Wind energy

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Wind is a form of indirect solar energy, produced by convection currents in warmed air.

Ancient Egyptian sailing boat

People have been using wind power for travelling on water for at least 5,000 years.

It must also have occurred to people that they could harness the power of the wind for other purposes, such as pumping water or grinding grain, but we have little record of how they did so.

These windmills in Nashtifan (originally "Nish Toofan" or "storm's sting") in Iran, which can withstand winds of up to 74 mph, are claimed to have been in use for 1000 years. This video is from National Geographic. An academic discussion of their architecture can be found in a paper in the journal Vernacular Architecture. There is more on the development of the windmill here, and in Wikipedia.

One example we do have is windmills (see right) found in the Iran/Afghanistan border region, based on a design thought to have been created in eastern Persia between 500-900 A.D. In these designs the axis of the rotating part is vertical, making construction quite simple. In later designs used in Europe, and still found today, the axis is horizontal. These are more complicated because they have to be able to turn to match the direction of the wind, but they can produce more power.

Windmills have long been used to produce mechanical power for milling corn and pumping water, but nowadays wind turbines are used to produce electricity. These have been becoming increasingly big. Bigger wind turbines produce more power partly because they simply capture more wind, but there is another factor. The power available from wind depends very strongly on the wind's speed – it is proportional to the cube of wind speed – and wind speeds are faster the higher one gets above the ground. So bigger turbines can produce much more power than shorter ones because they're catching more wind and the wind is faster. Wind also tends to be more consistent (less intermittent) at higher altitudes so a taller turbine also produces power more consistently - it has a higher capacity factor.

GE Haliade-X 12MW turbine compared to some landmark structures

Wind speeds at sea also tend to be higher than on land so offshore wind farms such as those in the North Sea can have capacity factors up to about 45%, although around 30% is more common for wind farms in general.

However offshore wind farms are more expensive to build, and also more dangerous (in common with other maritime occupations, from fishing to oil and gas rig operations).

The Global Wind Atlas shows the onshore and offshore wind resources, and various statistics, of most of the world.

Global Wind Atlas.png


David MacKay explains the physics of wind energy in Sustainable Energy Without The Hot Air pages 263-268 (and discusses the potential for onshore wind energy in the UK on pages 32-34)

Windpower program

There is a considerable interest in wind power as a contributor to reducing our dependence on fossil fuel power sources. Unfortunately, the whole area is bedevilled by misunderstandings about precisely how much power can be obtained from wind turbines of all sizes and what exactly is their economic value. The WindPower program is aimed at clarifying some of these uncertainties. It is intended for both individuals and organisations.

The UK Wind Speed Database program is intended to present the Department of Energy and Climate Change's database in a more user-friendly form and to give users a better feel for the link between wind speed profiles and topography. Clearly, it is of use mainly to those concerned with UK wind power.

In addition to the WindPower and UK Wind Speed Database programs, this website covers a number of general issues associated with wind power such as wind statistics, the calculation of mean power, maximum turbine efficiency and the intermittent nature of wind power. The web pages on these topics can be navigated to from the technical webpage menu on the left. There is a also a reference library web page from which various publications and papers on wind power can be downloaded. This web page also gives access to accreditation test reports on a number of small turbines. Finally, there are a few videos on wind power which visitors to this site may find useful.

Wind Power (Technology and Economics) Electropaedia - Battery and Energy Technologies

Though modern technology has made dramatic improvements to the efficiency of windmills which are now extensively use for electricity generation, they are still dependent on the vagaries of the weather. Not just on the wind direction but on the intermittent and unpredictable force of the wind. Too little wind and they can't deliver sufficient sustained power to overcome frictional losses in the system. Too much and they are susceptible to damage. Between these extremes, cost efficient installations have been developed to extract energy from the wind.

Capacity factor

Calculating the mean power

"It should be noted that there is never a practical circumstance where the mean power output reaches anything like the rated power output. It is therefore a very misleading practice when the rated output of a wind turbine is quoted as if this was the available power from an installation. It has caused great confusion in discussions about the power contributions that wind turbines can make."

The capacity factor of wind John Morgan; Brave New Climate; 8 Nov 2015

Australian wind fleet data

UK offshore wind capacity factors – a semi-statistical analysis Roger Andrews; Energy Matters; 6 Oct 2017

The average capacity factor at 28 operating UK offshore wind farms is 33.6% (most recent 12-month average) and 34.5% (lifetime), increasing to 36.1% and 37.5% when four demonstration projects are discarded. There is a dependence of capacity factor on age, with older farms showing capacity factors of around 30% and younger ones factors of around 40%. This is interpreted to be a result of increased turbine sizes, with taller modern turbines accessing higher wind speeds at higher elevations. There is no evidence for significant degradation of turbine performance with time. A “generic” UK offshore wind farm coming on line in 2017 can be assumed to have a capacity factor of around 41%, although projections indicate that the turbines planned for the Hornsea II farm discussed in previous posts could have capacity factors exceeding 60%.

The data used in this post are from Energy Numbers. I have no way of verifying these data but have assumed them to be correct.

UK offshore wind capacity factors Andrew; Energy Numbers; 27 Jan 2017

Here are the average capacity factors for offshore wind farms in UK waters, newly updated to include data to the end of December 2016. And you might be interested in comparing these with the capacity factors and load-duration curves for Belgium, Denmark and Germany.

Wind Blowing Nowhere Roger Andrews; Energy Matters; 23 Jan 2015
Sadly the graphics accompanying this article seem now to be lost

In much of Europe energy policy is being formulated by policymakers who assume that combining wind generation over large areas will flatten out the spikes and fill in the troughs and thereby allow wind to be “harnessed to provide reliable electricity” as the European Wind Energy Association tells them it will:

The wind does not blow continuously, yet there is little overall impact if the wind stops blowing somewhere – it is always blowing somewhere else. Thus, wind can be harnessed to provide reliable electricity even though the wind is not available 100% of the time at one particular site.

Here we will review whether this assumption is valid. We will do so by progressively combining hourly wind generation data for 2013 for nine countries in Western Europe downloaded from the excellent data base compiled by Paul-Frederik Bach, paying special attention to periods when “the wind stops blowing somewhere”. The nine countries are Belgium, the Czech Republic, Denmark, Finland, France, Ireland, Germany, Spain and the UK, which together cover a land area of 2.3 million square kilometers and extend over distances of 2,000 kilometers east-west and 4,000 kilometers north-south:

Quantifying wind surpluses and deficits in Western Europe Roger Andrews; Energy Matters; 7 Nov 2018
One of the graphics accompanying this article is missing

This post updates my January 2015 Wind blowing nowhere post using 2016 rather than 2013 data. The 2016 data show the same features as the 2013 data, with high and low wind conditions extending over large areas and a decreasing level of correlation with distance between countries. The post also quantifies the surpluses and deficits created by high and low wind conditions in January 2016 in gigawatts. The results indicate that wind surpluses in Western European countries during windy periods will be too large to be exported to surrounding countries and that wind deficits during wind lulls will be too large to be covered by imports from surrounding countries. This casts further doubt on claims that wind surpluses and deficits in one region can be offset by transfers to and from another because the wind is always blowing somewhere.

Energy density and local warming effects

Observation-based solar and wind power capacity factors and power densities Lee M Miller, David W Keith; IoP science Environmental Research Letters; 4 Oct 2018

Power density is the rate of energy generation per unit of land surface area occupied by an energy system. The power density of low-carbon energy sources will play an important role in mediating the environmental consequences of energy system decarbonization as the world transitions away from high power-density fossil fuels. All else equal, lower power densities mean larger land and environmental footprints. The power density of solar and wind power remain surprisingly uncertain: estimates of realizable generation rates per unit area for wind and solar power span 0.3–47 We m−2 and 10–120 We m−2 respectively. We refine this range using US data from 1990–2016. We estimate wind power density from primary data, and solar power density from primary plant-level data and prior datasets on capacity density. The mean power density of 411 onshore wind power plants in 2016 was 0.50 We m−2. Wind plants with the largest areas have the lowest power densities. Wind power capacity factors are increasing, but that increase is associated with a decrease in capacity densities, so power densities are stable or declining. If wind power expands away from the best locations and the areas of wind power plants keep increasing, it seems likely that wind's power density will decrease as total wind generation increases. The mean 2016 power density of 1150 solar power plants was 5.4 We m−2. Solar capacity factors and (likely) power densities are increasing with time driven, in part, by improved panel efficiencies. Wind power has a 10-fold lower power density than solar, but wind power installations directly occupy much less of the land within their boundaries. The environmental and social consequences of these divergent land occupancy patterns need further study.

Climatic Impacts of Wind Power Lee Miller and David Keith; Joule; 4 Oct 2018

We find that generating today’s US electricity demand (0.5 TWe) with wind power would warm Continental US surface temperatures by 0.24C. Warming arises, in part, from turbines redistributing heat by mixing the boundary layer. Modeled diurnal and seasonal temperature differences are roughly consistent with recent observations of warming at wind farms, reflecting a coherent mechanistic understanding for how wind turbines alter climate. The warming effect is: small compared with projections of 21st century warming, approximately equivalent to the reduced warming achieved by decarbonizing global electricity generation, and large compared with the reduced warming achieved by decarbonizing US electricity with wind. For the same generation rate, the climatic impacts from solar photovoltaic systems are about ten times smaller than wind systems. Wind’s overall environmental impacts are surely less than fossil energy. Yet, as the energy system is decarbonized, decisions between wind and solar should be informed by estimates of their climate impacts.

Two new papers examine how turbine-atmosphere interactions shape wind-power’s environmental impacts David Keith; The Keith Group / Harvard University; 4 Oct 2018

Today Lee Miller and I published a pair of papers on the interaction between wind turbines and the atmosphere. “Observation-based solar and wind power capacity factors and power densities” in Environmental Research Letters, and “Climatic impacts of wind power” in Joule. (Many thanks to the journals for arranging simultaneous publication.) Don’t miss Lee’s video abstracts for Joule and ERL.

From my perspective, there are two big takeaways. First, there are now two independent lines of high-quality data suggesting that models with atmosphere-turbine interactions are getting something important correct. Second, that wind power has a somewhat larger environmental footprint than many had assumed, that, specifically, the land footprint of wind is at least 10 times higher than that of solar.

Revealing the Dark Side of Wind Power Mark Buchanan; Bloomberg opinion; 4 Oct 2018

Any solution to global warming will almost certainly rely on an expansion of renewable energy, reducing carbon dioxide emissions with clean solar or wind energy and related technologies. It’s still far from clear, however, which technologies might deliver copious amounts of energy when we need it while avoiding negative environmental consequences.

Research published today may help clarify the situation — and it’s not encouraging for wind-power enthusiasts. It suggests that the power available from wind is much more limited than many experts thought, and that deployment on a larger scale could significantly raise temperatures over the Earth’s surface, as turbines alter atmospheric flows. The research highlights a painful but not altogether surprising reality: Even the cleanest renewable technologies come with environmental costs.


For wind power, researchers have debated how much energy might ultimately be harvested, with estimates of the available energy density — how much we might gather per unit of surface area — ranging all the way from 0.5 to 200 watts per square meter. The higher figures tend to come from studies of single turbines in isolation, and lower numbers when considering how, in larger wind farms, one turbine can disrupt wind flows and reduce the energy-gathering efficiency of other turbines nearby. The lowest estimates come from theoretical studies of the physics of atmospheric flows. The new study comes down firmly on the lower end of the range.


Miller and Keith found something even more surprising in another study that looked at a related question: What should we expect the climate impact of significant wind energy generation to be? Removing energy from atmospheric winds means those winds carry less energy afterward, moving more slowly, among other things. To explore the possible consequences, the researchers used an atmospheric model to simulate the effect of low-density wind turbines operating over the windiest one-third of the continental U.S. to generate enough power to meet current U.S. electricity demand — a plausible scenario for wind-power use in the late 21st century.

The simulations revealed that interactions of the turbines with the atmosphere would likely lead to a redistribution of heat in the lower atmosphere, resulting in a 0.54 degrees Celsius (0.97 degrees Fahrenheit) warming within the wind farms’ region itself, and an increase of 0.24 degrees Celsius (0.43 degrees Fahrenheit) over the continental U.S. This result, they note, actually matches up pretty well with recent satellite observations of local warming around wind farms operating in California, Illinois, Iowa and Texas. They also found that an expansive wind farm would need to operate for more than a century or so before the reduction of global carbon dioxide emissions would offset the local warming effect.

Constraint - grid balancing

UK Wind Constraint Payments Euan Mearns; Energy Matters; 5 Sep 2016

Electricity generation from wind power has grown dramatically in the UK in recent years (Figure 2) and so has the challenge to balance the grid, especially when it is very windy. One of the balancing tactics deployed by National Grid is to pay wind farms to switch off when it is windy. This cost, borne by the consumer, is called a constraint payment. In 2015, UK consumers forked out £90 million to pay subsidy driven wind farms to switch off. The amount of UK wind that is constrained is growing with the level of penetration. At 10% wind penetration, 6% of the wind power available is constrained.

Wind Drought

‘Wind drought’ may have long-term implications for US energy power generation

Drop in wind levels affected states from Washington to Florida, caused wind power output to fall dramatically short of expectations – Rife

Effect of Climate Change

Southward shift of the global wind energy resource under high carbon dioxide emissions Kristopher B. Karnauskas, Julie K. Lundquist, Lei Zhang; Nature Geoscience; 11 Dec 2017

The use of wind energy resource is an integral part of many nations’ strategies towards realizing the carbon emissions reduction targets set forth in the Paris Agreement, and global installed wind power cumulative capacity has grown on average by 22% per year since 2006. However, assessments of wind energy resource are usually based on today’s climate, rather than taking into account that anthropogenic greenhouse gas emissions continue to modify the global atmospheric circulation. Here, we apply an industry wind turbine power curve to simulations of high and low future emissions scenarios in an ensemble of ten fully coupled global climate models to investigate large-scale changes in wind power across the globe. Our calculations reveal decreases in wind power across the Northern Hemisphere mid-latitudes and increases across the tropics and Southern Hemisphere, with substantial regional variations. The changes across the northern mid-latitudes are robust responses over time in both emissions scenarios, whereas the Southern Hemisphere changes appear critically sensitive to each individual emissions scenario. In addition, we find that established features of climate change can explain these patterns: polar amplification is implicated in the northern mid-latitude decrease in wind power, and enhanced land–sea thermal gradients account for the tropical and southern subtropical increases.

Global warming will weaken wind power, study predicts Damian Carrington; The Guardian; 11 Dec 2017

The research, published in the journal Nature Geoscience, used the same climate models and projected future emissions as the UN’s Intergovernmental Panel on Climate Change. Losses of wind energy stretched from the central US to the UK, Russia and Japan for both medium and high emissions scenarios. If emissions remain high in the future, wind energy increases were also seen a smaller number of regions.


Time-lapse installation of wind turbine at Vattenfall’s European Offshore Wind Deployment Centre located just off the north east coast of Scotland in Aberdeen Bay

U.S. Offshore Wind Power Industry Emerges Off Rhode Island Bloomberg

The U.S. Energy Department has invested more than $300 million in offshore wind research, development, and demonstration projects. The U.S. has more than 4,000 gigawatts of potential offshore wind capacity located within 50 miles (80 kilometers) of U.S. coasts, Jose Zayas, office director for the Wind and Water Power Technologies Office at the U.S. Energy Department, said by e-mail.

Eight-MW giant makes offshore wind power cheaper Christine Rüth;; 5 Sep 2016

A new offshore wind turbine from Siemens is set to lower the cost of wind power generated on the high seas. Siemens believes it is well on the way to reaching its goal of producing offshore wind energy at a total cost of less than ten euro cents per kilowatt-hour (kWh) by 2020. In fact, it expects that generation costs for offshore wind power plants will decline to less than eight cents per kWh by 2025. Siemens and other companies in the wind energy business agreed on this target at the beginning of June 2016. Siemens' new wind turbine can generate eight megawatts (MW) of electrical power – previous systems were capable of no more than seven MW. The new turbine has a rotor diameter of 154 meters, which is the same as its predecessor model, but it can generate up to ten percent more energy per year, depending on its location. That is enough to supply 8,000 households with electricity.

Offshore wind turbine system that can be completely pre-assembled and pre-commissioned in controlled harbour conditions; 18 Oct 2016

Thanks to an innovative offshore wind turbine construction process developed by the ELISA project, this traditional barrier to the use of wind energy has finally been overcome. This innovation, the ELISA technology 5MW fully operational prototype, is located in the Canary Islands and is the first bottom-fixed offshore wind turbine completely installed without the need for costly and scarce heavy-lift vessels.

GE Renewable Energy launches the uprated Haliade-X 13 MW wind turbine for the UK’s Dogger Bank Wind Farm

  • 190 Haliade-X turbines for Dogger Bank A and B
  • 13 MW variant of GE Renewable Energy’s Haliade-X

These first two phases (Dogger Bank A & B) will each feature 95 Haliade-X 13 MW wind turbines.

The Haliade-X 13 MW is an enhanced version of the successful 12 MW unit which has been operating in Rotterdam since November 2019 and which recently secured its provisional type certificate§ from DNV-GL. The uprated 13 MW Haliade-X will also feature 107-meter long blades and 220-meter rotor. One spin of the Haliade-X 13 MW can generate enough electricity to power a UK household for more than two days.

“In addition to this, today’s announcement will bring huge economic benefits to the North East of England, where 120 skilled jobs will be created during construction of the windfarm, along with 120 skilled jobs during the maintenance phase.


Floating wind-farms – unlocking energy on the ocean Stephen Tindale; Climate Answers; 15 Aug 2016


Giant Wind Turbines Now At Eight Megawatts, And Getting Larger Peter Kelly-Detwiler; Forbes; 1 Jan 2017

News arrived in late December from the waters off the United Kingdom that the first of MHI Vestas (a joint venture between Vests and Mitsubishi Heavy Industries) 8.0 megawatt (MW) turbines is now delivering commercial power to Dong Energy’s Burbo Bank Extension. The entire 258 MW project – to be completed in Q1 of 2017 – will need only 32 such turbines. This is a significant milestone, as wind turbines have become increasingly more powerful over a relatively short timeframe. This 8 MW machine is currently the largest commercial turbine in the world. Less than ten years ago, at the original Burbo Bank project, a 3.6 MW turbine was inaugurated, the largest in the industry at the time.

As large as they are, turbine expansions have not yet fully maxed out. The industry is already eyeing machines in the 10-12 MW range in order to future cut costs. And while MHI Vestas is the first out of the block with its deployment of an 8 MW machine, two other manufacturers have 8 MW machines in the offing. Meanwhile, here in the U.S., Deepwater Wind just energized five of its 6 MW GE turbines. So the big machines are not just limited to offshore Europe.

Researchers' idea will blow you away: 656-foot long blades on wind turbines Rob Nikolewski; Los Angeles Times; 13 Mar 2016

Efforts to increase wind power mean that turbine blades are getting bigger and bigger. But a new design in the works takes the idea to levels most people can barely imagine: Blades up to 656.2 feet long — more than two football fields. Today's longest blades are 262.5 feet. The blades at Imperial County's Ocotillo wind farm, which sends electricity to San Diego, are 173.9 feet long.

Palm Trees Inspire UVA Team’s Revolutionary Design for Offshore Wind Turbines Elizabeth Thiel Mather; University of Virginia; 11 Dec 2015

In 15 years, a forest of giant wind turbines – able to protect themselves in severe weather by folding in their rotor blades like palm trees in a hurricane ­– could be planted off the coast of Virginia, delivering enough energy to power as many as 500,000 homes, thanks to research that has earned a $3.56 million federal grant for the University of Virginia School of Engineering and Applied Science.

A large offshore wind farm has been commissioned for construction beginning in 2016 off the southern coast of the United Kingdom, and is planned to have 32 turbines sized at 8 megawatts each, equivalent to the power needed for 180,000 homes.

Construction of the largest land-based wind turbine ever built in the United States (in 2016). Unusually this design has a concrete tower.

Watch MidAmerican build tallest wind turbine in the U.S. Donnelle Eller; The Des Moines Register; 29 Jun 2016

It took about 30 weeks, but MidAmerican Energy has built the tallest land-based wind turbine in the nation in southern Iowa.The Des Moines-based power company captured construction of the 379-foot concrete turbine in a video posted on YouTube

The foundation alone required about 70 trucks of concrete and 90 tons of steel rebar. Altogether, the tower has about 80 miles of reinforcing steel running through it. The 2.4-megawatt wind turbine weighs an amazing 1,200 tons.

Vertical axis

Vertical Axis Wind Turbines Matthew Brown; Stanford University coursework submission; December 13, 2016

Recent resarch has shown that VAWTs can be packed significantly closer than HAWTs with less drop in efficieny, making them much better suited for wind farms. [6] Experimental data shows wind speed recovering to 95% of the far field wind speed within 6D. [7] Even if individual VAWTs are less efficient than HAWTs, the tighter spacing of counter-rotating turbines allows VAWT farms to have higher power densities. While a modern HAWT farms produce 2-3 W per square meter, field experiments with VAWT farms show a potential production of 30 W per square meter. [8] This could potentially address one of the major drawbacks of wind power: that it uses a large amount of space.

In additon to densely packed land-based wind farms, there has also been renewed interest in VAWT for use in offshore wind farms. [5,9] While HAWTs typically place the transmission and generator high in the air (close to the axis of rotation), VAWTs can locate these heavy components lower down. This can make maintenence easier and safer, and placing components under the water level improves the stability of the system. Another advantage of VAWTs for offshore farms is the the vertical axis of symmetry: the direction of the wind is irrelevant. [5]

Savonius rotor

Cheap oil killed sailing ships. Now they’re back and totally tubular Emma Bryce; Wired; 29 May 2018

Somewhere between Finland and Sweden, a ship surges through the icy Baltic Sea with a strange white tower protruding, totem-like, from its deck. It may not look like it, but this tall spindle is a sail: the same winds buffeting people about on board channel through the 24-metre-high tower, providing clean, auxiliary power, just like the canvas sails of yesteryear.

Tuomas Riski, the man behind it all, stands at the base of the totem, introducing his invention to a group of note-scribbling journalists. He wears a light, navy suit, seemingly oblivious to the blasting Baltic winds. Above him the tower whirrs in the wind: at its peak it can reach 225 rotations per minute, pushing the ship past the tiny, pine-sprouting granite islands that pepper the Archipelago Sea. “You don’t think it’s making too much noise?” Riski asks, briefly furrowing his brow. In any case, the humming of this slender sail seems a small price to pay for the promise that it will cut fuel use by 300 tons a year, and significantly reduce the ship’s emissions in the process – helping to make this one of the cleanest passenger vessels in the world.

Called the Viking Grace this 2,800-person passenger ferry runs daily between Turku in Finland and Stockholm in Sweden across the Baltic’s Archipelago Sea: the 25th of April marked only its 13th day travelling with the sail, which is known as a Flettner Rotor Sail. Riski, the CEO of Finnish cleantech company Norsepower, has spent the last six years fine-tuning its design to make it worthy of this ship. But this modern sail has roots in an idea that’s actually almost 100 years old: Norsepower is the first company to successfully resurrect the historic concept for the modern age. Now, as pressure intensifies for the global shipping industry to decarbonise, Norsepower plans to bring back these fuel-saving mechanical sails to the decks of huge tankers that roam the seas today.


Try not to jiggle while watching these amazing bladeless wind turbines Jon Comulada; UpWorthy; 12 May 2016

A startup in Spain has created a wonderfully innovative alternative to traditional wind turbines.

New Whirlwind-Attracting Bladeless Micro Wind Turbine Gets Harvard Cred Tina Casey; CleanTechnica; 1 May 2015

The startup Vortex Bladeless is developing a — you guessed it — bladeless micro wind turbine shaped like a super-long popsicle stick only rounder, like an ice cream cone without any ice cream. From a distance it looks like a pole stuck in the ground, so at first glance you might thing that there isn’t anything there. However, the technology does generate electricity, and it has attracted interest from Harvard University as well as SunEdison’s TerraForm Power renewable energy unit and Dat Venture, a startup incubator recently launched by the IT consulting firm Efron Group, so you’re probably going to start hearing more about Vortex Bladeless sooner rather than later.

Windstalk concept is a wind farm without the turbines Darren Quick; gizmag; 13 Oct 2010

Devised as a potential clean energy generation project/tourist attraction for Abu Dhabi’s Masdar City, the Windstalk concept consists of 1,203 carbon fiber reinforced resin poles, which stand 55 meters (180 feet) high and are anchored to the ground in concrete bases that range between 10 and 20 meters (33-66 ft) in diameter. The poles, which measure 30cm (12 in.) in diameter at the base, tapering up to a diameter of 5cm (2 in.) at the top, are packed with a stack of piezoelectric ceramic discs. Between the discs are electrodes that are connected by cables that run the length of each pole – one cable connects the even electrodes, while another connects the odd ones.

Bladeless Wind Turbine — Reality Check guest contributor; CleanTechnica; 21 May 2015

The Vortex Bladeless wind turbine ... is, unfortunately, yet another example of an impractical, uncompetitive wind turbine that is getting too much hype for its extremely weak results and potential. The Vortex Bladeless wind turbine has essentially the same problems that all micro-wind turbines have. Wind non-experts don’t seem to understand these well enough to avoid big mistakes in their coverage ...

Bladeless Wind Turbines May Offer More Form Than Function Phil McKenna; MIT Technology Review; 27 May 2015

Startup Vortex Bladeless makes a turbine that looks intriguing, but it may not solve wind power’s challenges.

Kite power

Kite power - notes by David MacKay 14 Dec 2008 (updated 21 Apr 2011) PS copy

High Altitude Wind Power Reviewed Euan Mearns; Energy Matters; 4 Jul 2016

This post reviews the weird and wonderful world of high altitude wind power. It looks into the reasons for wanting to go high, explains tethered flight and explores the main competing technologies of

1) airborne generation (Google Makani) and
2) ground based generation (KiteGen) and compares their strengths and weaknesses.

Kite Power Solutions

Has 2 kites on single generator shaft

Kite Power Solutions website

One of world's first kite-driven power stations to open in Scotland Ian Johnston, Environment Correspondent; Independent; 6 Oct 2016

One of the world’s first commercial-scale, kite-driven power stations is set to be created near Stranraer in Scotland

Kite Power Systems has already demonstrated a small kite-driven power station in Essex. now plans to build a 500-kilowatt system at the Ministry of Defence’s West Freugh Range near the southern Scottish town after securing planning permission. This will be the first of a significant scale in the UK and only the second in the world after a research project in Italy. The kites fly to heights of up to 450m in a figure-of-eight pattern, pulling a tether as they rise which turns a turbine that produces electricity. By having two kites working in tandem, one going up as the other floats back down, electricity can be generated continuously. David Ainsworth, business development director at Kite Power Solutions, the firm behind the system, told The Independent that the system was mainly designed to be used offshore with the West Freugh power station designed to demonstrate its capabilities. “Our systems basically float and the cost of the mooring is much lower than a wind turbine,” he said. He said traditional offshore wind turbines needed to be kept upright in the sea, so the mooring had to be quite rigid, adding to the cost. “They are talking about 10 euro cents per kilowatt-hour [for the electricity produced], we’re basically going to halve that,” he said. “We’re very optimistic we’ll have several hundred megawatts installed by 2025.” A full-sized kite will be 40 metres wide and be capable of generating two to three megawatts of electricity, about the same as a 100m conventional turbine.

“The number of days we won’t be generating is very few, less than 10 days a year,” Mr Ainsworth said. “The number of really, really still days you get offshore is very small.”

On the rare still days, a small fan is used to keep the kite aloft so it can start generating as soon as the wind picks up. The project has received backing from oil company Royal Dutch Shell and the UK Government.

Kite Power Systems

Kite/wing with single tether Kite Power Systems website


Flying wing, 2 tethers. Aerodynamic Lift – something for nothing? Euan Mearns; Energy Matters; 10 Oct 2016

Discussion of Mearns' work with KiteGen, principles and projected performance of their product etc

High Altitude Wind Power Reviewed Euan Mearns; Energy Matters; 4 Jul 2016

Euan Mearns' post about high altitude wind power generally also has more information on the Kite Gen approach

Tethered helicopter

Flying Electric Generators Sky Wind Power

Many means have been proposed for capturing the energy available in high altitude winds, but only those people who have not carefully considered the state of current technology doubt that capturing this energy should be achievable now. After much study on the various methods for capturing high altitude winds, we settled on a “Flying Electric Generator” (FEG), or a “rotorcraft”, for addressing the world’s major energy and global warming problem objectives. This was first proposed by Bryan Roberts. In the mid-2000s, he obtained a patent for a “Windmill Kite”, a variation of which we call a flying electric generator. We believe the FEG technology will lead the way in capturing the energy at these truly high altitudes where the very high altitude wind energy exists.

We submitted a peer reviewed paper “Harnessing High-Altitude Wind Power” of the IEEE Transactions on Energy Conversion, Vol 22, No.1, in March, 2007. It was co-authored by Ken Caldeira and Elizabeth Cannon, Dean of the Schulich School of Engineering, University of Calgary.

Balloon / Aerostat mounted turbines

Altaeros Energies

Helium-filled Buoyant Airborne Turbine

Introducing the Altaeros BAT: The Next Generation of Wind Power altaerosenergies; YouTube; 20 Mar 2014

Altaeros Energies is announcing the first planned commercial demonstration of its BAT (Buoyant Airborne Turbine) product in partnership with the Alaska Energy Authority. The Alaska project will deploy the BAT at a height of 1,000 feet above ground, a height that will break the world record for the highest wind turbine in the world. Altaeros has designed the BAT to generate consistent, low cost energy for the remote power and microgrid market, including remote and island communities; oil & gas, mining, agriculture, and telecommunication firms; disaster relief organizations; and military bases. The BAT uses a helium-filled, inflatable shell to lift to high altitudes where winds are stronger and more consistent than those reached by traditional tower-mounted turbines. High strength tethers hold the BAT steady and send electricity down to the ground. The lifting technology is adapted from aerostats, industrial cousins of blimps, which have lifted heavy communications equipment into the air for decades.

Tethers and airspace

Airspace concerns StratoSolar

The platforms at 20 km altitude (65,000 feet) are far above commercial aircraft, in unregulated airspace and present no hazard to aviation. The main airspace concern is the potential hazard of tethers to aviation.

Background: High altitude tethered aerostats are not new. There have been tethered aerostat radars suspended almost permanently at 4.8km altitude along the southern US border since 1980. The company TCOM provides a wide range of tethered aerostat solutions, primarily to the military. TCOM aerostats have flown as high as 10km.

What is new is:

  • the tethered platform altitude of 20km which places tether hazards in Class A airspace
  • the permanent nature of the platform and tethers
  • a potential increase in the number of systems deployed.


Germany Faces Huge Cost Of Wind Farm Decommissioning

In Germany, more and more wind turbines are being dismantled. The reason: subsidies are running out, the material is worn out or it is simply more profitable to replace old wind turbines with new ones. The dismantling, however, is extremely complex and expensive.

Rare earth production

Big Wind’s Dirty Little Secret: Toxic Lakes and Radioactive Waste

Safety / failures

Forget Eagle Deaths, Wind Turbines Kill Humans James Conca; Forbes; 29 Sep 2013

comparison of safety of wind, coal and nuclear, with suggestions for improving the former

humans need about 3,000 kWhrs per person per year to have what we consider a good life (United Nations Human Development Index). In the old days, you generally needed to own a few people to get that much energy. The advent of coal, followed by hydro, gas and nuclear, changed all that, and raised 4 billion people up out of abject poverty, saving billions of man-years, perhaps more than offsetting these other collateral deaths.

Wind Industry In Freefall: Wind Turbines Keep Dropping Like Flies & Hard Hats Won’t Help StopTheseThings; 7 Jan 2015

list of wind turbine collapses from an anti-wind power site whose byline is "We're not here to debate the wind industry, we're here to DESTROY IT!", which also dubs itself "THE TRUTH ABOUT THE GREAT WIND POWER FRAUD".


Wind turbines also kill birds and bats. The numbers of birds killed are far fewer than those killed by domestic cats and by collisions with windows, but they tend to kill rarer, sometimes endangered, species such as eagles and other raptors.

Will Wind Turbines Ever Be Safe For Birds? Emma Bryce; Audubon; 16 Mar 2016

Sure, it’s green energy—but it also results in hundreds of thousands of bird deaths each year.


An assessment was conducted of the known and documented effects of electricity generation on vertebrate wildlife in the New York/New England (NY/NE) region. The focus of the literature review was peer-reviewed literature and scientifically accepted and published reports or documents regarding effects of electricity generation on wildlife. Results were used to construct a Comparative Ecological Risk Assessment in order to make objective comparisons among the six types of electricity generation important to the NY/NE region: coal, oil, natural gas, hydro, nuclear, and wind. All life cycles of electricity generation affect wildlife and, therefore, pose risks to wildlife individuals and populations. The degree and extent of the risks depend on the energy generation source. There are many ways to classify the impacts of electricity generation on wildlife. Effects can be direct and/or indirect; acute or chronic; individual or cumulative; and local, regional, or global. Each type of effect was explored in this study. Acidic deposition, climate change, and mercury bioaccumulation are identified as the three most significant and widespread stressors to wildlife from electricity generation from fossil fuels combustion in the NY/NE region. Risks to wildlife vary substantially by life cycle stage. Higher risks are generally associated with the resource extraction and power generation stages, as compared to other life cycle stages. Overall, non-renewable electricity generation sources, such as coal and oil, pose higher risks to wildlife than renewable electricity generation sources, such as hydro and wind. Based on the comparative amounts of SO2, NO x, CO2, and mercury emissions generated from coal, oil, natural gas, and hydro and the associated effects of acidic deposition, climate change, and mercury bioaccumulation, coal as an electricity generation source is by far the largest contributor to risks to wildlife found in the NY/NE region.

Wind turbines much better for birds and bats than alternatives Michael Barnard; Medium; 22 Apr 2019

How significant is the mortality of wind turbines upon birds and bats?

Short Answer

Replacing all fossil fuel generation with wind turbines world wide would save tens of million birds lives annually. In the USA, the best numbers show that roughly one in 86,000 birds are killed annually by wind energy. Bats are put at much more significant risk from fossil fuel and other human impacts than by wind turbines. Displacement of fossil fuel generation makes wind a strong net benefit to birds and bats. Global warming and pollution are the threats; wind power is part of the solution, not a problem.


Bat Killings by Wind Energy Turbines Continue Amy Mathews Amos; Scientific American; 7 Jun 2016

A research review published in January of this year found that wind turbines are, by far, the largest cause of mass bat mortality around the world. White-nose syndrome, the deadly fungal disease that has decimated bat populations throughout the northeastern U.S., came in second. Biologist Cris Hein of the nonprofit group Bat Conservation International says that if the current industry practices continue and wind turbine installation grows, bat populations already weakened by the fungus will crash. Industry has balked at holding the blades still at higher wind speeds, however, saying the energy loss will be larger than scientists claim


Factcheck: Whale strandings and offshore windfarms Simon Evans; Carbon Brief; 26 May 2017

Last Saturday, two dead whales washed up on the coast of Suffolk, in eastern England, and a third was spotted floating at sea.

What happened next illustrates how news can spread and evolve into misinformation, when reported by journalists rushing to publish before confirming basic facts, or sourcing their own quotes.

The death of the whales generated a lot of media attention in the UK. However, much of the coverage was based on the speculation of one volunteer coastguard. The three whales became a “family”, even though they were each from a different species. And their deaths were pinned on noise from offshore windfarm construction, even though pile-driving at a nearby site finished two months ago.

Carbon Brief has spoken to half a dozen experts on whales and underwater noise to try to get to the bottom of the story. Our findings cast huge doubt over whether offshore windfarms were to blame for the whale deaths, as implied by much of the media coverage.