In the late hours of this past Sunday, an unprecedented winter storm swept across the state of Texas. As temperatures reached record lows in various areas across the state, utilities began to falter and fail. Spikes in power demand associated with the rapidly dropping temperatures were unable to be serviced by the state’s ERCOT (Electric Reliability Council of Texas) managed electric supply grid. A system with attributes of a leading-edge renewable energy system (Texas wind energy’s nameplate capacity of 31GW leads every other state, and would rank fifth in the world as a country) failed to meet the demands of Texas residents when they needed it most.
Much has been said about why the failures occurred, but none have had a strong focus on factual occurrences and causes. Efforts have been made to paint green energy as bad, or hydrocarbons as bad, but these are just efforts to distract and divide people who need to work together on a system that will operate reliably and efficiently for Texas residents when they need it most. To begin to understand why the failure occurred, it is necessary to look at the makeup of the system and the events during and leading up to the failure. Future articles will delve deeper into specific aspects of the events of the crisis, causes, impacts and potential preventative measures.
The Texas power grid, at first glance, appears to be an unfathomably complicated mess; the pre-World War II Buchanan Dam to the state and the art solar plants of West Texas along with everything produced in-between generating electricity and feeding it to the ninth-largest economy in the world by GDP. Mainstream news would leave one to believe our unregulated and isolated grid was prime for disaster and what happened on Feb. 15 was nearly inevitable with our cavalier attitude towards independence at all costs, leaving us cold and scrambling in the dark. The truth, though, is much more nuanced.
Let us start by re-addressing some often confused and/or misstated facts. The electrical grid of the United States is much more complicated than the often stated “Eastern, Western and Texas” breakdowns. Texas does indeed operate as a mostly independent system but there are interconnections from both the Eastern and Western grids (as well as Mexico) to Texas. The grids stretching out across North America are operated by Transmission System Operators which is the category everyone’s new favorite entity, ERCOT (Electric Reliability Council of Texas), falls into. Transmission System Operators are the real coordinators that keep electricity flowing in the United States; they are not-for-profit companies coordinated by local governments and utilities to oversee the production, distribution, and sale of utilities in their areas. ERCOT is a not-for-profit cooperative effort of every municipal utility company, power production facility and distribution entity in Texas designed to oversee keeping the lights affordable and reliably on in the state; this brings us to our second fact.
At least as early as Feb. 12, while Gov. Greg Abbot was working on a statewide disaster declaration, ERCOT reached out to the Department of Energy to request exemptions to the national rules which dictate how much pollution power plants can produce. ERCOT was not asleep at the wheel, as seems to be a common narrative; they had a plan to push our state’s power plants into overdrive and produce as much electricity as possible from sources that could be throttled. ERCOT doesn’t control how much energy our solar plants can absorb or the seasonal flow of the rivers through our hydroelectric dams, but they could turn up the wick on our coal, oil and natural gas plants in anticipation of the coming weather event. Graciously, President Biden’s acting Secretary of Energy David Huizenga granted temporary exemptions.
An interesting note regarding ERCOTs request for relief from emissions limits: the additional energy produced by ERCOT generators which might be facing output limits or offline due to federal emissions limits would be able to produce and sell power above those emissions limits so long as the price was above $1,500 per MWh, or at rates 460% higher than the $325 per MWh energy was trading at on Feb. 11 as prices started to spike in Texas. The stated purpose per the Department of Energy order (Order No. 202-21-1) issued by the Biden-appointed acting Secretary of Energy David Huizenga: “To minimize environmental impacts”. The DOE order further went on to state that the order did not provide relief from obligations to purchase allowances for emissions. It is unclear how much of the emergency demand met was produced under this requirement, but it does appear the DOE placed perceived long-term environmental impacts above immediate threats to human life and livelihoods in an extreme weather event. Despite this, the economics of generating electricity for this spot demand would result in prices greater than $1,500/MWH anyway (energy settled at $8,718/MWH on Feb. 15 at 2 a.m.). This is a characteristic feature of the open energy market ERCOT seeks to foster and a challenge for Texas consumers who hoped to save money with variable-rate electricity contracts. Households buying at market rates can face prices nearly 100 times higher than typical market rates when statewide demand is high. Conversely, these high prices ensure producers are eager to meet surges in demand even when great effort is required.
After DOE approved ERCOTs request to enable increased capacity, it would appear ERCOT was prepared and had a plan in place; fossil fuel plants were operating at maximum capacity and surely our diverse electrical grid was prepared for a worst-case scenario? As we now know this wasn’t the case and nearly as soon as temps dropped so did power production and the lights dimmed across Texas, now we want to know why? The answer to this question is likely extraordinarily complicated but ERCOT’s own data can be used to draw out some conclusions.
Texas is the nation’s leader in wind energy; with a nameplate capacity of 30,904 MW (as of Feb. 15) Texas power demand for the first days of February could have theoretically been supplied mostly (about 75%) by wind.
Days like Feb. 8 are impressive reminders of the utility of a well-functioning wind generation system. At peak production on that day, wind produced over 20GW (or around two-thirds of total production in Texas). But this chart also shows several other characteristics about the energy production capabilities of Texas and some important comparisons must be made between wind and thermal supply. Wind production is not steady, and nameplate capacity is rarely achieved. At times, wind production dropped to around 1MWH, or around 97% below nameplate capacity (coincidentally, just as the most severe weather was impacting most of Texas). During this time, natural gas sources were producing nearly double their rates compared to the early days of February. These numbers tell some important information about the durability of production of each, wind and thermal sources, but these systems are not isolated from each other and the interactions between the two systems during the peak load event of Feb. 15 warrants review. This article will review some events which could be cause and effect interactions between the two systems, but further study is needed.
The below graph from the EIAs reporting of ERCOTs data (available on EIA.gov) showing what the state’s needs were starting Feb. 14 and continuing until the end of Feb. 15, the day the power started to turn off for millions of Texas residents.
This graph highlights a few other keys elements which may be relevant to our power woes this last week. Around 6 p.m. on Feb. 14, demand peaks at approximately 70,000 MWH as it initially passes demand forecast. This was below the record supply for the state (73.8GWH on 15AGU2021) and occurred while wind was producing around 9,000 MWH (a production peak not to be seen again for several days) and as Texans weathered unprecedented days-long winter chill.
Immediately after the peak in demand at 6 p.m. on Feb. 14, wind production begins dropping and natural gas, the strongest swing producer of electricity in Texas, ramps up to meet demand and then plateaus. Sometime around 2 a.m. on Feb. 15, natural gas and coal facilities trip offline, followed by some nuclear production around 6 a.m.; this was the beginning of the disaster as the system became overloaded and begun to “shed load” (an industry term for disconnecting load from the electrical grid to prevent damage to the grid and its sensitive equipment). Wind production continues to drop throughout the day reaching a paltry output of around 650MWH.
The precise reason for the natural gas facilities going offline is important to review, and from preliminary reports, it seems many of the issues could be prevented by weatherizing equipment and implementing other design changes to improve operability in (unprecedented) low temperatures. Certainly, states like Pennsylvania show that reliable cold weather natural gas generation is possible. A later follow-up to this article will review the interaction between available natural gas supply, weather-related supply issues and shutdowns at natural gas electric plants.
Now, as we had stated above, Texas’s power generation network is vast and complex. It is well past the scope of this article to suggest only wind power’s failure caused our systems crash but when one is presented with a graph where power generation drops from just over 9,000 MW to just under 1,000 MW while that power source’s energy (wind in this case) is in abundance it is worth asking why? It is certainly worth taking notice when the curve of our systems overall failure matches that of a specific power generation source for that system so closely. But why? Why when the front was coming and the winds were at their strongest did wind power drop so quickly? As it turns out wind generation is a relatively sensitive process. Wind Turbines must strike a delicate balance between producing as much energy as possible and remaining viable and reliable long-term. Extreme winds and extreme weather mean wind turbines brakes must be engaged and the blades held in place to keep wind and ice from tearing the blades, bearings and foundations apart. We are left with a system that, just as power demand begins to increase due to historic cold, must be shut off. Many have been keen to point out that wind farms operate in places colder than Texas and are equipped with blade heaters or other de-icing means or winterization packages. While this is true, these units still must shut down for de-icing to mitigate the risk of ice damaging moving blades or being thrown at nearby environs. Further, while they are shut down with de-icing heaters active, they are relying on stored or grid energy to run the heaters and eventually bring them back online. And even those windmills with winterized systems must shut down above certain wind speeds to prevent overrun. The Atlantic County Utilities Authority reports their Jersey-Atlantic Wind Farm shuts down at wind speeds above 45 mph.
Now, to state once more, drawing far-reaching conclusions from any of the presented charts on their own is dangerous. Wind power does provide a great resource for Texas and our systems record production of 23 MW on Jan. 4 this year provided 45% of the needed electricity for our state at the time. What we can see and what we can conclude though is that in this instance wind power did fail us; other system failures aside it is easy to see wind power stopped working just as we needed it the most. Perhaps an over investment in wind and under investment in, say, natural gas, or even nuclear production capacity has contributed the deadly grid failure we just experienced. Without a doubt, some old-fashioned fossil fuel backups can help keep Texas out of the stumbling darkness in the future but only if we learn from and acknowledge current failures.
And let’s be careful not to give a pass on unsteady renewable energy sources by saying we will steady them out with large battery banks, which presently do not exist and are not necessarily very environmentally friendly to manufacture, or may even depend on unfair labor practices where raw materials are mined.
James Higdon studied mechanical engineering at the University of Texas at San Antonio and runs a small business where he specializes in managing vintage and exotic automotive investments and servicing. Tanner Powell has worked in the energy industry for the past 13 years, specializing in oil and gas projects, and has a Bachelor of Science in mechanical engineering from Texas A&M University – Kingsville.