Wind power

• 1. Introduction

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  Wind power supplied about 2,700 terawatt-hours of electricity in 2025, over 8% of the world's total. That figure was almost nothing a few generations ago. In 1887, a professor in Scotland charged batteries with a cloth-sailed machine in his garden, and his neighbours turned down the free light because they thought electric power was the work of the devil. From a holiday cottage in Kincardineshire to gigawatt-sized farms anchored in the open sea, the story of catching the wind runs through physics, economics, and a stubborn question. How do you build a reliable grid on a fuel that comes and goes as it pleases? This documentary follows the answers. It looks at why doubling the wind speed gives you eight times the power, why a strong gust on one day can be worth nothing on the market, and why a hydroelectric dam can quietly hold its water until the wind drops.

• 2. Physics Of The Wind

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  Wind power is proportional to the third power of the wind speed. Double the speed and the available power rises eightfold. Increase the speed by a factor of 2.1544 and the power grows by a full order of magnitude, a tenfold jump. This cubic relationship makes location everything, because an average wind value alone does not tell you how much energy a turbine will produce there.

  The global wind kinetic energy averaged roughly 1.50 megajoules per square metre across the years 1979 to 2010. The Southern Hemisphere ran richer at 1.70, the Northern leaner at 1.31. The atmosphere behaves like a thermal engine, absorbing heat where it is warm and releasing it where it is cool, producing wind kinetic energy at a rate of 2.46 watts per square metre against friction.

  Through wind resource assessment, planners estimate potential globally, by country, or for one site. The Global Wind Atlas, built by the Technical University of Denmark with the World Bank, maps this potential worldwide. Tools such as Renewables.ninja go further, simulating hourly wind speed and turbine output rather than averaging across years.

  The Weibull model closely matches the actual spread of hourly wind speeds at many locations. Its shape factor often sits close to 2, which means a simpler Rayleigh distribution can stand in when precision matters less. Regions in the higher northern and southern latitudes hold the greatest promise of all.

• 3. Anatomy Of A Wind Farm

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  Almost every large wind turbine shares one design. It is a horizontal axis machine with an upwind rotor of three blades, fixed to a nacelle on top of a tall tubular tower. A wind farm gathers hundreds of these in one place, and the land between them stays open for farming or other uses.

  Within a farm, turbines connect through a medium voltage collection system, often 34.5 kilovolts, along with a communications network. Engineers space them roughly seven rotor diameters apart in a fully developed layout. At a substation, a transformer steps that medium voltage up for the high voltage transmission system.

  Most modern turbines pair variable speed generators with a partial or full-scale power converter between the generator and the collector system. They use doubly fed machines with partial-scale converters, or squirrel-cage induction and synchronous generators with full-scale converters. These designs ride through low-voltage faults and behave well on the grid. Black start, the ability to power up a dead grid from scratch, is being developed for places like Iowa that draw most of their electricity from wind.

  Before a single turbine spins, the transmission system operator hands the developer a grid code. It specifies the power factor, the steadiness of frequency, and how the turbines must behave during a system fault. The largest onshore farms dwarf early efforts, with the Gansu Wind Farm rated at 7,965 megawatts.

• 4. The Move Offshore

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  Offshore wind farms sit in large bodies of water, usually the sea, where the wind blows more often and harder. As of November 2021, the Hornsea Wind Farm in the United Kingdom was the largest of its kind, rated at 1,218 megawatts. These projects carry less visual weight on the landscape and reach higher capacity factors, but they cost considerably more to build and maintain.

  Getting that power ashore shapes the engineering. Near offshore farms link to land by alternating current, while far offshore farms use HVDC. Wind resources rarely sit close to dense population, and as transmission lines stretch longer, losses grow and new modes of loss stop being negligible.

  When transmission capacity cannot carry the generation, farms must produce below their potential or shut down, a process called curtailment. It wastes possible clean generation, yet it guards against grid overload. Building new lines from remote, windy, lightly populated regions to crowded load centres remains one of the harder problems. A possible future answer is an HVDC super grid linking widely dispersed areas. Offshore wind currently makes up about 10% of new installations.

• 5. Taming The Variability

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  For any single generator, there is an 80% chance wind output changes less than 10% in an hour, and a 40% chance it changes 10% or more across five hours. That unpredictability is the central engineering tension. Instantaneous generation and consumption must stay in balance to keep the grid stable.

  Wind output swings hourly, daily, and seasonally, while annual variation stays comparatively small. A conventional plant, once scheduled, can usually deliver its nameplate capacity around 95% of the time. Wind cannot, so it needs energy storage or other dispatchable sources to deliver a reliable supply.

  Solar power tends to fill the gaps. High-pressure systems bring clear skies and calm winds, while low-pressure systems bring cloud and gusts. Across the seasons, solar peaks in summer and wind often runs higher in winter, so the two partly cancel each other's swings. This is why wind generation tends to be higher at night and in winter when solar output is low.

  Hydroelectricity complements wind especially well. When the wind blows hard, nearby hydro stations hold back their water, then ramp up quickly when the wind drops, with virtually no lost energy and no extra water used. Where a suitable head of water is absent, pumped-storage, compressed air, or thermal storage can hold high-wind energy for later. In the summer of 2021, wind power in the United Kingdom fell to its lowest winds in seventy years.

• 6. The Economics

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  Onshore wind is one of the lowest-cost electricity sources per unit of energy, often cheaper than new coal or gas plants. It is capital intensive but carries no fuel costs, so its price stays far more stable than the volatile prices of fossil fuels. A 2021 Lazard study of unsubsidized power put new wind-generated electricity at 26 to 50 dollars per megawatt-hour, against new gas at 45 to 74 dollars. Offshore wind landed around 83 dollars.

  Grid parity, the point where wind matches traditional sources, arrived in parts of Europe and the United States in the mid-2000s, according to BusinessGreen. Prices kept falling as blades grew longer and lighter and turbine performance improved. The compound annual growth rate of cost reduction was 4% per year from 2016 to 2021, down from 10% per year across 2009 to 2021.

  The value of that power is more complicated than its cost. The merit order effect pushes market prices down in hours with heavy renewable generation, because variable renewables have low marginal costs. For wind plants exposed to market pricing in high-renewable markets, profitability can be challenged. In Germany, the presence of wind energy reduced consumer costs by about 5 billion euros a year by lowering the marginal price.

  Subsidies are fading. As of 2021 they still often supported offshore wind, but onshore wind in countries like China no longer needed them, provided no competing fossil fuel subsidies got in the way. In 2021, the CEO of Siemens Gamesa warned that high steel and input costs were squeezing manufacturers' margins.

• 7. From Garden Cottage To Open Sea

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  Wind-powered machines for grinding grain and pumping water were developed in what is now Iran, Afghanistan, and Pakistan by the 9th century. Centuries later, wind pumps drained the polders of the Netherlands and watered livestock across the American mid-west and the Australian outback.

  The first wind turbine built to produce electric power went up in Scotland in July 1887. Professor James Blyth of Anderson's College in Glasgow installed a 10-metre cloth-sailed machine in the garden of his holiday cottage at Marykirk, charging accumulators developed by the Frenchman Camille Alphonse Faure. It made his cottage the first house in the world lit by wind power. After the people of Marykirk refused his offer of surplus light for their main street, he built another turbine to supply emergency power to a local asylum, infirmary, and dispensary at Montrose.

  Across the Atlantic, Charles F. Brush constructed a far heavier machine in Cleveland, Ohio, over the winter of 1887 to 1888. Its rotor stretched 17 metres across, mounted on an 18-metre tower, yet it was rated at only 12 kilowatts. The connected dynamo charged batteries or ran up to 100 incandescent bulbs, three arc lamps, and various motors in his laboratory.

  The 1973 oil crisis pushed Denmark and the United States toward utility-scale generators built for the grid. U.S. installed capacity reached 25.4 gigawatts by 2008 and 60 gigawatts by 2012. In 2023, the world added 116.6 gigawatts of new capacity, a 50% jump over 2022, bringing the global total to 1,021 gigawatts by year's end.