Wind PowerBy Jon and Lex

What is wind power?

  • Wind is the movement of air from an area of low pressure to high pressure caused by the unequal heating of Earth's surface
  • This wind can be converted into wind power, allowing it to be used as a useful source of energy in the form of wind turbines, wind mills, and wind pumps
    • Wind turbines- provide electricity
    • Windmills- provide mechanical power
    • Wind pumps- used to propel ships
Wind Turbines in the Mountains
Wind Turbines in the Mountains

How does a wind turbine work?
  • Energy from the wind is converted to rotational energy by the rotor
  • When the blades turn, the rotor turns a shaft, which transfers the motion into the nacelle
  • The slowly rotating shaft enters a gearbox that greatly increases the rotational shaft speed
  • The high-speed shaft is connected to a generator that converts the rotational movement into electricity at medium voltage (hundreds of volts)
  • The electricity flows down heavy electric cables inside the tower to a transformer, which increases the voltage of the electric power to the distribution voltage (thousands of volts)
  • The distribution-voltage power flows through underground lines to a collection point where the power may be combined with other turbines and then sent to nearby farms, towns, residences
    • Or the electricity can be sent to a substation where the voltage is increased to transmission-voltage power (hundreds of thousands of volts) and sent through above-ground transmission lines to distant cities and factories
  • Small turbines need a wind speed of at least 9 mph, while larger commercial turbines need a wind speed of at least 13 mph
    • 33 mph is ideal, generating maximum power at this speed
    • 45 mph or higher and the wind turbine will shut down through its system of brakes
    • Kinetic energy in wind increases exponentially in proportion to its speed
    • General rule of thumb- 2X in wind speed= 8X power potential
    • However, there is a limit to how much energy a turbine can extract from wind, and it's called the Betz limit (59%)
  • The larger the rotor blade, the higher the power output

Different types of wind turbines:
  • Wind turbines are based on direction of the rotating axis
  • Two types of wind turbines are horizontal and vertical.
    • Horizontal-axis wind machines- windmills as pictured above (most wind turbines commercially used)
    • Vertical axis wind machines- look like egg beaters; need a bigger footprint to build (takes up more space); less efficient because rotor elevation is lower which means slower wind

What are the advantages and disadvantages of wind energy?

· Advantages-
o Wind energy doesn’t harm the environment- clean and renewable energy source
o Wind turbines take up less space than other power stations
o Newer technology is making wind energy more efficient
o Good way to generate energy in remote locations
o Can be combined with solar electricity
o Wind energy is the safest way to provide energy
o Wind energy is independent- we don't have to rely on other countries for our energy
· Disadvantages-
o Wind is unreliable
o Wind turbines produce a lot less electricity than the average fossil fuelled power station
o Wind turbine construction can be expensive
o They make an extremely loud noise, like a small jet engine
o Not the most efficient form of energy, because it can only be used in certain areas where enough wind is generated
o Negative effect on aesthetics of landscape
o Can harm wild bird populations if they hit the blades

Why isn't wind energy used everywhere? Wind power in the U.S.?

  • Wind is only a renewable resource in the right area
  • Wind requires careful planning- how fast and how much wind blow in a certain area are key factors
  • Higher altitudes= faster winds; over open seas= more wind because no windbreaks
  • In 2008, the U.S. was ranked number one in the world for wind power capacity
  • Energy in U.S. as of 2005:
    • 52% coal
    • 20% nuclear
    • 16% natural gas
    • 7% hydropower
    • 5% other- including wind, which generated less than 1%
  • However, wind has the potential to provide up to 10.8 trillion kWh per year (the U.S. uses around 3.6 trillion kWh per year) according to the American Wind Energy Association

How does wind compare to other energy sources? Why is it better or worse?

  • The main purpose of wind energy is to decrease CO2 emissions and create a healthier environment for everyone to live in
  • In 2006, wind power supplied .6% of U.S. electricity but it reduced CO2 emission from other sources of electricity production by 1%
  • Expensive to build, but after built, electricity is almost free
  • Variable cost= fuel cost and maintenance cost that depend on power output
  • Fixed cost= higher for wind because same capacity produces less power (nuclear produces 3X as much as wind for same capacity)
  • Coal is winds main competition
  • Wind is not an answer to all problems, but at a slightly higher business price, we can use wind energy and save fossil fuel energy

What does the future look like for wind power?

  • Finite energy sources such as coal oil and natural gas are quickly being depleted
    • Therefore the United States is being pressured to find an alternative energy source that will be sustainable, and wind power fits that description
  • Due to continuous technology improvements the cost of wind power continues to decrease making it not only a sustainable and clean energy source but an inexpensive one as well
    • In the early 1980's, wind power cost about 30 cents/kWh, and in 2006, wind power costs as little as 3-5 cents/kWh, showing the advancement in technology for wind power
    • Wind turbine technology will continue to advance, and the price will continue to decrease
      • Looking into the future, wind power is the most cost effective source of energy considering not only the advancement in technology allowing its productivity to increase, but considering the amount of fossil fuels that can be saved--that price is intangible, but it can be assumed to be far greater than the cost difference between wind and coal
      • The steady decline in the cost of wind power and rise of efficiency due to technological advances; accompanied by the renewable clean energy wind power produces, make wind power the sustainable energy source the U.S. is looking for to replace the coal, oil, and natural gases that will soon be depleted