Carbo Energy
Carbo Energy builds hybrid non-aqueous redox flow batteries for grid-scale storage, delivering near-lithium energy density (190–200 Wh/L) with zero fire risk and a 40-year lifespan. Its containerized 250 kW modules use a multi-electron phenothiazine catholyte and chloroaluminate anolyte, achieving 2.84V cell voltage with power and energy decoupled for scalable duration.
- Battery Technology
- Energy
- Clean Technology
- Chemical Technology
- Hardware
Funding
Funding not disclosed
Founders
Founder details are not available yet.
Product
Problem
Grid-scale energy storage must grow 25× by 2030 to meet renewable energy integration targets, yet current lithium-ion solutions degrade rapidly at deep cycling, require full replacement every 8–10 years, and carry inherent thermal runaway fire risk. There is also insufficient lithium supply on Earth to produce the storage capacity the grid needs, and insurance premiums for li-ion systems are rising 15–30% annually as permitting near populated areas becomes more difficult.
Solution
Carbo Energy builds hybrid non-aqueous redox flow batteries that deliver near-lithium energy density (190–200 Wh/L) with a 40-year system lifespan and zero fire risk. The chemistry pairs an AlCl₃:N-ethylurea anolyte with a phenothiazine-based catholyte in diglyme, operating at a nominal 2.84V cell voltage with a 2-electron redox mechanism that enables multi-electron energy storage. The modular system is housed in a standard 20-foot container with a 250 kW cell stack, where power is decoupled from energy — adding storage capacity means increasing tank volume, not adding cells. The electrolyte tolerates up to 50,500 ppm water contamination and is non-pyrophoric, eliminating the need for a glovebox and reducing operational complexity. With active material costs of $126/kWh and installed CAPEX of $183/kWh, the system achieves a 20-year LCOS of $0.08–0.10/kWh, significantly undercutting lithium-ion alternatives.
Target Audience
Primary customers are electric utilities, grid operators, and large-scale renewable energy developers that need long-duration, fire-safe storage with multi-decade operational lifespans, as well as AI-driven datacenter operators requiring 4–12 hours of backup storage.
Features
- Energy density of 190–200 Wh/L achieved through multi-electron redox chemistry (2-electron phenothiazine oxidation) in a flow battery format
- 2.84V nominal cell voltage with a 2.5 m³ anolyte tank (6.878 M AlCl₃) and 2.5 m³ catholyte tank (~2.5 M phenothiazine-OEG-FTFSI)
- Power and energy decoupling: system includes 2,500 L tanks per side, total 5,000 L electrolyte, enabling storage duration extension by adding tank volume
- Series-connected bipolar plate configuration in a 250 kW electrochemical reactor module
- Non-pyrophoric, water-tolerant chemistry (accepts 50,500 ppm water) that requires no glovebox for handling or maintenance
- Complete system housed in a standard 20-foot container (~20 m² footprint, 6–7 tonnes weight) with plug-and-play grid connection via PCS
- Validated with >8,000 charge cycles at <0.2% capacity fade per cycle, with electrolyte refresh extending system life to 40 years
- Active material cost of $126/kWh and installed CAPEX of $183/kWh, with 20-year LCOS of $0.08–0.10/kWh