The concept of Deep Water Wind foundations, as an alternative or successor to Floating Offshore Wind, appears to be gathering momentum.
The traditional notion of the floating offshore wind foundation, where a heavy —typically triangular— structure is moored to the seabed using mooring lines, is being challenged. A couple of recently-unveiled designs look more like a cross between a traditional fixed-bottom jacket foundation and a guyed radio mast.
An example Deep Water foundation: the FTLP+™ (Image credit: OSI Renewables)
What are the potential advantages of Deep Water foundations versus traditional wind floaters?
1. Structural performance
Here's a wave tank video of the MPS hybrid, with a like-for-like comparison with traditional designs, courtesy of Dr Graham Foster, CTO/Chair at MPS. As you'll see from this demonstration, the hybrid design offer a reduced response to heave, tilt and surge.
2. Cost
MPS claim that a PelaFlex Hybrid GS foundation would cost £12m apiece for the UK market, versus £18m for a PelaFlex TS Floating TLP — and £25m for a reference semisub (which, unlike the MPS designs, would likely be manufactured overseas). These figs are “high level… a full economic analysis is in the works”, which is fair enough. To put that into the context of planned UK North Sea commercial-scale floating wind farms, the span of savings sum to £450m for Green Volt (~35 turbines) to £2.2bn for Ossian (~170 turbines).
OSI Renewables is bound to know the maths well, given the substantial pedigree of its parent Oil States International in delivering foundations for oil & gas projects. But has anyone seen them publish comparable savings figures?
3. Carbon intensity
The hybrid foundations designs should offer superior carbon figures versus a traditional floater, given that their mass would be approximately half (approx 2,500 vs 5,000 tonnes). Steel and concrete are two of the most carbon-intensive materials to manufacture, so there's an immediate benefit at the point of manufacture - the lifecycle stage shouldering the bulk of the product's carbon burden. This reduced mass would also suggest substantially lower emissions during the Transport & Installation part of the construction phase. Especially assuming that local production is more likely than with a semisub (certainly in the example of MPS’s native market, the UK). The same applies to any return-to-port operation that occurs during the Operations & Maintenance phase.
Again, when we think of the the thousands of turbine foundations that would be required to fulfil the vast areas that currently can only be served by floating wind, and multiple that by the thousands of tonnes of steel that could be saved, and the transport carbon miles to install them, we can see the huge potential to reduce the carbon footprint of offshore wind. No power generation source is truly zero carbon, though such innovations could make offshore wind relative less carbon intense, as measured in tCO₂e/TWh.
4. Installation complexity
Finally, I suspect that the installation is greatly simplified versus for a TLP floater, given the complexity (and high cost) of fixing those to the seabed. It won't be as simple as a monopole or jacket, of course. Though if they were a viable solution for the bathymetry and soil conditions, then a hybrid wouldn't be anymore in contention than a floating foundation. Likewise with their compatibility with ‘other users of the sea’, such as fishing fleets: hybrids are likely better than catenary-moored semisubs in terms of navigability and gear entanglement, but worse than with vertically-mooted TLPs.
5. In life
Floating wind foundations are more complex, and therefore expensive, to monitor than their fixed-bottom cousins from a conditional monitoring perspective. That's because they are moored using relatively-flexible moored lines, and thus the platform experiences six degrees of freedom (6DOF, below).
6DOF, or Six degrees of Freedom. (Image credit: 6DOF GregorDS, CC BY-SA 4.0, Wikimedia Commons)
A traditional floating platform would also require a dynamic Inter Array Cable (IAC) to overtake the electrical power. This would all necessitate complex asset integrity condition monitoring instrumentation.
A hybrid foundation would naturally still be exposed to the same metocean forces, though would be relatively a lot more stable — through exhibiting a reduced response to heave, tilt and surge. This would simply the required instrumentation, and burden for monitoring analysis. The IACs would certainly be under a lot less stress than on a totally floating platform — and that means a lot less stress for Asset Managers and their insurers alike!
Finally, the chances are that a hybrid foundation could potentially exhibit less cumulative damage, and thus increase the ability to extend the operational life of a windfarm far offshore. This will, I suspect, will require an offshore demonstrator to prove this fully.
In conclusion
It's great that as we approach the arrival of 100-500MW floating wind projects, a new type of engineering solution for foundations is entering the fray. One that could markedly improve the structural performance of turbines far offshore, and greatly improved cost, carbon intensity, ease of installation, operational performance and asset longevity.
Go deep!
NB: I’m not affiliated in any way with the mentioned companies.
On a recent trip to Hokkaido in Japan, I had the chance to see the operational Ishikari Bay offshore wind farm, just to the west of Sapporo. At 112MW, it may seem small, at least to those in Europe, but Ishikari is very special for Japan. Upon its Commercial Operations Date on 1 January 2024 it became Japan's largest offshore wind farm . It's also the first to use 8MW turbines (the most recent projects, at the ports of Akita and Noshiro, used 4.2MW models). Ishikari Bay New Port Offshore Wind Farm, 2024 Despite enjoying 30,000km of coastline , and each gigawatt of offshore wind having the ability to shave an impressive $300m p.a. off the balance of trade figures for imported fossil fuel , Japan's installed capacity of offshore wind now sits at around 280MW, inclusive of test and demonstration projects. By comparison, the UK, another island nation amongst the ten largest EEZs , has almost 14GW . The gap has two main causes. Firstly, the UK's seabed topography is m...
When visiting Haugesund in Norway recently, for Norwegian Offshore Wind's floating wind festival, I dined with a local. He told me that Haugesund had, in recent years, suffered from being "the bit in the middle - the Cinderella", in relation to maritime powerhouse Bergen (three hours up the west coast) and the hydrocarbon capital Stavanger (two hours down it). With a population of around 38,000 people, Haugesund's population is just 13% and 25% of Norway's second and third cities, respectively. Its region Haugaland gave birth to the name Norway (which means Northbound Route), and notable resident King Harald Fairhair gave us a modern descriptor. But many of its most notable people are those who emigrated to the USA, when the herring boom ended, including the paternal grandfather of Marilyn Monroe (from where her birth name Mortensen originates). The author taking the plunge, before the sauna, at Floating Wind Days, Haugesund, May 2025. Modern Haugesund ...
This is the autobiography of Dr Eddie O'Connor, the Irishman founder of wind farm developer Airtricity, wind/solar developer Mainstream Renewables and supergrid company Supernode. (As always, my views are my own). Before his own firms, he cut his teeth working for ESB (Ireland's then monopoly power generator and transmission provider), before leading Bord na Móna (BNM) the state-owned producer of peat for power stations. The memoir's title comes courtesy of a Civil Servant's label of Eddie during the period when he more than halved BNM's workforce (before increasing productivity from under 1,700 tonnes per head, to over 5,000). In short: it's a great book. Eddie is a no-nonsense and thoughtful writer and, given his impressive achievements, modest. The main focus is on his time at the four companies, and his leadership ethos, and only very briefly about his upbringing. Within its 230 pages, A Dangerous Visionary describes how he built Airtricity, whic...
Comments
Post a Comment