Offshore Wind Farms
Do you need a licence to develop a wind farm?
Yes, a number of licences and planning permissions are required to develop an offshore wind farm starting with an investigative licence to evaluate the site for suitability. This leads to a full planning permission application for the offshore wind farm involving environmental, socio-economic and other studies.
In order to carry out the initial investigative work, a Foreshore Licence must be obtained from the Department of Housing, Local Government and Heritage. DP Energy applied for this licence in December 2020.
How are offshore wind turbines held in place?
The depth of water in which the wind farm is built dictates how the turbines are held in place. Shallow water (water depth < 45m) allows the turbines to be fixed directly to the seabed using Monopile (one connection point). Where the water is moderately deep (45m-60m) Jacket or Tripod foundations are used. In deep water (60-80m+) the turbines will almost certainly be mounted on floating structures anchored to the seabed using mooring lines. For these floating projects, there There are four principal types of floating foundations: Barge, Semi-submersible, Tension Leg Platform and Spar, as seen in the diagram below:
What surveys must be undertaken before the wind farm can be built?
There are a vast array of surveys that are required in order to assess the environmental impacts on the project and to obtain planning permission. This includes:
- Geophysical Surveys: looks at the profile of the seafloor.
- Geotechnical Surveys: looks at what the sea floor is made of.
- Wind Resource Monitoring: measures the speed and direction of the wind.
- Metocean Surveys: measures wave height and tide/current over time.
- Baselines surveys which assess the habitat and animals present.
- Birds and Marine Mammal Surveys: log the birds, mammals and species utilising the area.
- Navigational Risk Assessment.
- Socio-economic impact.
- Visual impact.
What is an offshore substation and what does it do?
An offshore substation collects the electricity generated from each of the turbines at a single location it transforms the voltage from turbine voltage to export voltage which is necessary for the power to be exported to the grid network.
What is EMF?
EMFs or Electromagnetic Fields occur both naturally (e.g. from the sun) as well as from man made electrical devices and cables. EMFs are generated by everyday commonly used appliances such as computers, electric blankets and hair-dryers as well as by wind turbines, power cables and all other forms of electricity generation. There has been extensive research into EMFs and this has shown that EMFs generated by offshore wind farm cables are not strong enough to harm humans or animals.
What happens to floating turbines in severe weather?
Both the turbines and their supporting floating structures are designed to deal with extreme weather conditions. The floating platform will heave with the waves like any other floating device anchored to the seabed in heavy seas. However, these are large and heavy structures with a significant degree of physical inertia compared to small vessels operating in the sea environment, which means they are relatively stable.
What happens to the blades in severe wind conditions?
Wind turbines (including the rotor and blades) are designed to withstand extreme weather conditions including Typhoons and Hurricanes. Typhoon rated turbines are designed to be suitable for waters off Taiwan and Japan and for similar conditions off the east coast of the USA.
Wind turbine blades are designed for extreme load conditions and start to pitch from winds speeds of 12metres/second upwards in order to ‘spill’ some of the wind and reduce loads. For wind speeds in excess of about 25metres/second the blades are fully pitched out of the wind so as to minimise loading on the blades and structure.
Different turbine ratings are used based on the different site conditions; this is one of the reasons that measurement of wind is so important. A typical high wind rated turbine for high wind speed sites in Ireland would be designed for in excess of 70metres/second gusts or 140knts.
Will the blades sink or float if broken/damaged by weather?
In the rare event that there is blade loss or partial loss the blades should sink relatively quickly.
Clarus Offshore Wind Farm
Why have you chosen to investigate off the coast of Clare/Kerry?
A constraint analysis was conducted to show the potential and the limitations of developing an offshore wind farm off the West Coast. The Clarus Offshore Wind Farm location was identified as potentially the best site following this analysis. The study included:
- The proximity to potential grid connection points.
- Water depths
- The speed of the winds in the area.
- The prevailing seabed conditions (mud, sand, rock etc..)
- Proximity to port facilities for development, operation and maintenance and decommissioning.
- Fisheries in the area.
- The number of environmentally sensitive areas.
- Existing and planned developments.
- Existing cables.
- Shipwrecks/Archaeology in the area.
What area will the Clarus Offshore Wind Farm cover?
The area covered by the wind farm will be approximately 300km².
How far offshore will the turbines be?
We aim to have the turbines approximately 12NM off the coast, that’s about 22kilometers, but until the surveys are complete this is an estimate.
How big will the wind turbines be?
The size of the turbines will depend on the technology commercially available at the time of construction. The objective being to utilise the most up to date and efficient turbines available at the time of reaching a Financial Investment Decision (FID).
Currently the largest offshore wind turbine in the market has a 15MW capacity. At this juncture, we have not decided on a size for the turbines but given the rate of progress on turbine technology advancements it is likely we will be looking for turbines in excess of a 15MW capacity which could have a height to tip height of some 300m.
How many wind turbines will be in the Clarus Offshore Wind Farm?
The number of wind turbines used in the wind farm will clearly depend on the technology used. Based on the utilisation of 15MW turbines as are currently commercially available around 70 wind turbines would be required to build out the 1GW design.
This will be reviewed as turbine technology advances.
Where will the cables come ashore?
We are currently looking at a number of potential landfall sites. In order to narrow down the options we are taking into account matters such as stakeholders in the area, population density, seabed substrate, proximity to grid connection, other developer activity, fishing activity in the area and the environment nearshore, at landfall and further inland.
Will you need to build a new substation?
Yes, there will be one or more substations at sea, and another substation onshore.
When will the wind turbines be in place?
We are working towards having the project operational by 2030, however, further surveys must be undertaken to enable detailed design activities to proceed and to ensure that we take into account all aspects of possible impacts such as environmental, physical and socio-economic. The 2030 target is in order to have the wind farm operational in time to contribute to the Government climate action plan, which aims at having 80% of Ireland’s electricity generated from renewable sources by 2030.
When are the surveys being carried out?
Aerial bird and marine mammal surveys for Clarus will commence in 2022. They will continue for two years to document all of the birds and mammals utlising the site in order to establish both seasonal and annual variations. Geophysical/Geotechnical surveys will commence in 2023.
By how much will the wind farm reduce Ireland’s carbon (CO2) emissions?
The proposed 1000 MW Clarus Offshore Wind Farm Project could potentially generate 3,942,000 MWh of electricity per year. This is enough clean green energy to supply 938,571 houses yearly and to reduce CO2 emissions by 1,281,150 tonnes CO2 every year.
This is equivalent to a passenger car (2018 average CO2 emissions 120.4 g CO2/km) driving the circumference of the world over 260,000 times.
Calculations based on:
Average household electricity usage in 2017, 2018 (https://www.cru.ie/wp-content/uploads/2017/07/CER17042-Review-of-Typical-Consumption-Figures-Decision-Pap) 4,200 kWh/year (4.2 MWh/year)
Average carbon intensity of electricity in 2019 (https://www.seai.ie/publications/Energy-Emissions-Report-2020.pdf, https://www.epa.ie/ghg/energyindustries/) 325 g CO2/kWh
Capacity factor for offshore wind (www.eirgridgroup.com/site-files/library/EirGrid/EirGrid-TES-2019-Report.pdf) 45%
1000MW x 8760h x 45% = 3,942,000 MWh
3,942,000 MWh / 4.2 MWh/year = 938,571 houses powered/year
3,942,000 MWh x 325000 gCO2/MWh = 1,281,150,000,000 gCO2/MWh = 1,281,150 tonnes CO2/year
How much energy will the Clarus Offshore Wind Farm produce and how many houses could it power?
Wind turbines only produce energy when the wind blows and consequently it is the consistency of the winds offshore (as well as the ability to use large rotor diameters to catch that wind) that is one of the biggest positives for offshore wind farms.
Offshore, there is limited or no interference from land based features; topography, trees, buildings etc. and all of these features slow the wind near to the ground (i.e. less than 400-500m altitude) where wind turbines operate and reduce the energy they can produce.
Accurately calculating wind farm energy yield requires detailed assessment and of course measured on site wind data and we have yet to deploy measuring equipment for the Clarus site. This measurement campaign forms part of our investigative Licence Application. However, based on modelled wind speeds from global/regional scale models, onshore meteorological data and other sources we conservatively estimate the proposed 1,000 MW (1 GW) project could generate upwards of around 3,900 GWh of electricity per annum. That’s 3,900,000,000 kWh if we express in the units you would see on your household electricity bill.
Where will the electricity from the wind farm go?
Electricity generated by each turbine will be collected through inter turbine sub-sea cables to one or more offshore substations and then exported through larger cross section sub-sea export cables to shore where it will feed into the Irish electricity network. Once in the network the electricity will go to power Irish homes and businesses and in the future potentially even produce hydrogen for use in the gas network.
It is also possible (even likely) that given Ireland’s huge potential resource Irish Offshore wind energy may well be used to supply our European neighbours with clean green power and we may well become a net power exporter.
Will Clarus Offshore Wind Farm create new jobs?
Yes, and already is. The project has already resulted in the creation new jobs. This expansion in the DP Energy Irish team also extrapolates out to increased demand for additional support from environmental consultants, specialist vessel surveyors, and engineering technical businesses and other suppliers, even during this early development process.
This demand and opportunity will only increase as the project progresses through the different stages from planning to detailed engineering design, to construction and then into operation and maintenance. The potential for Ireland as a whole in the creation of new high value jobs from the offshore wind industry is significant.
We will always strive to support local supply chain and local employment and will post information about employment opportunities regularly.
Will there be a community benefit fund?
In relation to the Community Benefit Fund, the details of the Government’s Renewable Energy Support Scheme (RESS) are currently being reviewed.
Does the equipment used in the survey affect the animals in the area while it is being used?
There may be temporary impacts as a result of vessel and survey activity; fish may avoid the immediate area around the survey vessel once operations have started and are unlikely to return to the area until the sound source has passed. The effect is essentially the temporary displacement from the immediate area surrounding the survey activity.