Greenov has initiated the first sea trial of the SubSea Quieter. This noise mitigation system is based on an innovative membrane designed to mitigate the impact of maritime activities on underwater ecosystems.

With six years dedicated to its development, the SubSea Quieter offers a solution for coastal and offshore companies to minimise their environmental footprint.

The initial prototype, tailored for 2.5-metre diameter piles, will undergo extensive real-world testing for two months starting in early 2024. These trials aim to validate the acoustic performance and user-friendliness of the future full-scale system.

Also read: Heerema installs top section of new Noise Mitigation System

Reducing underwater noise

The rapid propagation of sound underwater — four times faster than in the air — makes it imperative to mitigate the disruptive effects of human activities on marine life, which relies heavily on sound for navigation, communication, and feeding.

Pile driving operations used for wind turbine installation generate intense underwater noise, reaching up to 260 dB, causing significant disturbances to aquatic fauna. With the sources of underwater noise increasing, global regulations, particularly in Europe and France, are therefore increasingly stringent in reducing these impacts.

SubSea Quieter

The SubSea Quieter system is a noise abatement technology that aims to impede the transmission of underwater noise from works operations in the marine environment. It can also contain turbidity generated by coastal works. The SubSea Quieter system is based on a multi-layer membrane into which a fine particle of air is injected to create a barrier to the sound waves.

Subsea Quieter concept and solution
SubSea Quieter concept and solution.

Particularly innovative and relatively simple to use, the system reduces noise by 10 to 35 dB depending on the sound frequencies, i.e., a 94 to 99 per cent reduction in the acoustic power of marine operations, a performance well above that of existing systems such as bubble curtains.

Greenov has developed two types of the SubSea Quieter:

  • The SubSea Quieter Blue Shield, which takes the form of a curtain to enclose an extended area corresponding to coastal/port work.
  • The SubSea Quieter Pile Driving, a set of membrane panels that are attached together to form a double barrier around the pile, and which are then inflated prior to pile driving operations.

The SubSea Quieter has won several recognitions in France such as Prix Décibels d’or 2024, selected as one of the thirty start-ups in the first French Blue Tech Index 2023, Prix Port du Futur 2022, Prix Du Ministère de la Transition Ecologique, Prix Solar Impulse, etc.; as well as the AMBA Global Start-up of the Year 2022 award and the prestigious European EIC Accelerator program.

Also read: European project seeks to reduce the impact of underwater noise

Full-scale test in Q1 2024

The company is now testing the SubSea Quieter pile driving system for the first time. Testing began in December 2023 with the assembly of the system and an initial validation of the subsystems in air. They will be followed by a series of tests over a four-week period between February and March 2024 under sea conditions in the Port of Saint-Nazaire (France).

Illustration of the test in St Nazaire
Illustration of the test in St Nazaire (by Greenov).

The trials are being carried out in collaboration with Bouygues Travaux Publics Régions France and Quiet-Oceans, two companies providing their expertise in marine civil construction and underwater acoustics.

Entirely designed and manufactured by a network of partners in the Pays de la Loire region, France and Europe, the system is 10 metres high, 5 metres in diameter and weighs 25 tonnes. It is equipped with membrane panels held in place by two metal structures: a high structure equipped with powerful winches that allow the system to slide around the pile to be beaten, and a low structure that functions as a basket into which the membrane is folded before being deployed until the seabed.

Image of the Subsea Seaquieter prototype (by Greenov).
Image of the SubSea Quieter prototype (by Greenov).

Towards market launch and fund-raising

With these tests, Greenov aims to confirm the viability of its system and accelerate its commercialisation. Following these trials, the company hopes to see its SubSea Quieter become the new standard solution in the underwater noise reduction market, estimated at EUR 350 million/year worldwide, and will launch a dedicated subsidiary called Sealence in mid-2024.

Greenov will soon be raising EUR 10 million to complete its R&D work and expand internationally, with its sights set on the European, North American and Asian markets, and several exciting projects already signed. Directly and with local partners, Greenov aims to create more than 200 jobs.

Picture (top): Representation of the two types of the SubSea Quieter (by Greenov).

Also read: VIDEO: How holes in a propeller reduce underwater noise