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Basics of Farm/Residential Small Wind Turbines. Tony Jimenez Cooperative Extension Wind Webcast 13 February 2009. Wind Turbine Applications Wind Characteristics & Energy Potential Estimating Turbine Energy Production Wind Turbine Topologies Wind Turbine Technology & System Architecture
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Basics of Farm/Residential Small Wind Turbines Tony Jimenez Cooperative Extension Wind Webcast 13 February 2009
Wind Turbine Applications • Wind Characteristics & Energy Potential • Estimating Turbine Energy Production • Wind Turbine Topologies • Wind Turbine Technology & System Architecture • A Sampling of Currently Available Turbines • Small Wind Turbine Policy • Small Wind Turbine Sizing & Installation • Wrap Up Presentation Overview
Sizes and Applications • Small (10 kW) • Homes • Farms • Remote Applications • (e.g. water pumping, telecom sites, icemaking) • Intermediate • (10-1000 kW) • Village Power • Hybrid Systems • Distributed Power • Large (1 MW - 3+MW) • Central Station Wind Farms • Distributed Power • Community Wind
Off-Grid Home with Wind/PV System • West of Boulder, CO, at 9,000 ft • Bergey 1500 wind turbine, 1.5 kW, 70 ft tower • Solarex PV panels, 480 W • 24 VDC battery, 375 Ah • Onan generator, propane-fueled, 3 kW (at altitude) • Trace inverter, 120 VAC, 1 phase • Propane used for range, refrigeration, space heat, hot water (w/solar pre-heat) • First wind turbine installed in 1978, fourth wind turbine now in service • PV installed 1984 w/ tax credits • System cost about $20,000
On-Grid Home with Wind System • Tehachapi, CA, net metering for utility bill reduction • Bergey Excel wind turbine,23 ft rotor, 10 kW • Total installed cost was $34,122 in October 1999 (Prices have increased since then) • California Buy-Down Program, $16,871 cash rebate • Estimated payback: 8 years
On-Grid Farm with Wind System • Southwestern Kansas • Utility bill reduction • Bergey Windpower Excel wind turbine10 kW, 23 ft rotor, 100 ft tower • ~21,000 kWh/year generation, utility bill savings ~$2,800/year • Installed in early 1980s, ~$20,000, received federal tax credit • Maintenance costs $50/year • One lightning strike, damage was covered by farm insurance
Bergey Excel 10-kW turbine Reduces energy costs for residents of a subsidized elderly housing complex Entirely funded by a federal Residential Energy Assistance Challenge (REACH) grant Wind turbine and tower cost $40,190 Installation cost $24,346 3-year maintenance package included Town debated: Is the wind turbine a tower (not subject to zoning) or a structure (regulated by zoning)? Verdict: turbine is NOT a structure Case Study - Maine Senior Housing Complex
Case Study: Public School • Quinter High School, Quinter, KS • Entegrity EW15, 50kW, 100 ft tower • $145,000 installed cost, 2007 • $9,100 annual utility bill reduction, plus… • $2,800 income from electricity sales • 12 year simple payback
Wind Direction Wind rose from a site in Montana
WIND SHEAR Height Wind Speed, m/s m 12.6 50 12.2 40 11.7 30 11 20 10 10 8.8 5 0 SURFACE Courtesy: Alternative Energy Institute
Using Wind Shear • Typically measurements from low levels are extrapolated upwards • [v2 = v1 * (h2/h1)] • = Wind Shear Exponent • “Theoretical” shear exponent: 0.14 • Range from 0.1 to 0.3 is common
ENERGY AND POWER ENERGY, ABILITY TO DO WORK ENERGY = FORCE * DISTANCE Electrical Energy , kWh POWER = ENERGY/TIME (Rate at which energy is being created or used) Generator Size, kW
P - power, watts - density of air, kg/m3 A - area, m2 (A = D2 / 4) v - wind speed, m/s Power in the Wind P = 0.5 A v3 Courtesy: Alternative Energy Institute
Power Density Power Density = P/A = 0.5 v3 Wind Class W/m2 at 50 m Wind speed at 50 m 1 0 - 199 0 - 5.9 m/s 2 200 - 299 5.9 - 6.7 m/s 3 300 - 399 6.7 - 7.4 m/s 4 400 - 499 7.4 - 7.9 m/s 5 500 - 599 7.9 - 8.4 m/s 6 600 - 800 8.4 - 9.3 m/s 7 > 800 > 9.3 m/s
Calculation of Wind Turbine Power • Power from a wind turbine = Cp ½ A V3 • Effect of wind speed, V • Effect of rotor diameter on swept areaA = Pi D2 / 4 • Effect of elevation and temperature on air density, • Limits on power coefficient (efficiency): Cp= 0.2 - 0.45 (theoretical max = 0.59)
Calculating Turbine Output • Get wind resource data (wind speed distribution or a least an annual average) • Scale data to wind turbine hub height [v2 = v1 * (h2/h1)] • = 0.14 (0.1 - 0.3) (wind shear) • Multiply the wind speed distribution by the wind turbine power curve • Adjust for elevation • Derate by 8%-15% to account for losses (availability, yaw, blade soiling, electrical, etc.)
Wind Turbine Performance • Small & Medium Wind Turbines • 5% - 25% Capacity Factor • 10 kW WTG @ 12% Cap Factor ==> 10,500 kWh/year • (10 kW x 8760 hours/year x 0.12) • Large Wind Turbines • 25% - 45% • 1.5 MW WTG @ 35% Cap Factor ==> 4,600,000 kWh/year
Wind Turbine Topologies • Drag vs Lift machines • Horizontal Axis vs Vertical Axis • Upwind vs Downwind • Two vs Three blades
Drag Machines Courtesy: Alternative Energy Institute
Lift Machines Courtesy: Alternative Energy Institute
TYPES HAWT VAWT Courtesy: Alternative Energy Institute
Downwind & Upwind Courtesy: Alternative Energy Institute
Two Blades vs Three Blades • Advantages of two blades • Cheaper, lighter • Advantages of three blades • Rotor is always balanced => less cyclic loading => less wear & tear
Small Wind Turbines Are Different • Utility-Scale Wind Power1,000 - 3,000 kW+ wind turbines • Installed on wind farms, 10 – 300 MW • Professional maintenance crews • 13 mph (6 m/s) average windspeed • Small Wind Power300 W - 100 kW wind turbines • Installed at individual homes, farms, businesses, schools, etc. • On the “customer side” of the meter, or off the utility grid entirely • High reliability, low maintenance • 9 mph (4 m/s) average wind speed 1,500 kW 10 kW
Small Wind Turbines • Configuration:2 or 3 blades aimed into the wind by the tail • Blades:Fiber-reinforced plastics • Over-Speed Protection:Furling (rotor turns out of the wind) • Generator:Direct-drive, permanent magnet alternator (no brushes), variable-speed operation • Controller: Electronic device that delivers - DC power for charging batteries- AC power for utility interconnection • Result:– Simple, rugged design– Only 2–4 moving parts– Little regular maintenance required Bergey EXCEL, 10 kW
Small Wind Turbine Towers Guyed Tower Self-Supporting Tower Tilt-Up Tower
Over-Speed Protection During High Winds • Angle Governor:The rotor turns up and to one side
The Wind Turbine Controller • Battery-Charging • Converts “wild” AC power to DC for charging batteries • Regulates the battery voltage to prevent overcharging • When the battery is fully charged: • Power is diverted to another load, or • The rotor is unloaded and allowed to “freewheel” • Grid Interconnection • “Inverter” converts the power to constant frequency 60 Hz AC • UL label may be required
On-Grid Wind System without Storage Meter AC Inverter Windturbine Load 02770329
Maintenance, Warranty, and Lifetime • “Low Maintenance” not “No Maintenance” • Inspection and maintenance every 6-12 months • Inspect mechanical and electrical connections, check for corrosion, check guy wire tension, inspect/replace leading-edge tape, etc. • Beyond 10 years: blade or bearing replacement may be needed • Warranties • 2-5 years, coverage of materials and workmanship • Lifetimes of 15 to 30 years with regular maintenance “A wind turbine will see as many operating hours in one year as an automobile will see in 200,000 miles!”
A Sampling of Currently Available Small Wind Turbines(Mention does not imply endorsement)
Southwest WindpowerFlagstaff, Arizona www.windenergy.com Skystream 1.8 kW (www.skystreamenergy.com) AIR-X 300 W Whisper 100900 W Whisper 2001000 W Whisper 400 3 kW
Bergey Windpower www.bergey.comNorman, OK 1 kW BWC Excel10 kW
Abundant Renewable EnergyNewberg, Oregon www.abundantre.com ARE1102.5 kW, 12 ft Dia. Battery-ChargingGrid-Connect ARE44210 kW, 24 ft Dia. Battery-ChargingGrid-Connect
Wind Turbine Industries, Inc. Prior Lake, MN Jacobs 31/2020 kW
Entegrity Windwww.entegritywind.com EW15 60 kW
Northern PowerBarre, Vermont www.northernpower.com/ NorthWind 100/21100 kW, 69 ft dia.Grid-Connect
Other Names(as of June 2007, not comprehensive) • Start-Up Companies • Aerovironment, Earth Turbines (debut June 2008), Endurance (debut June 2007), Energie PGE, Mariah Power, PacWind, Selsam, Ventera (debut June 2007) • Imports • Aircon, Bornay, Eoltec (Pine Ridge Products, Montana), Fortis (Fortis America), Iskar (DC Power Systems, California), Kestrel (DC Power Systems, California), Proven (3 dealers in North America), Swift, Wind Energy Solutions, various Chinese turbines • Micro Turbines (< 1 kW) • Aeromag/Aeromax, Hornet, Amp Air, EverFair, etc.
Policy Options for Small Wind • Investment Incentives (rebates, buy-downs, grants, etc.) • Investment Tax Credits • Accelerated Depreciation (for small businesses) • Net Metering • Sales or Property Tax Reductions/Exemptions • Anemometer Loan Programs • Emerging: • Production incentives • Green tag aggregation and sales Strategies for Supporting Wind Energy, A Review and Analysis of Policy Options, www.nationalwind.org/pubs/strategies/default.htm These policies all affect wind turbine economic performance !
Residential Small Wind Incentives www.dsireusa.org $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ Property Tax Exemptions $ Personal State Tax Credits $ Puerto Rico $ RPS Feed-in Tariff Residential Small Wind Incentives www.dsireusa.org $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ Property Tax Exemptions $ Personal State Tax Credits $ Puerto Rico $ RPS Feed-in Tariff PRODUCTIVITY INCENTIVES MINOR INCENTIVES BUYDOWNS/GRANTS Federal investment tax credits are available for turbines 100 kW and less. Productivity Incentives & Loans Buydown/Grants Productivity Incentives Loans Buydown/Grants & Net Metering Net Metering & Loans Net Metering, Loans & Prod. Incentives Net Metering & Prod. Incentives Buydown/Grants, Net Metering, & Loans Net Metering Oct 16, 2008
Net Metering for Wind29 states have net metering for all rural consumers 100 100 250 100 100 50 40 60 25/2,000 20 25/100 25/125 1,000/1,650 30 25 2,000 500 50/3,000 No Limit 10 1,000 2,000 2,000/25 40 2,000/25/10 25 25/500/2,000 10/500 100 30 1,000 2,000 20/100 DC 100 100 25/300 100/10 80,000 10/100 Size limits for each statenoted in kW 50 25/100 2,000 50/100 Revised: 2Apr08 Source: www.dsireusa.org Treatment of Net Excess Generation: Monthly Annual or monthly @ retail rate Varies by utility None Individual Utilities Investor-Owned Utilities Only, Not Rural Cooperatives Investor-Owned Utilities and Rural Cooperatives