Sizable Energy provides offshore long‑duration energy storage by using a patented pumped‑hydro system that moves dense sea‑salt brine between a seabed reservoir and a floating surface tank. The modular design delivers >90 % round‑trip efficiency, can scale from megawatt‑hour to gigawatt‑hour capacity, and can be installed alongside offshore wind or solar farms, eliminating land use and reducing capital costs.
Funding
$8M raised to dateRaised to date based on public sources. This may differ from the amount the company actually raised and is based only on what is publicly available on the internet.
Founders
Product
Problem
The rapid expansion of intermittent renewable generation creates a need for large‑scale, long‑duration energy storage, yet traditional on‑shore pumped‑hydro is constrained by geography, land availability, and long construction timelines.
Solution
Sizable Energy delivers long‑duration storage by adapting proven pumped‑hydro principles to an offshore environment. The system consists of a seabed reservoir and a floating surface reservoir linked by a penstock, with reversible pump‑turbines that move dense, saturated sea‑salt brine between the two tanks to store and release energy. By leveraging ocean depth as the gravitational head, the solution provides high round‑trip efficiency while eliminating land use and enabling deployment in any deep‑water location. The architecture is modular, allowing capacity to be scaled from megawatt‑hour to gigawatt‑hour levels and to be co‑located with offshore wind or solar farms. A patented design, validated in wave‑basin tests and full‑scale at‑sea proof‑of‑concept trials, underpins a cost‑effective, low‑LCOS storage option for grid‑scale applications.
Target Audience
Primary customers are utility‑scale renewable developers, grid operators, and energy‑storage project developers seeking low‑cost, long‑duration storage solutions that can be deployed offshore alongside wind or solar assets.
Features
- Patented offshore pumped‑hydro architecture with a seabed brine reservoir, a floating surface tank, and a connecting penstock.
- Reversible pump‑turbines that transfer saturated sea‑salt brine, providing gravity‑based energy storage with >90 % round‑trip efficiency.
- Fully modular units that can be assembled in series to achieve capacities from 1 MWh up to multi‑GW‑h, enabling rapid scaling.
- Zero land footprint and compatibility with existing offshore wind or floating PV installations for synergistic power‑to‑storage integration.
- Utilization of standard maritime components and local manufacturing to reduce supply‑chain risk and lower capital costs.
- Designed for deployment at depths of 500 m or greater, with proven resilience in harsh ocean conditions through wave‑basin and at‑sea testing.
- Cloud‑connected monitoring and control software that automates charge/discharge cycles and provides real‑time performance analytics.