• A Cleaner Future for Mankind



    A New Technology for Grid-Scale Electricity Storage


    MGH is a patent-pending technology co-invented by Jean-Michel Germa, president of MGH, Richard Perez, research professor at the State University of New York (SUNY) and Marc Perez (PhD Columbia University) that leverages the vast potential of the oceans to massively store electricity with a minimal environmental footprint.


    MGH uses static gravitational potential as the underlying storage medium - transferring massive solid weights between the ocean's surface and floor for charging and discharging.

    When there is a surplus of electricity on the grid, electricity is used by a motorized lifting device to raise the weights from the sea floor 1000+ meters to the surface where they are tethered to a floating offshore platform. The tethering of weights at the surface effectively stores the energy used to lift them as gravitational potential. The system is fully charged when all the weights are tethered at the surface in this fashion.

    When dispatching stored electricity, the weights are released from the surface and drive a generator located on the platform. During the transfer from the surface to the sea floor, stored potential energy is released as electricity onto the power grid. When all the weights arrive on the sea floor, the system is fully discharged. The floating platform is connected to the power grid via an underwater high-voltage power line. On shore the cable can be buried underground to minimize environmental impact.


    While the MGH system's primary operational context is to provide transmission-level storage services for the grid, it can be also be used in direct combination with variable-output renewables like wind and solar and render them dispatchable; thereby enabling high penetration of renewable electricity.

    Three States of MGH Activity: 

    • Charging:      Surplus electricity drives lifting devices to pull weights to ocean surface from ocean floor

    • Stored:           Electricity is stored as static gravitational potential energy

    • Discharging: Weights are lowered to seafloor, driving electrical generators and sending electricity back to shore.

  • WHY MGH?

    A Growing Need for Storage Solutions

    A fast evolving energy context


    Global energy demand is anticipated to double by 2050 driven by the growth of world population (2 billion more people) and the development of emerging economies.



    Finite fossil and conventional nuclear energy reserves will be under increasing pressure to meet this demand and their operational costs stand to increase.

    Energy storage will facilitate the high penetration of variable renewable resources onto power grids.


    Renewable resources are inexhaustible and have the potential to progressively replace these conventional resources while offering a solution to the increasingly urgent need of reducing greenhouse gas emissions.



    Wind and solar energy resources are inexhaustible, but they are variable. This is because they are driven by inherently variable meteorology. Power grid operators have the responsibility to match demand and supply at all times; therefore they must develop operational solutions if they are to integrate increasing amounts of renewables on their grids. These solutions include demand-side management and smart grid interconnection. However effective, these solutions, alone, will not be able to match supply and demand without one critical catalyst: energy storage.

    Long-term Energy Storage Solutions are Needed


    Less than 3% of the electrical generating capacity in the world can be stored today using the following technologies:


    • Pumped Hydroelectric Energy Storage (PHES). This technology, which exploits the transfer of water between two elevations, represents more than 99% of the global electrical energy storage market. For economical operation prospective PHES installations require a large height differential (mountainous terrain).  
    • Compressed Air Energy Storage (CAES). The development of this energy storage technology—which uses underground caverns or external containers as pressure vessels to store compressed air—is still minimal today although the potential is large. Conventional CAES requires the heating of gasses during decompression and typically uses fossil fuels to achieve this.  Researchers are working hard to make this process adiabatic by reusing the heat generated during compression to heat the gasses during decompression.
    • Electrochemical Batteries, this technology group is likely the most familiar because of their ubiquity in consumer products.  Although perfect for such applications because of their high energy density, modularity and efficiency, they have found more limited energy storage potential for stationary grid-scale applications due their high cost. Their modularity makes them well suited for demand-side applications.


    Other storage technologies such as pumped thermal energy storage (PTES) or hydrogen-based technologies could become contenders for the massive future electricity storage market.


    The rapid growth of variable renewables like wind and solar necessitates an equally rapid growth of the energy storage sector.  Significant R&D work focusing on reducing the economic and environmental costs of each of these technologies is currently being expended to meet this future demand.  A demand in which we are convinced MGH will play a major role. 


    Jean-Michel Germa


    Jean-Michel is a pioneer of the renewable energy sector having founded and operated La Compagnie du Vent, France's first wind power company.  He currently finances R&D and venture capital work in the cleantech sector including the development of MGH.

    Claudia Delbosc

    Executive Assistant

    Claudia is an executive assistant with more than 15 years of experience in renewable energy technologies (wind, PV, solar thermal, energy storage).

    Richard Perez

    Senior Advisor


    Richard Perez, Research Professor at the Atmospheric Sciences Research Center of the State University of New York, is a world-renowned researcher and specialist in the weather’s stochastic impact on the production of solar energy and of its impact on the management of power grids.  


    Bernard Monluc

    Managing Director

    Bernard is a naval architecture engineer and a former French naval officer, specialized in development and management of innovative and high added value projects in the maritime sector and the marine renewable energy sector.

    Matthieu Colléter

    VP Operations

    Matthieu brings his 15-year experience in oil & gas and renewable energy to MGH and to other cutting-edge activities in the cleantech sectors.

    Nicolas Hontebeyrie

    VP Finance

    Nicolas has been developing international experience in finance (Capital Markets, M&A, Private Equity) for nearly 20 years, with a particular focus on energy and infrastructure.

    Maxime Garbay

    Project Engineer

    Maxime is a young and creative French engineer working on the technical development of MGH technology since 2013




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    34470 PEROLS - FRANCE