If you’ve ever criss-crossed the waters on a sailing boat or flown a kite on a colourful day in autumn, you are perfectly familiar with the power of wind energy.
Although wind enables humanity to pursue a lot more than enjoyable past-times like sailing. It is at the forefront of the renewable energy technologies that are driving change around the world at a rapid pace. Over the past five years, the capacity to generate electricity with wind has grown at an average 13 % annually, according to Professor of Engineering Andrew Blakers from the Australian National University. Renewables are on course to overtake fossil fuels in the long run, he said in an article in the independent non-profit media outlet The Conversation.
“Remarkably, because of the slow or non-existent growth rates of coal and gas, current trends put the world on track to reach 100% renewable electricity by 2032,” prof. Blakers and ANU Research Fellow Matthew Stocks wrote.
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Wind technology has come a long way. In itself, harnessing the power of wind is nothing new – humans have been doing it for thousands of years. The ancient Egyptians used wind to sail along the Nile River and more than 2,000 years ago the first wind mills were built in the Middle East and Asia to pump water and mill grain.
The first attempt to use wind for electricity generation took place in the late 19th century in Scotland. Admittedly, it wasn’t much of a success to start with. In the 1887, Scottish Professor James Blyth is said to have been the first person to successfully construct a windmill that could produce power. He built the project in his garden and used the energy to light up his cottage, kindly offering to do the same for his neighbours. This was not well received. The villagers considered electricity the work of the devil and wanted no part in it. Only the local asylum ended up accepting his offer of free power. These days, however, a modern commercial wind turbine doesn’t just produce enough electricity to keep a handful of light bulbs burning.
Blyth's "windmill" at his cottage in Marykirk in 1891
A common onshore wind turbine with a 2.5-megawatt (MW) to 3 MW capacity can produce enough power for 1,500 average European households, according to the Belgium-based WindEurope association. And some countries are really charging ahead when it comes to meeting their energy requirements through wind power. Last year’s undisputed champion was Denmark, setting a new record by producing 43 % of its electricity through wind. That’s nearly half of the country being powered by wind energy alone!
Put simply, wind is air shifting around the surface of the earth due to changes in temperature and pressure. So what makes it such a great renewable energy source? Well, for one, it is a free, abundant and nondepletable. In addition, wind energy generation it doesn’t produce greenhouse gas emissions during operation. That is why worldwide investment in wind has been growing year after year.
“Many governments have understood that wind power brings great benefits to their societies, as it is emission-free, cheap, domestic and accessible and offers a very attractive pathway to achieving the Paris agreement. The general, robust growth of wind power around the world which goes hand in hand with further geographic diversification is very encouraging.” World Wind Energy Association (WWEA) Secretary General Stefan Gsänger said in a statement.
With its rising popularity, the cost of the technology is also steadily declining due to competition. According to Bloomberg New Energy Finance’s Wind Turbine Price Index, wind turbines set for delivery in the second half of 2017 averaged USD 990,000 per MW, down from USD 1.15 million a year earlier. In the second half of 2010, costs had still been in excess of USD 1.5 million per MW. Other market analyses confirm this trend. “The growing cost-competitiveness of certain alternative energy technologies globally reflects a number of factors, including lower financing costs, declining capital expenditures per project, improving competencies and increased industry competition. The next frontier is energy storage, where continued innovation and declining costs are expected to drive increased deployment of renewables, which in turn will create more demand for storage,” said George Bilicic, Vice Chairman and Global Head of US financial advisory and asset management firm Lazard Ltd., in a statement. The upward trend is not expected to level off any time soon.
Australia has abundant potential to further expand when it comes to renewable energies. For wind power to be harnessed effectively, you need low population areas with smooth landscapes. This increases wind speeds while limiting turbulent wind conditions that could damage turbines. Apart from Antarctica, Australia is the world’s least densely populated continent by far, and most of its centre is made up of desert. There is no shortage of flat areas with hardly any people around – it’s perfect! Of course, there is a bit more to finding optimal locations for wind power generation. “The best sites result from a combination of elevation, local topography and orientation to the prevailing wind,” according to the website of Geoscience Australia, a public sector organisation.
These ideal wind speeds can be found in the southern parts of the continent and reach a maximum around Bass Strait, according to the organisation. Overall, Geoscience Australia believes the country to have some of the best wind resources in the world. Transcendence’s Renewable Energy and Sustainable Development Advisor and former Deputy Chief Minister of the Australian Capital Territory, Simon Corbell, agrees with the assessment. “Australia is a renewable energies superpower. It has incredible renewable energy resources,” he said. Wind resources are particularly good in the states of South Australia, Victoria and Tasmania, he added. “That is one of the reasons why we are seeing very significant wind developments in those states.”
There are certainly some exciting projects in the pipeline. The Australian state of Victoria, for example, will become home to the world’s first major crop farm project that is to be fully run on wind energy. Vegetable grower Nectar Farms wants to spend AUD 565 million on expanding its 10-hectare hydroponic glasshouse operation to 40 hectares, supplying produce locally and internationally. Initially, the required energy for this was to come from gas, but the cost turned out to be too high. Nectar Farms then looked into renewables, and a decision was made that all its electricity requirements would be met through a nearby wind farm.
According to Bulgana, that is enough to power 130,000 homes. And it’s also enough to supply Nectar Farms and all of its greenhouses with electricity. The project fits perfectly with the Victoria’s commitment to generate 40% of energy through renewables by 2025. The government is investing AUD 146 million to drive renewable energy projects, and its support has led to the development of two new wind farms that will contribute a total of 100 MW, according to Victoria’s Renewable Energy Action Plan.
Meanwhile South Australia has set a renewable energy target of 50% by 2025, and its Climate Change Strategy 2015 – 2050 foresees zero net emissions by 2050. The state is home to what last year became the world’s largest lithium ion battery storage facility at the Hornsdale Wind Farm. The battery was built by American energy company Tesla Inc. and the race to create an even larger battery has been on ever since. Another state is planning to achieve zero emissions even earlier than South Australia. Tasmania is targeting to meet all its electricity needs through renewables by 2022.
The key reasons driving change are environmental and financial. Switching to renewables makes economic sense, according to former ACT Deputy Chief Minister Simon Corbell. “Australia’s existing fleet of coal-fired power plants is approaching the end of its operational life,” he said. “That generation has to be replaced by something new, and at the moment the cheapest form of new-build electricity generation available in the Australian market is wind or solar.” While we have seen some public debate on whether fossil fuels or renewables are cheaper, the crucial point is whether you talk about existing power generation or new-build. According to a fact check by the The Conversation, coal works out cheaper if you focus on already existing energy generation.
“In 2017, the marginal cost of generating power from an existing coal station is less than AUD 40/megawatt hour (MWh), while wind power is AUD 60-70/MWh,” explained Ken Baldwin, Director of the Energy Change Institute at Australian National University (ANU) in the fact check. However, these figures change when you look just a few years ahead and focus on new-build power plants. “The projected price for new supercritical coal power comes in at around AUD 75/MWh,” ANU’s Ken Baldwin said. “That is higher than recent prices for newly installed wind power of around $60-70/MWh over the 20-year contract period,” he added.
After all, construction costs are high for both renewables and fossil fuel power stations, but sun and wind are free, while coal and gas are not. And that makes fossil fuel power plants vulnerable to price fluctuations. “While coal prices remain in the medium range, in Australia gas is very expensive. We have some of the most expensive gas prices in the world,” former ACT Deputy Prime Minister Simon Corbell said.
Wind farms offer hundreds of jobs during the construction phase, but require little labour once a project is up and running. But there are still jobs to be had, and the potential is in the supply chain, according to former ACT Deputy Prime Minister Simon Corbell. “We have seen significant growth in areas of wind farm manufacture in Australia, such as towers,” he said. “For example, Portland in the southwest of Victoria is now seeing significant growth in tower manufacturing for wind farms, because of their physical location and their existing manufacturing capabilities.” So Australia is working toward taking advantage of opportunities in the supply chain, but a lot more needs to be done as many parts are still imported from overseas.
While the humble windmill marked the beginning of turning wind into mechanical power, today’s turbines are complex, state-of-the-art pieces of technology. But how exactly do they work? First of all, you need wind, of course. Just like a sailboat won’t move if the sails are slack, a wind turbine won’t generate electricity without wind. So you need to find is a nice, windy spot for your turbine. If you have ever walked on a high bridge or climbed a mountain, you will know that wind is often stronger higher up. Therefore, commercial wind turbines tend to have high towers to take advantage of faster wind speeds at altitude. These towers can be as tall as a 20-storey building. On top of those towers are usually three, and sometimes two, rotor blades. From far away, they can look too thin to ideally capture wind. In reality, though, they can measure up to 60 metres, offering a huge surface that is shaped to perfectly utilise wind to make the blades turn.
In fact, it is the blade size that determines the amount of electricity a turbine can generate. Little turbines with shorter blades designed to power a single house, for instance, may only have a capacity of 10 kilowatt (KW). The largest turbines can generate up to 8,000 KW – you see, the difference is huge. Not only wind speed and blade size matters, though, but also wind direction. A turbine can only work optimally if it faces into the wind at the right angle. To ensure it does, a sensor on top of the turbine transmits data on wind speeds and direction, and the blades position themselves accordingly.
If wind speed is too high and could cause damage, such as during a storm, the blades can also be turned out of the wind. When operating, a turbine’s rotor blades turn around a shaft, setting it in motion. That rotation alone is too slow to generate electricity yet. That is why the shaft first connects to a gearbox, which works similarly to transmitters you find in cars. Set between the rotor blades and the generator, the gearbox increase the number of rotations from up to 60 rotations per minute (rpm) to as fast as up to 1800 rpm – enough to produce power.
The electricity then travels to a transformer. Transformers can increase or decrease voltage. To allow electricity to be transported over long distances with minimal loss, it might be increased to as high as 500,000 V. Later at the point of destination, other transformers will lower the voltage for the average household, which requires only between 110 and 240 V, depending on the country.
The two main types of wind turbines are divided into those with a vertical axis and a horizontal axis. The blades of a vertical axis turbine rotate around an axis that runs perpendicular to the ground. This type is less common. With horizontal axis turbines, the blades rotate on an axis that is parallel to the ground. Most commercially available wind turbines are horizontal axis turbines. They are better able to utilise higher wind speeds at altitude. To make optimal use of a good wind area and the required infrastructure, turbines are often grouped into wind farms across a large area of land or water.
A giant project that operates off the coast of England has 87 turbines. The Walney Extension wind farm with a total capacity of 659 MW produces enough to power nearly 600,000 homes, according to Danish co-owner Orsted, the world’s largest offshore wind developer. Another example of a huge wind farm is situated in Texas and includes 420 wind turbines across 57,000 acres of land. The Horse Hollow Wind Energy Center’s combined capacity is around 735 MW. But wind turbines don’t all have to look the same, and they don’t have to be huge. In Paris, for instance, several “wind trees” with tiny green, leaf-shaped turbines on branches are to generate enough power to light up parking spaces in the French capital.
Surely, you can’t get any greener than a wind turbine tree!