Dr. Brent Bennet: Forget about what broke: the texas blackout was inevitable
We continue to learn new things about why Texas suffered a catastrophic series of blackouts due to the Polar Vortex. Dr. Brent Bennet has been at the forefront of examining this key question: was there enough reliable capacity on the grid to keep the lights on?
The answer, according to Bennet, is an emphatic no.
More than 40 people died because of the blackouts in Texas, and the situation would be even worse in Minnesota if we sustained prolonged blackouts due to an overreliance on unreliable wind and solar energy resources. Make sure to sign our petition demanding reliable energy from your elected officials.
As the joint hearings in the Texas Legislature unfolded last week, there was much discussion about what broke during the tragic blackouts from Feb. 15-18. It is evident that there were problems due to the low temperatures, which affected some power plants, natural gas production and distribution, and the ability of crews to restore power. But information is also surfacing about many human errors, including that ERCOT let the grid frequency ride too close to the edge, causing problems at some power plants. Large portions of critical natural gas infrastructure in the Permian Basin were also cut off by the blackouts because the transmission provider was not aware of the locations of that infrastructure.
It is important for legislators and Texans to know what went wrong, but the fact that has been missing from the discussion, especially in the media coverage, is that Texas NEVER had enough reliable capacity to make it through this event without blackouts. Even if every power plant and wind turbine had been operating at the same level of reliability that they do during the peak summer days, the combination of high demand, low wind speeds, and no sun during the cold mornings and nights meant that there were at least a few hours the night of Monday, February 15, when blackouts were inevitable.
State leaders should focus less on what broke and who is to blame and more on how Texas’ reliable electric generation capacity has fallen so low.
Looking at the forecasted demand for Monday and Tuesday, the magnitude of the capacity gap is hard to ignore. If every power plant that was online Sunday night continued to operate throughout the week and if wind generation was double its actual output—a rough assumption based on more than 50% being iced over and offline—there would have still been a period of over 24 hours between Monday and Tuesday, and a brief period Wednesday morning, when demand would have exceeded supply. As shown in Figure 1 below, that gap between total generation (stacked blocks) and forecast demand (dotted lines) would have reached nearly 10 GW by Monday at 8 PM. The lack of reliable capacity on our grid and the predictably low amount of wind and solar resources during this event made some degree of blackouts inevitable.
Figure 1: Actual demand and generation (in MW) prior to the 2/15/21 blackout and forecast demand and generation assuming no thermal generation failures and twice the actual wind generation
It is true that 14 GW of thermal generation—gas, coal, and nuclear—was offline prior to this event for various reasons, including planned maintenance and regular outages. While that is a high number, it is not very far above historical norms for February. However, even if the outage rate was only 4 GW, which is the norm for peak summer days, reserves would have fallen below 1 GW Monday night (see Figure 3), necessitating a level 3 emergency and rolling blackouts. The numerous failures Monday and Tuesday turned what might have been a manageable rolling blackout situation—as what occurred in 2011—into a catastrophic multi-day blackout. However, it must be emphasized that the primary cause of this event is more than a decade of bad policy that has left Texas short of reliable capacity.
Figure 2: Forecast demand and generation (in MW) assuming no thermal generation failures and twice actual wind generation
As the Texas Legislature seeks to correct the problems that led to this calamity, likely placing a heavy focus on weatherization, policymakers must recognize that it is not possible or prudent to manage against every extreme weather risk. It is reasonable to expect some power plant failures and some rolling backouts during weather this extreme, the coldest weather the entire state has seen since the 1980s. However, when reliable capacity fails to keep up with demand growth, the odds of these precarious situations become greater, and the room for error far slimmer.
There is only about is only about 76 GW of thermal generation available in ERCOT, a number that is roughly equal to summer peak demand and is not expected to grow as demand continues to grow over the next 5 years. Given the normal outage rate of 3-4 GW for thermal generation, any situation that places more than 70 GW of demand on that fleet requires near flawless operation to avoid blackouts. With demand growing between 1% and 2% every year in Texas, relying solely on variable wind and solar generation to meet that growth increases the odds that shortages will happen. That is not a political statement. It is simple math.
Common wisdom, including among our team, is that a shortage was most likely to occur during the hottest Texas summer afternoons, when demand is consistently high and wind generation tends to fall off. During each of the summers from 2018 to 2020, a combination of ERCOT’s extreme summer demand scenario and the 5th percentile of low wind output would have left the grid more than 4 GW short of capacity. Despite two emergency situations in August 2019 and near misses in August 2018 and August 2020, Texas managed to avoid blackouts. With potentially up to 18 GW of solar capacity coming online over the next few years—contributing a much larger fraction of its capacity during peak times than wind does—the Texas grid may be in better shape over the next 3 summers if (and a big if) that solar capacity comes through and more coal and gas plants do not retire.
What few people saw coming was the potential for a winter shortage, since demand is typically much lower during winter peaks than during summer peaks. This year’s event exposed the fallacy in that thinking, and a quick look at the numbers in Figure 4 shows why.
Figure 4: ERCOT winter generation forecasts (in MW) for scenarios with low wind, normal thermal outages, and extreme demand
Wind and solar usually contribute very little during winter peaks, with solar producing little at 8 AM and nothing at 8 PM, the two peak demand hours during the winter, and wind usually bottoming out during the coldest hours after a cold front. Therefore, situations where demand on thermal generation exceeds 70 GW, which is a telltale indicator of blackout potential, may actually be more likely in the winter over the next few years than in the summer. Even though this was a once-in-a-generation event—demand was expected to smash the previous winter record by more than 15%—Figure 4 shows that any significant winter storm may be enough to put the Texas grid over the edge as demand grows and no reliable capacity is added.
The straightforward math has said for years that Texas needs to have more reliable generating capacity to meet its growing demand. Instead, state and federal subsidies have tripled our unreliable wind and solar capacity in the last decade and pushed out reliable generation. The tragic blackouts turned that math into a hard reality for millions of Texans and left at least 70 dead in southern states.
So far, Texas has not required wind and solar to meet a reliability standard, and that must change if we continue relying more on those resources. Just as we require coal and gas power plants to reduce their pollution to levels that approach the emissions of wind and solar, we should require wind and solar to move closer to the reliability level of coal and gas. It is abundantly clear that the Texas market has failed to appropriately price the reliability costs of wind and solar, and without a reliability standard, more frequent blackouts are inevitable. Life:Powered will be at the forefront of developing and promoting a reliability standard for wind and solar during the remainder of this legislative session.