Matthew Lackner, University of Massachusetts Amherst
Northern California has some of the strongest offshore winds in the U.S., with immense potential to produce clean energy. But it has a problem. Its continental shelf drops off quickly, making building traditional wind turbines directly on the seafloor costly if not impossible.
Once water gets more than about 200 feet deep – roughly the height of an 18-story building – these “monopile” structures are pretty much out of the question.
A solution has emerged that’s being tested in several locations around the world: making wind turbines that float. In fact, in California, where drought is putting pressure on the hydropower supply and fires have threatened electricity imports from the Pacific Northwest, the state is moving forward on plans to develop the nation’s first floating offshore wind farms as we speak.
So how do they work?
Three main ways to float a turbine
A floating wind turbine works just like other wind turbines – wind pushes on the blades, causing the rotor to turn, which drives a generator that creates electricity. But instead of having its tower embedded directly into the ground or the sea floor, a floating wind turbine sits on a platform with mooring lines, such as chains or ropes, that connect to anchors in the seabed below.
These mooring lines hold the turbine in place against the wind and keep it connected to the cable that sends its electricity back to shore.
Most of the stability is provided by the floating platform itself. The trick is to design the platform so the turbine doesn’t tip too far in strong winds or storms.
There are three main types of platforms:
- A spar buoy platform is a long hollow cylinder that extends downwards from the turbine tower. It floats vertically in deep water, weighted with ballast in the bottom of the cylinder to lower its center of gravity. It’s then anchored in place, but with slack lines that allow it to move with the water to avoid damage. Spar buoys have been used by the oil and gas industry for years for offshore operations.
- Semi-submersible platforms have large floating hulls that spread out from the tower, also anchored to prevent drifting. Designers have been experimenting with multiple turbines on some of these hulls.
- Tension leg platforms have smaller platforms with taut lines running straight to the floor below. These are lighter but more vulnerable to earthquakes or tsunamis because they rely more on the mooring lines and anchors for stability.
Each platform must support the weight of the turbine and remain stable while the turbine operates. It can do this in part because the hollow platform, often made of large steel or concrete structures, provides buoyancy to support the turbine. Since some can be fully assembled in port and towed out for installation, they might be far cheaper than fixed-bottom structures, which requires specialty boats for installation on site.
Floating platforms can support wind turbines that can produce 10 megawatts or more of power – that’s similar in size to other offshore wind turbines and several times larger than the capacity of a typical onshore wind turbine you might see in a field.
Why do we need floating turbines?
Some of the strongest wind resources are away from shore in locations with hundreds of feet of water below, such as off the U.S. West Coast, the Great Lakes, the Mediterranean Sea, and the coast of Japan.
In May 2021, Interior Secretary Deb Haaland and California Gov. Gavin Newsom announced plans to open up parts of the West Coast, off central California’s Morro Bay and near the Oregon state line, for offshore wind power. The water there gets deep quickly, so any wind farm that is even a few miles from shore will require floating turbines. Newsom said the area could initially provide 4.6 gigawatts of clean energy, enough to power 1.6 million homes. That’s more than 100 times the total U.S. offshore wind power today.
Globally, several full-scale demonstration projects are already operating in Europe and Asia. The Hywind Scotland project became the first commercial-scale offshore floating wind farm in 2017, with five 6-megawatt turbines supported by spar buoys designed by the Norwegian energy company Equinor.
While floating offshore wind farms are becoming a commercial technology, there are still technical challenges that need to be solved. The platform motion may cause higher forces on the blades and tower, and more complicated and unsteady aerodynamics. Also, as water depths get very deep, the cost of the mooring lines, anchors, and electrical cabling may become very high, so cheaper but still reliable technologies will be needed.
Expect to see more offshore turbines supported by floating structures in the near future.
Matthew Lackner, Professor of Mechanical Engineering, University of Massachusetts Amherst
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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“Expect to see more offshore turbines supported by floating structures in the near future.”
All for nothing.
It’s truly sad to see this slow-moving disaster of wasted effort and attention called “climate action.” And it’s all based on unsound attribution to CO2 emissions of what cannot be ruled out as natural. It’s the right thing to do, to keep on exposing the misconceptions.
“It’s truly sad to see this slow-moving disaster of wasted effort and attention called “climate action.”
Isn’t that the truth! We are watching a slow-motion trainwreck to which most of our leaders appear to be oblivious. CO2 is not a reason to turn the world upside down.
The unfortunate outcome of these actions is clear to some people. “I told you so”, will be said, but that may be too late to prevent the crash.
Idiocracy combined with political powergrabbing. That’s what is powering the CO2 “crisis”.
“…there are still technical challenges….” The devil is in the details.
I’m betting on warp core tech
It turns out this is not just some professors dream. The link below shows the last of five floating wind turbines being installed off Aberdeen, Scotland, a couple weeks ago.
http://www.oedigital.com/news/489202-video-boskalis-delivers-final-turbine-for-kincardine-floating-wind-farm
It will interesting to see how these units perform.
“It will interesting to see how these units perform.”
At a guess, badly?
So, we are not allowed to drill for oil, but we can tie down thousands of cables.
Ok…
https://www.cornwalllive.com/news/cornwall-news/40m-wave-hub-near-hayle-1392269
Nearly there.
Off-shore bird shredders – http://jasonendfield.weebly.com/home/isle-of-man-sea-bird-populations-plummet-as-wind-farms-overwhelm-the-irish-sea?fbclid=IwAR1dkKoNDvTk9MJuxNxpxRP-pHYgxKeGpysldICyqBiUOPUt8H-T_TYhyw8
Future Build-outs of Offshore Wind Turbine Systems in New England
https://www.windtaskforce.org/profiles/blogs/high-costs-of-wind-solar-and-battery-systems
– MA, RI, and CT are planning to have 8460, 880, and 4160 MW, respectively, a total of 13,500 MW of offshore wind by 2035, much greater than the above 1600 MW.
– If the same simulation were made for 13,500 MW of wind turbines, the up/down spikes would be about 10,000 MW
– The existing CCGT plants would be inadequate to counteract them, i.e., output curtailments would be required.
– The 2035 date has a ring of urgency to it, but likely would be unattainable in the real world. See page 13 of NE-pool URL
It would take at least 20 years to build out 13,500 MW wind turbines off the coast of New England, plus large-scale solar systems to reduce the NE grid CO2/kWh by about 30%
With that much wind and solar, the NE grid would become very unstable. The NE grid would need:
1) Curtailments of wind output, kWh, on windy days
2) Curtailments of solar output bulges on sunny days
2) Major connections to the Canadian grid
3) Grid-scale batteries, with a capacity of 3 to 4 TWh; turnkey capital cost about $1.5 to $2 TRILLION, at $500/kWh, delivered as AC
https://www.iso-ne.com/static-assets/documents/2020/02/2020_reo.pdf
https://nepool.com/uploads/NPC_20200305_Composite4.pdf
https://www.windtaskforce.org/profiles/blogs/reality-check-regarding-utility-scale-battery-systems-during-a
NOTE: Nearby countries import German overflow electricity, when it is windy and sunny, at low grid prices (because of a German surplus), and export to Germany, when it is not windy and not sunny, at high grid prices (because of a German shortage).
The Netherlands is one of the major beneficiaries.
German households get to “enjoy” the highest electric rates in Europe, about 2.5 times as high as the US
Denmark, another wind country, is second!
https://wattsupwiththat.com/2021/04/08/germanys-windexitold-wind-turbines-dismantled-without-replacementlooming-massive-power-outage/
Maine Offshore Wind Turbine Systems are Dead
The ocean waters near Maine are deep. Almost all offshore wind turbines would need to be floating units, anchored at the seafloor with at least 3 long cables.
The 700-ft tall wind turbines would need to be located at least 25 miles from any inhabited islands, to reduce the visuals, especially with strobe lights, 24/7/365
The wind turbines would be far from major electricity demand centers, such as Montreal and Boston.
Transmission systems would be required to connect the wind turbines to demand centers
All that would make the cost of electricity produced by these wind turbines more expensive than those south of MVI.
http://www.windtaskforce.org/profiles/blogs/deep-water-floating-offshore-wind-turbines-in-maine
Maine is Desperate to Stay in the Wind Turbine Business
Maine wind/solar bureaucrats likely are in active discussions with stakeholders to add 751 MW of onshore wind turbines.
Maine wind/solar bureaucrats are not in active discussions with stakeholders to add offshore wind turbines, as shown by the interconnection proposals on page 13 of URL
https://nepool.com/uploads/NPC_20200305_Composite4.pdf
European Companies Building Offshore Wind Systems
Almost the entire physical supply of US East Coast offshore wind systems would be by European companies, because they have the required expertise and the domestic onshore and seagoing facilities, due to building at least 25,014 MW (end 2020) of offshore turbine systems, during the past 35 years.
Those companies would hire qualified US labor, as needed.
Those companies would build US facilities, as needed.
Those companies would not be interested in training a potential competitor.
The EU vs the US
The US, with a low-cost, self-sufficient, energy sector would attract European, Korean, Japanese, etc., energy-intensive, heavy-industry and industrial product production to the US.
Europe is interested to make sure the US has a high-cost electrical sector, with lots of high-priced wind and solar and batteries, to handicap the US, and to enhance its competitiveness vs the US. The UN is helping out by urging the US to expensively reduce its CO2 by 50% by 2030, which is not possible. See URL.
https://wattsupwiththat.com/2021/04/21/the-latest-co2-fantasy/
– Europe desperately needs more low-cost gas from Russia to remain competitive on world markets
– Europe has to build out wind and solar to limit energy imports from unstable countries; the US does not need to.
What could possibly go wrong and how much will the subsidies be? Has anyone figured out how to build them without mining, smelting and fossil fuels yet?
So let’s see, the most sustained winds are in Northern California well away from most population centers. How much line loss will there be conveying the electricity to Portland, San Francisco, Seattle, Los Angeles? And how about the power lines that will need to be placed in the pristine northern forests of California? We’ve seen how well PGE keeps them clear of vegetation.
California is planning floating wind farms offshore to boost its power supply – here’s how they (are supposed) work
Do the floating platforms account for locked rotor forces as is common for large turbines or motors/generators on land?
Steve
And then there is the issue of maintenance cost. Land-based wind turbines are difficult enough, but maintenance in an unforgiving marine environment is probably going to add an order of magnitude. Routine maintenance will be rather expensive, but non-routine stuff (repairs) gets very, very expensive, very, very quickly.
Floating wind turbines? God help us. Well, it is now official. What, if any affect at all co2 has on the greenhouse has been surpassed by something just discovered called the madhouse gas and alarmists are the largest emitters.
Joe
Ref to the very first picture:
https://www.equinor.com/en/what-we-do/floating-wind.html
“Equinor and partner Masdar invested NOK 2 billion to realise Hywind Scotland”
https://en.wikipedia.org/wiki/Hywind_Scotland
Construction cost: £264m
£8.8B/GW
Someone badly needs to go to jail.
Oddgeir
The very FACT that we can build such things is ALONE PROOF that we do NOT need them.
And the next tsunami will presumably tip them all over, pull out all the anchor cables and destroy the power cables. Still, they will probably blame it all on climate change!
In the deeper oceans, tsunami waves are rarely more than a few feet high.
When I think of California doing something that is a difficult and expensive engineering project, I think back to their high speed rail they were building. One of the few things you can guarantee is that it will be an order of magnitude more expensive and require much more time to accomplish and will provide half of the energy they expected.
The entire project will be an exercise in very expensive stupidity and a waste to the taxpayers.
As a sometime oceangoing seafarer, I would not insure such a device against catastrophe.
Floating wind turbines. Sounds like a fairly simple engineering challenge. Let’s put Ibrahm X. Kendi and Robin DiAngelo on the problem.
How these are supposed be defensible from a potential enemy attack from the sea?
Right in the path of migrating whales the left has been so vociferously blaming everyone else for any/all damage the whales suffer.
Add in all of those wind platform steel cables into the migration path of the whales either proves eco-alarmist claims wrong or increases whale damage many times.
Nuclear.
How about putting the present California government on barges and pushing them out to sea.
If the wind turbine floats, does that mean it’s a witch? I can never remember.
$5 says if they build this they’ll underbuild the stays and the suckers will float together because of drag and have bumfights.
I read no discussion of the length, cost, and placement of transmission lines required to move the electricity from offshore to onshore. This does not include some type of transformers or other methods of regulating the power from offshore to onshore.
Submarine transmission cable costs are somewhere between $115,000 to $300,000 per mile.
Before such a project is completed in California, I suspect the costs will multiply by 10X or more.