Offshore Wind Turbine Project – Statoil’s Hywind Scotland–A Positive Viewpoint

By Roger Sowell – Re-Blogged From


This article’s overall topic is part of the questions, what should a modern civilization do to look to its future electrical energy needs? Then, what steps should be taken now to ensure a safe, reliable, environmentally responsible, and cost-effective supply of electricity will be available in the future? These questions have no easy answers; they occupy a very great deal of time, energy, and written words.

More to the point, what should an advanced society do in the present, when it is very clear that two of the primary sources of electric power will be removed from the generating fleet with 20 years, and half of that removed within 10 years?


Figure 1 Artist’s Depiction – Hywind Scotland credit Statoil ASA Environmental Statement



Two scenarios are discussed: first the world electric generating situation, then that in the United States.

The basic facts are these: at present, worldwide electricity is provided by six primary sources: coal burning, natural gas burning, nuclear fission, hydroelectric, oil burning, and a mix of renewable energy systems. Of the renewables, most of the power is from wind turbine generators (WTG), second is solar power, and the rest is from a few other sources that include geothermal, biomass, biogas, and others. (source: EIA and other reputable entities). For approximate percentages, in 2012 the world’s electric power was provided by Coal 39.6, Natural Gas 22, Hydroelectric 17.6, Nuclear 10.7, Oil 5, Wind 2.4, Solar 0.5, and Other 2.1. Figures for different countries are available from various references.

In the United States, however, the mix of energy sources is changing rapidly over the next two decades. The essential facts in the US are a great number of nuclear plants will retire; many coal-fired plants will retire, many natural gas plants will be built; and a great number of wind turbine generators will be built. Within 20 years, almost every one of the 98 nuclear plants in the US will retire. Half of those will be shut down within 10 years. That is most significant, because coal plants produce 30 percent and nuclear plants produce 18 to 19 percent of all the electricity in the US. With most of those shut down in 20 years, the US is facing a deficit of almost one-half of the electricity supply. In energy terms, coal and nuclear provide approximately 2,000 million MWh per year. (EIA for 2016). For the shorter term, ten years from now, one-half of those shutdowns will occur, leaving a shortfall of 1,000 million MWh per year.

An aside to look more closely at coal burning power plants and their rapid closures in the US. Coal is no longer king, no matter what anyone says about the matter. The fact is, as I have long stated and written, that coal burning power plants were intentionally given a pass on environmental issues. They were not forced to comply with many of the environmental requirements of the US Clean Air Act. Instead, the coal industry found ways to “perform maintenance” that added capacity, while retaining the grandfathered status. Only a few coal burning power plants were required to comply with the pollution laws. Recently, that all changed. Now, coal burning power plants are closing in record numbers because the owners cannot afford to install the expensive pollution control equipment. (Reference: MIT paper, 2016, MITEI-WP-2016-01; also see I am aware that this is a controversial statement at WUWT, having made this statement before and receiving blistering comments on that. Yet, facts are very stubborn things; they do not care one bit what anyone thinks of them. Facts just are.

The facts of US nuclear power plants are just as plain: the fleet of 98 plants is aging. Almost half, 47 out of 98 still running, are between 40 and 47 years old. (reference: ) Within 10 years, it is almost certain that all of those reactors will be shut down permanently and retired. Many of the nuclear plants are losing money and have done so for a few years. Some have received direct government subsidies recently to keep running. These direct payments are in addition to the numerous other subsidies that US nuclear plants receive, such as for indemnity from radiation releases, federal guarantees on construction loans, softening of safety regulations, laws prohibiting lawsuits during construction, and others. .

In the arena of electricity generation at grid-scale, conventional and new technologies contend for market share. Over the past decade, new technologies that use renewable energy as the motive force have become more prevalent. Wind and solar technologies are two that are presently at the forefront of market share and development effort. As the traditional mix of generating technology changes in the next two decades, wind energy will certainly play a greater and greater role. In early 2017, combined output from hydroelectric and renewable sources slightly exceeded nuclear power plant output (Figure 1 from EIA, figures in billion kWh per month). Also notable from Figure 2 is the almost complete absence of energy from wind (dark green area) before 2010.


Figure 2 US Renewables with Hydro v Nuclear

The growth of wind energy has been substantial in only 7 years, from almost zero percent to 7.5 percent of US total electricity. The growth in wind energy is shown also in Figure 3, where wind energy, for the first time, was the same as the output of hydroelectric plants in 2014-2015. As an aside, Figure 3 is the real hockey stick. The data is from EIA, but the graph is my own. This graph made quite a splash on Twitter on 5/2/2016 among the #windenergy crowd. (@rsowell is my handle)


Figure 3 US Hydro v Wind Energy

The US has more than adequate wind resources and natural gas resources to fill the generating gap from retired nuclear and coal power plants. Onshore wind capacity at present stands at a bit more than 84,000 MW, (windexchange reference) with another 25,000 MW under construction. Natural gas power plants of 190 GW could easily be built to meet the need. Wind turbines of 170 GW could be installed and remain well below 20 percent of all electricity generated annually. The added 170 GW of wind is well below the estimated 11,000 GW of wind capacity that exists onshore in the US.(Lopez, A. et. al. Technical Report NREL/TP-6A20-51946, July 2012) These figures, 190 GW for natural gas, and 170 GW for wind energy are found as follows. The need is for new natural gas power plants to generate 1,000 million MWh per year. By dividing 1000 million by 8766 hours per year we obtain 114,076 MW (and multiply by 1 million). By then dividing by 0.6, the natural gas power plant capacity factor, we obtain 190,127 MW or 190 GW to install.

The 170 GW of wind capacity to install over the next decade is found similarly, but using 0.35 as the capacity factor. The desired result is to have wind energy make up 20 percent of the total electricity in the US annually, the “penetration” as it is known. With existing wind energy already at 7 percent penetration, the need then is for 13 percent from new wind turbines. Multiplying 0.13 times 4,000 million MWh/y we obtain 520 million MWh/y. As before, we divide by 8766 and multiply by 1 million to obtain 59,320 MW. This divided by the capacity factor of 0.35 gives 169,486 MW, which is rounded nicely to 170 GW of new wind capacity.

The nice result here is that total installed natural gas power plant capacity would exceed wind plant capacity. Therefore, when wind speed declines below generating speed, the natural gas power plants have plenty of capacity to make up the power deficit. Wind generating capacity at present is approximately 84 GW, and the new capacity to install is 170 GW. The total of 250 GW is less than existing natural gas power plant of approximately 260 GW. When the new natural gas power plant is added, there is 260 (old capacity) plus 190 (new capacity) which yields 450 GW of natural gas power plant capacity.

This gives a viable solution for the first ten years. Natural gas capacity would be 450 GW total, wind would be 250 GW total, and wind penetration would be a nice, round figure of 20 percent.

The second decade would require similar added capacity. An additional 170 GW of wind capacity would add 13 percent more to the penetration. That would then be 20 plus 13 for 33 percent total. That would present almost zero problems on the national grid. Total wind capacity would then be 250 GW plus 170 GW, which yields 420 GW. (reference DOE Wind Vision site states slightly more than 420 GW can be added by 2050 in their analysis. ) Natural gas capacity would be another 190 GW, for a total then of 450 plus 190 to yield 640 GW. With 640 being comfortably greater than 420, there is adequate natural gas power plant capacity to take over when the wind speed declines.

One question arises, then; can wind turbine generators be added at a rate necessary to achieve 170 GW over ten years? That is an average of 17 GW per year. From actual history, it is noted that in 2012, US wind capacity of a bit more than 13 GW was added. Also, 10 GW was added in 2009. It is clear, then, that 17 GW per year should be no problem. The US wind energy supply chain would be required to increase output by 4/13 or approximately 30 percent.

A second concern sometimes is expressed, as the land area required for a large number of wind turbines. That is not a problem, however. Studies of actual, modern, efficient wind farms found that on average, total land required is 85 acres per MW installed capacity. (Reference: Land Use for Wind Farms Technical Report NREL/TP-6A2-45834, August 2009 ) The study used hectares, giving 34 h per MW. Converting appropriately, we obtain 85 acres per MW installed. The total land area, then, for 420 GW or 420,000 MW of wind capacity is 85 multiplied by 420,000 and divided by 640 acres per square mile. The result is then 55,800 square miles when rounded up a bit. For perspective, that is almost exactly the area of the state of Iowa, which has 56,272 square miles. Of course, the wind parks would be spread out over the states and not all concentrated in Iowa. Another consideration is almost all of the land with wind turbine generators can and would be used for its original purpose.

Why the focus on wind and natural gas? One might prefer to build sufficient nuclear plants or more coal power plants instead of wind and natural gas power plants. Nuclear and coal power plants are discussed below.

It would be extremely difficult, if not impossible to build a sufficient number of nuclear power plants – 40 to 50 of them – in the next decade to replace those that retire. Recent news (7/31/2017) shows that the two new nuclear plants under construction in South Carolina at the V.C Summer plant have been halted with no intention to finish building them. (see ) The South Carolina plants are approximately 35 percent complete, many years behind schedule and several $billion dollars over budget. The projects were halted when the revised estimate to complete showed $26 billion. In order to start up 40 to 50 nuclear plants ten years from this date, the 40 to 50 plants must be approved and under construction today also. Clearly, that has not happened. New nuclear plants also have a very high price for electricity produced.

It would also be unwise to build new coal-burning power plants since the remaining amount of US coal that can be mined at a profit is limited to 20-30 years or less at current prices. (Reference: Luppens, J.A., et al, 2015, Coal geology and assessment of coal resources and reserves in the Powder River Basin, Wyoming and Montana: U.S. Geological Survey Professional Paper 1809, 218 p., ) If coal prices rise, perhaps by increased demand or subsidies, more coal can be mined. However, high coal prices require a coal burning power plant to have higher electricity sales prices. That simply would not occur with natural gas and wind power at such very low prices as today. New coal-fired plants would lose money, just like the new nuclear plants would.

World-wide, the numbers are similar. Coal production is limited to no more than 50 years, unless some force increases the price at the mine-mouth. (Rutledge, David, “Estimating long-term world coal production with logit and probit transforms,”  International Journal of Coal Geology, 85 (2011) 23-33 )

Why onshore wind?

Why, then, the big push for wind technology? Below are listed a few reasons in support of wind power. Following that is a description in some detail the new 30 MW Hywind wind park being installed off the northeast coast of Scotland by Statoil.

Onshore wind farms have benefited greatly from private and public funding over the past decade. The wind turbine generators are already low-cost to install and operate. Projects are profitable in the Great Plains region of the US where the sales price for power is 4.3 cents per kWh. (source: 2015 Wind Technologies Market Report ) The federal subsidy is to end in 3-4 years. Most importantly, the installed cost has steadily decreased over the years, by a factor of 3 in the past 7 to 8 years. The low capital cost is the primary reason that wind power is being installed at 8 to 13 GW per year in the US. It must be acknowledged that the reductions in capital cost per kW occurred only because the federal and state subsidies for wind technology allowed developers to design, build, and install better and better designs. Whatever arguments there may be against subsidies, wind turbine generators have benefitted substantially from the subsidies.

Installed costs will continue to decrease as more improvements are made. Designers have several improvements yet to be implemented such as larger turbines, taller towers, and increased capacity factor. Oklahoma just announced a 2,000 MW project with 800 turbines of 2.5 MW each. Onshore wind farms will soon have the larger size at 4 MW then 6 MW turbines similar to those that are installed now in the ocean offshore.

Wind repower projects have even better economics. Repowering is the replacement of old, inefficient wind turbine generators with modern, usually much larger, and much more efficient systems. The wind will not have changed, was not used up, in the same location. In fact, the taller turbines reach higher and into better wind that typically has greater speed and more stability. The infrastructure is already in place for power lines and roads. Repowering may be able to incorporate legacy towers as the upper section of new, taller towers for larger wind turbine generators.

Wind power extends the life of natural gas wells. Wind power creates less demand for natural gas. This reduces the price of natural gas. That helps the entire economy, especially home heating bills, plus the price of electricity from burning natural gas. But, this also reduces the cost to make fertilizer that impacts food, since natural gas is the source of hydrogen that is used to make ammonia fertilizer.

Wind power is a great jobs creator. Today, there are more than 100,000 good jobs in the US wind energy industry. Many of the wind industry jobs are filled by aeronautical engineers. Instead of designing airplanes with two wings that fly in a straight line, they design wind rotors with three wings that turn in a circle. There are approximately 1.2 jobs per MW of installed capacity, with 84,000 MW and 100,000 jobs. That’s approximately the same ratio as in nuclear power plants, with 1 job per MW.

Wind provides security of energy supply. No one can impose an embargo on the wind. There are no foreign payments, and no foreign lands to protect with the US military.

Wind provides a good, drought-independent supplemental income via lease payments to thousands of families nationwide, due to the distributed nature of wind turbine projects. Almost 100 percent of the land can continue in its original activity, grazing cattle or farming. Marginal land with no economic activity now produces income for the landowner. 85 acres is required for 1 MW of WTG.

Wind power promotes grid-scale storage research and development. Wind energy generated at night during low demand periods can be stored then released when demand and prices are higher. As always, some losses occur when energy is stored and released later. Storage and release on demand has spinoff into electric car batteries. EVs will reduce or eventually eliminate gasoline consumption, and that will spell the end for OPEC. The entire world’s geopolitics will change as a result. Recently, the CEO of BP, the major international oil company, predicted that the next decade or two would bring such a surge of EVs that oil demand would peak, then decline. The CEO is right, too. When it becomes patriotic to drive an EV rather than a gas guzzler, EV sales will zoom. A gas guzzler will be seen as an OPEC enabler.

Wind power hastens nuclear plant retirements as electricity prices decline. Nuclear plants cannot compete with cheap electricity from cheap natural gas. As stated above, wind energy keeps natural gas prices low by reducing the demand for natural gas.

Power from wind is power without pollution. Wind power has no damaging health impacts from smoke, particulates, or noxious sulfur or nitrogen oxides. The American Lung Association encourages clean, pollution-free wind power.

Summary to this point.

The utility-scale power generation mix in the US will change substantially, even dramatically over the next ten and twenty years. Nuclear power will be almost non-existent. Coal power will also be greatly reduced or almost absent. Wind power will be four to five times as much capacity and generation compared to today. Natural gas power will grow to replace the nuclear and coal production, but will loaf along as wind generation occurs. Only when the wind dies down will natural gas power plants roar to life at full throttle. This describes the US situation.

Several other nations also have similar issues to face. Of the approximately 450 nuclear power plants still operating world-wide, roughly one-half will retire within 20 years, and for the same reasons as do those in the US. Old age, inability to compete, and safety concerns will shut them down. A similar analysis can be done for each major nuclear power country with aging reactors, including Japan, France, Canada, UK, and Germany. On average, with 20 years being exactly 240 months, that is roughly 1 reactor per month to be retired. The booming business of the future will be reactor decommissioning.

Next is part two, the specifics on offshore wind and the Hywind Scotland wind park.

Why, then, offshore wind?

In addition to all the benefits of onshore wind power listed above, offshore wind farms have a few benefits of their own. First, a couple of drawbacks that exist with offshore wind power. It is well-known that offshore wind power has higher costs to install, and higher operating costs due to accessibility issues when compared to onshore wind farms. However, these drawbacks are somewhat offset by the much larger wind turbine generators that can be installed, taller towers, and better wind as measured by both velocity and stability. Lease payments do not flow to private landowners, typically, but to the government that controls the local part of the ocean.

For areas that do not have the very good onshore wind that exists in the interior of the US, offshore may be an ideal place to develop wind energy.

Larger turbine designs for offshore wind projects can be evaluated and adapted for onshore projects.

Much of the world’s population lives in cities near the ocean. Transmission lines to bring the energy from the offshore wind turbine generators to the cities may be shorter, compared to running long distances overland.

For those who cannot see the beauty in a technologically advanced wind farm, an offshore wind farm can place the systems out of sight.

The marine industries get a boost with offshore wind farms.

Offshore wind farms are ideally situated for a few forms of grid-scale storage. In particular, one of those is pumped storage hydroelectric with the ocean as the lower reservoir and a dedicated lake higher up onshore. Another form is the MIT submerged storage spheres.

Offshore wind farms very recently, Spring of 2017, won an auction in Germany that contained zero government subsidy as part of the bid. With more and more advances in the technology, the era of subsidized offshore wind farms may be over. Time will tell.

Offshore wind farms bring additional capacity to play. Using the US for example, the government estimates 11,000 GW of wind capacity is economically feasible onshore. An additional 4,000 GW of wind capacity is economically feasible offshore. Offshore wind power increases the US total by a bit more than one-third.

Finally, offshore wind power brings affordable electricity to islands that presently have very expensive electricity due to burning oil in power plants, or diesel in piston-engine generators. Offshore wind power is a mainstay of Hawaii’s plan to obtain 100 percent of the electricity in the islands from renewable sources. Some storage will be necessary to balance out the fluctuations in demand.

The Hywind Scotland floating wind farm uses the moored spar technology, appropriately modified for the single-tower system of a wind turbine generator.

Hywind Scotland Project


Figure 4 Conceptual Layout From Hywind Environmental Statement



As depicted in Figure 4, Hywind Scotland has five floating, seabed-moored spar-type wind turbine generators rated at 6 MW each for 30 MW installed capacity. Note, these are the same size as the offshore wind park in Rhode Island in the US. Block Island system offshore Rhode Island started production in 2016. Note, however, the Block Island system’s towers are not floating, but are anchored to the ocean floor.

Each Hywind Scotland WTG has three mooring lines anchored to the seabed. These mooring lines split into two, so there are six anchor points on the floating tower. (ES 4-5) see Figure 5 below.


Figure 5 Undersea Mooring Schematic – from ES

WTG has a proprietary motion compensation system to ease the load on critical bearings. (ES 3-1)

WTG has three rotor blades. The rotor blades are pitch-controlled. Rotating speed varies with wind strength, from 4-13 RPM (ES 4-19).

The WTG are provided by Siemens, a major vendor of offshore wind turbine generators. The model is SWT-6.0-154. Access is available by boat and a ladder system inside each tower.

Hub height for the WTG is 101 meters above sealevel.

Cut-in wind speed where power generation begins is 3-4 m/s. Cut-out wind speed for WTG protection is higher than 25 m/s. (6.6 mph – 55 mph) (ES 4-19) See Figure 6 for wind direction and range of speeds at the site. Wind speed is higher than cut-in speed more than 95 percent of the time.


Figure 6 Wind Rose Showing Direction/Speed – from ES

Power is collected from the 5 WTGs and brought to shore via a single cable along the seabed, length approximately 25 to 35 km. The power is tied into the national grid. Power is at 33 KV, 50 HZ and AC. Undersea power cable to shore is armoured and 0.5 m diameter. Power can be drawn from shore if the need arises. Diesel-powered generators can also be used at any WTG (ES 4-6)

Each WTG is connected via inter-array cable, 33 kV at 50 HZ and AC. Cables are armoured and approximately 0.5 m diameter. The temporary loss of any one WTG for repairs or maintenance will not affect the output of the others. (ES 4-5)

A smaller floating WTG prototype operated 10 km off the west coast of Norway since 2009 to 2014 and withstood 20 m waves and 40 m/s winds (approximately 88 mph). The prototype was a single WTG with 2.3 MW capacity. (ES xi and 3-1)

Seafloor area required is 15 km-2. With capacity of 30 MW, the ratio is 2 MW per km-2. (ES 4-2)

Water depth is 95 – 120 meters (ES 8-8)

Each of the WTG Units will be equipped with code-compliant navigational lights for marine operations and aviation that will automatically turn on in the dark. (ES 4-7)

Statoil ASA, a Norwegian oil and gas company, is the designer, and investor. Statoil has more than 40 years of offshore oil and gas experience with more than 40 separate offshore installations, most of which are in the harsh conditions of the North Sea. Statoil designed and built the world’s largest object that was ever moved over the Earth’s surface, the Troll A platform. Troll A was designed in the late 1980s, approximately 30 years ago. It began operating in 1996. Troll A is a complex concrete and steel structure that sits on the ocean floor in more than 300 meter deep water. The platform itself is far above the ocean surface. Troll A is more than 470 meters from top to bottom. Statoil also has long experience with power cables along the ocean floor from shore to offshore structures.

Hywind Economics

Economics are improved over the initial one-turbine, 2.3 MW prototype. The prototype generated 40 GWh over several years and demonstrated a 50 percent annual capacity factor during one year. Lessons learned at Hywind Scotland’s 30 MW system will be employed in future, large-scale wind parks. Hywind Scotland’s installed cost is GB £210 million (approximately US$276 million. $/kW = 9210.) But, this includes undersea cables. Note, this is just a bit less than the Block Island 30 MW system in the US, which cost US$300 million.

The unsubsidized economics for the small, 30 MW Hywind Scotland system gives a sales price of electricity at $215 per MWh sold for a 12 year simple project payout. This is based on 45 percent annual capacity factor and investment as above. Revenue would be an average of $23 million per year. With public funding sources as described in the Environmental Statement, the economics are very likely substantially better. This price point, $215 per MWh, is competitive with peaker power prices.

With economy of scale and 60 percent reduction in installed cost for a larger 600 MW park, and 12 year simple project payout, no subsidies, the electricity could be sold at $89 per MWh. At that price point, offshore wind becomes competitive with baseload natural gas power with LNG at $10 per MMBtu as the fuel used.

Bird Collisions

The environmental impact on numerous species are included in the Environmental Statement. The impact on birds is summarized here.

Avian collision mortality was predicted in the Environmental Statement for species that commonly fly at rotor height (101 m) using a range of modelling scenarios. This showed that the predicted additional mortality was negligible compared to the numbers of birds that die from existing background mortality causes. (ES 11-1)

With one exception, predictions of the size and duration of potential impacts shows that for all species for all times of year effects would have negligible impact on receptor populations. The exception is razorbill, for which a potential disturbance effect of low impact for the breeding population is identified owing to the very high densities sometimes present in August, a period when individuals of this species have heightened vulnerability to disturbance. This impact is nevertheless judged not significant. (ES 11-1)

The negligible impact conclusion is consistent with studies in the US on bird mortality from wind turbines. In the US, approximately 1 billion birds die annually from various causes. Ninety-six percent of those are caused by collisions with buildings, power lines, automobiles, and encounters with cats. Less than 0.003 percent were due to wind turbine impacts. (Erickson, USDA Forest Service General Technical Report PSW-GTR-191 (2005), Table 2 ) In addition, bird fatalities decline as older, truss-style support towers are demolished and modern, monopole support towers are installed.


There is a need for electric power generation technologies to replace the rapidly aging and retiring nuclear power plants in several countries within the next decade. Also, coal at today’s prices has a limited horizon of 20 to 50 years. In the US, coal power plants are shutting down due to pollution equipment costs. It is prudent to develop safe, reliable, and affordable means of generating power. Wind power has improved dramatically in the past decade to take its place as such – safe, reliable, and affordable. More improvements are identified and already in the pipeline. In addition, wind as an energy source is eternally renewable and sustainable. The benefits of reduced natural gas demand, lower natural gas price, less air pollution, improved human health from lung diseases, economic benefits for land owners with wind farm leases, increased jobs, increased domestic manufacturing and service businesses, all make wind energy desirable.

The offshore, 30 MW Hywind Scotland floating spar wind energy system is built and backed by the very experienced Norwegian company, Statoil ASA. Even though it has subsidies, the project’s unsubsidized economics would make it attractive against peaker power plants. The improved economics due to economy of scale will make this competitive with main gas-powered plants where LNG is imported for fuel. The Hywind Scotland technology for wind turbine generators, floating moored spar supports, and undersea power cables is already proven. The location chosen, off the eastern seaboard of Scotland, has excellent wind with 40 to 50 percent capacity factor.

A 600 MW or larger offshore wind farm using the Hywind Scotland design can be expected in the next decade. Wind energy technology continues to improve with demonstrated, year-over-year reductions in cost to install.



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