Protecting the Grid

With the coronavirus pandemic, the elections, and the western wildfires hogging the news, you may not have noticed that 2020 has been a record-setting year for storms. Since May, twelve storms including six major hurricanes made landfall in the US bringing dangerous winds, storm surges, and heavy rainfall to communities spanning from the Gulf Coast to New England. Massive power outages accompanied these storms, leaving over five million people without electricity for days and in some instances for weeks. By putting climate physics into an engineering risk model, a Purdue-led interdisciplinary team of researchers is helping to protect our electrical grid against major storms.

This past August, Tropical Storm Isaias knocked out power for over 2.5 million customers across New York, New Jersey and Connecticut. Later that month Hurricane Laura struck Louisiana, killing at least 15 people and leaving hundreds of thousands more without electricity. Six weeks after Laura, Hurricane Delta made landfall in Louisiana just 13 miles from where Laura had come ashore—some affected areas still had not gotten power and water access restored since Laura. Two weeks after Delta, Hurricane Zeta became the 5th named storm to make landfall in Louisiana. As Zeta rushed inland, it affected 5 states, killing at least 6 people and leaving over 2 million without power. And the 2020 Atlantic Hurricane season is not yet over.

Loss of electricity in our homes, businesses, hospitals and other critical infrastructure is inconvenient at best, and life-threatening at worst. Power outages cost Americans tens of billions of dollars each year and, in an increasingly digital world, deeply affect our daily lives—how we learn, work, socialize, and shop. With nine in ten major outages in the US caused by hurricanes, researchers have worked to develop predictive models that can provide estimates of the extent of power outages prior to a storm landfall. Such short-term forecasts allow utilities to improve their preparation, response and recovery efforts. However, resilience investment decisions in electric power systems require the ability to credibly characterize long-term power outage risks, and this means including climate change in infrastructure risk models.

The effect of climate change on hurricanes is complicated. Current studies show rising temperatures are causing hurricanes to become stronger, produce more rainfall, cause higher storm surges, though it remains unclear whether the total number of tropical storms and hurricanes will increase or decrease. Incorporating this information into hurricane outage risk models is both difficult and computationally intensive. A new study led by postdoctoral researcher Negin Alemazkoo (Industrial Engineering) uses a novel method that, for the first time, links projections of hurricane activity under climate change with electric power distribution infrastructure risk models, providing a pathway for better integration of climate physics within intricate engineering risk models.

The research team, which includes Purdue Professors Roshanak Nateghi and Daniel Chavas, PhD candidate Benjamin Rachunok, and scientists from Sandia National Laboratory and the University of Massachusetts, built a transparent, inexpensive, and efficient modeling framework that was able to efficiently propagate the uncertainty associated with a host of climate change projections through a power outage risk model to identify what drives the uncertainty in long-term outage risks under climate change. Is it driven by climate change-triggered shifts in hurricane frequency or hurricane intensity? The authors find that power outage risk under climate change is primarily driven by uncertainty in the future frequency of non-intense hurricanes. This uncertainty creates large variances in the expected annual fraction of affected customers that ranges from more than a 30% decrease to a 40% increase. The wide range of possible future outcomes needs to be accounted for in power distribution systems contingency planning in terms of emergency operations and systems hardening efforts designed to reduce infrastructure vulnerability. These findings are also important for utility regulatory commissions to consider when setting and enforcing Reliability Standards.

Because most of the U.S. power transmission and distribution network (i.e., the grid), is above ground, the analysis did not include potential impact to grid-hardening measures such as undergrounding power lines—which are susceptible to hurricane-induced flooding—but the statistical relationships in the outage risk model used in this work can be coupled with a simulation model to explore alternative grid designs and consider technological changes, such as an increased adoption of renewable energy or distributed generation, in evaluating long term power outage risks. The approach used in this study can also be extended to account for potential changes in distribution of landfall locations for a more comprehensive analysis of power outage risk under climate change. These future studies would be substantially improved by efforts to better understand how hurricane frequency will change as the climate continues to warm.

 

Alemazkoor, N., Rachunok, B., Chavas, D.R. et al. (2020). Hurricane-induced power outage risk under climate change is primarily driven by the uncertainty in projections of future hurricane frequency. Sci Rep 10, 15270. https://doi.org/10.1038/s41598-020-72207-z