Energy from the Wind:

Wind is the response of the atmosphere to uneven heating conditions. Local topography (mountains) can enhance or restrict the natural wind flow.

While wind is certainly a renewable energy source, it is also an erratic one. Energy storage is probably more critical for wind power than for any other form of alternative energy.

Basics of Wind Energy:

• Kinetic Energy of wind is: 1/2 * mass * velocity * velocity
• momentum in the wind = mass x velocity
• Power per unit area = KE * momentum --> MV² *MV
• So Power that can be extracted from the wind goes as velocity cubed (V³)
• 27 times more power is in a wind blowing at 60 mph than one blowing at 20 mph

For average atmospheric conditions of density and moisture contant:

Power per sq. meter = .0006 V³

• velocity measured in meters per second
• Power then measured in KILOwatts
• 1 meter per second is approximately 2 mph
• 20 mph wind =10 m/s --> Power generated equals:

  .0006 * 10³ = .0006 * 1000 = .6 KILOwatts per square meter
  which is 600 watts per square meter
  this is identical to average solar power per square meter

So, on average a 20 Mph wind will produce 600 watts per square meter of Power. But, Windmills can not operate at 100% efficiency because the structure itself impedes the flow of the wind

• Theoretical maximum efficiency is 59%
• Picaresque Dutch Windmill (4=arms) = 16%
• Rotary, multiblade = 30%
• High speed propeller (vertical) = 42%

Clearly, wind power is a highly variable source and hence energy storage is crucial. In fact, this is the biggest knock on Wind Energy from Solar Advocates. Its true that its a problem, but its also true that the levelized cost of Wind Energy is substantially less than solar (see below).

Rotary type windmills have high torque and are useful for pumping water

High speed propeller types have low torque and are most efficient at high rotational velocities --> useful for generation of electricity

Example calculation:

• Windmill efficiency = 42%
• average wind speed = 10 m/s (20 mph)
• Power = 0.0006 x 0.42 x 1000 = 250 Watts per square meter
• Electricity generated is then .25 KWH per sq. meter
• If wind blows 24 hours per day then annual electricity generated would be about 2200 KWH per sq. meter

• But, on average, the wind velocity is only this high about 10% of the time
• typical annual yield is therefore 200-250 KWH per sq. meter

To Generate 10,000 KWH annual then from a 20 mph wind that blows 10% of the time

• windmill area = 10,000 KWH/220 KHW per sq. meter = 45 sq meters
• This is a circular disk of diameter about 8 meters
• This is not completely out of the question for some homes
• Even a small windmill (2 meters) can be effective:
  • 20 mph 10% of the time --> 2500 KWH annually
  • 40 mph 10% of the time --> 20000 KWH annually
  • 20 mph 50% of the time --> 12500 KWH annually
  • 4 small windmills at 20 mph 10% of the time --> 10000 KWH annually

Wind Energy can be competitively priced:

• Wind turbine technology has steadily improved
• Typical capacity for a single unit is now 250-500 KW
• Relatively low capital costs; very low operating costs
  Price Comparison --> Levelized Costs: (includes start-up costs)
  • Wind: 4.8 cents per KWH
  • Coal: 6.2
  • Photovoltaics: 16.0
  • Advanced Gas Turbine: 4.6

Current Grid Connected Wind Power:

    Country/region          MW Installed
        ------------------------------------
        United States   -       1700
        Denmark         -       520
        Germany         -       330
        United Kingdom  -       145
        Netherlands     -       132
        Spain           -       55
        Greece          -       35
        Italy           -       10
        Other OECD      -       70
        India           -       50
        China           -       25

Some aggressive goals for wind power:

• to install 10,000 MW of capacity in the U.S.;
• to build a $4 billion domestic wind industry capable of delivering 3,000 MW annually;
• to create tens of thousands of new, long-term, skilled jobs;
• to achieve levelized costs below four cents per kilowatt-hour;
• to make wind power a major option in achieving the nations global climate change objectives; and
• to make the U.S. wind energy industry the worlds technology leader and lowest cost supplier.

Capacity in the US is Large

• Contour Map

• Where the Wind Blows
• Where the wind blows on the Internet
• California Wind Production Report

Costs:

• American Wind Energy Association claims levelized costs to be 4.8 cents per KWH
• Electrical Power Research Insitute claims the 1993 levelized cost was 7.3 cents per KWH
• In 1980, the levelized cost was about 25 cents per KWH
• Projected future costs are 3-3.5 cents per KWH
• Lower costs reflect economies of scale and improved turbine design

Domestic Production in California:

• 1992: Wind produced 1.1% of total electricity used
• 15,000 wind turbines located at Altamont Pass (East of San Francisco), Tehachapi (near Bakersfield) and San Gorgonio Pass (near Palm Springs)
• This is 54% of the world's production! (Denmark has 20%)
• Peak capacity is 1600 MW

Other States:

• Southwest Minnesota --> 25 MW capacity sold at 5 cents per KWH
• Planned 100 MW facility for Northern Minnesota for 1996 to be sold at a cost of 4.2 cents per KWH
• State law in Minnesota --> by 2002 wind energy capacity should reach 425 Mega Watts

Potential Wind Capacity at Some Locations in the US:

Note: Total electrical energy generated by fossil-fuel plants in 1990 was 2000 billion KWH

• Along the Aleutian Chain --> 402 Billion KWH
• Offshore New England --> 318 Billion
• Offshore South Carolina --> 283 Billion
• Great Plains effort (see below) --> 210 Billion
• Off Shore Texas Gulf Cost --> 190 Billion
• East-West Axis of Lake Superior --> 35 Billion
• North-South Axis of Lake Michigan --> 29 billion
• North-South Axis of Lake Huron --> 23 Billion
• East-West Axis of Lake Erie --> 23 Billion
• East-West Axis of Lake Ontario --> 23 Billion

• Total Capacity --> 1500 billion or 75% of fossil fuel capacity

Some Large Scale Projects:

Aleutian Project --> Stretch turbines out over the entire 1300 mile chain. Use electricity to create Hydrogen. Liquefy the Hydrogen and ship it to California.

Great Plains I: --> One turbine Tower per square mile stretched out from Texas to Canada.

• 300,000 total towers
• Each tower 850 feet high
• each tower has 20 generators and is powered by a two blade propellor of diameter 50 feet.
• Capacity of single tower is 500 KW capacity so total capacity is 150,000 Mega Watts (1/2 the US consumption

• Note, we already have 600,000 oil wells in the US and no one seems to mind

  Great Plains II: --> Clustered wind farms of 165 individual turbines seperated by 60 miles laid out in 300 mile swatch from Texas to Canada

Problems: (?)

• In some locations it will be difficult to connect to the existing grid --> therefore make hydrogen or store energy in batteries
• Installations may be unsightly (but so is air pollution)
• Could interfere with functions on agricultural land
• Susceptible to storm damage (tornado alley) so replacement costs have to be well-calculated
• They are a hazard to migrating birds
• Worse of all - they could potentially interfere with TV reception

Conclusions:

• Price of wind power is coming down.
• There is enormous capacity
• Wind power is a lot more promising that Solar PV production line facilities
• Energy storage, however, is still a problem
• Costs to the consumer will only be competetive if mass production of wind turbines is achieved

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