By Planning Engineer (Russell Schussler)
Influential academics as a body are encouraging an energy transition to renewables, discussing remote hopes and ignoring huge obstacles and greater costs, which will worsen reliability and eventually result in unbearable blackouts.
Part 1 of this series discussed how the findings of academics are often misunderstood so as to make the transition to a high level of renewable penetration seem much easier than it will be. A major part of the problem is that academics study some problems, determine those are solvable and that is then misinterpreted to imply that greater emerging problems are also solved or easily solvable. In this posting we will look at what Academics are studying to determine if they are asking the right questions.
An earlier post discussed many reasons why approaching net zero would be challenging. For now we will focus on one major challenge to solar and wind penetration. Before any large generating resource can be connected to the grid, detailed interconnection studies must be performed. These studies seek to determine what will be needed to make sure the resulting system is robust enough to meet requirements for dependable stable operation. If the system in the area is strong and the resource adds additional robustness, then the interconnection requirements are minimal. If the system is weak in that area and especially if the connecting resource “leans” on the system, then significant costly improvements and additions may be needed in the area and across the wider system.
What makes a system strong or robust? In additions to high-capacity transmission lines, the anchoring source is large rotating machines that operate in synchronism with the grid. They provide inertia, they can respond quickly through ramping, they can inject vars, they increase short circuit MVA (mega volt amperes). All good things necessary for a reliable power system. Asynchronous generation, sources which don’t spin with the system, such as wind and solar, do not as readily add strength to a system; rather they tend lean on other resources.
Synchronous generators provide essential reliability services which are needed for the operation of the grid. The primary services are voltage control, frequency control and balancing services. Conventional generators (coal, natural gas, nuclear, hydro) readily provide these ser vices because they rotate in synchronism with the grid. Not all resources do. To quote from the US Office of Energy Efficiency & Renewable Energy”:
However, newer technologies such as wind, solar, many energy storage technologies, and new types of load controls operate through the use of power electronics and control systems that don’t operate in the same way as historic technologies. Newer technologies offer interesting (bold italics added) opportunities because their control systems can be tuned to operate similar (bold italics added) to conventional generation.
Rest assured the “interesting opportunities” offered by newer technologies will be extremely challenging, and before these challenges can be met much research development and successful engineering will need to be performed or the system will dangerously degrade. Also note the use of the word “similar”; do not believe that it means “similarly well in a satisfactory manner.” (I can throw a football similar to the way Tom Brady does, but believe me I could not sustain a high school offensive drive.) The challenges associated with integrating large amounts of wind and solar do not consist of minor details that can easily be worked out once we find a way to get enough megawatt hours at the right time from wind and solar resources to replace fossil fuel resources. Wind and solar will add complexity, cost and uncertainty for a long time. The less well these resources perform, the greater the likelihood of service reductions and blackouts. As noted, solar, wind and batteries, when providing power to the grid, typically lean on conventional technology.
It is a crucial question as to what will provide support when wind and solar have displaced the major supporting elements of the power grid. Hydro capacity is pretty well maxed out in most locations. Nuclear has potential to reduce CO2 while supporting the system, but faces considerable social and political challenges. Without some currently unspecified approach to add significant robustness to the system through the provision of essential reliability services, the increased retirement of conventional synchronously rotating generation and its replacement with asynchronous wind and solar will continue to make blackouts and outages more frequent and severe. There is much work to be done to make solar and wind better emulate essential reliability services, but such work is in the early stages and the results are at best mixed. Let’s look at what is being studied by academics supporting a net zero transition. One would hope that these major concerns would be a prime area of discussion and research within the academic community.
Conveniently as I was finishing up Part 1, I came across this article, Review on 100% Renewable Energy System Analyses—A Bibliometric Perspective. There has been a huge increase on scholarly publications relating to the net zero transition, as can be seen in the figures below taken from the article.
If we are serious about increased grid penetration from renewable resources, it is critical that additional successful impactful research be done. Breakthroughs will be needed in the planning and operating the grid to ensure reliability as the amount of asynchronous and intermittent wind and solar resources make up more and more of the generation mix. While batteries can help with the intermittency problem, they too are asynchronous resources, and thus may contribute to greater challenges. Wind, solar and batteries push toward an insufficient supply of synchronous resources, which anchor the system through their ability to provide inertia, vars (volts amperes reactive) and other desirable system needs.
As noted in the article, the study of renewables to achieve a net zero grid, is an international effort with many links among the contributors. Of particular value is the graphic below supplied in the article which shows keywords from the published articles. This graphic describes what is is being studied and receiving attention.
There are a few key words linked to the major problems associated with grid reliability. The relevant key words are: intermittency, electric power transmission, transmission capacity, seasonal variation, power flows, backup capacity, microgrids, energy demand, weather and storage capacity. There are a large number of words associated with cost, which is good. However, the keyword ‘levelized costs’ shows up, which is a reminder many are unaware of grid issues. Levelized cost does not consider the grid impacts of generation resources and solely focuses on the economics of generation divorced from grid impacts. This approach is very much out of place in confronting the challenges of obtaining a net zero grid. Trying to justify renewables by quoting levelized cost seems like either a major mistake or mis-direction. There are many words tied to reasons for reducing CO2 such as atmospheric pollution, decarbonization, air pollutions mortality, global climate and, low carbon. However, discussion of drivers and need are not helpful in figuring out how to achieve net zero. There are words linked to geographical locations where studies have gone on. From my review it does not appear that any significant number of these studies are about the grid and how it might be made to operate, but rather mostly resource-based evaluations and justifications for the need to reduce CO2 and calls to action.
What’s striking and most concerning is what is not found in this graphic of key words. Reliability, stability, inertia, voltage control, balancing, vars, spinning reserve, ramping, quick standby, contingencies, damping and oscillations for example. Words commonly associated with the interconnection process of new resources are nowhere to be found within this review of academic papers on the subject of a net zero transaction. Another notable omission is nuclear. Nuclear power is the best hope for a low carbon resource that could provide critical grid support. Is the group collectively serious?
The article talks of Energy System Models (ESMs) used to evaluate energy systems. They describe one model thusly,” EnergyPLAN is one of the most widely used ESM tools to evaluate energy systems with high shares of RE (Renewable Energy), applying simulation assumptions.” Taking a lesson from Part 1 of this series that statement should be understood as saying,” EnergyPLAN is one of the most widely used ESM tools to evaluate certain very limited components of energy systems with high shares of renewable energy, applying simulation assumptions”. The other programs referenced can be described similarly as only covering a limited portion of concerns around the proposed energy transitions. There is a lot of modelling and lot of studying going on, but evidently, the mainstream academics are not focused on the major challenges around generation, transmission and distribution of energy from asynchronous renewable resources nor are they concerned with promoting synchronous resources which could help. These models are concerned with backup, transmission and capacity at only the most superficial and basic levels when it comes to power supply concerns.
Imagine a body of academic literature surrounding a proposed transition away from both animal and vegetable sources for human diets. Most would hopefully recognize the inherent insanity if the major keywords were flavor, texture, scent, appearance and satiety while words like health, calories, nutrition, protein, fats, carbohydrates and digestible were missing from the literature. A vast literature seeking to eliminate beams from skyscraper would be suspect if the keywords did not include words like loadings, shear, stress and vibrations. The situation with these studies as to the grids ability to handle net zero carbon appears equally insane and ridiculous. A group of studies this large advancing an agenda to greatly increase asynchronous renewable (wind, solar and battery) penetration should show some consideration of the major challenges that will need to be addressed.
Studies about how much energy can be produced from these resources, how it can be stored and how it can be transported, where transmission is treated like plumbing, do not help us advance past the significant hurdles which lie ahead. Seeing many nations advance in lock step toward the goal of increased asynchronous intermittent penetration with no well-studied remediation actions in place is frightening. Instead of joint cheerleading, we should be sharing and documenting the challenges to better work around them.
There are many technical publications and many technical journals which grapple with the concerns around essential reliability services. For example, engineers, academics and scientists jointly grapple with the critical such as providing synthetic or virtual inertia through inverter technology to aid the Texas grid. There is some hope that advanced computer controls can be developed so that asynchronous resources perform similarly enough to maintain the grid at higher penetration levels. It should be recognized that the talk is of possibilities not probabilities. Here the National Renewable Energy Laboratory concludes “Ongoing research points to the possibility of maintaining grid frequency even in systems with very low or no inertia”. The unsaid part of that statement is that it may not even be possible to maintain grid frequencies with low inertia. It’s also certainly in the mix at this point, based on the statement from National Renewable Laboratory, that in the next 20 years the best we may be able to do at higher penetration levels of asynchronous renewables is maintain frequency in a highly inferior manner with a boatload of reliability problems, with increasing blackouts at untenably high prices.
The published papers in this area tend to focus more on dealing with problems in the present as system needs are emerging, not critiquing or advocating for potential changes, nor warning of the dangers of the long-term trends. There are many general differences between the literature studying actual grid reliability concerns and the studies in the net zero bibliography. They vary as to advocacy, audience, visibility and impact on policy. Part III of this series to be titled “Visionaries and Problem Solvers” will discuss the differences between these two groups in more detail and compare their distinctive approaches and the important resulting implications.
While the academics I would term as “visionaries” do not highlight or study major grid reliability concerns, I think such concerns are becoming more well known to them. The typical approach of visionary academics, to concerns about observed and emerging grid problems, has been to call for “Smart Grids” as if that magically solves everything. Modern grids are “smart” but as with any “smart” technology there are all kinds of applications that could be adopted, so of course not all potential “smart” applications could be employed on any given systems. Some small subset of “smart” applications may provide particular benefits in some circumstances and make it easier for asynchronous wind, solar and batter resources to interconnect and operate with the grid. Unfortunately, it is common for renewable proponents to make the leap to presume that “Smart Grids” could solve many or all of the grid problems associated with wind, solar and batteries. This is a false and dangerous presumption.
This ties to one last observation from the IEE bibliography keywords: “Supergrid” comes up frequently in the keyword search. This is likely because the limitations of “Smart Grids” in accommodating intermittent power are becoming more and more apparent and undeniable. “Supergrids”, the next big thing, can be poised to stifle emerging worries and bolster hopes of greater greenhouse gas emission reductions despite the technical problems seen by conventional grids and even Smart Grids. Rest assured large “Supergrid” applications will introduce additional problems, complexity and many issues which will need to be solved. They do not deserve to be considered as the next magic panacea. Perhaps there are limited opportunities where the simplest “Supergrid” applications might be considered in a long-term approach across a wide area, but overall, the concept is highly speculative and not ready for widespread promotion. Including the term in calls for a net zero transition only serves to misinform and distract policy makers. It’s disappointing to find it as a keyword on the net zero listing. Especially in light of the many crucial terms that did not show up. We should be careful to ignore the distractions of what might be possible one day and advocate for plans consistent with reasonable expectations.
The academic literature arguing for a net zero transition of the electric grid focuses on lesser problems and ignores the larger roadblocks. As a whole the body of studies might be seen to falsely suggest that the transition is within reach. The papers in this literature should include the disclaimer: “This paper only looks at a limited set of problems associated with a net zero transition. Solving the problem(s) studied here still leaves many unsolved and potentially unsolvable problems on the table and furthermore it is likely that this solution may aggravate existing problems as well as creating new ones.” Barring major breakthroughs in the areas of critical technical challenges (which don’t seem to be receiving a lot of attention at the policy level) the grid cannot reliably support the envisioned increase penetration of wind and solar need to get anywhere close to a net zero goal. Influential academics as a body encouraging an energy transition while focusing on lesser concerns, discussing remote hopes and ignoring huge obstacles will lead to increased likelihoods of greater costs, worsening reliability and eventually unbearable blackouts.
Thanks to Roger Caiazza for review and helpful comments
This link will allow you to see a 25 second clip of the Eastern Interconnection, the largest grid, responding to a fault and generator outage . On February 26, 2008 a substation fire caused a chain reaction that caused several system elements to trip off line, culminating in the loss of two large nuclear generating units. When generation is lost the rotating machines in the system very quickly increase generation. Because the loss was two large generating units, the protection schemes in Florida called for load shedding as well. The impacts of this event were felt throughout the entire grid. What the graphic shows is the patterns of generation in the east increasing and decreasing their frequencies to ride out this disturbance. In no harmful impacts were experience outside of Florida. This is because the large generators with their inertia were able to change frequency and dampen the oscillation. An electric system where the large rotating machines were replaced with today’s wind and solar applications would show great stress. In an over stressed system, the observed oscillations would continue and grow until many units were tripped off the grid and the resulting instability led to widespread blackout.
via Climate Etc.
January 9, 2023 at 02:07PM