Rural Small Wind Energy:

Transcription

1 Rural Small Wind Energy: Resource Overview and System Components Phil Hofmeyer, Ph.D. Asst. Professor of Renewable Energy Morrisville State College MVCC Small Wind Energy Conference June 27, 2009

2 Hi, I want a windmill. You sure? Yeah, I can t wait to tell the utility company to go you know where. Hmm. Bet they ll be glad to hear that. How much wind do you have? Wind? Oh, we ve got lots of wind. It s always windy here. Gipe 2004, p /27/

3 The take home message of the day A wind generator without good wind is like a dam without water Neither works very well (if at all) There is wind everywhere, but not everywhere has enough How much is enough? How do you know your resource? 6/27/

4 Overview Wind power maps Turbulence Turbine components Electrical components and interconnection Estimating wind power and energy 6/27/

5 What is wind? Different surfaces lead to unequal heating at the Earth s surface 6/27/

6 Regional air currents Valley winds from late morning to evening 6/27/

7 Regional air currents Valley winds from evening to morning 6/27/

8 Air speed (velocity) 200% 120% 100% 50% 6/27/

9 Measuring wind anemometers What instrument do you use? At what height? 6/27/

10 Yearly winds 30 MSC weather station data 25 Miles per hou ur Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average Maximum Wind Mean wind 6/27/

11 Daily winds Wind power will often require storage Electricity demand Average e wind spe eed Midnight Morning Noon Evening 6/27/

12 Wind Power Maps NY Wind Explorer Wind power maps provide interpolated spatial wind data 6/27/

13 Turbulence Tower height is among the most important variables leading to an economically viable wind project. Taller towers: Reduce turbulence impacts Increase power output Cheaper energy 6/27/

14 Small wind turbine components Tail vane Brushes Nacelle Stator Nose Cone Mounting bracket or yaw assembly Shaft Blades Tower Conductors 6/27/

15 Towers Guyed Lattice Tower Free-standing Monopole 6/27/

16 Generic system components: Net metered Inverter Service panel 1437 DC disconnect AC disconnect Electricity meter 6/27/

17 Generic system components 6/27/

18 Power from wind OK we now have an understanding of the wind resource and of the machines that extract power from wind. Can we easily estimate how much power and energy we can produce? What does it really mean to have a 10 kw turbine? 6/27/

19 A little physics We try to extract wind power through a turbine to do work» Electricity generation»pump water»grind grains How does wind speed relate to wind power? P = 0.5*ρAVρ 3 6/27/

20 Reading into math P = 0.5*ρAV 3 P is power in watts ρ (rho) is air density (usually 1.2 kg/m 3 ) A is windswept area (m 2 ) V is wind velocity (m/s) 1. Which of these variables is most important? 2. Which of these variables can we easily control? 6/27/

21 Windswept area Wind turbines are measured by height, rotor diameter, and generator capacity Rotor diameter What is the windswept area of a 10 m rotor diameter? A = π*r 2 A = 3.14 * (5 m) 2 A = 78.5 m 2 *Bl Blade length this the radius 6/27/

22 Wind Power Example A 10 kw wind turbine has a 7 meter rotor diameter. What is the available power in a 6 m/s wind? P = 0.5*ρAV 3 P = 0.5 * 1.2 * (3.14 * ) * 6 3 P = 4985 watts (or ~5 kw) 6/27/

23 But, that s not the whole story We just calculated the power available in the wind, not what will be captured by the wind turbine. Most wind turbines operate at approximately 20 to 25% efficiency. This means that 10 kw system would likely only produce:» 4985 W * = 997 W (or ~1 kw) 6/27/

24 Manipulating rotor diameter What if we double rotor diameter from 7m to 14 m (hold wind speed at 6 m/s)? P = 0.5*ρAV 05*ρAV 3 P = 0.5 * 1.2 * (3.14 * 7 2 ) * 6 3 P = watts (or ~20 kw) P = * 0.2 = 3988 watts (~ 4 kw) Doubling rotor diameter resulted in a 4x increase in power! 6/27/

25 Changing sites What if we found a spot that doubled the wind speed (with the original 7m rotor)? P = 0.5*ρAV 05*ρAV 3 P = 0.5 * 1.2 * (3.14 * ) * 12 3 P = watts (or ~40 kw) P = * 0.2 = 7976 watts (~ 8 kw) Doubling wind speed resulted in an 8x increase in power! 6/27/

26 Wind speed power curves Peak power Furling speed Power out tput (watts s) Cut-in speed Rated speed Wind Speed 6/27/

27 Power to energy To convert power to energy, multiply power by hours If you know your average daily wind speed and your rotor diameter, you can estimate power output There are 24 hours per day and 365 days each year, so there are 8760 hours per year 6/27/

28 Power to energy example What is the yearly energy output of a 10 kw turbine that is producing an average of 1.3 kw? 1.3 kw * 8760 hours/year = 11,388 kwh/yr An average home uses bt between 700 and 1,000 kwh/month (or upwards of 12,000 kwh/yr) 6/27/

29 Small wind power summary Know your resource (wind is not for everyone) Wind speed, direction, daily highs and lows, yearly highs and lows Get into smooth air Reduce turbulence Tallest tower you can afford Ignore power ratings. All you need to know is the rotor diameter and the wind speed. 6/27/

30 Contact Information Phil Hofmeyer, Ph.D. Assistant Professor Ph: Web: