Why a Sushi Analogy Explains the Future of Grid-Scale Energy Storage
You probably keep hearing people say that integrating more renewable electricity generation requires the development of large amounts of storage. But why is this true? Operating the electric grid without energy storage is sort of like operating a sushi restaurant without a refrigerator: if you can't store raw fish, you either run out because people eat it all, or it rots somewhere and gets wasted. Both are bad for business. That's sort of what happens with renewable electricity: if you can’t store electricity, either we run out (and that's not good), or we have an oversupply and a lot is wasted (i.e., curtailed), also not good.
That’s why Michael Marshak—chemist, professor at CU Boulder, and founder of Otoro Energy—is betting on flow batteries. (In sushi, Otoro is a prized, energy-dense fatty tuna, by the way). In this episode of Beyond Lithium, we dug into how he’s using a stable, non-toxic composition of metal (chromium) with a consumer-safe chelator similar to EDTA (which is found in consumer staples like shampoo and mayonnaise) to reimagine large-scale battery chemistry.
Here are 5 takeaways from the episode that energy professionals, battery developers, and grid planners can use to make smarter, safer, and more scalable storage decisions.
1. Design Grid Storage Like a Logistics Network, Not Just a Battery
Marshak points out that the grid isn’t just short on storage—it’s short on storage in the right place. He likens the challenge to Amazon logistics: “You want your warehouse close to your customers.” Centralized storage far from load centers creates a transmission bottleneck, especially during emergencies or weather events. Locally deployable flow batteries help solve this problem—especially if they're safe enough to install near homes or businesses.
2. Otoro’s Flow Battery Chemistry Tackles the Scalability Bottleneck
Traditional vanadium-based flow batteries are expensive and resource-constrained. Marshak’s team developed a high-voltage, water-based battery using a modified chelating agent (a variant of EDTA) bound to chromium. This shift not only improves performance but also radically simplifies scaling: “You want to store more energy? Just add more tanks,” Marshak says. No new electrodes or extra modules—just more electrolytes.
3. Are Toxicity and Fire Risk Dealbreakers for Distributed Storage?
Otoro’s chemistry isn’t just cost-effective—it’s clinically benign. Chromium bound to EDTA is so stable it’s used in kidney function tests. “You can literally inject this into humans,” Marshak explains. And because the battery operates in neutral-pH water, the system is inherently non-flammable and chemically safe—traits that may be essential for permitting future deployments in neighborhoods, businesses, and critical infrastructure areas.
4. Higher Voltage = Higher Efficiency—Even in Water
Marshak’s battery achieves an impressive 1.62 volts, near the upper theoretical limit for water-based systems. That voltage brings two key benefits: higher power (because power scales with the square of voltage, P = IV = V^2/R) and higher efficiency (due to lower relative resistive losses). Unlike traditional electrolysis, which needs high voltages and precious metal catalysts to split water, Otoro’s chelated chromium chemistry uses abundant materials and water and non-precious electrodes. This formulation and architecture also helps avoid side reactions—achieving long shelf lives and low self-discharge.
5. Target High-Value Use Cases, Not Just $0.05/kWh DOE Goals
While the U.S. Department of Energy's Long Duration Storage Shot targets a levelized cost of $0.05/kWh, Marshak warns against making that the first milestone. “You won’t be profitable for a very long time if that’s your entry point,” he says. Instead, Otoro is focused on remote, expensive-to-electrify markets (e.g., islands, military sites, microgrids) where storage offsets high diesel or peak-demand costs. These are the proving grounds where new chemistries can gain traction—and revenue—before scaling to the broader grid.
Catch the full episode here: https://open.spotify.com/episode/1iAkgz9FK75KJRQG8uc3R7?si=89a05710eb9e4c99
