AIRBORNE WIND TURBINES Sean Metcalf Special Thanks: Sam Musa, Joshua Owens, and Greg Hutcheson

1. AIRBORNE WIND TURBINESSean MetcalfSpecial Thanks: Sam Musa, Joshua Owens, and Greg Hutcheson OBJECTIVE: Determine the feasibility of using Airborne Wind Turbines (AWT) as an alternative way of utilizing wind energy to reduce the use of non-renewable energy sources.

2. Figure 1: Description of how the AWT operates BACKGROUND INFO: • Makani Power, Joby Energy, KiteFarms and KiteGen have developed working prototypes and designs for high altitude AWTs • Desired to produce more and consistent energy more cost effective than conventional solar and wind power • Developed fixed-wing AWT, operational at altitudes of 250 to 600 meters. • Makani Power tested prototype capable of 30 kW production.

3. RESEARCH & ANALYSIS: • Research feasibility of utilizing AWT’s as an alternative source to harvest wind energy in the effort to reduce the use of non-renewable energy sources • Conduct thermodynamic analysis and compare maximum power output for 30 kW AWT and a 30 kW conventional wind turbine Figure 2: Makani M30 AWT technical specifications

4. Figure 3: Wind energy production comparison (wind power information and figure used from www.energy.gov ) COMPARISON: • AWT offshore wind farm applications • AWT’s perform better at low wind speeds than conventional wind turbines • Can produce about twice the power of a traditional wind turbine the same size • Wind power represents %32 of all new electric capacity additions in the U.S. for 2010 • Accounts for $14 billion in new investment • U.S. wind power capacity reached 50,000 MW, enough electricity to power 13 million homes annually

5. SAFETY & IMPACT: • Operates below altitude of commercial flights and above the height of migratory birds • 90% less material than a conventional turbine • Can operate in hurricane conditions with winds in excess of 50 m/s with gusts reaching 80 m/s • During extreme weather, it can land autonomously until conditions normalize Figure 4: Comparison of area and height between conventional turbines and the AWT

6. ANALYSIS: Thermodynamic derivation for rate of work or power output for a wind turbine using assumptions: Assumptions: • Reversible process • Control volume • Heat Transfer and Potential Energy are negligible • Steady-State • Constant wind velocity Note: Equations uses constant for Betz ‘ Law, which limits the theoretical max. power efficiency for any turbine design to be %59. Observations: It is observed that the energy available in the wind for a turbine is only in the form of kinetic energy.The total power that can be derived from wind using a wind turbine is:

7. CONCLUSION: • AWT system is feasible because it yields more energy more often because it taps into a more consistent and powerful wind at a higher altitude • Doesn’t harvest most of the energy available to it, but it harvests what would otherwise remain untouched • Promising solution for harvesting offshore and land renewable wind energywith low initial investment • Mechanical, electrical, and computer automation systems maintenance for AWT’s would create more jobs • Table 1: Using the above Power equation the following table shows the power yield for a 30 kW conventional turbine (model # FD 10-30/12 manufactured by Wind Resource Energy) and a 30kW AWT (model M30 Manufactured by Makani).

8. References: • http://www.makanipower.com/how-does-it-work/ • http://news.harvard.edu/gazette/story/2009/03/the-key-to-energy-independence-go-fly-a-kite/ • http://online.wsj.com/article/SB10000872396390444230504577617971067036752.html • http://www.jobyenergy.com/faq • http://web.mit.edu/windenergy/windweek/Presentations/Wind%20Energy%20101.pdf • http://energy.gov/articles/energy-report-us-wind-energy-production-and-manufacturing-surges-supporting-jobs-and