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Wind Energy

By: Laura Quinn

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A Little Background

• End of 2006: Worldwide capacity of wind-powered generators was 74,223 megawatts.

• Currently produces less than 1% of world-wide electricity

• Accounts for approximately 18% of electricity use in Denmark, 9% in Spain, and 7% in Germany.

• Globally, wind power generation more than quadrupled between 2000 and 2006.

• Estimated 1% to 3% of energy from the Sun that hits Earth is converted into wind energy. This is about 50 to 100x more energy than is converted into biomass by all the plants on Earth through photosynthesis.

Cost and Growth

• Requires more money upfront, but saves more long term.

• US 2003: $1600/kilowatt

• Fastest percentage growth in the US:-25% in 2002 to 38% in 2003

• Costs expected to decrease as demands increase & technology advances

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How it Works

• Modern wind power is generated in the form of electricity by converting rotation of turbine blades into electrical current through an electrical generator

• Wind power is used in large scale wind farms for national electrical grids as well as in small individual turbines for providing to rural areas or grid isolated locations.

Turbine Sites

• Site must be >10mph average wind speed

• Constant, even paced wind

• Cannot be located at temperatures less than -20 degrees C

Turbine Sites: Onshore

• Hilly/mountainous regions on ridges about 3km inland from the nearest shoreline (wind speeds up over the incline)

• Look for deformed trees due to wind power

• Aesthetically controversial

Turbine Sites: Near-Shore

• Located in land within 3 km of shoreline and on water within 10 km of land.

• Sea shores are a primary source of convection from the heating and cooling of the land and sea which gives ample wind supply.

• Air is more dense then on mountains, creating better environment for turbines

• Issues include aesthetics, migratory complications, aquatic habitat, etc.

Turbine Sites: Offshore

• Developed in zones about 10 km from land• Offshore turbines are less obtrusive and overall

wind production is best at open sea• Generally more expensive due to extra length for

submersion and maintenance from salt water• Transmission of energy is carried through

underwater cables• Denmark supplies 25-30% of energy from offshore

wind turbines.• Proving to become most popular location for turbine

sites.

Utilization: Large Scale

• Average output of 1 megawatt of wind power is equivalent to the average consumption of about 160 American households

• As of 2005, wind accounted for 1% of total energy production worldwide

-Germany is world leader with 32% production (6% of their electricity)

Total Installed Wind Power Capacity (End of Year Date)

Rank Nation 2005 (MW) 2006 (MW)1 Germany 18,415 20,6222 Spain 10,028 11,6153 United States 9,149 11,6034 India 4,430 6,2705 Denmark 3,136 3,1406 China 1,260 2,6047 Italy 1,718 2,1238 United Kingdom 1,332 1,963• Portugal 1,022 1,716• France 757 1,567

Utilization: Small Scale

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Roof mounted turbine: Charges a 12 volt battery

Size: about 2m in diameter (900 watts)

Plus: People are more conscious of energy usage therefore using less

China: about 300,000 small scale turbines

What are the Issues?

• Scalability

• Theoretical Potential

• Economics and Feasibility

Scalability

• At what scale does wind energy have to height in order to satisfy a substantial portion of world’s energy demand?

• It is still very small scale worldwide and would take much investment: Is it worth it?

• No countries produce more than 10% electricity from wind energy besides Denmark

• Devils Advocate: Wind is a very clean alternative that can be used in unison with other renewables do fuels our world.

Theoretical Potential

• Theoretically, if there were 6 turbines/sqKm with 77m diameters that produced 1.5 MW and covered 13% of total global land area, we could power the world 5x over.

• Realistically, only 4-10% of that area is usable

• To obtain this theoretical potential, many turbines must be installed worldwide

Economics and Feasibility

• Costs of pollution for electrical generation, reduced agricultural productivity etc…

• Uncertain financial returns

• Investing in a market that puts their success rates in the hands of mother nature?

Intermittency and Variability

• Electricity generated from wind can be accessed hour to hour, daily and seasonally

• However, wind energy is a substantial challenge to the grid system because to maintain grid stability, energy supply and demand must remain in balance

• Variability of output of wind energy is not entirely predictable

Energy Storage

• To increase amount of usable wind energy, surplus energy would be stored in a usable form such as pumped storage hydroelectricity.

• Fly-Wheel energy storage: Accelerating a rotor to a very high speed and maintaining the energy in the system as inertial energy.

Pollution? Gain?

• Almost invisible compared to other energy production

• Ex: 1% of UK’s national electricity supply in ‘04 had negligible effects on CO2 emissions

• Wild life migration, ridge line pollution, displacement of small scale fishing industries

• Over its lifetime, a wind turbine produces 20-30x as much energy needed for its manufacture, construction, operation and decommissioning.

• Payback rates: turbines payback energy invested within about 3 months.

• Cutting forests? Unlikely to be a problem because natural open spaces proves best for wind production

• Impact on bird migratory patterns? - Small in comparison to other human

activities (traffic, power lines, high rise buildings)- Proven to have negative impacts, but as

technology increases, these can be alleviated (ex. Protected areas around blades, Darrieus Wind Turbine, avoiding migratory routes of birds as turbine development sites)

• Aesthetics

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Ecological Print

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