Wind Power

“The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.”

-William Arthur Ward

Where does wind power come from?

All renewable energy (except tidal and geothermal power), including the energy in fossil fuels, originates from the sun.

The sun radiates 174,423,000,000,000 kilowatt hours of energy to the earth per hour.

About 1 to 2 per cent of the energy coming from the sun is converted into wind energy.

This is about 50 to 100 times more than the energy converted into biomass by all plants on earth.

The Coriolis EffectThe regions around the equator are heated more by the sun than the rest of the globe.This unequal heating combined with the rotation of the planet causes the wind and also its apparent bending.This apparent bending force is known as the Coriolis force. (Named after the French mathematician Gustave Gaspard Coriolis 1792-1843).

What is Electricity?

Electricity is created when electrons move from one atom to another.We control and distribute electricity to our homes, schools, and businesses. Every day, we use electrical energy to do a lot of work, from lighting light bulbs to airconditioning.

Secondary Energy Source

Electricity is known as a secondary energy source. We get electricity by converting other sources of energy – like the thermal energy of burning coal, oil, or natural gas or the kinetic energy of moving air molecules in the wind and water molecules over a dam. Wind, sunlight, and fossil fuels are called primary energy sources. Normally, we convert these primary energy sources into electricity by using an electric generator. This picture shows some of the generators inside Hoover Dam!

CoalUS reserves stand at 275 billion tons, an amount that is greater than any other nation in the world.

At current rates of use this supply can last over 150 yrs.

Coal fired power plants produce 42% (52%) of all the electricity in the US

86% of all mined coal is burned for power production.

Proven coal reserves: United States 273 billion tons Russia 173 billion tons China 126 billion tons India 93 billion tons Australia

90 billion tons

The downside to coal

Burning coal is a leading cause of smog, acid rain, global warming and air toxics.

In an average year, a typical coal plant generates:

3,700,000 tons of carbon dioxide (CO2), the primary human cause of global warming. This is as much carbon dioxide as cutting down 161 million trees.

10,000 tons of sulfur dioxide (SO2), which causes acid rain that damages forests, lakes, and buildings, and forms small airborne particles that can penetrate deep into lungs.

500 tons of small airborne particles, which can cause chronic bronchitis, aggravated asthma, and premature death, as well as haze obstructing visibility.

The down side cont. 10,200 tons of nitrogen oxide (NOx), as much as would be emitted by half a million late-model cars.

720 tons of carbon monoxide (CO),

220 tons of hydrocarbons, volatile organic compounds (VOC), which form ozone.

170 pounds of mercury, where just 1/70th of a teaspoon deposited on a 25-acre lake can make the fish unsafe to eat.

225 pounds of arsenic, which will cause cancer in one out of 100 people who drink water containing 50 parts per billion. * 114 pounds of lead, 4 pounds of cadmium, other toxic heavy metals, and trace amounts of uranium

Of the natural gas used in the US in 2010, almost 90% was produced domestically.

The supply of natural gas is not as dependent on foreign producers as is the supply of crude oil, and the delivery system is less subject to interruption.

The availability of large quantities of shale gas should enable the United States to use a domestic supply of gas for many years and produce more natural gas then it consumes.

More gas from shaleShale gas refers to natural gas that is trapped within shale rocks. Over the past decade, the combination of horizontal drilling and hydraulic fracturing has allowed access to large volumes of shale gas that were previously uneconomical to produce. The production of natural gas from shale formations has rejuvenated the natural gas industry in the United States.

Types of Natural gas

Hydraulic FracturingHydraulic fracturing (commonly called fracking) is a technique in which water, chemicals, and sand are pumped into the well to unlock the hydrocarbons trapped in shale formations.When used in conjunction with horizontal drilling, hydraulic fracturing enables gas producers to extract shale gas economically.

The goodNatural gas is cleaner-burning than coal or oil. Burning natural gas emits much lower levels of carbon dioxide (CO2) and sulfur dioxide than burning coal or oil. When used in efficient combined-cycle power plants, natural gas combustion emits less than half as much CO2 as coal combustionThe High bridge plant in Saint Paul.

The badThe fracturing of wells requires large amounts of water.If mismanaged, hydraulic fracturing fluid can contaminate surrounding areas.Fracking also produces large amounts of wastewater, that requirse treatment before disposal or reuse.

The ugly According to the United States Geological Survey, hydraulic fracturing "causes small earthquakes, but they are almost always too small to be a safety concern. In addition to natural gas, fracking fluids and formation waters are returned to the surface. These wastewaters are frequently disposed of by injection into deep wells. The injection of wastewater into the subsurface can cause earthquakes that are large enough to be felt and may cause damage."

How electricity is generated

A generator is a device that converts mechanical energy into electrical energy. In 1831, Michael Faraday discovered that when a magnet is moved inside a coil of wire, electrical current flows in the wire.This discovery, known as Faraday’s Law, proves that there is a relationship between electricity and magnetism.A typical generator uses powerful magnets and many coils of wire.

Generators

All wind turbines have a generator inside them.

The blades are connected to a drive shaft that connects to the generator via a set of gears.

Note in this diagram that the generator will spin much faster than the blades are moving!

IMA of a gear train = driven/driver

Measuring Electricity

By using a generator, we are able to take mechanical energy (rotating blades) and convert it into electrical energy.Electricity is measured in units of power called "Watts.” One watt is a small amount of power. An average light bulb in your house may use 60-100 watts when it is on.

KilowattsA kilowatt represents 1000 watts. A kilowatt-hour (kWh) is equal to the energy of 1,000 watts working for one hour. Kilowatts and kilowatt-hours are useful for measuring amounts of energy used by large appliances or households. One Megawatt is equal to 1,000 kilowatts, or 1,000,000 watts. A typical refrigerator uses 120 kWh of energy/month.A typical home in the US uses 920 kWh/month.

MegawattsThe average modern utility scale wind turbine produces 1.5-2 megawatts of electricity.

The largest ones can produce 5 megawatts!One megawatt is enough electricity for about 300+ average households here in the US.

This is the largest wind turbine in the world. The rotor diameter is 413 feet.It will produce 7 megawatts of energy or 20 million kWh per year.This would be enough energy to supply 2,000 homes in the USIt is located in Germany.

Wind Energy

At the beginning of 2008, wind energy was producing 93,881 megawatts of electricity throughout the world.If each megawatt can supply 300 homes this works out to a little over 28 million homes that can be powered by wind energy!In 2008 the US surpassed Germany as the #1 wind energy producer!

Top 5 states in wind production

-Texas, with 10,085 MW ( 7,116 MW)

-Iowa, with 3675 MW ( 2,790 MW)

-CA, with 3177 MW ( 2,517 MW)

WA, with 2104 MW ( 1,375 MW)

-MN, with 2152 MW( 1,752 MW)

Total US wind energy production is over 33,000 MW (25,170 MW)

This generates enough electricity to power the equivalent of nearly 10 million homes. (9 million)

It avoids the emissions of 57 million tons of carbon annually and reduces expected carbon emissions from the electricity sector by 2.5 percent.

Arizona posted the fastest growth rate in the third quarter followed by Pennsylvania, Illinois, Wyoming and New Mexico.

Wind accounts for 3% of our electricity production.

It is estimated that Minnesota could produce 75,000 MW per year.

Power generation in Minnesota

Minnesota relies heavily on coal fired power plants to generate electricity.Total power generated in 2005 was near 28,000 MW.Minnesota has a goal of generating 25% of its power through wind by 2020.This would mean wind power would need to grow from 1,752 MW to over 7,000MW.

US wind potential

North Dakota currently has 1424 mw of installed capacity, but its potential is 138,400 MW — or 126 times the size of Xcel's Monticello plants!The US has a goal of generating 20% of its power through wind energy by 2030.

Wind TurbinesLarge wind turbines have specially designed blades!

The blades have a pointed tip!

Note that the blades are angled!

Large blades for large wind turbines

Aerodynamics of Wind turbinesThe blades are designed like helicopter rotors or wings.Air moving over the curved surface travels faster to meet the air at the end of the blade.Faster moving air has less pressure which causes lift on the curved side of the blade.This lift helps the rotors to turn

What makes the rotor turn

-As a rotor turns the tips travel much faster than the areas near the hub.For some large wind turbines the tips are moving at 100 mph!-The faster moving tips also create drag.-To lessen the drag the rotor tips are more narrow than the rotor area near the hub.

Tower HeightTowers have to be tall enough for the blades.Usually the tower is as high as the diameter of the rotor.The higher the tower the stronger the wind.Wind speed increases with distance from the ground.

Better Designs

General Electric’s new wind turbine will generate 60% more power than comparable 2002 models.

Unsubsidized costsWind energy costs from $48 to $95 per megawatt-hour.Natural gas costs $61 to $89 per megawatt-hour.Coal costs $62 to $141 per megawatt hour.Five states, Iowa, MN, Wyoming and North and south Dakota generate 10 % or more of their electricity from wind.

Wind turbine field near Sandia, New Mexico

Wind Turbines on buildings!These small turbines are located on parts of buildings

where the wind is concentrated.

Wind Turbine field in Minnesota

Wind Turbine field off the coast Denmark.The Danes goal is 50% of their power through the wind

by 2030

Rock climbers are used to help inspect the blades!

Economics

Wind energy employs more than 75,000 people in the US.Individuals investing in wind turbines enjoy healthy annual returns of up to 16% on their investments.