Solar Energy III Wind Power.

Should we increase electricity production via wind power? A. Yes B. No

Which best captures your opinion of wind farms? A. They are a blight on the landscape B. I don’t really notice them C. They are really cool looking D. I hate the lights at night E. I hate the sound

Approximately 2% of the solar power that reaches the earth’s surface is converted into wind. Approximately 2% of the solar power that reaches the earth’s surface is converted into wind. About 9.92 x J per year About 9.92 x J per year This is about 175 times the present world energy usage. This is about 175 times the present world energy usage.

History Large sailing ships could generate 10,000 hp. Large sailing ships could generate 10,000 hp. Used extensively in Europe in the 19 th century Used extensively in Europe in the 19 th century Used for pumping water in the US. Used for pumping water in the US. Most new development for generating electricity Most new development for generating electricity

Early wind generators focused on single large generators Early wind generators focused on single large generators Grandpa’s Knob (Vermont) could generate up to 1.2 MW of power in the 1940’s. Grandpa’s Knob (Vermont) could generate up to 1.2 MW of power in the 1940’s. 200 ft diameter blades 200 ft diameter blades

New interest in wind electricity after oil embargo in New interest in wind electricity after oil embargo in Early NASA wind generator (1975) could generate 100kW of power in 18mph wind. 125 ft long blade diameter. Early NASA wind generator (1975) could generate 100kW of power in 18mph wind. 125 ft long blade diameter.

Boeing Mod 5B wind turbine on Oahu could generate 3.2 MW of electricity. Boeing Mod 5B wind turbine on Oahu could generate 3.2 MW of electricity. 320 ft diameter on a 192 ft tall tower 320 ft diameter on a 192 ft tall tower

Many Different Styles Savonius Rotor Darius Rotor American multivane 2-Blade Wind Turbine 3-Blade Wind Turbine

Wind Turbine Styles Horizontal axis wind turbine (HAWT) Horizontal axis wind turbine (HAWT) Most modern wind generators are this typeMost modern wind generators are this type

Wind Turbine Styles Vertical axis wind turbine (VAWT) Vertical axis wind turbine (VAWT)

Choice of style depends on application Multi-blade has good starting torque. Good for applications like pumps. Multi-blade has good starting torque. Good for applications like pumps. 3-blade has high starting torque but is more efficient at high rotation rates. Used for generating electricity 3-blade has high starting torque but is more efficient at high rotation rates. Used for generating electricity

Wind Farms Rather than using single large generator, we usually use several smaller generators to make wind farms Rather than using single large generator, we usually use several smaller generators to make wind farms

Practicalities Because there are no objects to create fiction and turbulence, wind speed tends to increase with increasing height. Because there are no objects to create fiction and turbulence, wind speed tends to increase with increasing height. Optimal height is ~300 m. Optimal height is ~300 m. Most commercial wind mill towers are ~50m high. Get ~80% of wind potential at this height. Most commercial wind mill towers are ~50m high. Get ~80% of wind potential at this height.

Power from Wind Power extracted from windmills depends on Power extracted from windmills depends on Area of the windmillArea of the windmill Mass flowMass flow Wind velocity changeWind velocity change P extracted = [density×area×speed]×[difference in speed] P extracted = [density×area×speed]×[difference in speed]

Betz Limit Power extracted by wind turbines depends on difference between incoming and outgoing wind velocity. If all the energy were extracted, the wind would stop, and the turbine would stop, so there is a maximum power that can be extracted. Power extracted by wind turbines depends on difference between incoming and outgoing wind velocity. If all the energy were extracted, the wind would stop, and the turbine would stop, so there is a maximum power that can be extracted.

Betz Limit Maximum power extractable is Maximum power extractable is P(kW) = 2.8310 -4 D 2 v 3 P(kW) = 2.8310 -4 D 2 v 3 D is blade diameter (m) D is blade diameter (m) v is wind speed (m/s) v is wind speed (m/s)

What is the maximum power extractable from a 2 m radius turbine in a 20 mph wind? A kW B kW C. 0.8 kW D kW

Betz Limit Maximum power extractable is Maximum power extractable is P(kW) = 2.8310 -4 (4 m) 2 (8.9 m/s) 3 P(kW) = 2.8310 -4 (4 m) 2 (8.9 m/s) 3 P = 3.19 kW P = 3.19 kW

If the wind speed increases to 25 mph how much will the power increase? A times B. 1.6 times C. 2 times D. 5 times

Betz Limit P(25 mph)/P(20 mph) = (11.2 m/s) 3 /(8.9 m/s) 3 = (11.2/8.9) 3 P(25 mph)/P(20 mph) = (11.2 m/s) 3 /(8.9 m/s) 3 = (11.2/8.9) 3 P(25 mph) = 1.98P(20 mph) P(25 mph) = 1.98P(20 mph) About twice as much power About twice as much power

Maximum theoretical efficiency is 59% of the Betz limit. Maximum theoretical efficiency is 59% of the Betz limit. Modern windmills are around % of maximum theoretical efficiency Modern windmills are around % of maximum theoretical efficiency

Note v 3 indicates that a wind of 15 miles per hour generates 3 3 =27 times as much power as a wind of 5 miles per hour. Note v 3 indicates that a wind of 15 miles per hour generates 3 3 =27 times as much power as a wind of 5 miles per hour.

Real windmills get 75-80% of this

Average Wind Speed at 80 m

US Power Grid

Rated Output A wind generator has a rated power output a a particular wind speed, e.g. 10 kW at 20 mph. A wind generator has a rated power output a a particular wind speed, e.g. 10 kW at 20 mph. If wind speed drops so does power, e.g. if wind drops to 15mph, P=(15/20) 3 10kW = 4.2kW. If wind speed drops so does power, e.g. if wind drops to 15mph, P=(15/20) 3 10kW = 4.2kW. If wind speed increases too much, usually feather the blades so they don’t get damaged. If wind speed increases too much, usually feather the blades so they don’t get damaged.

Home Wind Power? HORNET - LOW WIND SPEED turbines with Split-Core PMA HORNET - LOW WIND SPEED turbines with Split-Core PMASplit-Core Hornet's are designed for class 3 to 7 or AVERAGE wind zones. Hornet's are designed for class 3 to 7 or AVERAGE wind zones. wind zoneswind zones Super low cost turbines! Super low cost turbines! 59" diameter blade 59" diameter blade MPH MPH 1200 Watts 65 MPH (under load) 1200 Watts 65 MPH (under load) ~$ ~$ Note at 11mph P=800/27=30W Note at 11mph P=800/27=30W

States with more than 2000 MW of Installed Wind Capacity Texas10085 Texas10085 Iowa3675 Iowa3675 California3177 California3177 Minnesota2192 Minnesota2192 Washington2104 Washington2104 Oregon2104 Oregon2104 Illinois2046 Illinois2046

States with more than 2000 MW of Installed Wind Capacity Texas12354 Texas12354 California5829 California5829 Iowa5177 Iowa5177 Illinois3568 Illinois3568 Oregon3153 Oregon3153 Oklahoma3134 Oklahoma3134 Minnesota2987 Minnesota2987 Kansas2967 Kansas2967 Washington2808 Washington2808 Colorado2332 Colorado2332

Which state has the most installed wind power capacity? A. California B. Iowa C. Texas D. Minnesota E. Kansas

European Union Installed Wind Capacity

Which nation in Europe has the most installed wind power capacity? A. United Kingdom B. Germany C. Poland D. France E. Holland

Installed Global Wind Capacity

Concerns About Wind Power Wind is intermittent; not consistently reliable ~15-20% is considered safe. Wind is intermittent; not consistently reliable ~15-20% is considered safe. Aesthetics. Aesthetics. Noise: New designs are very quiet Noise: New designs are very quiet Danger to birds and bats. Needs more study. Danger to birds and bats. Needs more study. Potential electromagnetic disturbance for TV/ Radio Potential electromagnetic disturbance for TV/ Radio

Potential Solutions Use large scale batteries to even out supply. Use large scale batteries to even out supply. Research on Vanadium Redox batteries. Research on Vanadium Redox batteries. Mid scale test facility is being constructed. Mid scale test facility is being constructed.

Pro-Wind Site Estimates Man-made structure/technology Associated bird deaths per year in US (Source) Feral and domestic catsHundreds of millions (AWEA) Power lines million (AWEA) Windows (residential and commercial 100 million-1billion (TreeHugger) Pesticides70 million (AWEA) Automobiles60-80 million (AWEA) Light communication towers40-50 million (AWEA) Wind turbines10-40 thousand (ABC)

Help for the birds Site their farms mostly on land that's already disturbed (i.e. farmland.) Site their farms mostly on land that's already disturbed (i.e. farmland.) Site wind farms out of migratory flight paths Site wind farms out of migratory flight paths Make the transmission lines that connect to wind farms more bird-friendly Make the transmission lines that connect to wind farms more bird-friendly Monitor the impact of wind farms on birds. Monitor the impact of wind farms on birds. Set aside land in affected areas for bird habitat. Set aside land in affected areas for bird habitat. Paint wind turbines anything but white Paint wind turbines anything but white

Advantages Renewable Renewable No CO 2 emissions No CO 2 emissions Competitive price per kW-h Competitive price per kW-h Less than 1% of the land would be used for foundations and access roads, the other 99% could still be used for farming. Less than 1% of the land would be used for foundations and access roads, the other 99% could still be used for farming.

Power in the wind (Betz Limit) P(kW) = 2.8310 -4 D 2 v 3 D is the diameter in meters V is the wind speed in meters per second D 2 because area of windmill increase with D 2 V 3 because KE in wind is proportional to v 2 and an additional v because of rate at which energy is brought to windmill