Winds are stronger and more consistent offshore than a comparable onshore wind project. There is greater potential to install larger turbines at sea relative to onshore. The combination of high wind speeds and larger turbines allows for more energy generation. Not only will an offshore wind farm generate more energy, but it will also generate energy on a more consistent basis. This makes it easier for the grid operator to integrate this renewable electricity source.
The Programme for Government (2020) has set ambitious targets for decarbonisation by 2030 with a plan to deliver at least 5GW of offshore wind by that date. Ireland now has a major opportunity to benefit from the significant reduction in the cost of offshore wind seen throughout Northern Europe in recent years.
Floating turbines can be located in areas with sea depths over 60 metres, harnessing the best wind resources and opening new sites to power generation. Most offshore wind turbines today are fixed to the seabed, so-called bottom-fixed, and in more shallow waters. The next generation of turbines are designed to float in the water allowing development further out to sea where winds are stronger, but the water depths make bottom-fixed designs uneconomic. Most offshore wind floater designs are similar to the ones applied for the oil and gas platforms. Floating turbines are moored to the seabed with multiple mooring lines and anchors, in much the same way as a floating oil platform. Floating wind turbine motion controllers use sensors to regulate the turbine blades in adverse conditions, reducing strain on the moorings and maximising electricity production. There are three main designs of floaters for offshore wind (spar buoy, semi-submersible and tension leg platform) and both steel and concrete can be used as a construction material.
Spar-Buoy Tension Leg Platform Semi-Submersible
A Spar Buoy design relies on gravity for its stability, Tension Leg Platforms (TLP) are reliant on the tension of the mooring system and Semi-Submersible rely on buoyancy.
Floating offshore wind off the South and West Coasts would provide Ireland an opportunity to harvest some of the best wind resource there are, not only for domestic purposes but also through interconnection with the rest of Europe.
ESB is currently evaluating different floating wind concepts and will select the optimal solution for Moneypoint Offshore Wind Farm.
The waters off the west coast of Ireland have the best wind resource in Europe for producing clean, renewable energy from offshore wind generation. While the harsh environment can be challenging from a construction and operation perspective, this area benefits from exemplary wind speeds. Studies of the seabed using existing data sources indicates that this area off County Clare/Kerry is potentially suitable for developing a floating offshore wind farm project with its sea depths of 100 - 120m. The first phase of the project would be located approximately 16km (at the nearest point) from the coastline. The site assessment study also took account of potential connection options to the national grid. The project team is currently evaluating the option to connect into ESB’s Moneypoint Power Station on the Shannon Estuary.
A foreshore licence confers the holder with the right to undertake certain specified survey and site investigation works such as geotechnical investigations and wind resource measurement on a non-exclusive basis for a defined period of time within the foreshore. The foreshore is defined as the land and seabed between the high water mark of ordinary or medium tides (shown HWM on Ordnance Survey maps) and the twelve nautical mile limit. The licence does not represent any form of planning permission.