Wind – a renewable energy resource

Energy transformations in wind turbines

How do wind turbines work? Moving air pushes against the blades of the turbine, making them spin. Some of the kinetic energy of the moving air is transformed into the mechanical energy of the spinning blades. (The wind still has some kinetic energy as it flows away from the turbine.) The shafts and the gears inside the gear box transfer energy from the turbine to the generator. (The gears make the drive shaft to the generator spin faster than the shaft connected to the blade hub.) The generator transforms mechanical energy into electrical energy. Some of the original kinetic energy supplied by the wind is ‘wasted’ as it is transformed into heat energy and sound energy within the turbine. Image sourced from http://www.alliantenergykids.com/wcm/groups/wcm_internet/@int/@aekids/documents/image/022691.jpg

What affects the amount of electrical power produced? Wind What affects the amount of electrical power produced? Factors affecting the amount of electrical power produced by wind turbines include: The speed of the wind The number of blades The length of the blades The shape of the blades The pitch (angle) of the blades to the wind The use of gears The type of generator used

Advantages of wind turbines Advantages of wind turbines include: Wind is a renewable energy resource. It will never run out. Wind turbines do not produce greenhouse gases or other pollution when operating. Wind energy is free. Across the world there are regions where there are strong winds that can be used to generate electricity. Wind energy is available day and night. Wind turbines can be used in remote areas where there is no access to the electricity grid. Wind turbines are relatively efficient. Wind turbines can be installed on land where cattle or sheep graze.

Disadvantages of wind turbines Disadvantages of wind turbines include: The electrical power delivered varies because wind speed and direction vary. Sometimes the wind speed is too low to even start rotation. Very strong winds can damage turbines. It can be costly to connect a wind farm to the electricity grid due to the distances involved. Some people think they spoil the landscape. Some people believe the sound they produce is annoying or even harmful. However, tests by sound engineers have determined that the loudness of sound heard in any location depends on wind direction and speed, and that no infrasound (very low frequency sound) is produced There may be some impact on local bird populations.

Other Technical Issues Wind Other Technical Issues Factors such as the topography of the surface of the Earth from where most of the wind comes, and of the site, have a big impact on the amount of electrical power that can be generated at a site. A good site might have a 35 % capacity factor – this means that the turbines will produce 35% of their capacity on average over a year. In many countries, most wind turbines are constructed off-shore , usually because people do not want them across the land. This is much more expensive, and presents problems such as corrosion by seawater.

Wind Social Issues Communities can object to the installation of a proposed wind farms due to concerns about : The potential damage to local sacred Aboriginal sites The effect on the appearance of the landscape and possible impact on any local tourist industry Noise The possible impact on the local environment, and on local populations of birds and other animals

What do you think of these objections? Wind What do you think of these objections?

Wind In Australia Snowtown Wind Farm See STELR Case Study Notes

Alternative Technologies Wind Alternative Technologies Some types of wind turbine may have a vertical axis Other vertical egg-beater turbines, with different blade shapes Darrieus turbine

Typical Scientific Qualification Level Project Development Stage Wind Careers Example Early Stage Career Opportunities Power Design Engineer Plant Optimisation Engineer Wind Engineer Ecologists Typical Scientific Qualification Level Electrical Control Engineer Development Engineer Design Engineer Construction Manager Community Engagement Officer Electrical Technician Development Officer Heritage Monitors Development Approval Construction Operations Project Development Stage See STELR Career Profiles

Career Profile Wind Name: Rick Morgans Job: Wind Mapper Employer: Cyclopic Energy Rick measures and simulates the wind flow for potential sites for small scale wind turbines in cities, using computer modeling Read Rick’s career profile on the STELR website.

Career Profiles Wind Name: Cindy Hull Job: Avian Ecologist Employer: Roaring 40s Finds ways to reduce the impact of wind farms on bird populations Read Cindy’s career profile on the STELR website.

Revision Questions Wind What energy transformations occur when a wind turbine operates? Why is wind energy considered to be a renewable energy resource? What factors affect the amount of energy ‘captured’ by a wind turbine? How efficient are wind turbines? What are three disadvantages of using wind turbines to produce electrical energy? List two issues that scientists and engineers need to consider when developing a wind farm.