Energy Sources

Wind energy: wind turbines are getting taller, bigger and better

During the first half of 2019, Scotland generated 9.8 million MWh of electricity from just one energy source. That much electricity is enough to power all the homes in that country twice. The best part about it is that the electricity was generated from a renewable source, wind.

Wind energy is the process of using the naturally occurring air flow to generate electricity using turbines. When the wind blows, the blades on the turbine capture the wind’s kinetic energy causing a rotor to spin. The rotor is connected to the main shaft which spins a generator to create electricity. A typical turbine will start generating electricity when wind speeds reach around 6 mph and will shut down at wind speeds above 55 mph to prevent equipment damage.

There are three main types of wind energy: utility-scale has turbines above 100 kW used to power a grid; distributed or small wind has turbines below 100 kW used to power a house or building not connected to the grid; and offshore wind has turbines erected in large bodies of water, they are larger and produce more power.

The average utility-scale turbine installed in 2017 was rated at 2.32 MW; however, manufacturers are pushing for land-based turbines over 4 MW and offshore turbines over 10 MW. Wind turbine manufacturer MHI Vestas launched in 2018 a 10 MW turbine; similarly, GE introduced the 12 MW Haliade-X, which will stand at 853 feet tall.

The taller the turbine and the longer the blades, the better. The higher they are into the atmosphere, the more steadily the wind blows increasing the turbine’s capacity factor, making them more reliable. Increasing the reliability of wind energy is important because, as with solar, it generates power intermittently. This intermittency requires a backup source to take over in generating electricity when the wind is not, which is usually provided by natural gas plants and an increasing use of batteries. Reliability also translates in lower costs.

Advances in wind turbine technology have been crucial for the rapid growth in wind development in the United States. For example, the gear box connects the low-speed shaft with the high-speed shaft increasing the rotational speeds. This component is heavy and costly, and engineers are exploring direct-dive generators that do not need gear boxes. Other developments include longer and lighter rotor blades, taller towers, more reliable drivetrains, and performance-optimizing control systems. Additionally, prices have fallen from over 55 cents per kWh to below 3 cents per kWh today. But like everything else in life, there are also disadvantages like the unpleasant noise generated by the turbines, the impact on flying animals which sometimes are killed when flying into the rotors, aesthetic impact on the scenery, and remoteness of location.

There are many benefits of renewables despite their disadvantages and reassuring results from large projects are demonstrating to countries and developers that investing in clean energy is paying off. As of December 2016, in the United States the total operating wind generated capacity was 81.3 GW and Texas alone accounted for almost a quarter of that. Developing nations are taking notice too and looking at renewables when it comes to new electric power generation projects. One example is Kenya that has launched the largest wind power farm in Africa which is part of their ambitious goal to have 100% of their produced energy come from green sources by 2020. The wind farm known as Lake Turkana Wind Power is comprised of 365 wind turbines which will generate about 310 MW increasing the country’s electricity supply by 13%. But Kenya is no stranger to renewables; around 70% of its electricity come from renewable sources like hydroelectric and geothermal.

Based on the encouraging results that wind power is having, Scotland hopes to fulfill its electric demand solely using renewable energy sources. They expect to meet this goal within the next year. With more and more countries setting similar goals, the use of renewables is only going to increase.

Sources:

American Wind Energy Association, U.S. EIA, Energy.gov, Sciencealert.com, CNN

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