The Winds of Change: What are Turbines made of?

Today we’ll look at the turbines. For the purpose of this post, I’ll divide turbines into three components: Foundation, Tower, Blades. But first here’s an image showing the overview of an offshore wind farm which I thought might be useful.

Overview of a wind farm from On the Use of Scaled Model Tests for Analysis and Design of Offshore Wind Turbines – Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/publication/323118519_On_the_Use_of_Scaled_Model_Tests_for_Analysis_and_Design_of_Offshore_Wind_Turbines [accessed 5 Nov, 2021]

Foundations take up a quarter to a third of the cost of constructing a wind farm and their feasibility is the making or breaking of a project. There are several types of Foundations – Gravity bases, Suction Bucket Bases, Monopile, Tripod, and Floating (which SSE and DP energy are planning for Waterford and Cork respectively). Today I’ll cover Monopile Foundations in a little detail as they are most likely for near shore turbines in Waterford. I include a little on Jacket Foundations too as they can act as artificial reefs which is often cited as an advantage. The floating systems we will leave for another time.

Different foundations to support offshore wind turbines based on water depths. Reference same as previous image.

Monopile is a single foundation inserted into the ground or seafloor and are roughly the same diameter as the tower. They are used closest to shore and will likely be what Energia and others are considering for the Waterford Coast. Monopiles have a simple design that installs quickly. Disadvantages are that installation noise can disorient, injure or kill marine life sensitive to pressure waves and wind, wave and seismic loading can cause early fatigue damage to the structure if it is not accounted for during installation.

Jacket foundations are used for turbines further offshore and I don’t believe they are proposed for any Waterford wind farms. The larger surface area of the lattice configuration may provide an artificial reef location, providing a new habitat for local species though it also may allow invasive species to establish and spread. Installation requires pile drivers the noise of which may injure or kill some marine life. Changes to local water patterns may be detrimental to native marine ecosystems.

Towers: Turbine towers are made from tubular steel and come in sections, usually three. They are easy enough to recycle. There. That was fast.

Blades: The bigger the blades are the more energy they generate. GEs Haliade X, which is likely to be considered for Waterford, is now being fitted with blades (made in Cherbourg) over 100 metres long. Turbine blades are made from fibreglass (older blades) or carbon fibre (newer blades). This means they are light and strong but it also means they are hard to recycle. This is becoming an issue now as the first generation of wind farms reach the end of their lifespan (wind farms currently last 20-25 years before they are decommissioned). There are experiments with converting the blades into useable substances, for instance into pellets to use in concrete or as glue, but the energy required for such transformations can be an issue.

Some people are getting creative. In Denmark, bike shelters are being made from turbine blades as are a number of playgrounds in the Netherlands. However, a lot of old blades are buried in places like the turbine graveyard, by the North Platte River in Casper, Wyoming in the U.S. Between last September and this March, it became the final resting place for 1,000 fibreglass turbine blades. Here in Ireland, UCC are looking at using parts of turbines for a Greenway bridge but how many old blades a country the size of Ireland can dispose of may be an issue. Perhaps we could live in them? As a non-home owner I would certainly consider it!

I have read elsewhere that there are experiments with lighter fabric-based skin on frames but I am not sure how that is developing. I’ll look at alternatives to the traditional windmills on which the turbine is based – which having been in use for 1000s of years are not really as innovative as they are made out to be – in another post.

I think I’ll start looking at impacts on wildlife, what they are and how they are measured, next Saturday…

Other posts in the series are…

The Winds of Change: Introduction to a series

Windy Wednesday: The distance to the horizon for Dummies

The Winds of Change: The Proposal(s)

Windy Wednesday: Some Windfarms

The Winds of Change: Block Island

Windy Wednesday: An Artist’s Impression in Progress

Links and References

https://www.windpowerengineering.com/comparing-offshore-wind-turbine-foundations/
https://www.designboom.com/design/denmark-repurposing-wind-turbine-blades-bike-garages-09-27-2021/
https://www.bbc.com/news/business-51325101
https://www.researchgate.net/figure/Different-foundations-to-support-offshore-wind-turbines-based-on-water-depths_fig5_323118519

Windy Wednesday: Some Windfarms

Below I have picked out four wind farms and listed their specifications. I have also added my own notes as to why they are of interest in the case of the wind farms planned for the Copper Coast, three of which I have listed below for comparison

Energia’s North Celtic Sea Project (5-10km offshore) proposes a 600-800MW(approx.600,000 homes) wind farm and suggests that between 40-60 turbines are the usual amount (many factors will determine that, geography, turbine type and height, distance from shore. For example the London Array at 600MW has 175 turbines).

ESB/Equinors’ Celtic Offshore Wind proposal (10km offshore) is also for 600MW (approx. 600,000 homes) and has no mention of the amount of turbines.

SSE Renewables floating wind farm The Celtic Sea Array(25km offshore) proposes an 800MW wind farm with no turbine estimate.

Beatrice

Beatrice. Irish Independent June 2020.

Beatrice Up to 2007, wind farms were only built in depths of 20 metres and less. Then came the experimental two turbine Beatrice wind farm off the east coast of Scotland (25km from shore and at a 40 metre depth). Beatrice has since been expanded closer to shore. What’s interesting to note is that Beatrice powers homes in southern Scotland via a 160km long subsea cable and underground cables to Blackhillock Substation in Northern Aberdeenshire via underground cables. This required the construction of two new converter stations, one at Blackhillock, which, at the size of 24 football pitches, is now the largest substation in the UK.

Of added interest re:the length of this cable to us on the Copper Coast is that the governments of the UK, Northern Ireland and Ireland commissioned a study about a decade ago which concluded that the development of an offshore interconnected grid would provide the UK with an increase of imports in the form of renewable generation from the Irish market and improve the interconnector capacity between both markets (Aoife Foley, Paraic Higgins, The evolution of offshore wind power in the United Kingdom, 2013). Could the power generated on the Copper Coast be used in the UK?

Distance from Shore: 13km

Area:131 square km

Water Depth: 56 metres.

Number of Turbines: 84

Turbine Height:188 metres (maximum pile depth to the highest point of the blade sweep up to 288)​

Turbine Type: Siemens Gamesa 7MW

Foundation: Jacket (with the jacket substructures up to 81m tall).

Operator: SSE on behalf of a joint venture partnership.

Electricity Generation: 400, 000 homes.

The London Array

London Array wind farm as viewed from the air in February 2019 Source:Bodgesoc

Once the biggest offshore wind farm in the world, the London Array is 20km off the Kent coast. Maintained and operated from the port of Ramsgate. Turbines are between 650 and 1200 metres apart. The blades have a swept area of one and a half times the size of Wembley Stadium’s football pitch. The turbines are designed to run for more than 20 years. That means basically that after two decades or so many wind farms will be decommissioned. Like our Metal Man and his pillars. Only eleven times taller. And more numerous.

Distance from Shore: 20km

Number of Turbines: 175

Turbine Height to tip of blade:147 metre

Turbine Type: Siemens 3.6MW

Water Depth: 25 metres

Foundation: Monopile (i.e. basically an extension of the turbine underwater)

Area: 100 square km

Operator: RWE, Orsted, Masdar & La Caisse de dépôt et placement du Québec (CDPQ)

Electricity Generation: 500, 000 homes.

Hornsea 1 Image Credit: Volodimir Zozulinskyi/Shutterstock.com

Hornsea 1

Located off the Yorkshire coast, Hornsea One spans a huge area over five times the size of the city of Hull. The offshore wind farm uses 7 MW wind turbines, with each one 190 metres tall – larger than the Humber Bridge concrete towers.

Distance from Shore: 120km

Number of Turbines: 174

Turbine Height to tip of blade:190 metre

Turbine Type: Siemens Gamesea 7MW

Water Depth: 25 – 30 metres

Foundation: Monopile

Area: 407 square km

Operator: Orsted

Electricity Generation: 1 million homes.

Dogger Bank

Dogger Bank. Image Windpower Monthly

Dogger Bank Wind Farm is an offshore wind farm that will be the largest in the world when it’s finished, knocking Hornsea 1 off the top spot. It’s worth noting as it is located between 130km and 190km from the North East coast of England. Turbines are GE’s Haliade X 13 and 14 MW, over two and a half times taller than the Statue of Liberty and are likely to be considered by some developers for the Waterford coast. Dogger Bank will be capable of powering up to 6 million homes on completion in 2026. The subsea export cables will make landfall in Yorkshire, where around 30km of underground cables will take the electricity to converter stations near Cottingham before passing through the adjacent Creyke Beck substation onto the National Grid.

Distance from Shore: 130-190km

Number of Turbines: 600 (up to 200 for each phase).

Turbine Height: 260 metres

Turbine Type: General Electric’s Haliade X 13/14MW

Water Depth: 18-63metre.

Foundation: Monopile

Area: 8660 square km

Operator: SSE Renewables/Equinor/Eni

Electricity Generation: 6 million homes

Block Island Wind Farm ©John Supancic

BONUS Farm: Block Island off Rhode Island. America’s first offshore wind farm was operational in 2016 and its operation has since been taken over by the Danish company Orsted. Though it is a pilot windfarm – 5 Haliade 6MW turbines less than 5km offshore – this ‘little’ windfarm deserves its own post because for most of this summer the turbines were shut down and the island’s residents did not know why. I’ll post about it on Saturday and move the planned post for creating an artist’s impression of turbines further along.

Other Posts: The Winds of Change: Block Island, The Winds of Change: Introduction to a Series, The Winds of Change: The Proposals, Windy Wednesday: Distance to Horizon for Dummies,

The Winds of Change: The Proposal(s)

Proposed windfarms of the Waterford and Cork coasts: Map http://www.bluehorizon.ie

The above image from Blue Horizon* is probably the simplest way to illustrate what wind farms are being proposed for the coast of Waterford and Cork. In addition to these blocks, imagine 12 x 4km strips leading to shore at various points from Cork to Ballycotton to Bonmahon to Bannow. Those are areas to be surveyed for potential cable corridors – ultimately about 1km wide – for burying cables. They are included in images below. You can stop reading now if you like but I will go in to a bit more detail on companies and cable corridors below. There is a post on calculating distances from shore here.

*Blue Horizon are a group of interested indviduals who have come together calling for all offshore wind projects to be placed at least 22km from the Waterford coast, following the approach taken across the EU. Their website is a great resource

The Companies Proposing

Energia (once Viridian) is an Independent company and ESB’s main competitor. It used to be Irish owned but in 2006 it was sold to a Bahrain based investment group Arcapita and in 2016 sold on to US private equity firm I-Squared Cap, an independent global infrastructure investment manager. Energia have just been granted a licence to carry out Site Investigation works related to the potential development of a fixed (that is with turbines built into the sea bed) wind farm with an output capacity of 600-1000MW in the Celtic Sea off County Waterford. That MW would power very roughly half a million homes. It is the biggest single area being surveyed and the one closest to the coast. They are exploring 7 options for cable corridors and landfalls. Energia have recently been saying this wind farm is to be 10km offshore but as we can see it is (or was) planned for considerably closer than the ESB/Equinor proposal which is 10km and I certainly heard of a 5km distance some time earlier in the year. Watch this space.

Potential cable corridors for Energia’s wind farm. Image take from WLRFM’s website/Blue Horizon interview.

DP Energy Ireland is a Cork-based company owned by Maureen De Pietro and Simon De Pietro. DPEI are investigating the feasibility of Inis Ealga Marine Energy Park (IEMEP). Their’s is one of the few websites with photos of their team. They seem to be particularly interested in floating rather than fixed platforms. They are exploring 3 options for cable corridors and landfalls.

Potential cable corridors for DPEI’s wind farm aka ‘Marine Park’.

ESB, sure we all know them right?The Irish Government-owned power company and Energia’s rival are working with developers Equinor – a Norwegian government-owned group – on a number of projects. In my reading so far the ESB and Energia proposals for the Waterford coast have not had any distinction made between them and it’s possible they are in competition for the same area. ESB’s Helvick Offshore Windfarm is planned for 10km off shore and will take up 140 square km. ESB/Equinor are also working on Celtic 1, a fixed wind farm planned for 8km off Ballycotton. It will take up 120 square km. Its planned to be 600MW which would power over half a million homes. After that Celtic 2 is planned which is a floating wind farm. They are also working on a project, Sea Stacks, 12km off Dublin which will be 800MW.

SSE are a Scottish registered company (they also have pictures of some of their team on their site) and they are exploring two potential cable corridors and landfalls at Bannow Bay Wexford and Bonmahon, Co.Waterford for, I assume, their proposed floating windfarm planned for 25km off shore.

I am not going to go near Shell…we’ll the Cork lads deal with that.

A note about cable corridors and surveys.

SSE Renewables from their application to survey potential cable corridors and cable landfalls.

Cables carrying power from offshore to land need to be buried in the sea bed. Above is an image from SSE’s application for permission to survey for cable corridors. The requested area to survey for the corridors is 4km wide. In actuality they say they may survey a 1km strip of sea bed and after initial surveys may possibly only survey only one corridor in detail. I imagine this framework also applies to the other ten cable corridors being investigated for this clutch of windfarms. Surveying involves both geophysical/non-invasive (e.g. acoustic soundings) and geotechnical/invasive (e.g. vibrocore, boring, sampling) methods. This seems to suggest major disturbance over a wide variety of areas from inshore to off. Sadly, no matter how far out the windfarms are, the cable corridors – and cable landfalls (which I will look at along with shore based assemblage/construction/supply bases when I know more) will likely be a major consideration.

In the cable corridors there are echoes of Shell to Sea’s campaign against the natural gas pipeline. Anyone wishing to read more on that – and perhaps brace themselves – should read Once Upon a Time in the West:The Corrib Gas Controversy by Lorna Siggins. It’s a sobering read.

Next Wednesday I’ll do a short post describing some of the biggest existing and planned wind farms. Next Saturday I’ll have a look at creating an artist’s impression of an off shore wind farm. Comments are turned off but any information, comments, corrections etc are welcome via the contact form on this blog. I will consider guest posts too.