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Article | Argonne Collaborative Center for Energy Storage Science

Energy storage for the grid: Q&A with Susan Babinec

With 20,000 power plants, 200,000 miles of high-voltage transmission lines, 60,000 substations and 3 million miles of power line, the nation’s electrical grid is perhaps the largest and most complex machine ever assembled.

At the U.S. Department of Energy’s (DOE) Argonne National Laboratory, scientists are using their expertise and world-class facilities to modernize grid operations while increasing its security and resilience. A variety of new technologies are being integrated into this future grid and energy storage is a critical component for all sectors – electricity generation, transmission and distribution. Argonne will build on its rich legacy in energy storage towards stationary technologies for the future grid.

Susan Babinec joined Argonne last year as the program lead for stationary storage. She is responsible for devising a comprehensive energy storage strategy that combines Argonne’s grid and energy storage capabilities with a vision of a future grid. In the Q&A below, Babinec discusses key trends and the lab’s deep bench in energy system R&D to pursue innovative solutions for the future grid energy storage.

Q. Why is stationary storage important now?

A. Overarching stationary grid storage concepts are not new, but the emerging critical need for storage on the grid is what’s new. Our aging grid is under serious rebuild: the new future” grid in many ways will be quite different than the original and one way is substantial storage.

Economics guides grid redesign — the foundational questions are: What are electricity generation assets? And what are the locations and nature of the demand? New grid electricity generation is often via renewables, solar and wind, because these are increasingly the lowest cost source — with heavy regional flavors. The variability of renewables is an issue as customers need around-the-clock electricity; energy storage is an excellent and versatile solution, which is why it is in high demand.

The other half of the why now” story is the rapidly declining energy storage prices, further improving the bottom line. There is a global scale-up of battery manufacturing for electric vehicles (EVs), which is smoothing out manufacturing and supply chain issues and driving down costs. Energy storage grid options that didn’t make financial sense three years ago are valid today.

Argonne has an amazing combination of depth and breadth in both grid and storage. So, we have a very nice starting point. Argonne is well recognized for its expertise in grid systems planning, operations, resilience and security.

Q. Although the current market role of storage is small, will this change as renewables gain ground?

A. Yes. As I just mentioned, renewables and stationary storage technologies are coupled, and both are experiencing incredible growth. As renewable content on the grid increases, not only the absolute demand for storage increases but also the duration needed increases and the affordable cost decreases. The storage duration guides the type of appropriate technologies.

Viable Lithium-ion (Li-ion) durations today go up to about four hours to six hours — solar load shifting is a great four-hour example. After that, it is no longer economically viable and new concepts are needed. Flow cells become a great option in the four- to 12-hour range. They separate power from energy by using tanks of stored electrolytes, which are pumped across electrodes to generate power. If you need longer duration, you simply increase the size of the tanks, which hold the storage electrolytes. New flow cell chemistries have been a focus of the Joint Center for Energy Storage Research, a DOE Energy Hub led by Argonne.

The segment beyond 10 to 12 hours is called long-duration storage (LDS), which is generally needed when renewables get up to about 50% or more. It requires super low-cost capital — $50 to$60 per kilowatt hour (kwh) — with a material cost around \$25 per kwh. Chemistries will need to be based on Earth-abundant and super-low-cost materials; likely this means new supply chains. Candidates include lead, sodium, potassium, manganese dioxide, to name a few. Today, we are in an interesting situation where many cities and states are setting high renewables targets that will require LDS, but economically viable solutions are not available. Some consider this the next holy grail for storage since it is so challenging.

Q. What is Argonne’s future grid storage vision and strategy?

A. The ultimate objective is to establish a leadership role for both storage technologies and system designs based on demonstrations of high-impact innovations. This is Argonne’s reputation in other areas; it’s ambitious and will take some time. It’s possible because we have such great resources, not only in energy storage and the grid, but also in manufacturing, computational science, materials, analytical science and other sciences. The stationary storage program will have significant cross-cutting collaborations.

Our approach is to initially leverage existing resources for near-term problems, which have adjacency to existing projects, and then to strategically expand capabilities for the longer term. Grid innovations are dominated by economics, so we will use economic analysis even in the earliest stages of project design.

In terms of specific technologies, Li-ion is dominant today, so, I categorize our initial approach as technology that is either related to Li-ion or not. There is a bit of a quandary, since we are broadly a fundamental and low TRL (Technology Readiness Level) focused lab that needs to get started by addressing immediate applied problems on incumbents, but we do have two excellent projects already. Medium term, we are modifying approaches to chemistries that we are familiar with. Then longer term, we will seek new capabilities.

Q. How has Argonne leveraged its knowledge and capabilities to develop solutions?

A. Argonne has an amazing combination of depth and breadth in both grid and storage. So, we have a very nice starting point. Argonne is well recognized for its expertise in grid systems planning, operations, resilience and security. We are the national hub for energy storage and have resources across the entire innovation life cycle, including manufacturing. This combination can uniquely enable Argonne to provide comprehensive solutions to complex problems that are difficult to get elsewhere.

In terms of specific grid-storage projects, three come to mind. The first is a collaboration with the grid group for a solar/storage system design requiring both cost-effectiveness and resiliency for a 20-year lifetime. Batteries degrade in a very complex manner and typically are used for about eight years. Since their capacity is the key to value generation, this project required us to combine our deep Li-ion degradation knowledge with the grid design skills applied to competing requirements. This very tricky balancing act yielded tremendous savings to our customer and it looks as though there will be even more complex designs in that future. It was a fun project and I greatly appreciate the depth both sides brought to the solution.

Another Li-ion related project is artificial intelligence (AI) for accelerated battery degradation prediction. This project is perfect for Argonne, since we have a massive battery testing database as the energy storage national hub, a large population of world-class computational scientists, and a world-leading supercomputer. The problem to be solved is that accurate grid modeling and economics require precise life data, which is very time and resource intensive to generate. Today, approximations must be used, and these create risks which limit design creativity. Our goal is to reduce life evaluation time from the typical two or two and a half years today to two to three weeks, which will be a huge breakthrough and is a cornerstone of our strategic buildout.

The third project is Planned Second Life (P2L), which targets transitioning used EV batteries to the grid. This makes sense in terms of the circular economy — it must happen since there will be so many used transportation batteries. While today there are minimal physical barriers to the transition, the Argonne question is: What technologies will enable the economic optimization of that transition and reduces risks so that this occurs broadly? The basic needs are to quickly evaluate the state of health of individual cells and packs and then next to use AI to determine optimal placement on the grid in terms of reliability, lifetime and economic value. Another nuance is to determine best timing for the transition in advance using health data. These are complex and interrelated considerations and we will leverage our full suite of Li-ion knowledge and upcoming AI. It is also complementary to our recycle program.

Q. Is Argonne exploring long-duration storage chemistries?

A. Yes, we have started. Remember, this is an especially tough problem as the solutions must be both safe and super-low cost and so we are looking closely at economics as we screen potential chemistries. The size of this market will be huge since the durations are so long, and as such raw material and supply chain requirements are an early consideration — this is an opportunity for innovations in a somewhat newer domain for a national lab.

The list of electrochemical possibilities includes active electrochemical couples based on lead, manganese dioxide, molecular oxygen and sulfur and low-cost metals, such as zinc. The electrolytes will likely be substantially aqueous, and salts will be based on abundant sodium and potassium most likely. Cell and electrode designs and their manufacture will also need significant innovations to hit the cost target — here our electrochemistry and manufacturing capabilities will be combined.

Other Argonne technologies make sense at this large scale — examples include various types of chemical and thermal storage. For these, system efficiencies and storage vessel designs are critical. Argonne also has a strong legacy in pumped-hydro storage; this mature technology is reinventing itself to meet changing grid needs.

In short, our fundamental capabilities, combined with understanding of what is critical in the grid, can give rise to breakthroughs in this very challenging topic.

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