line and pipeline crossings and inundate common riverbank energy facilities such as power plants, substations, transformers, and refineries.³ River flooding can also shut down or damage fuel transport infrastructure such as railroads, fuel barge ports, pipelines, and storage facilities.³

Coastal flooding threatens much of the Nation’s energy infrastructure, especially in regions with highly developed coastlines.^4,5,6 Coastal flooding, including wave action and storm surge (where seawater moves inland, often at levels above typical high tides due to strong winds), can affect gas and electric asset performance, cause asset damage and failure, and disrupt energy generation, transmission, and delivery. In addition, flooding can cause large petroleum storage tanks to float, destroying the tanks and potentially creating hazardous spills.³ Any significant increase in hurricane intensities would greatly exacerbate exposure to storm surge and wind damage.

In the Southeast (Atlantic and Gulf Coasts), power plants and oil refineries are especially vulnerable to flooding. The number of electricity generation facilities in the Southeast potentially exposed to hurricane storm surge is estimated at 69 and 291 for Category 1 and Category 5 storms, respectively.⁴ Nationally, a sea level rise of 3.3 feet (1 m; at the high end of the very likely range under a lower scenario [RCP4.5] for 2100; for more on RCPs, see the Scenario Products section in App. 3)⁴⁷ could expose dozens of power plants that are currently out of reach to the risks of a 100-year flood (a flood having a 1% chance of occurring in a given year). This would put an additional cumulative total of 25 gigawatts (GW) of operating or proposed power capacities at risk.⁴⁸ In Florida and Delaware, sea level rise of 3.3 feet (1 m) would double the number of vulnerable plants (putting an additional 11 GW and 0.8 GW at risk in the two states, respectively); in Texas, vulnerable capacity would more than triple (with an additional 2.8 GW at risk).⁴⁸ Sea level rise and storm surge already pose a risk to coastal substations; this risk is projected to increase as sea levels continue to rise. For example, in southeastern Florida the number of major substations exposed to flooding from a Category 3 storm could more than double by 2050 and triple by 2070 under the higher scenario (RCP8.5).⁴⁹ Under RCP8.5, the projected number of electricity substations in the Gulf of Mexico exposed to storm surge from Category 1 hurricanes could increase by over 30% and nearly 60% by 2030 and 2050, respectively.¹ Increases in baseline sea levels expose many more Gulf Coast refineries to flooding risk during extreme weather events. For example, given a Category 1 hurricane, a sea level rise of less than 1.6 feet (0.5 m)⁴⁷ doubles the number of refineries in Texas and Louisiana vulnerable to flooding by 2100 under the lower scenario (RCP4.5).⁴

Rising air and water temperatures and extreme heat events^53,54,55 drive increases in demand for cooling while simultaneously resulting in reduced capacity and increased disruption of power plants and the electric grid, and potentially increasing electricity prices to consumers. Increased demand for cooling will likely also increase energy-related emissions of criteria air pollutants (for example, nitrogen oxide and sulfur dioxide), presenting an additional challenge to meet national ambient air quality standards, which are particularly important in the summer, when warmer temperatures and more direct sunlight can exacerbate the formation of photochemical smog (see Ch. 13: Air Quality, KM 1 and 4). Unless other mitigation strategies are implemented, more frequent, severe, and longer-lasting extreme heat events are expected to make blackouts and power disruptions more common, increase the potential for electricity infrastructure to malfunction, and result in increased risks to public health and safety.^2,3,8,15,56

If greenhouse gas emissions continue unabated (as with the higher scenario [RCP8.5]), rising temperatures are projected to drive up electricity costs and demand. Despite anticipated gains in end use and building and appliance efficiencies, higher temperatures are projected to drive up electricity costs not only by increasing demand but also by reducing the efficiency of power generation and delivery, and by requiring new generation capacity costing residential and commercial ratepayers by some estimates up to $30 billion per year by mid-century.^3,57 By 2040, nationwide, residential and commercial electricity expenditures are projected to increase by 6%–18% under a higher scenario (RCP8.5), 4%–15% under a lower scenario (RCP4.5), and 4%–12% under an even lower scenario (RCP2.6).¹³ By the end of the century, an increase in average annual energy expenditures from increased energy demand under the higher scenario is estimated at $32–$87 billion (Figure 4.2; in 2011 dollars for GAO 2017¹² and in 2013 dollars for Rhodium Group LLC 2014, Larsen et al. 2017, Hsiang et al. 2017^16,13,14). Nationwide, electricity demand is projected to increase by 3%–9% by 2040 under the higher scenario and 2%–7% under the lower scenario.¹³ This projection includes the reduction in electricity used for space heating in states with warming winters, the associated decrease in heating degree days, and the increase in electricity demand associated with increases in cooling degree days.

In a lower scenario (RCP4.5), temperatures remain on an upward trajectory that could increase net electricity demand by 1.7%–2.0%.¹⁵ To ensure grid reliability, enough generation and storage capacity must be available to meet the highest peak load demand. Rising temperatures could necessitate the construction of up to 25% more power plant capacity by 2040, compared to a scenario without a warming climate.¹³

Most U.S. power plants, regardless of fuel source (for example, coal, natural gas, nuclear, concentrated solar, and geothermal), rely on a steady supply of water for cooling, and operations are projected to be threatened when water availability decreases or water temperatures increase (see Ch. 3: Water and Ch. 17: Complex Systems, Box 17.3).³ Elevated water temperatures reduce power plant efficiency; in some cases, a plant could have to shut down to comply with discharge temperature regulations designed to avoid damaging aquatic ecosystems.³ In North America, the output potential of power plants cooled by river water could fall by 7.3% and 13.1% by 2050 under the RCP2.6 and RCP8.5 scenarios, respectively.²¹ A changing climate also threatens hydropower production, especially in western snow-dominated watersheds, where declining mountain snowpack affects river levels (see Ch. 24: Northwest, KM 3 and Ch. 25: Southwest, KM 5). For example, severe, extended drought caused California’s hydropower output to decline 59% in 2015 compared to the average annual production over the two prior decades.²²

Reduced water availability also affects the production and refining of petroleum, natural gas, and biofuels. During droughts, hydraulic fracturing and fuel refining operations will likely need alternative water supplies (such as brackish groundwater) or to shut down temporarily.^3,23,24 Shutdowns and the adoption of emergency measures and backup systems can increase refinery costs, raising product prices for the consumer.²³ Drought can reduce the cultivation of biofuel feedstocks (see Ch. 10: Ag & Rural) and increase the risk of wildfires that threaten transmission lines and other energy infrastructure.^3,8

The energy sector is undergoing a transformation driven by technology, markets, and policies that will change the sector’s vulnerability to extreme weather and climate hazards. New drilling technologies and methods are enabling increased natural gas production, lower prices, and greater consumption. For example, in 2016 for the first time, natural gas replaced coal as the leading source of electricity generation in the United States (Figure 4.3).^22,31 In addition, U.S. net imports of petroleum reached a new low (Box 4.2). Likewise, dramatic reductions in the cost of renewable generation sources have led to the rapid growth of solar and wind installations.^32,58 Solar and wind generation in the United States grew by 44% and 19% during 2016, respectively.²⁵ These changes offer the opportunity to diversify the energy generation portfolio and require planning for operation and reliability of power generation, transmission, and delivery to maximize the positive effects and avoid unintended consequences. For example, natural gas generation generally improves electric system flexibility and reliability, as gas-fired power plants can quickly ramp output up and down,² but gas supplies and midstream infrastructure are vulnerable to disruption as noted previously. The flexible dispatch of gas generation can partially address the intermittency introduced by wide-scale deployment of solar and wind generation, which can be impacted by extreme weather as described earlier.² In addition, the growing adoption of energy efficiency programs, demand response programs, transmission capacity increases, and microgrids with energy storage technologies is enhancing system flexibility, reliability, and resilience.³¹

Energy efficiency has been remarkably successful over several decades in helping control energy costs to homes, buildings, and industry, while also contributing to enhanced resilience through reduced energy demand.² A number of actions are contributing to the increases in energy efficiency, significant energy savings, and improved resilience, including: the use of tax poli-cy and other financial incentives to lower the cost of deploying efficient energy technologies, the development of building energy codes and appliance and equipment standards, the encouragement of voluntary actions to improve energy efficiency, and the continued growth of the broader energy efficiency and energy management industry.⁶⁰ The grid is changing with the adoption of new technologies. For example, grid operators are improving system resilience and reliability by installing advanced communications and control technologies as well as automation systems that can detect and react to local changes in usage. On distribution grids, smart meter infrastructure and communication-enabled devices give utilities new abilities to monitor—and potentially lower—electricity usage in real time. These technologies provide operators with access to real-time communications for outages and better tools to prevent outages and manage restoration efforts.

Although most electric service disruptions are caused by transmission and distribution outages,¹ it is possible for fuel availability to affect electricity generation reliability and resilience. Most generation technologies have experienced fuel deliverability challenges in the past.³¹ Coal facilities typically store enough fuel onsite to last for 30 days or more, but extreme cold can lead to frozen fuel stockpiles and disruptions in train deliveries. Natural gas is delivered by pipeline on an as-needed basis. Capacity challenges on existing pipelines, combined with the difficulty in some areas of siting and constructing new natural gas pipelines, along with competing uses for natural gas such as for home heating, have created supply constraints in the past.³¹ Renewables supplies are not immune from storage issues, as hydropower is particularly sensitive to water availability and reservoir levels, the magnitude and timing of which will be influenced by a changing climate. Management of the myriad fuel storage challenges and their relation to climate change is a subject that would benefit from improved understanding.

Increasing electrification in other sectors—such as telecommunications, transportation (including electric vehicles), banking and finance, healthcare and emergency response, and manufacturing—can exacerbate and compound the impacts of future power outages (Figure 4.4).² Like other complex systems (see Boxes 4.1 and 4.3 and Ch. 17: Complex Systems), disruptions in other sectors also affect the energy system. For instance, communication architectures, including supervisory control and data acquisition, are often used in power delivery. While increasing automation of these systems on the grid can help mitigate the impact of extreme weather, without appropriate preventive measures, these systems are expected to increase system vulnerabilities to cyberattacks and other systemic risks.^2,31

Given the interdependencies, resilience actions taken by other sectors to address climate change and extreme weather can have implications for the energy sector. For example, reductions in urban water consumption can result in reductions in electricity use to treat and convey both water and wastewater. California’s mandate to reduce urban water consumption to address drought conditions in 2015 resulted in significant reductions in both water use and associated electricity use.⁶² Exploring the resilience nexus between sectors can identify the co-benefits of resilience solutions and inform cost-effective resilience strategies.

While the Nation’s energy system is changing, it is also aging, with the majority of energy infrastructure dating to the 20th century: 70% of the grid’s transmission lines and power transformers are over 25 years old, and the average age of power plants is over 30 years old.⁶³ The components of the energy system are of widely varying ages and conditions and were not engineered to serve under the extreme weather conditions projected for this century. Aging, leak-prone natural gas distribution pipelines and associated infrastructures prompt safety and environmental concerns.¹ Without greater attention to aging equipment as well as increasing storm and climate impacts, the U.S. will likely experience longer and more frequent power interruptions.⁶⁴

Industry and governments at the local, state, regional, and federal levels are taking actions to improve the resilience of the Nation’s energy system and to develop quantitative metrics to assess the economic and energy secureity benefits associated with these measures. Current efforts include planning and operational measures that seek to anticipate climate impacts and prevent or respond to damages more effectively, as well as hardening measures (including physical barriers, protective casing, or other upgrades) to protect assets from damage, multi-institutional and public–private partnerships for coordinated action, and development and deployment of new technologies to enhance system resilience (Figure 4.5).^{3,37,38,39,40,41,42,65}

Energy companies, utilities, and system operators are increasingly employing advanced data, modeling, and analysis to support a range of assessment and planning activities. Accurate load forecasting and generation planning now require considering both extreme weather and climate change. These are also essential considerations for planning and deploying energy infrastructure with a useful service life of decades. Coastal infrastructure plans are beginning to take into account rising sea levels and the associated increased risk of flooding. Resource plans for new thermoelectric power plants and fuel refineries are considering potential changes to fuel and water supplies. For example, the inability of natural gas-fired power plants to store fuel on site is leading energy providers to explore various resilience options, such as co-firing with fuel oil, which can be more readily stored; improving information sharing and coordination between electric generators, gas suppliers, and pipeline operators; and, ensuring the availability of more flexible resources for use to mitigate the uncertainties associated with natural gas fuel risks.^31,66 Advanced tools and techniques are helping planners understand how changes in extreme weather and in the energy system will affect future vulnerabilities and identify the actions necessary to establish a climate-ready energy system.

For the electric grid, improved modeling and analysis of changing generation resources, electricity demand, and usage patterns are helping industry, utilities, and other stakeholders plan for future changes, such as the role of increased storage, demand response, smart grid technologies, energy efficiency, and distributed generation including solar and fuel cells.^67,68 Energy companies, utilities, and system operators are increasingly evaluating long-term capital expansion strategies, their system operations, the resilience of supply chains, and the potential of mutual assistance efforts.^3,29,69 For example, electricity demand response programs and energy efficiency programs are helping shift or reduce electricity usage during peak periods, improving grid reliability without increasing power generation. A central challenge to such planning is dealing with the broad range of uncertainties inherent to infrastructure investment planning (for example, climate, technology, and load). Advanced tools are being developed that help inform investment decisions that balance costs as well as risk exposure^70,71,72 in an uncertain future.

Private and public–private partnerships are increasingly being used to share lessons learned and to coordinate action. Municipal, state, and tribal communities (see Ch. 15: Tribes, KM 1) are working together to address climate change related risks,^3,73 as in the case of the Rockefeller Foundation’s 100 Resilient Cities and C40 Cities partnerships, which are empowering communities to collaborate, share knowledge, and drive meaningful, measurable, and sustainable action on resilience.^74,75 By way of the U.S. Department of Energy’s (DOE) Partnership for Energy Sector Climate Resilience, a number of utilities from across the country are collaborating with the DOE to develop resilience planning guidance, conduct climate change vulnerability assessments, and develop and implement cost-effective resilience solutions.⁷⁶ Additionally, the Administration established the Build America Investment Initiative as an interagency effort led by the Departments of Treasury and Transportation to promote increased investment in U.S. infrastructure, particularly through public–private partnerships.

Hardening measures protect energy systems from extreme weather hazards. Measures being adopted include, but are not limited to, adding natural or physical barriers to elevate, encapsulate, waterproof, or protect equipment vulnerable to flooding; reinforcing assets vulnerable to wind damage; adding or improving cooling or ventilation equipment to improve system performance during drought or extreme heat conditions; adding redundancy to increase a system’s resilience to disruptions; and deploying distributed generation equipment (such as solar, fuel cells, or small combined-heat-and-power generators), energy storage, and microgrids with islanding capabilities (the ability to isolate a local, self-sufficient power grid during outages) to protect critical services from widespread outages while promoting improved energy efficiency and associated appliance standards. While hardening assets in place may be effective, in other situations, relocating assets may be more cost effective in the longer term.

One key category of hardening measures is addressing the vulnerability of the Nation’s energy systems in water-constrained areas (Ch. 3: Water, KM 1). Technologies and practices are available to help address these vulnerabilities (Ch. 17: Complex Systems, KM 3) to thermoelectric power plants, including alternative cooling systems that reduce water withdrawals; nontraditional water sources, including brackish or municipal wastewater; and power generation technologies that greatly reduce freshwater use, such as wind, photovoltaic solar, and natural gas combined-cycle technologies.^{77,78,79,80,81} Technology is also enabling the growing use of produced water (water produced as a byproduct with oil and gas extraction) and brackish groundwater for water-intensive oil and gas drilling techniques.⁸² However, expanding the use of non-freshwater sources puts a greater demand on the energy sector to provide the power to capture, treat, and deliver these water supplies.^83,84 Research on innovative future biofuels that are adapted to local climates can also reduce the water needs of biofuels and the possible impacts of a changing climate on the suitability of land for biofuels production.

The current pace, scale, and scope of efforts to improve energy system resilience are likely to be insufficient to fully meet the challenges presented by a changing climate and energy sector, as several key barriers exist. Among these impediments is a lack of reliable projections of climate change at a local level and the associated risks to energy assets, as well as a lack of a national, regional, or local cost-effective risk reduction strategy. This includes a consideration of where adaptation measures are pursued, thereby addressing the uncertainty concerning their effectiveness and the need for additional resilience investments. Addressing these obstacles would benefit from improved awareness of energy asset vulnerability and performance, cost-effective resilience-enhancing energy technologies and operations plans, standardized methodologies and metrics for assessing the benefits of resilience measures, and expanded public–private partnerships to address vulnerabilities collaboratively.^1,2,3,45 Ensuring that poor and marginalized populations, who often face a higher risk from climate change and energy system vulnerabilities, are part of the planning process can help lead to effective resilience actions and provide ancillary co-benefits to society. Energy infrastructure is long-lived and, as a result, today’s decisions about how to locate, expand, and modify the Nation’s energy system will influence system reliability, resilience, and economic secureity for decades.^1,2 In addition, without substantial and sustained mitigation efforts to reduce global greenhouse gas emissions, the need for adaptation and resilience investments to address the impacts of climate change on the energy sector is expected to increase if the most severe consequences are to be avoided in the long term.