CMBlu's Organic SolidFlow battery is a redox (reduction-oxidation) flow battery (RFB) containing electrolytes in the solid and liquid form. Nearly all the energy is stored in a carbon-based solid. The liquid electrolyte acts as a shuttle, moving charged ions between positive and negative sides through the battery stack to charge and discharge. The separate tanks and stacks make it possible to scale power and capacity independently.
Electromechanical
CMBlu
Pilot
CMBlu is collaborating with WEC Energy Group and EPRI to install a 1–2 MWh pilot project at Valley Power Plant in Milwaukee, WI to test the performance of the battery system, including discharge durations of five to ten hours.
Energy Dome has developed a CO2 Battery system for LDES, utilizing carbon dioxide as the storage medium. Key features include efficient heat capture during CO2 compression and a flexible, above-ground CO2 gas dome, allowing for diverse siting possibilities. The pilot project, a 2.5 MWe/4 MWhe grid-connected unit, has successfully demonstrated the technology's viability and was completed in two years despite global challenges.
Energy Dome
Mechanical
Charging Energy Dome's CO2 Battery
Discharging Energy Dome's CO2 Battery
Pilot
The CO2 Battery system's projected RTE of 75–80% hinges on the performance of the TES modules and the efficiency of the compressors and turbines. The pilot plant in Sardinia, with a capacity of 2.5 MWe/4 MWhe, has demonstrated promising results, confirming the system's anticipated operational capabilities. These outcomes have placed Energy Dome's technology at Technology Readiness Level 7.
CMBlu’s Organic SolidFlow battery module is being designed to enable scalability. This photo shows how the modules can be stacked to increase the system-level energy density. Each module has a targeted footprint of 21.5–26.9 ft2 (2–2.5 m2), depending on duration, and a 50 MW, 250 MWh system has a projected footprint of 33,906 ft2 (3150 m2) for the battery portion.
This photo shows Energy Dome's 2.5 MW, 4 MWh CO2 Battery unit in Sardinia, which has been operational since May 2022. Energy Dome is also workingwith Alliant Energy, which as prime won a United States Department of Energy award in 2023 to install a commercial-scale Energy Dome system in Wisconsin.
Storworks Power (Storworks) develops systems to store energy using heat, focusing on thermal power plants. Stackable blocks made of concrete material store the heat. Charging occurs by passing either hot gas, steam or hot air through steel tubes in the concrete blocks. To use the stored energy, a fluid such as water or carbon dioxide is passed through separate tubes to recover the heat/deliver it to a power cycle.
Storworks Power
The Storworks concrete modules are large, flat blocks with embedded pipes set into them. The modules, called "BolderBlocs," are about 40 feet (12 m) long.
The Concrete Thermal Energy Storage (CTES) pilot plant consists of 7 layers of BolderBlocs stacked in a brickwork-like pattern along with an additional cooling block layer at the bottom needed to insulate the foundations during operation.
Pilot
The CTES pilot plant is a 10-MWhe scale (2.5 MWe x 4 hours) system at Alabama Power's Plant Gaston in Wilsonville, AL. Lead by EPRI and funded by the U.S. Department of Energy, this facility is demonstrating the technology's performance for the steam-heated version by charging using supercritical steam at a pressure of 3500 psig (240 barg) from the host plant.
RedoxBlox leverages magnesium-oxide (MgXO3) pellets, operating through two modes: charging and discharging. Charging: MgXO3 pellets are heated from 1830°F (1000°C) to 2730°F (1450°C) within a pressure vessel. Discharging: Pressurized air introduced into the vessel reacts with MgXO2, reversing the previous reaction and reforming MgXO3 to be used to produce electricity at 50-55 AC-AC% RTE when integrated with a combined-cycle gas turbine GT.
RedoxBlox
Schematic of RedoxBlox's Thermochemical Energy Storage System
The progression of RedoxBlox's technology from initial concept to larger-scale prototypes, with each step validating and refining the system's capabilities. The successful operation of earlier prototypes laid the groundwork for the development of a small-scale pilot, driving the technology's potential toward practical application.
Pilot
Sub-Scale Prototype (pictured on the left): Features the advanced 10 kWhth capacity prototype, which underwent over 1400 hours of charge-discharge cycling in 2021, highlighting the system's chemical stability.
Small-Scale Pilot (pictured on the right): Features commercial-designed temperatures and pressures with simulated charge and discharge modes at 100 kWhth capacity, validating control strategies and capabilities.
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Abundant carbon-based molecules for the electrolyte have the potential to be low cost when manufactured at scale.
Long Lifetime
Projected to have a 20-year project life, capable of over 20,000 cycles, with minimal loss of capacity due to cycling.
Long-Duration Energy Storage:
Emerging Pilot Project Summaries
EPRI Insights | March 2024
1
Electrochemical
Uses reversible chemical reactions to generate electricity, with lithium ion batteries being the principal technology. New electrochemical batteries represent a promising frontier in long-duration energy storage.
3
Thermal
Stores and releases energy in the form of heat. Heat can either be stored sensibly using media such as concrete, gravel, sand, or salt or using a phase-change material, which provides additional heat from phase transitions.
2
Mechanical
Harnesses kinetic or potential energy to store and release energy. Potential energy systems, such as pumped hydro storage, use gravity and involve lifting mass when charging and lowering it to spin a generator to create power when discharging.
4
Chemical
Involves creating a low-carbon fuel or
performing a reversible thermochemical reaction that can generate heat. Hydrogen is the primary low-carbon fuel candidate and can be generated using electrolysis, or chemically through reforming a fossil fuel, coupled with carbon capture and storage.
Emerging LDES Technologies Overview
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This report summarizes four recent pilot projects, highlighting their technological processes, performance and cost metrics, and potential viability as demonstrated through field work of four emerging long-duration energy storage solutions. The long-duration energy storage technologies include Electrochemical, Mechanical, Thermal, and Chemical and typically have a duration of 10 hours or more.
CMBlu
(Electrochemical)
Energy Dome
(Mechanical)
Storworks Power
(Thermal)
RedoxBlox
(Chemical)
(click to visit each pilot project)
Estimated capital costs at $150–220/kWh, with the levelized cost of storage projected under $100/MWh for early projects. Potential to reduce to $50–60/MWh.
Cost Effective
Storworks anticipates the cost of a system exceeding 10 hours of duration retrofitted to an existing steam turbine asset would be $60–105/kWhe.
Cost Effective
Cost Effective
Energy Efficient
RTE of 75–80% with 100% depth of discharge, operating without capacity or power degradation with a projected 30+-year lifespan; energy density is 1.9 kWh/ft³.
Using the concrete heat recovery steam generator (HRSG), the turbines can be sized smaller and run efficiently all day long, sending extra energy to the heat storage system.
Energy Efficient
The production cost of its MgXO3 chemical pellets is anticipated to range from $600–800/ton (equivalent to $1.8–2.4/kWhth).
High Energy Density
RedoxBlox is making its system directly compatible with commercial turbomachinery, by repurposing existing infrastructure.
Commercial Uses
Schematic of the Organic SolidFlow Battery
Schematic of the Organic SolidFlow Battery
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Strategic Insights Investigators:
Purandhya Vij, Jordan Aljbour, Róisín Sharkey, Poorvi Patel
Thermal
Chemical