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.
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.
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…
Links and References