AIRBORNE WIND TURBINES
Sean Metcalf
Special 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.
BACKGROUND INFO:
Figure 1: Description of how the AWT operates
• 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.
RESEARCH & ANALYSIS:
• Research feasibility of utilizing
AWT’s as an alternative source
to harvest wind energy in the
effort to reduce the use of nonrenewable 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
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
Figure 3: Wind energy production comparison
(wind power information and figure used from
www.energy.gov )
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
ANALYSIS:
Assumptions:
• Reversible process
• Control volume
• Heat Transfer and Potential
Energy are negligible
• Steady-State
• Constant wind velocity
Thermodynamic derivation for
rate of work or power output for a
wind turbine using assumptions:
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:
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 energy with 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).
Type
Horizontal Shaft Wind Turbine
Airborne Wind Turbine
Make/Model
WER FD 10-30/12 (30kW)
Makani M30 (30kW)
Sky Area
78.5m2 (5m radius)
1809m2 (8meter wing span)
wind Speed (m/s)
Available power
(W)
Actual output
(w)
% total
Energy
Available power Actual output
(W)
(w)
% total Energy
7
9695.4
5300
54.7%
223313.3
15000
0.07%
10
28266.5
1800
6.37%
651059.1
30000
4.6%
13
62101.5
34000
54.7%
1430376.8
30000
2.1%
16
115779.5
29000
25.0%
2666738
30000
1.1%
References:
• http://www.makanipower.com/how-does-it-work/
• http://news.harvard.edu/gazette/story/2009/03/the-key-to-energy-independence-gofly-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-andmanufacturing-surges-supporting-jobs-and