The monopille - basically a really big piece of steel pipe - has become the dominant form of offshore wind turbine foundation in water depths of 2 to 30 meters (6 to 98 feet). The one in the picture will be 60 meters long and appear to be 8 meters in diameter (four adults 6 feet tall), or translated into American text, about 26 feet x 197 feet long, and they weigh around 715 tons. These will probably have end caps put on them. Then they will be floated/pulled by tugs where they will be pulled out of the water by really big cranes, the caps taken off, and then the piles will be lowered onto the desired location. Great Britain now has more offshore wind turbines installed than any other country, but until recently, almost all parts of these were made in other countries. This article "celebrates" the manufacture (finally!) of the most rudimentary aspect of these ultra-high tech systems in England. BTW, that is 2 inch thick steel plate which was rolled from an 82.4 foot long section, and the documentation/paperwork on the materials/inspection (quality control) is just almost as impressive as the welding/metalworking. In fact, as the Fluor Corporation found out when it went with (supposedly) cheaper Chinese made monopiles, bad welding and even worse workmanship documentation can add on hundreds of millions of dollars in cost/wipe out that much in profits. They had to "uninstall" most of the 175 of them, get most re-welded/properly inspected/certified for their Greater Gabbard project at the insistence of the project insurer (part of the $US 2.2 billion financing package). Oops…
Once it has been determined to be as perfectly vertical as can be obtained, the pipe is rammed into the seabed, so that at least 100 feet is buried in the seabed. Then a transition piece is placed on top of the monopole, adjusted so that it IS perfectly vertical, and it is grouted/cemented onto the foundation. The transition piece has arrangements for the underwater electric/fiberoptic cable to be attached to the turbine (tower, nacelle, hub, blades) so that the product (electricity) can be exported to the onshore electricity customers. Unless the wind farm is located close to the shore, the cables will lead to an offshore substation (or 3 of them, for the record setting London Array wind farm). These contain offshore warehouses, housing accommodations and switchgear/transformers and quite often High Voltage Direct Current (HVDC) converter systems (AC from the wind turbines to HVDC, DC from onshore to AC), and these HVDC units typically cost several hundred million dollars each. AC cables have 3 wires plus lots of fiber options, while HVDC only needs one wire (the ocean becomes the ground wire); the longer the line (distance to the turbines from the shore) and the greater the power flow, the more likely it is that HVDC will be chosen as the way to transmit the power to the shore.
In this particular instance, the Humber Gateway wind project is actually pretty small - 219 MW - and close to shore - 10 km (6 miles), so a 132,000 volt AC cable will connect the wind farm to the shore was selected. It is still a windy place with average winds of 8.75 m/s at hub height (http://www.4coffshore.com/windfarms/request.aspx?id=owsdb&version=2&windfarmid=UK10). But since it is close to shore, sort of small by present day standards and in fairly shallow water (11 to 18 meter depths, or 36 to 59 feet), it is not too costly - a bargain at $US 1.1 billion (736 million GBP). It will use the Vestas V112 x 3 MW "medium speed" turbines - not the ones designed for essentially constant gales (the V90 x 3 MW, which only average around 37% net outputs in mellow 20 mph average winds). The owner, German electricity giant E.ON, would obviously like the 73 turbines to be nice and productive. They will be installed over a 35 km^2 area - about 5 turbines per square mile, or 16 MW per square mile - ~45 to 50% net outputs should be possible with this turbine model and this wind resource. And for those concerned with intermittency, the blades should be spinning about 88% of the time…., and providing maximum power about 36% of the time.
The rate of offshore installations last year was close to double what it was for 2011. This graph shows how the this will accelerate during the next 3 years, in spite of the European economic recessions (almost all countries with a Euro currency plus Great Britain) and depressions (Spain, Portugal, Greece, Ireland, Italy, the Baltics).
In 2013, close to 7 GW - more than 5 times the record 2012 install rate - will go "on-line" at a cost of close to $US 30 billion. And while most of this will be in northern Europe - UK, Germany, France, Denmark, Sweden - China will also bring several arrays online (> 500 MW), with 300 MW already operational (but losing money due to high costs and insufficient FIT prices). Meanwhile, 2015 looks to be epic - with over $US 100 billion worth of projects placed online in just a single year. Offshore wind, especially for Germany, IS intended to be an economic stimulus, and IS intended to employ lots of people - well over 100,000 Germans by 2020. After all, the $US 30 or $US1 00 billion investment is also income for a lot of people and companies, too....
Part of the reason for this apparently rapid progress is that the infrastructure in the form of installation vessels - personnel transport, survey vessels, underwater worker supports, cable diggers, cable layers, and even ordinance disposal units (lots of bombs/ammunition from two world wars) - has finally reached a critical mass. An example is the two jack-up ships now in operation by the company Fred Olsen Windcarrier - see http://www.windcarrier.com/brave-tern. Each vessel cost well over $100 million; they are 433 feet long, can carry 6000 tons of parts in one trip, and they feature a huge 800 ton rated precision crane as well as the ability to lift themselves out of the water by about 10 meters in 45 meter deep water. In this way, they can lift huge weights (a 350 ton nacelle, for example) up to 102 meters above the water while being unaffected by waves (that's the jack up part). These are very windy areas of ocean where the turbines are being installed, and that means big waves that will move even big boats around if they are floating. Vessels like the "Brave Tern" and "Bold Tern" can do an install - the assembly of the 3 tower pieces, nacelle and blades - in less than 24 hours, weather permitting. And these boats rent for more than a quarter million dollars PER DAY.
To do offshore installs in an economically viable manner, a very complex schedule of events has to occur, and with provisions that weather may put things off for close to half the days in a year (too windy!). Obviously, the correct staging of parts, personnel and equipment at nearby ports has to be in place and fully functional, as delays can add millions of useless expense in a very short time period. After the foundations are installed, checked and inspected, the transition piece (around 300 tons) has to get installed/inspected. Then cables have to be connected and above all, protected from "scour" - getting disturbed by waves and also tides (often pretty intense +/- 120 to 30 feet in a day in the North Sea estuaries). The offshore substation - often weighing many thousands of tons - needs to be put in place and connected to the mainland. Then comes the big day for the turbine install (repeated for each turbine) followed by many weeks of wiring, inspection and commissioning, plus documentation. Many projects also have parallel underwater ecosystem monitoring, too, and everything needs documenting. The North Sea is a nasty place to work - near freezing water, rain, snow, icing, nasty waves and always the wind and tides. On one wind farm, a worker had a heart attack and fell into the water, while others have been crushed by moving equipment. And then there is the seawater and at minimum, 33,000 volt (33 kv) electricity, and sometimes 150 kv. This is not work for the feint of heart, physically unfit, prone to seasickness, don't like being cold and wet, and untrained. Indeed, many of the skills developed in the offshore oil and gas industry in the North Sea are being put to work with offshore wind - and at least wind turbines don't blow up or pollute the ocean with spills. In work like this, often there is no such thing as a second chance….
As far as the US is concerned, the Cape Wind project is now moving forward - some of the foundations might be installed this year, and the staging dockyard at New Bedford will soon be under construction. That project will use Siemens 3.6 MW x 120 meter rotors, tapping winds similar in intensity to those at Humber Gateway. There are even indications that a 20 MW array will soon be installed near Cleveland. Better late than never…. The neat thing about the Humber project is that it so SO transferable to lake Erie, and especially in NY State waters, where average wind speeds of 8.25 to 8.75 m/s are a lot better than those measure 3 miles offshore from Cleveland at their water intake ("Cleveland Crib"), which were 7.4 m/s at hub heights, and with essentially no vertical wind shear measured to date at that location. Units like the V112 or the SWT-3-120 - the so-called "moderate wind speed turbines", are ideally suited for such winds, while "fast wind turbines" like the V90 x 3 MW or the SWT-3-107 or the 5 and 6.15 MW RE Power turbines require average wind speeds in excess of 9 and even 10 m/s to justify their installation. Anyway, the V112 can be made in Colorado - American made, if Danish designed.
That's often the missing part of the equation - the economics work so much better if things are locally made, as is the case for the Danish Anholt wind farm (see http://www.dongenergy.com/SiteCollectionDocuments/wind/anholt/Anholt_offshore_wind_farm.pdf). That 400 MW project - due to be finished in a few months has foundations, transition pieces, towers, blades and nacelles all made in Denmark, and a huge local workforce doing the installation. And despite a spate of wretched weather even by Baltic Sea standards, it looks to come online on-time and under budget, justifying the faith of the pension funds who put up half the money for the $US 1.8 billion project. After all, pension funds aren't supposed to gamble… As for the company doing the project - DONG - well, it's owned by the people of Denmark (that's right, socialism), but they are still sticklers for the "on time under budget" phrase, something the the makers of the F35 fighter will never go near (as in, $35 billion over budget, years late). BTW, the F-35 may be a product ordered by the US Government, but it was built and designed by private industry, companies who sort of feel that the government really exists to service THEM.
Anyway, quite the contrast. An offshore wind rush in the North Atlantic/North Sea/Irish Sea/Baltic Sea, done with a mix of public and private savings as well as a lot of borrowing (= money creation) from banks, done with the multiple targets of job creation/industrial development/real wealth creation while at the same time making seriously large quantities of pollution free electricity, and avoiding a whole lot of CO2 pollution/importation of natural gas and corresponding export of money for that gas. Or in the US, our public works program, in this case the F-35 airplane, designed to battle.... who? And so expensive… and a pretty prolific consumer of jet fuel, if given the opportunity, but it's so expensive and so temperamental, management does not want it flown very much…. And F-35's don't produce anything, they just consume vast amounts of treasure (to build and operate it) and petroleum.
Meanwhile, Lake Erie waits. Those V112 units would "only" be spinning 82% of the time in WNY waters, and maxed out around 32% of the time with our 8.25 m/s average winds at 85 meters above Lake Erie. We could be making lots of electricity, employing lots of people in the process of making component and installing systems like the Vestas V112, building the boats to install them. And while there is not a lot of employment to maintain them, more jobs can arise from tourism - our version of "whale watching". Maybe we can even have sailboat races in and around the wind farm. And as for bass, walleye and maybe even trout fishing, those underwater foundations would serve as a catalyst to grow the things that big fish end up eating. Check out what happened in just a couple of years at this Dutch wind farm: http://www.offshorewind.biz/2013/02/28/video-underwater-life-on-offshore-wind-turbines/#.UTASITa11Zk.email (see embedded video):
A monopile for a 2 MW turbine now coated with sea life, and home to happy fish..