A Dutch startup, Ocean Grazer, is pioneering an innovative method of offshore power storage by deploying large-scale hydroelectric-like energy storage systems on the seabed. Their technology, known as the Ocean Battery, uses vast low-pressure reservoirs buried beneath the seabed connected to flexible underwater bladders. Excess renewable energy is used to pump seawater between these reservoirs and bladders, storing energy under hydrostatic pressure. When power is needed, water flows back through turbines to generate electricity, creating a closed, environmentally friendly system designed to last over 100 years[2].
This breakthrough addresses a major challenge in offshore re...
This breakthrough addresses a major challenge in offshore renewable energy: effectively storing intermittent power from wind and waves to smooth out supply and demand fluctuations. Ocean Grazer’s seabed storage avoids the environmental risks and limited lifespans of lithium-ion batteries and the inefficiencies of hydrogen storage. The company emerged as a spin-off from the University of Groningen and has rapidly gained recognition, winning awards such as the Prince Friso Engineering Award for its technology[2].
The Ocean Battery system leverages natural seawater pressure...
The Ocean Battery system leverages natural seawater pressure at depth to store energy akin to pumped hydroelectric storage on land but adapted for the marine environment. The reservoirs are buried with minimal seabed disruption, and the protective rockfill encourages marine life growth, making it an ecologically sustainable solution. This contrasts with other approaches that rely on chemical batteries or electrolyzers on offshore platforms, which often have higher maintenance costs and environmental concerns[2][1].
Ocean Grazer’s innovation fits into a broader trend of advan...
Ocean Grazer’s innovation fits into a broader trend of advancing offshore energy storage technologies to support the growing share of renewables, particularly offshore wind, which is expected to provide a significant portion of future energy needs. Projects like the Netherlands' OESTER initiative similarly explore a range of offshore storage technologies, including short-term battery storage in turbine foundations and longer-term compressed air and pumped hydro storage, aiming to integrate renewable energy reliably into the grid[1][11][13].
While Ocean Grazer focuses on seabed hydroelectric storage,...
While Ocean Grazer focuses on seabed hydroelectric storage, other companies and research institutions are developing complementary subsea battery systems and energy storage solutions to power offshore infrastructure, such as SubCtech’s modular lithium-ion subsea battery systems for offshore oil and gas and renewable power buffering[3][7].
With the global energy storage market projected to grow rapi...
With the global energy storage market projected to grow rapidly, and offshore wind capacity doubling in countries like the Netherlands, Ocean Grazer’s seabed power storage offers a promising, scalable, and environmentally sensitive solution to one of the most critical challenges of the energy transition: storing and delivering clean, reliable power from the ocean[2][8]. The company plans to scale up deployments following successful prototype demonstrations, contributing to a future where offshore renewable energy is both abundant and dependable.
🔄 Updated: 10/22/2025, 11:10:42 AM
The Dutch government is fast-tracking support for offshore power storage, as the University of Groningen spin-off Ocean Grazer—which has launched a seabed-based “Ocean Battery” using large buried reservoirs and flexible underwater bladders—sees demand surge amid plans to double offshore wind capacity following the Ukraine crisis[2]. “We face a huge challenge in transporting the energy to land efficiently and incorporating flexibility into the sustainable energy system,” says Ocean Grazer co-founder Marijn van Rooij, whose firm now employs 12 and has attracted awards, though no new Dutch regulatory changes specifically targeting seabed energy storage were detailed in the latest policy updates[2]. Meanwhile, German lawmakers revised the High Seas Environmental Protection Act (HSEG) in
🔄 Updated: 10/22/2025, 11:20:50 AM
The offshore energy storage landscape is shifting as Italy-based startup Sizable Energy raises $8 million to commercialize its innovative offshore pumped hydro system, positioning it to challenge traditional land-based storage limits with scalable, modular seabed reservoirs[1][3]. This development comes amid expectations that the global offshore energy storage market will grow to about $200 million by 2030, driven largely by rising offshore wind capacity and regulatory support in regions like Europe[2][4]. Sizable Energy’s co-founder, Manuele Aufiero, asserted, "There is no way we can keep up with renewables with traditional pumped hydro or batteries. We need something new," underscoring a competitive push toward novel subsea storage solutions that promise cost-effective, long-duration energy
🔄 Updated: 10/22/2025, 11:30:41 AM
The U.S. Bureau of Ocean Energy Management (BOEM) and the Bureau of Safety and Environmental Enforcement (BSEE) plan to unveil draft regulations by May 2026 to govern offshore energy storage, including novel seabed power storage technologies, but a formal deadline for finalizing rules has not yet been set. This follows Congressional mandates from the 2021 Bipartisan Infrastructure Law, though regulatory progress has been delayed due to technical complexities in the permitting system. Meanwhile, regulatory frameworks in Europe, such as Germany’s amendment to the HSEG law, explicitly exempt sub-seabed carbon storage from dumping bans and require planning permission with stringent environmental and safety criteria, indicating growing government recognition and structured oversight of seabed storage innovations[1][3].
🔄 Updated: 10/22/2025, 11:40:42 AM
Italy-based startup Sizable Energy has just raised $8 million to advance its groundbreaking offshore pumped hydro energy storage system, which uses flexible reservoirs connected by turbines to store renewable energy underwater at depths of 500+ meters. Their patented technology targets gigawatt-scale capacity and aims for a levelized cost of storage around €20 per kWh, roughly one-tenth the cost of traditional grid-scale batteries. A multi-megawatt pilot trial off Reggio Calabria, Italy, is planned to validate full system deployment later this year, potentially revolutionizing storage for offshore wind integration[1][3][7]. Simultaneously, Dutch startup Ocean Grazer is developing seabed-based "Ocean Battery" technology that stores energy in large low-pressure reservoi
🔄 Updated: 10/22/2025, 11:50:43 AM
Italy-based startup Sizable Energy has raised $8 million in a funding round led by Playground Global to accelerate development of its offshore pumped-hydro energy storage system, which uses ocean depth and super-salty water to store excess renewable power at scale[1][3]. Initial public reaction has been cautiously optimistic, with energy analysts noting the technology’s potential to resolve grid congestion and stabilize renewables, while environmental groups await confirmed data on seabed impacts; Sizable’s CEO, Manuele Aufiero, told TechCrunch, “We believe long-duration energy storage is required not only for renewable integration, but also for just making the grid resilient—we need something new”[7].
A rival Dutch system, Ocean Grazer’s “Ocean
🔄 Updated: 10/22/2025, 12:00:43 PM
Dutch startup Ocean Grazer has pioneered an offshore pumped hydro energy storage system using large, low-pressure reservoirs buried in the seabed—up to 100 meters long—linked to flexible bags under hydrostatic pressure on the seabed. Excess renewable energy pumps seawater into these bags to store energy, and when needed, water flows back through turbines generating electricity in a closed, environmentally protective system designed for over 100 years of operation[2]. Similarly, Italy-based Sizable Energy has raised $8 million to scale a modular offshore pumped hydro system that pumps dense, saturated brine between seabed and surface reservoirs at depths over 500 meters, targeting gigawatt-scale, long-duration energy storage with demonstrated reliability in harsh ocean environments
🔄 Updated: 10/22/2025, 12:10:48 PM
Sizable Energy, a startup developing offshore pumped hydro storage, recently raised $8 million to advance its system that stores gigawatt-scale electricity by pumping saturated sea-salt brine (20% denser than seawater) between a floating reservoir and a deep-water reservoir at depths over 500 meters. This closed-loop setup leverages ocean gravity to deliver long-duration energy storage with the lowest Levelized Cost of Storage (LCOS) among alternatives, providing a modular, environmentally friendly solution without the land-use constraints of traditional hydro or high maintenance of batteries[2][3][5]. CEO Dr. Manuele Aufiero highlighted the system’s potential to stabilize rapidly growing offshore renewables by offering affordable, resilient storage critical for grid reliability[2][3
🔄 Updated: 10/22/2025, 12:21:00 PM
In a significant development in offshore energy storage, startups like Sizable Energy and Ocean Grazer are pioneering innovative solutions to harness the seabed for power storage. Dr. Manuele Aufiero, CEO of Sizable Energy, emphasizes that their ocean-based system can store gigawatt-scale power at a cost-effective rate, making it crucial for stabilizing the grid as renewables surge[2][7]. Meanwhile, industry experts like Marijn van Rooij of Ocean Grazer highlight the limitations of traditional methods, such as lithium-ion batteries, and the potential for seabed storage to overcome these challenges by offering long-duration energy storage without significant environmental impact[4].
🔄 Updated: 10/22/2025, 12:30:54 PM
Consumer and public reaction to startup Sizable Energy's offshore seabed power storage innovation has been cautiously optimistic, highlighting excitement about its potential to stabilize renewable energy grids affordably and sustainably. Industry insiders praise the technology's scalable, low-cost approach, with Playground Global's Bruce Leak calling ocean depth “a practically unlimited resource” leveraged for gigawatt-scale storage at a fraction of battery costs[2]. Meanwhile, environmental advocates appreciate its closed system and minimal seabed disturbance, contrasting it favorably against lithium-ion batteries’ environmental drawbacks[6]. However, detailed broad consumer sentiment data remains limited as the technology is still in early sea trial phases off Italy[2][3].
🔄 Updated: 10/22/2025, 12:40:50 PM
**October 22, 2025, Breaking News**
Sizable Energy, an Italy-based startup, has secured $8 million in venture funding to advance its offshore pumped hydro storage system, which uses two flexible reservoirs—one floating, one on the seabed—connected by turbines to store electricity as super-salty water moves between them[5][9]. According to CEO Manuele Aufiero, “Our ocean-based system stores gigawatt-scale power affordably, making the grid more stable, resilient, and ready for the future,” with the company claiming a lower Levelized Cost of Storage (LCOS) than lithium-ion, even under optimistic projections for battery costs[2][3]. The technology, validated in September 2025 a
🔄 Updated: 10/22/2025, 12:50:51 PM
The offshore energy storage landscape is rapidly evolving with startups like Sizable Energy raising $8 million to commercialize ocean-based pumped hydropower storage, targeting gigawatt-scale deployment and aiming for storage costs around $23 per kilowatt-hour—roughly a tenth of grid-scale batteries[1][3][7]. This innovation is shifting the competitive landscape by addressing limitations of onshore pumped hydro and battery storage, enabling modular, scalable, and cost-effective solutions that leverage ocean depth and existing maritime infrastructure[3][7]. Meanwhile, battery-based offshore storage systems, such as Singapore's 7.5 MW floating battery barge and the EU’s OESTER project, underline a growing market projected to reach $200 million by 2030
🔄 Updated: 10/22/2025, 1:00:46 PM
In a significant shift in the competitive landscape of offshore energy storage, Sizable Energy's recent $8 million funding round highlights the growing interest in innovative solutions like ocean-based pumped hydro systems, which could revolutionize the industry by offering scalable and cost-effective storage options[1][3]. This development is part of a broader trend, with the global offshore energy storage market projected to see substantial growth, reaching approximately $200 million over the next decade[2]. The OESTER project and similar initiatives are further driving this expansion, focusing on technological advancements and regulatory support to facilitate the integration of renewable energy sources[4][15].
🔄 Updated: 10/22/2025, 1:11:05 PM
Experts in renewable energy storage widely regard Sizable Energy’s offshore pumped hydro system as a promising breakthrough, citing its potential to deliver gigawatt-scale, long-duration storage at a fraction of the cost of batteries. CEO Dr. Manuele Aufiero emphasized the system’s ability to stabilize grids amid surging renewables: “Without cost-effective long-duration storage, the grid cannot keep up, regardless of energy source”[2]. Bruce Leak, general partner at Playground Global, called the ocean depth “a practically unlimited resource,” highlighting that Sizable’s approach leverages this to achieve low-levelized cost of storage while avoiding land use and environmental constraints facing traditional pumped hydro[2]. Industry analysts also note that the project’s upcoming multi-megawatt sea
🔄 Updated: 10/22/2025, 1:20:36 PM
In a groundbreaking development, startups like Sizable Energy and Ocean Grazer are pioneering offshore power storage on the seabed, promising significant global impact by addressing the critical need for long-duration energy storage as offshore wind expands. The International Energy Agency estimates a requirement for up to 120 TWh of long-duration energy storage by 2040, and these innovations could play a crucial role in meeting this demand. Dr. Manuele Aufiero, CEO of Sizable Energy, highlights the potential, noting that "without cost-effective long-duration storage, the grid cannot keep up, regardless of energy source" [2][3].
🔄 Updated: 10/22/2025, 1:30:42 PM
## Breaking News Update: Startup Launches Scalable Offshore Energy Storage
**Technical Analysis**
Sizable Energy has secured $8 million to commercialize its gigawatt-scale offshore pumped hydro system, which uniquely leverages ocean depth by moving saturated sea-salt brine—20% denser than seawater—between a floating surface reservoir and a deep seabed reservoir, using gravity to store and release energy efficiently[1][2][5]. Their modular design enables storage from one to hundreds of gigawatt-hours, utilizes materials installable at depths of 500 meters or more, and claims the lowest Levelized Cost of Storage (LCOS) among long-duration technologies—even under optimistic lithium-ion cost projections[1][2][5]