Some projects that our team contributed are described below (based on the information from the GROW project webpage).

BUBBLES JIP: "During installation of monopiles and jackets at sea, the noise generated by high-energy piling may harm the marine environment. To mitigate the risk of noise for marine life, governments have adopted noise limits for pile-driving operations in their permits for offshore construction projects. Air bubble curtains reduce the sound-levels. A looped hose on the seabed - pressurized by air compressors – generates the bubble curtain. Currently, engineers base the bubble curtain designs on previous experience and not on scientific research. Companies experience large variations in the current performance of bubble curtains. A better understanding of the noise generation and mitigation mechanisms would enable better engineering of the bubble curtains, leading to screens that are more effective and to lower costs. Improved screens will control better the noise levels and will reduce the risk not to comply with the specific noise requirements per piling project. Bubbles JIP will contribute to more efficient and effective designs of bubble curtains to reduce noise during offshore installation. This project researches the current practice of bubble curtain generation. It will also research the sound propagation of piling noise through water and soil and the physical mechanism of noise attenuation by air bubbles. We will develop technology to measure the bubble size distribution and concentration over the water depth, also in relation to waves and current." Please see the project webpage for more details.

GDP Project: "This project Gentle Driving of Piles (GDP) aims to make the pile installation process more efficient. In this project the consortium aims to develop and test a novel pile installation method based on simultaneous application of low-frequency and high-frequency vibrators exciting two different modes of motion on the monopiles. This method is called “gentle” for its envisaged capability to reduce the driving loads and the emitted installation noise which is harmful for the environment, e.g. to mammals and fish.Next to the novel pile driving technique, the consortium aims to develop new models that explain the physics governing the novel pile installation technique, optimise the procedure and show that noise generated with GPD is considerably reduced compared to conventional installation methods. We will validate these models with experimental data collected from the dedicated measurement campaign of this project and data of previous project that are provided by the consortium partners.We strive to develop this technique without compromising the pile penetration speed and the soil bearing capacity, which is essential for a stable offshore wind turbine operation." Please see the project webpage for more details.

SIMOX Project: "By testing multiple techniques, SIMOX will develop new and necessary technical and environmental knowledge. Such techniques must enable the installation and decommissioning of XXL monopiles for very large offshore wind turbines in a sustainable, cost-effective, societally and environmentally acceptable manner. At the beginning of February, the Netherlands Enterprise Agency (RVO) decided to support this project. The participating companies are investing 2 million euro in this project and the government is contributing 4 million euro.Current installation methods for monopiles face major barriers for future large monopiles. The dominant method used now to drive monopiles into the seabed is the hydraulic impact piling (hammering). The major disadvantages of the impact driving method are the generation of underwater noise that can be harmful to marine fauna and inapplicability of the method to piles extraction at the end of their service time. Alternative installation technologies are being researched, developed, and tested at various Technology Readiness Levels (TRLs). However, none of these technologies has reached a TRL that makes it a preferred/ready solution for the installation of future XXL monopiles (with a diameter bigger than 7,5 up to 11 meter that weigh from 1000 to 2400 tonnes) under a broad range of soil conditions. With a better understanding of their performance and a validation of the underlying models, the development of these technologies can be enabled, which should ensure that offshore wind remains one of the lowest-cost, electricity generation options." Please see the project webpage for more details.

FLOW: "The generated levels of underwater noise from pile driving during the construction of large offshore wind farms are unacceptably high according to upcoming regulations. This results in serious delays and increased costs for the offshore wind industry since the pile driving activities have to be conducted at specific times during the year. During offshore pile driving, a hydraulic hammer hits the top of the pile and a stress wave is generated which propagates downwards. Part of the energy introduced into the system is spent on the pile progression into the soil whereas another part is irradiated into the water in the form of pressures waves from the vibrating surface of the shell. A third part of the energy enters the soil and generates elastic waves which propagate through the soil medium. The primary goal of this project is to understand and analyze the main sources of underwater noise generated from offshore pile driving and to test the available mitigation measures used in practice. For this reason, a new model will be developed which will include the hydraulic hammer, the monopile, the compressible viscous water and the water‐saturated seabed. By doing this, we aim at providing the offshore wind industry with the necessary tools in order to predict and eventually reduce the underwater noise for a wide range of system parameters. " Please see the project webpage for more details.