Last week’s deep-freeze in Texas, which disrupted the lives and safety of millions of people left without heat, power and water after a snowstorm led to rolling power blackouts and a near-collapse of the state energy grid–make clear the need for resource planners to stress-test utility grids for high-impact weather scenarios due to climate change, regardless of whether energy is generated from fossil fuels or renewable sources. So concludes a recent report from the independent, non-profit Electric Power Research Institute.

“My heart goes out to the EPRI employees and millions of Texas residents and businesses struggling to keep their light, heat and water on during this massive winter storm, during a global pandemic,” said EPRI President and CEO, Dr. Arshad Mansoor, speaking last week upon official release of the report, titled Exploring the Impacts of Extreme Events, Natural Gas Fuel and Other Contingencies on Resource Adequacy. “So much of our economy already rests on the electric sector, but as more of our economy becomes reliant on electricity, and our grid continues to integrate more low-carbon renewable resources, we must change the way we assess the reliability of our system.”

Dr. Mansoor applauded the dedication of utilities in Texas and across the Southwest in “responding efficiently and generously to increased weather events, which we no longer call an anomaly.” With this in mind, he added, the realities of climate change are prompting some grid operators to look at system planning and generators in a new way, to evaluate extreme weather readiness at the plant level.

“Our existing grid supply and delivery assets must be hardened for climate change scenarios regardless of generation—renewables and fossil fuels,” he said. “Extreme weather events have adversely impacted all generation types, some more than others, relative to the output that was expected in the ERCOT [Electric Reliability Council of Texas] resource adequacy planning. Finally, broader interconnection with other systems through new transmission will increase access to diverse resources and fuel supplies and is a critical piece of a resilient grid that accommodates more low-carbon resources.”

Billion-dollar weather events

Their report pointed to two central concerns that energy resource planners should be addressing with regard to “high-impact, low-frequency” (HILF) events, such as the Texas grid failure. First is the rising frequency and intensity of events that have a high impact on the power system. Second is the correlation of these events, which has led to the probability of high impact events being undercounted, when modeled based on available historical frequency data

EPRI has found that extreme weather events–defined as natural disasters including hurricanes and tropical storms, flooding, drought, extreme heat waves, extreme cold fronts, wildfires, high winds, tornados, thunderstorms, and snow or ice storms, which are unusual compared to the climatological average–caused 52.9 percent of U.S. power outages from 2000 to 2016. Most of the aforementioned weather phenomena are occurring more frequently as a result of climate change. And are also occurring with greater intensity, geographic coverage, and duration.

Additionally, the average annual number of “billion-dollar” weather events in the U.S.–i.e., disasters causing $1 billion in damage– has increased five-fold from 2.9 per year in the 1980’s, to 15 events per year over just the last four years (2017-2020). The average annual dollar impact of billion-dollar weather events has increased by a factor of 8.6 since the 1980’s, adjusted for inflation, from an average $17.8 billion in that decade to $153 billion from 2017-2019.

EPRI allows that some of the increase in “billion-dollar weather events” may be driven partly by an increase in wealth (e.g., home value), population, and people moving into geographic areas more prone to impact from extreme weather events. Still, the non-linear effect of increases in extreme event frequency,  along with greater intensity, wider geographic coverage and duration, is a major contributor to dollar damages. This, in turn, has significant implications for the energy industry.

EPRI says that in order to accurately project disruptive weather event probabilities in the future, systems planning for electric reliability needs to incorporate this rate of change in the planning process itself. Historical probabilities for the frequency, intensity, geographic scope, and duration of severe weather events need to be adjusted upwards to take recent climate trends into account.

Lessons from the Polar Vortex

EPRI offers by way of prior example, the January 2014 Polar Vortex, an extreme cold weather event spanning the U.S. Midwest, South Central, and East Coast regions, and generating record high electricity demand in these areas. The cold snap also fueled demand for natural gas, which resulted in a significant amount of gas-fired generation being unavailable due to natural gas curtailments. This “confluence of factors,” EPRI notes, led to the exhaustion of all electric reserves, the calling for demand management tools, voltage reduction measures and in some instances the shedding of about 300 MW (0.1 percent) of total load–“load-shedding” being a synonym for “rolling blackouts”–in the Eastern Interconnection (one of the two largest energy grids in North America) and in ERCOT.

Along with blackouts, record natural gas and electricity prices were reported during the first quarter of 2014. EPRI points to the 2014 Polar Vortex as an example of a common mode event: the power system experienced a dramatic simultaneous loss of available generating capacity, and that might not be captured using current standard models for testing resource adequacy.

The report notes that growing reliance of the bulk electric power system on gas-fired generation has increased the need to improve coordination between wholesale electricity and natural gas markets. This is critical, as the amount of natural gas in power generation is expected to significantly increase as coal fired and nuclear plants are replaced with gas-fired generating capacity. Over the last decade alone, the use of natural gas as a fuel for electric power generation in the U.S. increased from 969 TWh (26 percent) to 1,461 TWh (41 percent).

At the same time, variable power generation from solar and wind is increasing the variability of pipeline deliveries to gas-fired generators used to balance the electric grid. As a result, EPRI notes, intraday and even sub-hourly swings in demand for natural gas as a fuel for electric generation pose reliability risks for both gas pipelines and electric systems, and will create new challenges for pipeline operators.

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