Image Source: Smithsonian Magazine
As the winter season approaches, energy grids globally are gearing up to face the issues of increased demand, combined with decreased generation capabilities. If the winter seasons of the last few years are any indicator, it should turn out to be an interesting season as ISOs scramble to meet demand. Overall, the biggest risks seem to be twofold: decreased fuel resources and extreme weather events [1]. In the United States, Texas and the ERCOT grid once again seem to be the point at which failure is the most likely. For those that remember Winter Storm Uri in 2021, rolling blackouts and power outages across the region may be all too familiar.
Recently, the North American Electric Reliability Corporation (NERC) published its 2022-2023 Winter Reliability Assessment [1]. In the report, the organization lays out the challenges that the grid will face in the coming months and the means that ISOs have to mitigate the environmental stresses that come with the winter months. NERC conducts an assessment of all power pools across North America, however, three, in particular, stand out in this assessment of risk. The Midcontinent Independent System Operator, inc (MISO), Southern Power Pool (SPP), and Energy Reliability Council of Texas (ERCOT). All three of these system operators were the most greatly impacted by the effects of Winter Storm Uri, and it seems that once again, extreme weather events will play a role in their operation.
Image Source: U.S. Energy Information Administration
While ERCOT was by far the most impacted by the winter weather of '21, MISO and SPP faced their own challenges of increased load, combined with decreased reserves. In order to combat this, both ISOs have refocused their energies on improving "coordination and situational awareness," and running load-shedding tests to prepare for emergency situations. Time will tell if these improvements have the desired effects, however, the preparedness of each region can already be seen in their reserve margins. Under normal operating conditions, MISO and SPP have an anticipated reserve margin of 43.1% and 70.0%, respectively. However, under extreme conditions*, MISO's margins fall to -7.6%, while SPP's fall to just 9.3%. What does this mean? In the case of extreme load and scarce generation, MISO would be unable to meet the demand.
While this is not a great scenario, there are a number of ways to mitigate this. Load-shedding is a common practice, as well as the transfer of power from other ISOs. Even in the case of extreme conditions, both SPP and MISO should be able to handle the electricity demand.
ERCOT is a different story. Due to the setup of the US electrical grid, ERCOT is an "electrical island," with limited connection to both the eastern and western interconnects. Therefore, in the case of extreme conditions, ERCOT does not have the infrastructure to draw from the surrounding power pools. Another issue facing ERCOT is its expected reserve margins. Under normal operating conditions, ERCOT has a reserve margin of 36.4%. However, under extreme conditions, the margin drops to -21.6%. If ERCOT faces another winter storm, it will once again be unable to meet the demand of its customers.
Already, both the Pacific Northwest and the Midwest have faced the challenges that come with winter storms [2]. Winter Storm Diaz is the latest of these events, sweeping extreme winter conditions across the country. Word is still coming in about power outages, however, it is undoubtedly that these locations, will need to adapt quickly to handle the ever-changing circumstances. While these Northern regions, MISO included, are better equipped to handle winter weather, it is only a matter of time before a storm ventures South, challenging the infrastructure of the Southern states. It will be interesting to see how power pools such as ERCOT improve their protocols, after being so publicly exposed in the recent past.
*Note: "Extreme conditions" refers to uncharacteristic weather patterns, unexpected outages, etc.
Sources
[1] "Report: 2022-2023 Winter Assessment," Federal Energy Regulatory Commission, 25 October 2022. [Accessed: 9 December 2022].
[2] "Major Winter Storm Brings Blizzard Conditions to High Plains as it Tracks East," The Weather Channel, 13 December 2022. [Accessed: 13 December 2022].
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